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Sample records for experimental implant fixation

  1. Effects of gold coating on experimental implant fixation

    DEFF Research Database (Denmark)

    Zainali, Kasra; Danscher, Gorm; Jakobsen, Thomas

    2009-01-01

    -kinase activation. The present study investigated whether gilding implant Surfaces augmented early implant osseointegration and implant fixation by its modulatory effect on the local inflammatory response. Ion release was traced by autometallographic silver enhancement. Gold-coated cylindrical porous coated Ti6Al4V...... implants Were inserted press-fit in the proximal part of tibiae in nine canines and control implants without gold inserted contralateral. Observation time was 4 weeks. Biomechanical push-out tests showed that implant,,, with gold coating had decrease in mechanical strength and stiffness....... Histomorphometrical analyses showed gold-coated implants had a decrease in overall total bone-to-implant contact of 35%. Autometallographic analysis revealed few cells loaded with gold close to the gilded implant surface. The findings demonstrate that gilding of implants negatively, affects mechanical strength...

  2. Effects of gold coating on experimental implant fixation

    Science.gov (United States)

    Zainali, Kasra; Danscher, Gorm; Jakobsen, Thomas; Jakobsen, Stig S.; Baas, Jørgen; Møller, Per; Bechtold, Joan E.; Soballe, Kjeld

    2013-01-01

    Insertions of orthopedic implants are traumatic procedures that trigger an inflammatory response. Macrophages have been shown to liberate gold ions from metallic gold. Gold ions are known to act in an antiinflammatory manner by inhibiting cellular NF-κB–DNA binding and suppressing I-κ B-kinase activation. The present study investigated whether gilding implant surfaces augmented early implant osseointegration and implant fixation by its modulatory effect on the local inflammatory response. Ion release was traced by autometallographic silver enhancement. Gold-coated cylindrical porous coated Ti6Al4V implants were inserted press-fit in the proximal part of tibiae in nine canines and control implants without gold inserted contralateral. Observation time was 4 weeks. Biomechanical push-out tests showed that implants with gold coating had ~50% decrease in mechanical strength and stiffness. Histomorphometrical analyses showed gold-coated implants had a decrease in overall total bone-to-implant contact of 35%. Autometallographic analysis revealed few cells loaded with gold close to the gilded implant surface. The findings demonstrate that gilding of implants negatively affects mechanical strength and osseointegration because of a significant effect of the released gold ions on the local inflammatory process around the implant. The possibility that a partial metallic gold coating could prolong the period of satisfactory mechanical strength, however, cannot be excluded. PMID:18335533

  3. No effect of hydroxyapatite particles in phagocytosable sizes on implant fixation: an experimental study in dogs

    DEFF Research Database (Denmark)

    Rahbek, O; Kold, S; Bendix, K

    2005-01-01

    on the mechanical fixation and gap healing around experimental HA implants. Nonloaded implants (n = 30) were inserted bilaterally into the proximal tibia of 15 dogs with a 2-mm gap to the bone. The peri-implant gap was either (1) empty (n = 6) or filled with (2) hyaluronic acid (n = 8), (3) hyaluronic acid and HA...... particles (n = 8), or (4) hyaluronic acid and PE particles (n = 8). After 4 weeks, the animals were killed. The implant interface was evaluated by pushout testing until failure and by histomorphometry. Both HA and PE particles were found to be phagocytosed by macrophage-like cells in the interfacial tissue...

  4. Experimental assessment of a new direct fixation implant for artificial limbs.

    NARCIS (Netherlands)

    Tomaszewski, P.K.; Lasnier, B.; Hannink, G.J.; Verkerke, G.J.; Verdonschot, N.J.J.

    2013-01-01

    An alternative to prosthetic socket rehabilitation of patients with transfemoral amputation is realized by means of direct skeletal fixation devices. offering significant improvements in mobility and comfort. However, strain shielding due to high stiffness of these metal-based implants causes

  5. Experimental assessment of a new direct fixation implant for artificial limbs

    NARCIS (Netherlands)

    Tomaszewski, P. K.; Lasnier, B.; Hannink, G.; Verkerke, G. J.; Verdonschot, N.

    An alternative to prosthetic socket rehabilitation of patients with transfemoral amputation is realized by means of direct skeletal fixation devices, offering significant improvements in mobility and comfort. However, strain shielding due to high stiffness of these metal-based implants causes

  6. Periosteal augmentation of allograft bone and its effect on implant fixation - an experimental study on 12 dogs()

    DEFF Research Database (Denmark)

    Barckman, Jeppe; Baas, Jorgen; Sørensen, Mette

    2013-01-01

    Periosteum provides essential cellular and biological components necessary for fracture healing and bone repair. We hypothesized that augmenting allograft bone by adding fragmented autologous periosteum would improve fixation of grafted implants....

  7. The effects of hydroxyapatite coating and bone allograft on fixation of loaded experimental primary and revision implants

    DEFF Research Database (Denmark)

    Søballe, Kjeld; Mouzin, Olivier R G; Kidder, Louis A

    2003-01-01

    in each of the 8 treatment groups (total 64 implants in 32 dogs). The observation period was 4 weeks after revision. Outcome measures are based on histomorphometry and mechanical pushout properties. The revision setting was always inferior to its primary counterpart. Bone graft improved the revision......, to obtain the same level of fixation associated with primary implants. Our findings suggest that the combination of HA implant and bone graft may be of benefit in the clinical revision implant setting....

  8. VATS-guided epicardial pacemaker implantation. Hand-sutured fixation of atrioventricular leads in an experimental setting.

    Science.gov (United States)

    Furrer, M; Fuhrer, J; Altermatt, H J; Ris, H; Mettler, D; Althaus, U; Carrel, T

    1997-12-01

    In neonates and infants epicardial stimulation may be preferred to endocardial stimulation because of growth-associated lead problems and the risk of vascular complications associated with transvenous electrodes. This study analyzes the feasibility of atrioventricular implantation of a new epicardial lead using the video-assisted thoracic surgical (VATS) technique in an animal model. Bipolar steroid-eluting epicardial leads were implanted in seven young white pigs. In five animals bipolar atrial and ventricular pacing leads (n = 10) were inserted and fixed by the VATS technique, while two animals served as controls and underwent implantation through anterolateral thoracotomy. Surgical feasibility, pacing, and sensing thresholds of the leads as well as hemodynamic parameters during pacing were studied. Histological changes beneath the electrodes were evaluated 1 week after the implantation. All animals survived the pacemaker lead implantation. One animal which underwent thoracotomy died because of irreversible ventricular fibrillation induced by rapid ventricular pacing. One animal in the VATS group exhibited intraoperative herniation of the heart through the pericardial window. All animals with left-sided VATS implantations demonstrated good individual pacing and sensing threshold values. The mean cardiac output was 1.6 times higher during AAI-mode pacing as compared to VVI-mode pacing at a heart rate of 140/min. One animal died postoperatively due to respiratory failure. No displacements of the pacemaker leads were observed in the survivors. While VATS-guided implantation of epicardial, atrial, and ventricular leads is feasible, technical improvements of the system are mandatory for safe clinical application.

  9. Stress Modulation of Fracture Fixation Implants.

    Science.gov (United States)

    Beltran, Michael J; Collinge, Cory A; Gardner, Michael J

    2016-10-01

    Stress modulation is the concept of manipulating bridge plate variables to provide a flexible fixation construct that allows callus formation through uneventful secondary bone healing. Obtaining absolute stability through the anatomic reduction of all fracture fragments comes at the expense of fracture biology, whereas intramedullary nailing, which is more advantageous for diaphyseal fractures of the lower extremity, is technically demanding and often may not be possible when stabilizing many metaphyseal fractures. Overly stiff plating constructs are associated with asymmetric callus formation, early implant failure, and fracture nonunion. Numerous surgeon-controlled variables can be manipulated to increase flexibility without sacrificing strength, including using longer plates with well-spaced screws, choosing titanium or stainless steel implants, and using locking or nonlocking screws. Axially dynamic emerging concepts, such as far cortical locking and near cortical overdrilling, provide further treatment options when bridge plating techniques are used.

  10. Aetiology and Patterns of Implant Failure Following Fracture Fixation ...

    African Journals Online (AJOL)

    Background: Implant failure is traumatic for patient as it increases the cost of treatment and may negatively affect the confidence of patients in the superior outcome of operatively treated fractures. Hence the objectives for this study were to determine the proportion of implant fixations that fail, types and causes of implant ...

  11. Bone compaction enhances fixation of weightbearing titanium implants

    DEFF Research Database (Denmark)

    Kold, Søren Vedding; Rahbek, Ole; Vestermark, Marianne Toft

    2005-01-01

    are weightbearing, the effects of compaction on weightbearing implants were examined. The hypothesis was that compaction would increase implant fixation compared with conventional drilling. Porous-coated titanium implants were inserted bilaterally into the weightbearing portion of the femoral condyles of dogs...

  12. The effect on implant fixation of soaking tricalcium phosphate granules in bisphosphonate

    DEFF Research Database (Denmark)

    Jakobsen, Thomas; Baas, Jørgen; Bechtold, Joan E

    2012-01-01

    biomechanical implant fixation and osseointegration of experimental implant grafted with β-TCP granules (Conduit) could be improved by soaking the β-TCP granules in bisphosphonate (zoledronate). In 10 dogs, a pair of titanium coated implants surrounded by a 2.5 mm gap was inserted into the proximal part of each...... tibia. The gap was grafted with β-TCP granules either soaked with zoledronate or saline. At 12 weeks, the implants were evaluated with biomechanical push-out test and histomorphometrical analysis. We found that bisphosphonate increased one of the three biomechanical parameters, but found no difference...... in the amount of new bone or β-TCP granules between the two treatment groups. This study indicates that local treatment of β-TCP granules with zoledronate not only has the potential to increase implant fixation but also calls for further experimental research in order to optimize the dose of zoledronate....

  13. Parametric analysis of glenoid implant design and fixation type.

    Science.gov (United States)

    Geraldes, Diogo M; Hansen, Ulrich; Amis, Andrew A

    2017-04-01

    Common post-operative problems in shoulder arthroplasty such as glenoid loosening and joint instability may be reduced by improvements in glenoid design, shape, material choice, and fixation method. A framework for parametric analysis of different implant fixation configurations was developed in order to efficiently sift through potential glenoid component designs. We investigated the influence of design factors such as fixation type, component thickness, and peg position, number, diameter, and length in a multi-factorial design investigation. The proposed method allowed for simultaneous comparison of the mechanical performance of 344 different parametric variations of 10 different reference geometries with either large central fixation features or small peripheral pegs, undergoing four different worst-case scenario loading conditions, and averaging 64.7 s per model. The impact of design parameters were assessed for different factors responsible for post-operative problems in shoulder arthroplasty, such as bone volume preservation, stresses in the implant, central displacement or fixation stability, and the worst performing geometries all relied on conventional central fixation. Of the remaining geometries, four peripheral fixation configurations produced von Mises stresses comfortably below the material's yield strength. We show that the developed method allows for simple, direct, rapid, and repeatable comparison of different design features, material choices, or fixation methods by analyzing how they influence the bone-implant mechanical environment. The proposed method can provide valuable insight in implant design optimization by screening through multiple potential design modifications at an early design evaluation stage and highlighting the best performing combinations according to the failure mechanism to mitigate. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:775-784, 2017. © 2016 Orthopaedic Research Society

  14. Design of dental implants, influence on the osteogenesis and fixation.

    Science.gov (United States)

    Vasconcellos, Luana M R; Oliveira, Marize V; Graça, Mário L A; Vasconcellos, Luis G O; Cairo, Carlos A A; Carvalho, Yasmin R

    2008-08-01

    The fixation and the bone ingrowth at the interface of porous cylindrical implants (total porosity of 37% and average pores diameter of 480 microm) were compared in vivo to rough cylindrical implants (R (a) = 5.3 microm), both of commercially pure titanium, made by powder metallurgy. The implants were inserted into the tibias of 20 rabbits and the animals were sacrificed 4 and 8 weeks after surgery. The percentage of bone-implant contact observed in porous implant was significantly larger than in the rough ones for all of sacrifice periods, respectively, 57% vs. 46% after 4 weeks, and 59% vs. 50% after 8 weeks. The mechanical tests showed a significant increase in the shear strength of the porous implants for the two analyzed periods, 4 and 8 weeks (14 and 20 MPa), when compared with rough ones (4 and 13 MPa). These results suggest that porous implants improve the contact at the implant-bone interface and increase the fixation to the bone, improving the osseointegration. Thus, the porous implant might be an alternative to dental implant in less favorable conditions, and appear to be better fixed to bone, offering promising alternatives.

  15. Prospects of implant with locking plate in fixation of subtrochanteric fracture: experimental demonstration of its potential benefits on synthetic femur model with supportive hierarchical nonlinear hyperelastic finite element analysis

    Directory of Open Access Journals (Sweden)

    Latifi Mohammed

    2012-04-01

    Full Text Available Abstract Background Effective fixation of fracture requires careful selection of a suitable implant to provide stability and durability. Implant with a feature of locking plate (LP has been used widely for treating distal fractures in femur because of its favourable clinical outcome, but its potential in fixing proximal fractures in the subtrochancteric region has yet to be explored. Therefore, this comparative study was undertaken to demonstrate the merits of the LP implant in treating the subtrochancteric fracture by comparing its performance limits against those obtained with the more traditional implants; angle blade plate (ABP and dynamic condylar screw plate (DCSP. Materials and Methods Nine standard composite femurs were acquired, divided into three groups and fixed with LP (n = 3, ABP (n = 3 and DCSP (n = 3. The fracture was modeled by a 20 mm gap created at the subtrochanteric region to experimentally study the biomechanical response of each implant under both static and dynamic axial loading paradigms. To confirm the experimental findings and to understand the critical interactions at the boundaries, the synthetic femur/implant systems were numerically analyzed by constructing hierarchical finite element models with nonlinear hyperelastic properties. The predictions from the analyses were then compared against the experimental measurements to demonstrate the validity of each numeric model, and to characterize the internal load distribution in the femur and load bearing properties of each implant. Results The average measurements indicated that the constructs with ABP, DCPS and LP respectively had overall stiffness values of 70.9, 110.2 and 131.4 N/mm, and exhibited reversible deformations of 12.4, 4.9 and 4.1 mm when the applied dynamic load was 400 N and plastic deformations of 11.3, 2.4 and 1.4 mm when the load was 1000 N. The corresponding peak cyclic loads to failure were 1100, 1167 and 1600 N. The errors

  16. Fixation methods for implantable port chamber: comparative study using glue, self-stabilizing leg and suture fixations in rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Na, Hyoung Il; Shim, Hyung Jin; Kwak, Byung Kook; Kim, Hyeon Joo; Lee, Yong Cheol [Chung-Ang University College of Medicine, Seoul (Korea, Republic of)

    2004-12-15

    To evaluate the fixation strength and tissue reaction of the glue fixation and self-stabilizing leg fixation methods and to compare the results with those of the conventional tagging suture fixation method. Twelve healthy rabbits were selected and three different methods of implanting the port chamber were employed on the back of each rabbit. A total of thirty six port chambers were implanted with these three different methods, viz, the glue fixation method using tissue adhesive, the self-stabilizing leg method using a self-expandable stabilizing leg, and the suture fixation method. The fixation strength and the gross and histopathologic changes of each fixation method were evaluated at three days, one week, two weeks and four weeks after port implantation. The glue fixation method showed a good fixation strength, which was similar to that of the tagging suture method ({rho} = 0.3486). Five of the six ports (83%) implanted with the glue fixation method which were examined after two weeks showed cracks on the external surface, but this had no adverse effects on their function. A large amount of granulation tissue reaction was found at the bottom of the chamber ({rho} = 0.0025). The fixation with the self-stabilizing leg showed relatively lower fixation strength ({rho} = 0.0043), but no turning-over of the chamber occurred. The fixation strength improved with time after the first week, and minimal granulation tissue reaction was observed with this method. The glue fixation method exhibited equal fixation strength compared to the suture fixation, but showed cracking and a large amount of granulation tissue, whereas the fixation with a self-stabilizing leg showed weaker fixation strength.

  17. Bone compaction enhances implant fixation in a canine gap model

    DEFF Research Database (Denmark)

    Kold, Søren; Rahbek, Ole; Toft, Marianne

    2005-01-01

    A new bone preparation technique, compaction, has increased fixation of implants inserted with exact-fit or press-fit to bone. Furthermore, a demonstrated spring-back effect of compacted bone might be of potential value in reducing the initial gaps that often exist between clinical inserted impla...

  18. Combining bisphosphonates with allograft bone for implant fixation

    NARCIS (Netherlands)

    Mathijssen, N.M.C.; Buma, P.; Hannink, G.J.

    2014-01-01

    The aim of this review was to discuss the current state of research of combining bisphosphonates with allograft bone for implant fixation. The allograft bone can only be reached by the bisphosphonate once it has been revascularized. However, this can be circumvented by local administration of

  19. Assessment of modified gold surfaced titanium implants on skeletal fixation

    DEFF Research Database (Denmark)

    Zainali, Kasra; Danscher, Gorm; Jakobsen, Thomas

    2013-01-01

    shown to liberate gold ions through the process termed dissolucytosis. Furthermore, gold ions are known to act in an anti-inflammatory manner by inhibiting cellular NF-κB-DNA binding. The present study investigated whether partial coating of titanium implants could augment early osseointegration...... osseointegration compared to control titanium implants in a similar model. Since sufficient early mechanical fixation is achieved with this new coating, it is reasonable to investigate the implant further in long-term studies. © 2012 Wiley Periodicals, Inc....

  20. Bone graft materials in fixation of orthopaedic implants in sheep

    DEFF Research Database (Denmark)

    Babiker, Hassan

    2013-01-01

    biomaterials were placed in a well defined peri-implant gap. After the observation period, the bone-implant specimens were harvested and evaluated mechanically by a destructive push-out test and analyzed histologically qualitatively and quantitatively. Study II investigates the effect of DBM alone...... and the histological analysis by using the profound part of the implant. The implants in this study were inserted in the proximal humerus and only allograft was used in the peri-implant gap. In study I, the mechanical testing showed failure by the preloading in the composite group with and without BMA. There were...... with CB or allograft showed no significant differences on the mechanical testing and histological analysis to the control group, whereas DBM alone showed significant low mechanical fixation, low bone ongrowth and low bone formation. Study III showed no significant difference between the sampling methods...

  1. Systemic alendronate treatment improves fixation of press-fit implants: a canine study using nonloaded implants

    DEFF Research Database (Denmark)

    Jensen, Thomas B; Bechtold, Joan E; Chen, Xinqian

    2007-01-01

    % and significantly increased ultimate shear strength from 1.26 to 3.72 MPa. Also, the fraction of periprosthetic bone significantly increased from 10% to 18%. For implants surrounded by a gap, alendronate neither stimulated nor impaired implant fixation, bone ingrowth, or new bone formation in the gaps. Because......) was inserted into each proximal tibia of 16 dogs. On one side the implant was inserted press-fit whereas on the contralateral side, the implants were surrounded by a 2 mm concentric gap. Oral alendronate (0.5 mg/kg/day) was given 2 weeks following surgery to eight dogs. The dogs were euthanized after 10 weeks...

  2. Design-Optimization and Material Selection for a Proximal Radius Fracture-Fixation Implant

    Science.gov (United States)

    Grujicic, M.; Xie, X.; Arakere, G.; Grujicic, A.; Wagner, D. W.; Vallejo, A.

    2010-11-01

    The problem of optimal size, shape, and placement of a proximal radius-fracture fixation-plate is addressed computationally using a combined finite-element/design-optimization procedure. To expand the set of physiological loading conditions experienced by the implant during normal everyday activities of the patient, beyond those typically covered by the pre-clinical implant-evaluation testing procedures, the case of a wheel-chair push exertion is considered. Toward that end, a musculoskeletal multi-body inverse-dynamics analysis is carried out of a human propelling a wheelchair. The results obtained are used as input to a finite-element structural analysis for evaluation of the maximum stress and fatigue life of the parametrically defined implant design. While optimizing the design of the radius-fracture fixation-plate, realistic functional requirements pertaining to the attainment of the required level of the devise safety factor and longevity/lifecycle were considered. It is argued that the type of analyses employed in the present work should be: (a) used to complement the standard experimental pre-clinical implant-evaluation tests (the tests which normally include a limited number of daily-living physiological loading conditions and which rely on single pass/fail outcomes/decisions with respect to a set of lower-bound implant-performance criteria) and (b) integrated early in the implant design and material/manufacturing-route selection process.

  3. EXPERIMENTAL APPROVAL OF COMBINED FIXATION FOR FEMUR LENGTHENING

    Directory of Open Access Journals (Sweden)

    M. A. Stepanov

    2017-01-01

    Full Text Available Elimination of congenital shortening of lower limb still remains a complex and unsolved orthopaedic task which requires an improved fixation technique as well as adjusted tactics of treatment and rehabilitation procedures.Purpose of the study — experimental approval of femur lengthening technique by external fixation with Ilizarov apparatus and internal fixation by plate.Materials and methods. Femur lengthening was performed in 6 mongrel dogs. Average animal age was 1,5±0,3 years, average weight — 20±5 kg, femur length — 22±2 sm. External apparatus with two supports and a titanium plate of an original design were applied under general anesthesia on the right femur of animals. Lengthening was performed manually at a rate of1 mm per day in 4 stages at a distance of 10% from initial segment length. External apparatus was removed on the last day of distraction after locking the plate. X-ray examination was done on the day of surgery, in 7, 14 and 25 days from the onset of distraction as well as in 14, 30, 60 and 90 days after completion of distraction and removal of external apparatus. Three animals were taken out of experiment in 30 days of fixation, remaining three animals — in 90 days. After euthanasia the authors performed autopsy of the organic femur complex and tissues contacting the plate.Results. The use of operated limb was not restricted during the whole distraction period. The authors observed first roentgenological signs of distraction osteogenesis on 7th day of lengthening. By the end of distraction period, at 25th day, shadows of regenerates demonstrated longitudinal striated structures in all cases. Median lucency area of 1–5 mm was located diagonally and across the regenerate or was intermittent. In 60 days of fixation X-rays demonstrated homogeneous regenerate. External fixation index was 13,9±1,5 days/sm (p≤0,05. The authors observed no cases of implants fracture or deformity during the experiment

  4. Scleral fixation of one piece intraocular lens by injector implantation

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    Ertugrul Can

    2014-01-01

    Full Text Available Aim of Study: With an ab-interno technique of transscleral suturing of current one-piece posterior chamber intraocular lenses (PC IOLs by injector implantation in the absence of capsular support, we aimed to demonstrate the possibility of the implantation of one-piece acrylic PC IOLs that might be produced in the future for only scleral fixation through small clear corneal incision. Materials and Methods: Case report and literature review. Results: This procedure has been performed in eight aphakic eyes with four different types of IOLs. Good centration was achieved with minimal technical effort. All patients had well-centered and stable lenses postoperatively during 9-18 months follow-up. Conclusion: We managed to decrease the risks of surgical trauma and intricate surgical maneuvers requirement. With this technique, excessive fluid leakage and consecutive hypotony can be minimized.

  5. Soaking morselized allograft in bisphosphonate can impair implant fixation

    DEFF Research Database (Denmark)

    Jakobsen, Thomas; Baas, Jørgen; Bechtold, Joan E

    2007-01-01

    The use of impacted, morselized allograft is a well-established way to provide initial stability of revision joint replacements. We investigated whether rinsing morselized allograft in bisphosphonate and subsequently impacting it around experimental titanium-coated implants would further facilita...

  6. Revision of Minimally Invasive Sacroiliac Joint Fixation: Technical Considerations and Case Studies Using Decortication and Threaded Implant Fixation.

    Science.gov (United States)

    MenMuir, Brett; Fielding, Louis C

    2017-01-01

    Sacroiliac joint (SIJ) disease is increasingly recognized as a common source of low back pain. Arthrodesis of the SIJ has been shown to be clinically effective for this condition. In the last decade, minimally invasive (MI) SIJ fusion procedures have been developed to achieve the clinical effectiveness of open fusion procedures, with lower operative morbidity and faster recovery. However, SIJ fusion patients occasionally present with symptomatic nonunions necessitating revision. Four patients who previously underwent MI SIJ arthrodesis returned with complaints of SIJ related pain confirmed by examination. Radiographic assessment showed lucency after fixation with triangular titanium interference implants. Loose implants were removed, and the patients were revised with a different MI SIJ fusion system that utilizes decortication, placement of autograft and graft extender, and fixation with cannulated threaded implants. The trajectory of the revision implants was in a more ventral-to-dorsal and caudal-to-cranial trajectory to place the implants perpendicularly through the articular portion of the SIJ. The triangular implants typically exhibited haloing lucency on radiographs and CT scans, and most were easily removed using the manufacturer's instrumentation; only one implant was left in place as it was well-fixed. The removed implants exhibited little or no bony ongrowth. Decortication of the SIJ was performed, followed by placement of local autograft and fixation with 12.5 mm or 14.5mm diameter implants, as required. A more ventral-todorsal and caudal-to-cranial trajectory was established for the revision implants through the center of the articular region of the joint in order to maximize implant purchase in residual bone stock and achieve bony fusion through the articular portion of the SIJ. By six to twelve months post-revision, the presenting symptoms were successfully resolved in all patients. Patients demonstrating symptomatic pseudoarthrosis after SIJ

  7. Implant removal after internal fixation of a femoral neck fracture: Effects on physical functioning

    NARCIS (Netherlands)

    S.M. Zielinski (Stephanie); M.J. Heetveld (Martin); M. Bhandari (Mohit); P. Patka (Peter); E.M.M. van Lieshout (Esther)

    2015-01-01

    textabstractObjectives: The effect of implant removal after internal fixation of a femoral neck fracture on physical functioning was analyzed. Characteristics of patients who had their implant removed were studied, as it is currently unknown from which type of patients implants are removed and what

  8. Extraction of chronically implanted coronary sinus leads active fixation vs passive fixation leads.

    Science.gov (United States)

    Crossley, George H; Sorrentino, Robert A; Exner, Derek V; Merliss, Andrew D; Tobias, Serge M; Martin, David O; Augostini, Ralph; Piccini, Jonathan P; Schaerf, Raymond; Li, Shelby; Miller, Clayton T; Adler, Stuart W

    2016-06-01

    The Medtronic model 4195 (StarFix) left ventricular lead is an active fixation lead that provides additional support within the coronary sinus (CS) via deployable lobes. While this lead has been shown to have excellent stability within the CS, concerns about its extractability have been raised. The aim of this study was to compare the safety and efficacy of the extraction of the model 4195 lead vs other Medtronic CS leads in a prospective cohort study. Patients undergoing extraction of this and other CS leads for standard indications were prospectively enrolled and studied. The primary outcomes of interest were the removal success rates and associated complication rates. Patients were followed for a month postprocedure. The overall left ventricular lead extraction success rate was 97.6% (n = 205). Among 40 patients with chronic model 4195 leads, there were 37 successful extractions (92.5%) as compared to 98.8% for the 165 non-4195 leads. However, in 2 of the 3 StarFix lead extraction failures, standard extraction techniques were not used. All 10 of the model 4195 leads that had been implanted for less than 6 months were extracted without incident. In this largest study of CS lead extractions published to date, the overall success rate of the extraction of chronically implanted CS leads is high and the complication rate is similar in these lead models. The extraction of the model 4195 lead is clearly more challenging, but it can be accomplished in high-volume extraction centers with experienced operators. It is recommended that the model 4195 lead be extracted by experienced operators. Copyright © 2016. Published by Elsevier Inc.

  9. Vertical fixation with fibrin glue-assisted secondary posterior chamber intraocular lens implantation in a case of surgical aphakia

    Directory of Open Access Journals (Sweden)

    Jeevan S Ladi

    2013-01-01

    Full Text Available We report the first case of vertical fixation by fibrin glue-assisted secondary posterior chamber intraocular lens implantation in a case of surgical aphakia. Advantages of vertical fixation are discussed.

  10. Tissue reaction to implant corrosion in 38 internal fixation devices.

    Science.gov (United States)

    Thomas, K A; Cook, S D; Harding, A F; Haddad, R J

    1988-03-01

    The corrosion characteristics, metallurgical properties, and clinical performance of 38 retrieved internal fixation devices were correlated with the tissue reaction to these devices. Metallurgical parameters included thin and heavy inclusion content, Rockwell hardness, and grain size. The excised fibrous tissue strip was directly overlying each plate at removal and sectioned between screw-hole sites. The material studied from the 38 plates consisted of 201 screw-hole junctions with associated tissue biopsy sites. Clinical histories were obtained on all 38 patients with hardware removal. The average age at the time of plate insertion was 35.6 years (range, 4 to 75 years). Insertion diagnoses included acute trauma (35 patients), joint dislocations (two patients), and fracture nonunion (one patient). The devices included seven upper extremity bone plates, 19 lower extremity bone plates, and 12 hip screw plates. The devices remained in situ an average of 20.4 months (range, 3 to 60 months). Routine asymptomatic removals were performed on 17 of the patients, while the remaining 21 patients were symptomatic at the time of removal. Included in the reasons for symptomatic removal were pain associated with the implant (eight patients), nonunion (four patients), bursae prominence (three patients), and implant breakage (two patients). Significant correlations were found between average tissue reaction scores and average crevice corrosion scores; a trend of increasing average tissue reaction scores with increasing average screw surface corrosion scores also was observed for the 38 devices, although this relationship was not significant. Average crevice corrosion scores and average screw surface corrosion scores were highly correlated for all removals, and for the asymptomatic and symptomatic removal groups. The metallurgical parameters of thin inclusion content and heavy inclusion content also were significantly correlated for all removals, as well as for symptomatic removals

  11. Bone compaction enhances fixation of weight-bearing hydroxyapatite-coated implants

    DEFF Research Database (Denmark)

    Kold, Søren; Rahbek, Ole; Vestermark, Marianne

    2006-01-01

    The effect of bone compaction vs conventional drilling on the fixation of hydroxyapatite-coated implants was examined in a weight-bearing canine model. In each dog, one knee joint had the implant cavity prepared with drilling, the other with compaction. Eight dogs were euthanized after 2 weeks...

  12. Implantes de resina de poliuretana vegetal (Ricinus communis na tração linear, fixação e fusão vertebral no cão: estudo experimental Implants of Ricinus communis polyurethane resin in distraction, fixation and vertebral fusion in dogs: experimental study

    Directory of Open Access Journals (Sweden)

    M.G. Laranjeira

    2004-10-01

    Full Text Available Placa e espaçador de polímero derivado do óleo de mamona (PDOM (Ricinus communis foram avaliados clínica, radiográfica e histologicamente na tração linear, fixação e fusão vertebral cervical em 20 cães adultos, sem raça definida, pesando entre 17 e 22kg. Foram sacrificados quatro animais aos 10, 30, 60, 90 e 120 dias de pós-operatório. Após exposição da coluna cervical, por acesso ventral, o disco intervertebral de C4-C5 foi fenestrado e a abordagem ao canal medular foi feita por meio de fenda óssea. Um espaçador de PDOM foi colocado preenchendo o defeito ósseo. Os corpos vertebrais C4-C5 foram fixados com placa do mesmo material, utilizando-se dois parafusos corticais em cada corpo vertebral. Apenas um animal apresentou déficit neurológico no pós-operatório imediato. Radiograficamente as vértebras mostravam-se normais e alinhadas, sem colapso do espaço intervertebral, porém não houve neoformação óssea entre as vértebras. Ao exame mielográfico, não houve compressão da medula espinhal. Os implantes foram efetivos em manter a tração linear e fixação das vértebras cervicais e não ocorreu a fusão vertebral.Clinical, radiographic and histological evaluation of plate and biomechanical spacer of Ricinus communis polyurethane resin were performed in distraction, fixation and vertebral cervical fusion in 20 adult dogs, weighting between 17 and 22kg. Four animals were euthanized at 10, 30, 60, 90 and 120 days after surgery. After ventral exposition of cervical spine, cervical disk fenestration was performed on intervertebral spaces C4-C5 and a slot was created. A biomechanical spacer of Ricinus communis polyurethane resin was placed to fill bone defect. C4-C5 spinous processes were fixed with plate of the same material, utilizing two cortical screws in each spinal process. Only one animal had neurological signs immediately after surgery. Radiographic examination indicated that vertebrae were normal and aligned

  13. An Overview of Internal Fixation Implant Metallurgy and Galvanic Corrosion Effects.

    Science.gov (United States)

    Koh, Justin; Berger, Aaron; Benhaim, Prosper

    2015-08-01

    Orthopedic and hand surgery implants for internal fixation of fractures have evolved substantially over the past 50 years. Newer metal compositions have been used, and new standards have been applied to older alloys, resulting in modern implants with unique physical properties and better clinical performances. Conventional wisdom has long dictated that implanting different metals should be avoided, but few guidelines exist regarding the safety of using in proximity implant systems of dissimilar metals. To better characterize the landscape of internal fixation implant metallurgy, we have compiled the recommendations and conclusions of the currently available and pertinent literature. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  14. A paradigm for the development and evaluation of novel implant topologies for bone fixation: in vivo evaluation.

    Science.gov (United States)

    Long, Jason P; Hollister, Scott J; Goldstein, Steven A

    2012-10-11

    While contemporary prosthetic devices restore some function to individuals who have lost a limb, there are efforts to develop bio-integrated prostheses to improve functionality. A critical step in advancing this technology will be to securely attach the device to remnant bone. To investigate mechanisms for establishing robust implant fixation in bone while undergoing loading, we previously used a topology optimization scheme to develop optimized orthopedic implants and then fabricated selected designs from titanium (Ti)-alloy with selective laser sintering (SLS) technology. In the present study, we examined how implant architecture and mechanical stimulation influence osseointegration within an in vivo environment. To do this, we evaluated three implant designs (two optimized and one non-optimized) using a unique in vivo model that applied cyclic, tension/compression loads to the implants. Eighteen (six per implant design) adult male canines had implants surgically placed in their proximal, tibial metaphyses. Experimental duration was 12 weeks; daily loading (peak load of ±22 N for 1000 cycles) was applied to one of each animal's bilateral implants for the latter six weeks. Following harvest, osseointegration was assessed by non-destructive mechanical testing, micro-computed tomography (microCT) and back-scatter scanning electron microscopy (SEM). Data revealed that implant loading enhanced osseointegration by significantly increasing construct stiffness, peri-implant trabecular morphology, and percentages of interface connectivity and bone ingrowth. While this experiment did not demonstrate a clear advantage associated with the optimized implant designs, osseointegration was found to be significantly influenced by aspects of implant architecture. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Influence of the compliance of a patient's body on the head taper fixation strength of modular hip implants.

    Science.gov (United States)

    Krull, Annika; Bishop, Nicholas E; Steffen, Niels M; Lampe, Frank; Püschel, Klaus; Morlock, Michael M

    2017-07-01

    The strength of the modular fixation between head and stem taper of total hip replacement implants should be sufficient to minimise relative motion and prevent corrosion at the interface. Intraoperatively the components are assembled by impaction with a hammer. It is unclear whether the effective compliance of the patient's body modifies the strength of the taper interface under impaction assembly. The purpose of this study was to assess the influence of the compliance of the patient's body on the taper fixation strength. Cobalt-chrome and ceramic femoral heads were assembled with titanium alloy stem tapers in the laboratory under impaction. Impaction forces were applied with a constant energy, defined by the drop height of the impactor, according to standard experimental procedure. The compliance of the patient was simulated in the laboratory by varying the stiffness of springs mounted below the stem taper. Pull-off forces between head and neck were measured to determine fixation strength. Decreasing spring stiffness had no effect on the applied peak impaction forces during assembly or on the pull-off forces. Pull-off forces showed no difference between metal and ceramic head materials. Pull-off forces and impaction forces were independent of the spring stiffness below the stem taper, indicating that the compliance of the patient has no effect on the taper fixation strength. Impaction testing in the laboratory can therefore be performed under rigid fixation, without accounting for the compliance of the patient. Copyright © 2017. Published by Elsevier Ltd.

  16. In vivo implant fixation of carbon fiber-reinforced PEEK hip prostheses in an ovine model.

    Science.gov (United States)

    Nakahara, Ichiro; Takao, Masaki; Bandoh, Shunichi; Bertollo, Nicky; Walsh, William R; Sugano, Nobuhiko

    2013-03-01

    Carbon fiber-reinforced polyetheretherketone (CFR/PEEK) is theoretically suitable as a material for use in hip prostheses, offering excellent biocompatibility, mechanical properties, and the absence of metal ions. To evaluate in vivo fixation methods of CFR/PEEK hip prostheses in bone, we examined radiographic and histological results for cementless or cemented CFR/PEEK hip prostheses in an ovine model with implantation up to 52 weeks. CFR/PEEK cups and stems with rough-textured surfaces plus hydroxyapatite (HA) coatings for cementless fixation and CFR/PEEK cups and stems without HA coating for cement fixation were manufactured based on ovine computed tomography (CT) data. Unilateral total hip arthroplasty was performed using cementless or cemented CFR/PEEK hip prostheses. Five cementless cups and stems and six cemented cups and stems were evaluated. On the femoral side, all cementless stems demonstrated bony ongrowth fixation and all cemented stems demonstrated stable fixation without any gaps at both the bone-cement and cement-stem interfaces. All cementless cases and four of the six cemented cases showed minimal stress shielding. On the acetabular side, two of the five cementless cups demonstrated bony ongrowth fixation. Our results suggest that both cementless and cemented CFR/PEEK stems work well for fixation. Cup fixation may be difficult for both cementless and cemented types in this ovine model, but bone ongrowth fixation on the cup was first seen in two cementless cases. Cementless fixation can be achieved using HA-coated CFR/PEEK implants, even under load-bearing conditions. Copyright © 2012 Orthopaedic Research Society.

  17. Efficacy of a small cell-binding peptide coated hydroxyapatite substitute on bone formation and implant fixation in sheep

    DEFF Research Database (Denmark)

    Ding, Ming; Andreasen, Christina Møller; Dencker, Mads L.

    2015-01-01

    formation in concentric gap, and its enhancements on bone formation and implant fixation were at least as good as allograft. It is suggested that ABM/P-15 might be a good alternative biomaterial for bone implant fixation in this well-validated critical-size defect gap model in sheep. Nevertheless, future...

  18. Mechanical study of implant for lumbossacral spinal fixation

    OpenAIRE

    Afrane Serdeira; Tarcísio Eloy Pessoa de Barros Fº; Eduardo Barros Puertas; José Laredo Filho; Tomaz Puga Leivas

    2000-01-01

    Foram estudados, do ponto de vista mecânico, a rigidez e os pontos críticos de um implante para fixação interna da coluna lombossacra. Aplicou-se o implante sobre um modelo de madeira simulando o segmento lombossacro da coluna. Realizamos sete ensaios de flexo-compressão, sete de rigidez axial, sete de rigidez radial e um ensaio destrutivo. Os resultados demonstraram que o implante foi eficiente e seguro para uso em seres humanos.This work consists of a mechanical analysis of the resistance a...

  19. Right ventricular perforation by a passive-fixation pacemaker lead two weeks after implantation

    Directory of Open Access Journals (Sweden)

    Azeem S. Sheikh, BSc, MBBS, FCPS, MRCP

    2014-12-01

    Full Text Available Myocardial perforation is a rare complication of permanent pacemaker implantation. While most of the perforations occur at the time of implantation or within the first 24 h, delayed myocardial perforations are very rare. The clinical course is extremely variable with some patients presenting completely asymptomatic, while others can develop cardiac tamponade and haemodynamic instability. We report an unusual case of a subacute ventricular perforation caused by a passive-fixation lead two weeks after implantation and we successfully managed to extract the lead under local anaesthesia, without the patient undergoing surgery, as recommended in the previously published reports.

  20. Riboflavin-UV--a crosslinking for fixation of biosynthetic corneal collagen implants.

    Science.gov (United States)

    Wand, Kerstin; Neuhann, Raphael; Ullmann, Andrea; Plank, Katharina; Baumann, Michael; Ritter, Roland; Griffith, May; Lohmann, Chris P; Kobuch, Karin

    2015-05-01

    To evaluate riboflavin-UV-A crosslinking as an alternative suture-free fixation method for biosynthetic corneal collagen implants. A range of cell-free corneal implants consisting of recombinant human collagen type III were examined. In vitro, the implants were crosslinked with different riboflavin solutions and irradiations. Ex vivo, the biosynthetic corneal implants were placed on the anterior cornea of porcine and rabbit eyes after performing deep anterior lamellar keratoplasty with a trephine, femtosecond laser, or excimer laser. UV-A crosslinking was performed with isotonic or hypotonic riboflavin at either standard or rapid procedure. The corneas were excised, fixed in PFA 4%, and embedded in paraffin. Crosslinking effects on the implants and the adhesion between implant and corneal bed were evaluated by slit-lamp biomicroscopy, optical coherence tomography (OCT) images, and histologically. After the crosslinking procedure, the implants showed different degrees of thinning. The accuracy of cutting the corneal bed was highest with the excimer laser. Good adhesion of the implant in the corneal bed could be demonstrated in OCT images. This was more accurate in porcine eyes than in rabbit eyes. Histologically, crosslinks between implant and corneal stroma were demonstrated. There was no difference between standard and rapid crosslinking procedures. Riboflavin-UV-A crosslinking as a fixation method for biosynthetic corneal collagen implants was demonstrated to be promising. It can reduce suture-related complications such as haze formation and surface irregularity. Stability of the implants, especially shrinkage after riboflavin-UV-A crosslinking, needs to be further evaluated. Biostability, integration, and long-term outcome are further evaluated in in vivo animal experiments.

  1. Stress analysis of implant-bone fixation at different fracture angle

    Science.gov (United States)

    Izzawati, B.; Daud, R.; Afendi, M.; Majid, MS Abdul; Zain, N. A. M.; Bajuri, Y.

    2017-10-01

    Internal fixation is a mechanism purposed to maintain and protect the reduction of a fracture. Understanding of the fixation stability is necessary to determine parameters influence the mechanical stability and the risk of implant failure. A static structural analysis on a bone fracture fixation was developed to simulate and analyse the biomechanics of a diaphysis shaft fracture with a compression plate and conventional screws. This study aims to determine a critical area of the implant to be fractured based on different implant material and angle of fracture (i.e. 0°, 30° and 45°). Several factors were shown to influence stability to implant after surgical. The stainless steel, (S. S) and Titanium, (Ti) screws experienced the highest stress at 30° fracture angle. The fracture angle had a most significant effect on the conventional screw as compared to the compression plate. The stress was significantly higher in S.S material as compared to Ti material, with concentrated on the 4th screw for all range of fracture angle. It was also noted that the screws closest to the intense concentration stress areas on the compression plate experienced increasing amounts of stress. The highest was observed at the screw thread-head junction.

  2. Bio-Environment-Induced Degradation and Failure of Internal Fixation Implants

    Directory of Open Access Journals (Sweden)

    Yan Zhou

    2015-10-01

    Full Text Available Internal fixations provide fast healing but their failure remains problematic to patients. Here, we report an experimental study in failure of three typical cases of metals: a bent intramedullary stainless steel nail, a broken exterior pure Ti plate, and a broken intramedullary stainless steel nail. Characterization of the bent nail indicates that those metals are vulnerable to corrosion with the evidence of increased surface roughness and embrittlement. Depredated surface of the Ti plate resulted debris particles in the surrounding tissue of 15.2 ± 6.5 μm in size. Nanoparticles were observed in transmission electron microscope. The electron diffraction pattern of the debris indicates a combination of nanocrystalline and amorphous phases. The failure mode of the broken nail made of stainless steel was found to be fatigue initiated from the surface. This study clearly shows the biological-attack induced surface degradation resulting in debris and fatigue. Future design and selection of implant materials should consider such factors for improvement.

  3. New method of fixation of in-bone implanted prosthesis

    Science.gov (United States)

    Pitkin, Mark; Cassidy, Charles; Muppavarapu, Raghuveer; Raymond, James; Shevtsov, Maxim; Galibin, Oleg; Rousselle, Serge D.

    2013-01-01

    This article presents results on the effectiveness of a new version of the titanium porous composite skin and bone integrated pylon (SBIP). The SBIP is designed for direct skeletal attachment of limb prostheses and was evaluated in a pre-clinical study with three rabbits. In accordance with the study protocol, a new version of the pylon (SBIP-3) was implanted into the hind leg residuum of three rabbits. The SBIP-3 has side fins that are designed to improve the bond between the bone and pylon. The fins are positioned inside two slots precut in the bone walls; their length can be adjusted to match the thickness of the bone walls. After 13 (animal 1) or 26 wk (animals 2 and 3), the animals were sacrificed and samples collected for histopathological analysis. The space between the fins and the bone into which they were fit was filled with fibro-vascular tissue and woven bone. No substantial inflammation was found. We suggest that if further studies substantiate the present results, the proposed method can become an alternative to the established technique of implanting prostheses into the medullar canal of the hosting bone. PMID:24013918

  4. 2000 Volvo Award winner in biomechanical studies: Monitoring in vivo implant loads with a telemeterized internal spinal fixation device.

    Science.gov (United States)

    Rohlmann, A; Graichen, F; Weber, U; Bergmann, G

    2000-12-01

    Implant loads were measured in 10 patients using telemeterized internal spinal fixation devices. To determine the postoperative temporal course of implant loads. Little information exists regarding the temporal course of loads on internal spinal fixation devices. The telemeterized internal spinal fixator allows the measurement of three force components and three moments acting in the fixator. Implant loads were determined in up to 20 measuring sessions for different activities, including walking, standing, sitting, lying in the supine position, and lifting an extended leg while in the supine position. Implant loads often increased shortly after anterior interbody fusion was performed. Several patients retained the same high level even after fusion had taken place. This explains the reason why screw breakage sometimes occurs more than half a year after implantation. The time of fusion could not be pinpointed from the loading curves. The results show that fixators may be highly loaded even after fusion has occurred. A flexion bending moment acts on the implant even with the body in a relaxed lying position. This means that already shortly after the anterior procedure, the shape of the spine is not neutral and unloaded, but slightly deformed, which loads the fixators. Pedicle screw breakage more than half a year after insertion does not prove that anterior interbody fusion has not occurred.

  5. Non-metallic implant for patellar fracture fixation: A systematic review.

    Science.gov (United States)

    Camarda, Lawrence; Morello, Salvatore; Balistreri, Francesco; D'Arienzo, Antonio; D'Arienzo, Michele

    2016-08-01

    Despite good clinical outcome proposals, there has been relatively little published regarding the use of non-metallic implant for patellar fracture fixation. The purpose of the study was to perform a systematic literature review to summarize and evaluate the clinical studies that described techniques for treating patella fractures using non-metallic implants. A comprehensive literature search was systematically performed to evaluate all studies included in the literature until November 2015. The following search terms were used: patellar fracture, patella suture, patella absorbable, patella screw, patella cerclage. Two investigators independently reviewed all abstracts and the selection of these abstracts was then performed based on inclusion and/or exclusion criteria. A total of 9 studies involving 123 patients were included. Patients had a mean age of 33.7 years and were followed up for a mean of 18.9 months. The most common method for fracture fixations included the use of suture material. Good clinical outcomes were reported among all studies. Thirteen patients (10.5%) presented complications, while 4 patients (3.2%) required additional surgery for implant removal. There is a paucity of literature focused on the use of non-metallic implant for patellar fracture fixation. However, this systematic review showed that non-metallic implants are able to deliver good clinical outcomes reducing the rate of surgical complications and re-operation. These results may assist surgeons in choosing to use alternative material such as sutures to incorporate into their routine practice or to consider it, in order to reduce the rate of re-operation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Preclinical trial of a novel surface architecture for improved primary fixation of cementless orthopaedic implants.

    Science.gov (United States)

    Harrison, Noel; Field, John R; Quondamatteo, Fabio; Curtin, William; McHugh, Peter E; Mc Donnell, Pat

    2014-09-01

    A new surface architecture for cementless orthopaedic implants (OsteoAnchor), which incorporates a multitude of tiny anchor features for enhancing primary fixation, was tested in an ovine hemi-arthroplasty pilot study. Test animals were implanted with a hip stem component incorporating the OsteoAnchor surface architecture produced using additive layer manufacturing and control animals were implanted with stems containing a standard plasma sprayed titanium coating. Intra-operative surgeon feedback indicated that superior primary fixation was achieved for the OsteoAnchor stems and rapid return to normal gait and load bearing was observed post-operation. Following a 16-week recovery time, histological evaluation of the excised femurs revealed in-growth of healthy bone into the porous structure of the OsteoAnchor stems. Bone in-growth was not achieved for the plasma sprayed stems. These results indicate the potential for the OsteoAnchor surface architecture to enhance both the initial stability and long term lifetime of cementless orthopaedic implants. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Nitrogen fixation on early Mars and other terrestrial planets: experimental demonstration of abiotic fixation reactions to nitrite and nitrate.

    Science.gov (United States)

    Summers, David P; Khare, Bishun

    2007-04-01

    Understanding the abiotic fixation of nitrogen is critical to understanding planetary evolution and the potential origin of life on terrestrial planets. Nitrogen, an essential biochemical element, is certainly necessary for life as we know it to arise. The loss of atmospheric nitrogen can result in an incapacity to sustain liquid water and impact planetary habitability and hydrological processes that shape the surface. However, our current understanding of how such fixation may occur is almost entirely theoretical. This work experimentally examines the chemistry, in both gas and aqueous phases, that would occur from the formation of NO and CO by the shock heating of a model carbon dioxide/nitrogen atmosphere such as is currently thought to exist on early terrestrial planets. The results show that two pathways exist for the abiotic fixation of nitrogen from the atmosphere into the crust: one via HNO and another via NO(2). Fixation via HNO, which requires liquid water, could represent fixation on a planet with liquid water (and hence would also be a source of nitrogen for the origin of life). The pathway via NO(2) does not require liquid water and shows that fixation could occur even when liquid water has been lost from a planet's surface (for example, continuing to remove nitrogen through NO(2) reaction with ice, adsorbed water, etc.).

  8. Tumor endoprosthesis revision rates increase with peri-operative chemotherapy but are reduced with the use of cemented implant fixation.

    Science.gov (United States)

    Pugh, Luke R; Clarkson, Paul W; Phillips, Amy E; Biau, David J; Masri, Bassam A

    2014-07-01

    Chemotherapy may reduce osseointegration of tumor endoprosthesis, while delaying chemotherapy may reduce survival. We studied the effects of chemotherapy and cemented fixation on tumor endoprosthesis survivorship with a retrospective analysis of 50 consecutive patients receiving lower limb salvage surgery. We compared rates of radiographic loosening/revision and effect of cement fixation between chemotherapy/no chemotherapy cohorts. Chemotherapy increased the total revision rate (HR = 3.8 [1-14], P = 0.033), but did not affect aseptic loosening. Cement fixation reduced revision for loosening (HR = 0.09 (0.008-0.98), P = 0.012) and showed less radiographic loosening (HR = 0.09 (0.02-0.51), P = 0.00066). Cement fixation had lower rates of revision for loosening and radiographic loosening regardless of whether chemotherapy was given. We conclude that for these implants, cement fixation provides superior results to uncemented fixation. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Results of cataract surgery after implantation of an iris-fixated phakic intraocular lens.

    Science.gov (United States)

    de Vries, Niels E; Tahzib, Nayyirih G; Budo, Camille J; Webers, Carroll A B; de Boer, Ruben; Hendrikse, Fred; Nuijts, Rudy M M A

    2009-01-01

    To report the results of cataract surgery after previous implantation of an Artisan iris-fixated phakic intraocular lens (pIOL) for the correction of myopia. University center and private practice. This study comprised eyes with previous implantation of an iris-fixated pIOL to correct myopia and subsequent pIOL explantation combined with cataract surgery and in-the-bag implantation of a posterior chamber IOL. Predictability of refractive results, changes in endothelial cell density (ECD), and postoperative best corrected visual acuity (BCVA) were analyzed. The mean follow-up after cataract surgery in the 36 eyes of 27 consecutive patients was 5.7 months +/- 7.5 (SD). The mean time between pIOL implantation and cataract surgery was 5.0 +/- 3.4 years. After explantation of the pIOL and subsequent cataract surgery, the mean spherical equivalent (SE) was -0.28 +/- 1.11 diopters (D); the SE was within +/-1.00 D of the intended correction in 72.2% of patients and within +/-2.00 D in 86.1% of patients. The mean endothelial cell loss after the combined procedure was 3.5% +/- 13.2% and the mean postoperative BCVA, 0.17 +/- 0.18 logMAR. In patients with a history of implantation of an iris-claw pIOL for the correction of myopia, cataract surgery combined with explantation of the pIOL yielded acceptable predictability of the postoperative SE and minimal loss of ECD, resulting in a gain in BCVA.

  10. Implantation of posterior chamber foldable intraocular lens in the absence of adequate capsular support: iris fixation versus scleral fixation

    Directory of Open Access Journals (Sweden)

    Tamer Gamal Elsayed

    2015-01-01

    In the absence of adequate capsular support, fixation of posterior chamber foldable IOL by iris suturing is associated with significantly less IOL malposition and consumes a shorter operative time compared with scleral fixation. However, iris suture fixation is associated with a higher incidence of postoperative iridocyclitis in the early postoperative period.

  11. Incorporation of raloxifene-impregnated allograft around orthopedic titanium implants impairs early fixation but improves new bone formation.

    Science.gov (United States)

    Hermansen, Lars L; Sørensen, Mette; Barckman, Jeppe; Bechtold, Joan E; Søballe, Kjeld; Baas, Jørgen

    2015-02-01

    The anti-osteoporotic drug raloxifene reduces the risk of vertebral fractures by increasing bone mass density. We investigated whether raloxifene offers any benefits in augmenting early fixation of orthopedic implants in the setting of impaction bone grafting. 24 non-weight-bearing grafted gap implants were inserted bilaterally into the tibia of 12 dogs. The 2.5-mm peri-implant gap was filled with either raloxifene-impregnated or untreated bone allograft. Implants were harvested after 28 days. Implant fixation was assessed by mechanical testing and histomorphometric evaluation. Raloxifene-treated allograft reduced early implant fixation compared to untreated allograft, as measured by inferior maximum shear strength (p raloxifene group had more newly formed bone in the gap around the implant (p = 0.02), but also less allograft (p = 0.03). The accelerated allograft resorption in the raloxifene group explained the impaired early fixation, despite its stimulation of new bone formation. Our results with local and possible high-dose treatment are not consistent with current theory regarding the mechanism of how systemic raloxifene administration counteracts the decrease in BMD in postmenopausal women. Instead of being solely anti-resorptive as generally held, our results indicate a possible anabolic side of raloxifene.

  12. Comparison of migration behavior between single and dual lag screw implants for intertrochanteric fracture fixation

    Directory of Open Access Journals (Sweden)

    Katonis Pavlos G

    2009-05-01

    Full Text Available Abstract Background Lag screw cut-out failure following fixation of unstable intertrochanteric fractures in osteoporotic bone remains an unsolved challenge. This study tested if resistance to cut-out failure can be improved by using a dual lag screw implant in place of a single lag screw implant. Migration behavior and cut-out resistance of a single and a dual lag screw implant were comparatively evaluated in surrogate specimens using an established laboratory model of hip screw cut-out failure. Methods Five dual lag screw implants (Endovis, Citieffe and five single lag screw implants (DHS, Synthes were tested in the Hip Implant Performance Simulator (HIPS of the Legacy Biomechanics Laboratory. This model simulated osteoporotic bone, an unstable fracture, and biaxial rocking motion representative of hip loading during normal gait. All constructs were loaded up to 20,000 cycles of 1.45 kN peak magnitude under biaxial rocking motion. The migration kinematics was continuously monitored with 6-degrees of freedom motion tracking system and the number of cycles to implant cut-out was recorded. Results The dual lag screw implant exhibited significantly less migration and sustained more loading cycles in comparison to the DHS single lag screw. All DHS constructs failed before 20,000 cycles, on average at 6,638 ± 2,837 cycles either by cut-out or permanent screw bending. At failure, DHS constructs exhibited 10.8 ± 2.3° varus collapse and 15.5 ± 9.5° rotation around the lag screw axis. Four out of five dual screws constructs sustained 20,000 loading cycles. One dual screw specimens sustained cut-out by medial migration of the distal screw after 10,054 cycles. At test end, varus collapse and neck rotation in dual screws implants advanced to 3.7 ± 1.7° and 1.6 ± 1.0°, respectively. Conclusion The single and double lag screw implants demonstrated a significantly different migration resistance in surrogate specimens under gait loading simulation with

  13. External fixation of femoral defects in athymic rats: Applications for human stem cell implantation and bone regeneration

    Directory of Open Access Journals (Sweden)

    Terasa Foo

    2013-01-01

    Full Text Available An appropriate animal model is critical for the research of stem/progenitor cell therapy and tissue engineering for bone regeneration in vivo. This study reports the design of an external fixator and its application to critical-sized femoral defects in athymic rats. The external fixator consists of clamps and screws that are readily available from hardware stores as well as Kirschner wires. A total of 35 rats underwent application of the external fixator with creation of a 6-mm bone defect in one femur of each animal. This model had been used in several separate studies, including implantation of collagen gel, umbilical cord blood mesenchymal stem cells, endothelial progenitor cells, or bone morphogenetic protein-2. One rat developed fracture at the proximal pin site and two rats developed deep tissue infection. Pin loosening was found in nine rats, but it only led to the failure of external fixation in two animals. In 8 to 10 weeks, various degrees of bone growth in the femoral defects were observed in different study groups, from full repair of the bone defect with bone morphogenetic protein-2 implantation to fibrous nonunion with collagen gel implantation. The external fixator used in these studies provided sufficient mechanical stability to the bone defects and had a comparable complication rate in athymic rats as in immunocompetent rats. The external fixator does not interfere with the natural environment of a bone defect. This model is particularly valuable for investigation of osteogenesis of human stem/progenitor cells in vivo.

  14. Active middle ear implant application in case of stapes fixation: a temporal bone study.

    Science.gov (United States)

    Devèze, Arnaud; Koka, Kanthaiah; Tringali, Stéphane; Jenkins, Herman A; Tollin, Daniel J

    2010-09-01

    Driving the oval window directly with an active middle ear implant (AMEI) can produce high levels of input to the inner ear. Treatment of otosclerosis bypasses the stapes with a piston that penetrates the vestibule. Although this treats the conductive component of hearing loss, it does not treat the sensorineural part, which can be improved using an additional conventional hearing aid. Active middle ear implants have been proposed to be an alternative in treating otosclerosis in cases of mixed hearing losses. Seven temporal bones were prepared to expose the stapes and round window (RW). Stapes and RW velocities were measured while driving with an AMEI the stapes head with a bell-shaped tip. The stapes footplate was then fixed with acrylic cement; fixation was confirmed through attenuated RW velocities. A cylinder tip (0.5 mm) was then used to drive the inner ear through a stapedotomy with and without interposition of fascia. Driving the stapes with an AMEI produced mean maximum equivalent ear canal sound pressure levels (SPL) of 138 dB (0.25-8 kHz at 1 V [RMS]). Stapes fixation caused a approximately 25-dB attenuation. Driving with a cylinder tip through the stapedotomy produced 114 dB SPL (24 dB less than normal) and 110 dB SPL (28 dB less than normal) performance with and without fascia, respectively. Performance with fascia was greater than without. Driving the oval window with an AMEI in a scenario of stapes fixation was demonstrated to be feasible, with performance comparable to traditional AMEI coupling to the incus or stapes. These possibilities offer new perspectives to treat mixed hearing loss in case of fixed footplate.

  15. Dynamic hip screw versus DHS blade: a biomechanical comparison of the fixation achieved by each implant in bone.

    Science.gov (United States)

    O'Neill, F; Condon, F; McGloughlin, T; Lenehan, B; Coffey, J C; Walsh, M

    2011-05-01

    We biomechanically investigated whether the standard dynamic hip screw (DHS) or the DHS blade achieves better fixation in bone with regard to resistance to pushout, pullout and torsional stability. The experiments were undertaken in an artificial bone substrate in the form of polyurethane foam blocks with predefined mechanical properties. Pushout tests were also repeated in cadaveric femoral heads. The results showed that the DHS blade outperformed the DHS with regard to the two most important characteristics of implant fixation, namely resistance to pushout and rotational stability. We concluded that the DHS blade was the superior implant in this study.

  16. Early fixation of cobalt-chromium based alloy surgical implants to bone using a tissue-engineering approach.

    Science.gov (United States)

    Ogawa, Munehiro; Tohma, Yasuaki; Ohgushi, Hajime; Takakura, Yoshinori; Tanaka, Yasuhito

    2012-01-01

    To establish the methods of demonstrating early fixation of metal implants to bone, one side of a Cobalt-Chromium (CoCr) based alloy implant surface was seeded with rabbit marrow mesenchymal cells and the other side was left unseeded. The mesenchymal cells were further cultured in the presence of ascorbic acid, β-glycerophosphate and dexamethasone, resulting in the appearance of osteoblasts and bone matrix on the implant surface. Thus, we succeeded in generating tissue-engineered bone on one side of the CoCr implant. The CoCr implants were then implanted in rabbit bone defects. Three weeks after the implantation, evaluations of mechanical test, undecalcified histological section and electron microscope analysis were performed. Histological and electron microscope images of the tissue engineered surface exhibited abundant new bone formation. However, newly formed bone tissue was difficult to detect on the side without cell seeding. In the mechanical test, the mean values of pull-out forces were 77.15 N and 44.94 N for the tissue-engineered and non-cell-seeded surfaces, respectively. These findings indicate early bone fixation of the tissue-engineered CoCr surface just three weeks after implantation.

  17. 3D perfusion bioreactor-activated porous granules on implant fixation and early bone formation in sheep

    DEFF Research Database (Denmark)

    Ding, Ming; Snoek Henriksen, Susan; Martinetti, Roberta

    2017-01-01

    Early fixation of total joint arthroplasties is crucial for ensuring implant survival. An alternative bone graft material in revision surgery is needed to replace the current gold standard, allograft, seeing that the latter is associated with several disadvantages. The incubation of such a constr...

  18. [Percutaneous iliosacral screw fixation for pelvis insufficiency fracture after implantation of a pedestal cup: case report].

    Science.gov (United States)

    Fensky, F; Schäffler, A; Siebenlist, S; König, B; Stöckle, U

    2011-12-01

    Insufficiency fractures of the sacrum are frequently overlooked injuries especially in postmenopausal women with an osteoporotic bone structure and without a history of significant trauma. Plain radiographs are frequently inadequate in showing insufficiency fractures of the sacrum. Regarding this a fracture of a pubic ramus combined with appropriate clinical symptoms should raise the suspicion of a concomitant sacral injury. Therefore, further investigations including a CT scan are necessary.The case of an osteoporotic female patient with bilateral insufficiency fractures of the sacrum and a fracture of the right superior and inferior pubic ramus 5 weeks after primary total hip arthroplasty and implantation of a pedestal cup due to an intraoperative fracture of the right acetabulum is presented. To ensure early mobilization as well as avoidance of further concomitant morbidities a percutaneous iliosacral screw fixation was performed. This approach has been established as an operative treatment for minimally or non-displaced insufficiency fractures of the sacrum.

  19. Mechanical analysis of a rodent segmental bone defect model: the effects of internal fixation and implant stiffness on load transfer.

    Science.gov (United States)

    Yavari, S Amin; van der Stok, J; Ahmadi, S M; Wauthle, R; Schrooten, J; Weinans, H; Zadpoor, A A

    2014-08-22

    Segmental bone defect animal models are often used for evaluating the bone regeneration performance of bone substituting biomaterials. Since bone regeneration is dependent on mechanical loading, it is important to determine mechanical load transfer after stabilization of the defect and to study the effects of biomaterial stiffness on the transmitted load. In this study, we assess the mechanical load transmitted over a 6mm femur defect that is stabilized with an internal PEEK fixation plate. Subsequently, three types of selective laser melted porous titanium implants with different stiffness values were used to graft the defect (five specimens per group). In one additional group, the defect was left empty. Micro strain gauges were used to measure strain values at four different locations of the fixation plate during external loading on the femoral head. The load sharing between the fixation plate and titanium implant was highly variable with standard deviations of measured strain values between 31 and 93% of the mean values. As a consequence, no significant differences were measured between the forces transmitted through the titanium implants with different elastic moduli. Only some non-significant trends were observed in the mean strain values that, consistent with the results of a previous finite element study, implied the force transmitted through the implant increases with the implant stiffness. The applied internal fixation method does not standardize mechanical loading over the defect to enable detecting small differences in bone regeneration performances of bone substituting biomaterials. In conclusion, the fixation method requires further optimization to reduce the effects of the operative procedure and make the mechanical loading more consistent and improve the overall sensitivity of this rat femur defect model. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Iris Claw versus Scleral Fixation Intraocular Lens Implantation during Pars Plana Vitrectomy

    Directory of Open Access Journals (Sweden)

    Fereydoun Farrahi

    2012-01-01

    Full Text Available Purpose: To compare the outcomes of iris claw anterior chamber intraocular lens (ICACIOL with that of scleral fixation posterior chamber intraocular lens (SF-PCIOL implantation during pars plana vitrectomy (PPV as initial surgery to correct aphakia. Methods: Twelve patients with complicated cataract surgery or trauma who had suffered nucleus, whole crystalline lens or intraocular lens (IOL drop into the vitreous cavity, and undergone PPV with IC-ACIOL implantation over a period of one year were evaluated for the purpose of this study. Uncorrected visual acuity (UCVA, best corrected visual acuity (BCVA, central corneal thickness (CCT, spherical equivalent (SE refractive error, astigmatism and complications were recorded. The results were compared to outcomes of another group of 13 patients who had previously undergone PPV with SF-PCIOL implantation. Results: Mean improvement of UCVA was greater in IC-ACIOL eyes as compared to the SF-PCIOL group (-1.17±0.28 versus -0.89±0.21 logMAR, P=0.01, corresponding values for postoperative BCVA were 0.24±0.17 and 0.44±0.22 logMAR (P=0.041, respectively. Average postoperative SE was comparable in the IC-ACIOL and SFPCIOL groups at 0.6±1.03 and 0.56±1.23 diopters, respectively (P=0.290. However, 10 (83.3% IC-ACIOL eyes versus 6 (46.1% SF-PCIOL eyes had SE within 1 diopter of emmetropia (P=0.048. Mean postoperative increase in CCT was comaparble between the study groups (P=0.126. Conclusion: In the absence of sufficient capsular support, the use of an IC-ACIOL for correction of aphakia during PPV can be a good alternative and seems to entail better visual outcomes as compared to SF-PCIOL.

  1. Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices.

    Science.gov (United States)

    MacLeod, A; Simpson, A H R W; Pankaj, P

    2018-01-01

    Secondary fracture healing is strongly influenced by the stiffness of the bone-fixator system. Biomechanical tests are extensively used to investigate stiffness and strength of fixation devices. The stiffness values reported in the literature for locked plating, however, vary by three orders of magnitude. The aim of this study was to examine the influence that the method of restraint and load application has on the stiffness produced, the strain distribution within the bone, and the stresses in the implant for locking plate constructs. Synthetic composite bones were used to evaluate experimentally the influence of four different methods of loading and restraining specimens, all used in recent previous studies. Two plate types and three screw arrangements were also evaluated for each loading scenario. Computational models were also developed and validated using the experimental tests. The method of loading was found to affect the gap stiffness strongly (by up to six times) but also the magnitude of the plate stress and the location and magnitude of strains at the bone-screw interface. This study demonstrates that the method of loading is responsible for much of the difference in reported stiffness values in the literature. It also shows that previous contradictory findings, such as the influence of working length and very large differences in failure loads, can be readily explained by the choice of loading condition.Cite this article:Bone Joint Res 2018;7:111-120. © 2018 MacLeod et al.

  2. Flapless implant surgery: an experimental study.

    Science.gov (United States)

    Jeong, Seung-Mi; Choi, Byung-Ho; Li, Jingxu; Kim, Han-Sung; Ko, Chang-Yong; Jung, Jae-Hyung; Lee, Hyeon-Jung; Lee, Seoung-Ho; Engelke, Wilfried

    2007-07-01

    The purpose of this study was to examine the effect of flapless implant surgery on crestal bone loss and osseointegration in a canine mandible model. In 6 mongrel dogs, bilateral, edentulated, flat alveolar ridges were created in the mandible. After 3 months of healing, 2 implants in each side were placed by either flap or flapless procedures. After a healing period of 8 weeks, microcomputerized tomography at the implantation site was performed. Osseointegration was calculated as percentage of implant surface in contact with bone. Additionally, bone height was measured in the peri-implant bone. The mean osseointegration was greater at flapless sites (70.4%) than at sites with flaps (59.5%) (P flapless sites (10.1 mm) than at sites with flaps (9.0 mm) (P Flapless surgery can achieve results superior to surgery with reflected flaps. The specific improvements of this technique include enhanced osseointegration of dental implants and increased bone height.

  3. Development of an acoustic measurement protocol to monitor acetabular implant fixation in cementless total hip Arthroplasty: A preliminary study.

    Science.gov (United States)

    Goossens, Quentin; Leuridan, Steven; Henyš, Petr; Roosen, Jorg; Pastrav, Leonard; Mulier, Michiel; Desmet, Wim; Denis, Kathleen; Vander Sloten, Jos

    2017-11-01

    In cementless total hip arthroplasty (THA), the initial stability is obtained by press-fitting the implant in the bone to allow osseointegration for a long term secondary stability. However, finding the insertion endpoint that corresponds to a proper initial stability is currently based on the tactile and auditory experiences of the orthopedic surgeon, which can be challenging. This study presents a novel real-time method based on acoustic signals to monitor the acetabular implant fixation in cementless total hip arthroplasty. Twelve acoustic in vitro experiments were performed on three types of bone models; a simple bone block model, an artificial pelvic model and a cadaveric model. A custom made beam was screwed onto the implant which functioned as a sound enhancer and insertor. At each insertion step an acoustic measurement was performed. A significant acoustic resonance frequency shift was observed during the insertion process for the different bone models; 250 Hz (35%, second bending mode) to 180 Hz (13%, fourth bending mode) for the artificial bone block models and 120 Hz (11%, eighth bending mode) for the artificial pelvis model. No significant frequency shift was observed during the cadaveric experiment due to a lack of implant fixation in this model. This novel diagnostic method shows the potential of using acoustic signals to monitor the implant seating during insertion. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  4. [Challenging the dogma on inferiority of stainless steel implants for fracture fixation. An end of the controversy?].

    Science.gov (United States)

    Weckbach, S; Losacco, J T; Hahnhaussen, J; Gebhard, F; Stahel, P F

    2012-01-01

    Titanium plates represent the predominant implants of choice for fracture care in Central Europe, based on the apparently favourable properties related to improved "biocompatibility". The present study was designed to test the hypothesis that the use of stainless steel implants for selected fractures represents a safe and efficient treatment modality, which is not associated with an increased rate of complications and surgical revisions. We conducted a retrospective analysis of a prospective database during a 5-year study period (01/01/2006-12/31/2010) at an academic Level 1 Trauma Center on all fractures treated by stainless steel plates. Inclusion criteria consisted of all consecutive patients >15 years of age whose fractures were fixated with a stainless steel plate. All fractures were classified according to the AO/OTA system. Outcome parameters consisted of the rate of complications and surgical revisions, and the data were placed into context with the published complication rates for titanium plates. A total of 1,001 consecutive patients who underwent surgical fixation of fractures in the indication spectrum of this study were screened. Of these, 751 patients fulfilled the inclusion criteria. These patients had 774 fractures which were fixated with 859 stainless steel plates. Open fractures accounted for 9.6% of all injuries (n=74). The complication rate of the 774 fractures treated with stainless steel plates was 8.01% (n=62), with a surgical revision rate of 5.16% (n=40). These data are below the reported incidence of complications and surgical revisions for titanium plates in the identical indication spectrum in the pertinent literature published. The fixation of selected fractures with stainless steel implants represents a safe and efficient treatment option, which does not appear to be associated with increased complication rates. These data challenge the anecdotal superiority of titanium plates and should spur a new discussion on the use of stainless

  5. Fixation of Light Weight Polypropylene Mesh with n-Butyl-2-cyanocrylate in Pelvic Floor Surgery: Experimental Design Approach in Sheep for Effectiveness Evaluation

    Directory of Open Access Journals (Sweden)

    Sandra Barbosa

    2015-01-01

    Full Text Available Objective. The aim of this study was to find a proper experimental design and to evaluate n-butyl-2-cyanoacrylate (Histoacryl as a fixation method for a light-weight and large pore PP mesh (Synthetic PP Mesh-1 using the sheep as an animal model. Methods. Posterior vaginal implantation by means of episiotomy was used to implant 8 ewes which were evaluated macroscopically and histologically at 3 months (n=4 and 6 months (n=4 post-surgery. In previous pilot studies anterior vaginal implantation was evaluated, as well as different synthetic mesh materials, sizes and fixation methods (n=1 to 3 during three weeks. In all cases a clinical evaluation of the animal was performed. Results. A reduction in the mesh size (Synthetic PP Mesh-1 together with precise application of the surgical glue Histoacryl to fix the mesh yielded significantly better histocompatibility results (P<0.01 compared to larger size or other fixation methods. Conclusion. The combination of Synthetic PP Mesh-1 with Histoacryl offered a high degree of graft integration without vaginal ulceration and a minimal foreign body reaction, being the sheep a proper animal model to test these types of medical devices.

  6. Tibial revision knee arthroplasty with metaphyseal sleeves: The effect of stems on implant fixation and bone flexibility

    Science.gov (United States)

    Nadorf, Jan; Kinkel, Stefan; Gantz, Simone; Jakubowitz, Eike; Kretzer, J. Philippe

    2017-01-01

    Introduction Revision total knee arthoplasty often requires modular implants to treat bone defects of varying severity. In some cases, it may not be clear which module size and implant combination (e.g. sleeve and stem) should be chosen for a specific defect. When balancing implant stability and osseointegration against stress-shielding, it is important to choose an appropriate implant combination in order to match the given level of bone loss. Therefore, the necessity of stems in less extensive tibial defects and the advantage of different stems (lengths and stiffnesses) in combination with large metaphyseal sleeves on implant fixation and bone flexibility using a modular tibial revision knee system, were analyzed. Materials and methods Four different stem combinations for a tibial revision implant (Sigma TC3, DePuy) were compared to an intact bone. Standardized implantation with n = 4 synthetic tibial bones was performed after generating an Anderson Orthopaedic Research Institute (AORI) Type T1 bone defect. Axial torques around the longitudinal stem axis and varus-valgus torques were separately applied to the implant. Micromotions of bone and implant were tracked using a digital image correlation system to calculate relative micromotions at the implant-bone-interface and bone deformation. Results Overall, using stems reduced the proximal micromotions of tray and sleeve compared to no stem, while reducing bone deformation proximally at the same time, indicating some potential for proximal stress-shielding compared to no stem. The potential for increased proximal stress-shield due to reduced proximal deformation appeared to be greater when using the longer stems. The location of lowest relative micromotions was also more distal when using long stems as opposed to short stems. A short stem (especially a smaller diameter short stem which still achieves diaphyseal fixation) displayed less potential for stress-shielding, but greater bone deformation distal to the tip

  7. Experimental model of capsular contracture in silicone implants

    Directory of Open Access Journals (Sweden)

    Bastos Érika Malheiros

    2003-01-01

    Full Text Available The breast implant procedure is one of the most performed into Plastic Surgery and the contracture that occurs the capsule formed around the breast implants one of most frequent complication. We describe here one experimental model of capsule contracture in rats.

  8. Placement of Zygomatic Implants into the Malar Prominence of the Maxillary Bone for Apical Fixation: A Clinical Report of 5 to 13 Years.

    Science.gov (United States)

    Fortin, Yvan

    This study was designed to evaluate long-term performance of zygomatic implants using an alternative apical fixation point to establish the posterior restorative foundation for fixed full-arch restoration. A retrospective study of all consecutively treated patients with advanced maxillary resorption who were treated with zygomatic implants to support fixed prostheses from August 14, 2001 through November 24, 2009 was conducted; the final follow-up was August 31, 2015. All zygomatic implants were placed using the malar prominence of the maxillary bone for apical fixation. Initial study casts were analyzed to compute the anterior/posterior implant distribution, distance between bilateral zygomatic implants, and variation from ideal zygomatic implant positioning relative to the soft tissue crest. Soft tissue, implant, and restorative complications also were recorded. Fifty-eight consecutively treated patients with advanced maxillary resorption were included in the study- 18 men and 40 women, with a mean ± SD age of 65.3 ± 8.0 years and range of 49 to 85 years. Forty-nine patients received bilateral zygomatic implants placed apically into the malar process of the maxillary bone, and nine patients received similarly placed unilateral zygomatic implants with 107 zygomatic implants reported. All patients had supplemental anterior implants and were restored with a one-piece splint framework and fully implant-supported restoration. Follow-up of 5 to 13 years was conducted, with a mean follow-up time of 8.4 years per zygomatic implant. No losses of zygomatic implants occurred. No major surgical or restorative complications were observed. Utilizing the malar prominence of the maxilla for apical fixation of zygomatic implants predictably allows prosthetic placement of the implant platform in a favorable first molar position, eliminating prosthetic compromise.

  9. Angulated Dental Implants in Posterior Maxilla FEA and Experimental Verification

    Directory of Open Access Journals (Sweden)

    Hamed A. Hamed

    2018-02-01

    Full Text Available AIM: This study aimed to evaluate the effect of different implant angulations in posterior maxilla on stress distribution by finite element analysis and verify its results experimentally. METHODS: Two simplified models were prepared for an implant placed vertically and tilted 25° piercing the maxillary sinus. Geometric models' components were prepared by Autodesk Inventor then assembled in ANSYS for finite element analysis. The results of finite element analysis were verified against experimental trials results which were statistically analysed using student t-test (level of significance p < 0.05. RESULTS: Implant - abutment complex absorbed the load energy in case of vertical implant better than the case of angulated one. That was reflected on cortical bone stress, while both cases showed stress levels within the physiological limits. Comparing results between FEA and experiment trials showed full agreement. CONCLUSION: It was found that the tilted implant by 25° can be utilised in the posterior region maxilla for replacing maxillary first molar avoiding sinus penetration. The implant-bone interface and peri-implant bones received the highest Von Mises stress. Implant - bone interface with angulated implant received about 66% more stresses than the straight one.

  10. Tissue-implant interface at an absorbable fracture fixation plug made of polylactide in cancellous bone of distal rabbit femur.

    Science.gov (United States)

    Pihlajamäki, H; Böstman, O; Manninen, M; Päivärinta, U; Rokkanen, P

    1994-01-01

    The tissue-implant interface at a self-reinforced poly-L-lactide (SR-PLLA) expansion plug implanted in distal rabbit femoral cancellous bone was studied histologically, histomorphometrically, and microradiographically in 35 rabbits during consolidation of a transverse transcondylar osteotomy fixed with the SR-PLLA expansion plug. The absorbable plug for internal fixation of fractures and osteotomies measured 4.5 mm in diameter and 30 mm in length and had an expandable distal locking blade system. The femoral specimens were harvested in groups of 5-10 rabbits after a follow-up time of 3, 6, 12, and 24 weeks. The intact contralateral femur served as a control. Vigorous osteogenic response to the implant was already observed at 3 weeks postoperatively, and the osteoid surface fraction at 24 weeks was still significantly higher than in the unoperated contralateral femur. Incomplete union of the osteotomy seemed to result in increased fibrous tissue formation at the tissue-implant boundary. No signs of degradation of the SR-PLLA was observed within the entire follow-up period. The number of inflammatory cells at the tissue-implant interface was low. Consequently, the short-term biocompatibility of the implant was deemed acceptable. Clinical application of the expansion plug is being planned.

  11. Arthroscopic Fixation of Cell Free Polymer-Based Cartilage Implants with a Bioinspired Polymer Surface on the Hip Joint: A Cadaveric Pilot Study

    Directory of Open Access Journals (Sweden)

    Matthias Lahner

    2014-01-01

    Full Text Available This study investigates the adhesion capacity of a polyglycolic acid- (PGA- hyaluronan scaffold with a structural modification based on a planar polymer (PM surface in a cadaver cartilage defect model. Two cadaver specimens were used to serially test multiple chondral matrices. In a cadaver hip model, cell free polymer-based cartilage implants with a planar bioinspired PM surface (PGA-PM-scaffolds were implanted arthroscopically on 10 mm × 15 mm full-thickness femoral hip cartilage lesions. Unprocessed cartilage implants without a bioinspired PM surface were used as control group. The cartilage implants were fixed without and with the use of fibrin glue on femoral hip cartilage defects. After 50 movement cycles and removal of the distraction, a rearthroscopy was performed to assess the outline attachment and integrity of the scaffold. The fixation techniques without and with fibrin fixation showed marginal differences for outline attachment, area coverage, scaffold integrity, and endpoint fixation after 50 cycles. The PGA-PM-scaffolds with fibrin fixation achieved a higher score in terms of the attachment, integrity, and endpoint fixation than the PGA-scaffold on the cartilage defect. Relating to the outline attachment, area coverage, scaffold integrity, and endpoint fixation, the fixation with PGA-PM-scaffolds accomplished significantly better results compared to the PGA-scaffolds (P=0.03752, P=0.03078, P=0.00512, P=0.00512. PGA-PM-scaffolds demonstrate increased observed initial fixation strength in cadaver femoral head defects relative to PGA-scaffold, particularly when fibrin glue is used for fixation.

  12. Bone reactions at implants subjected to experimental peri-implantitis and static load. A study in the dog

    DEFF Research Database (Denmark)

    Gotfredsen, K; Berglundh, T; Lindhe, J

    2002-01-01

    AIM: The aim of the present experiment was to study peri-implant tissue reactions to lateral static load at implants subjected to experimental mucositis or peri-implantitis. MATERIAL AND METHODS: 5 beagle dogs were used. The mandibular premolars were extracted. After 12 weeks, 3 implants were...

  13. A comparative study on the in vivo degradation of poly(L-lactide) based composite implants for bone fracture fixation

    Science.gov (United States)

    Wang, Zongliang; Wang, Yu; Ito, Yoshihiro; Zhang, Peibiao; Chen, Xuesi

    2016-02-01

    Composite of nano-hydroxyapatite (n-HAP) surface grafted with poly(L-lactide) (PLLA) (g-HAP) showed improved interface compatibility and mechanical property for bone fracture fixation. In this paper, in vivo degradation of n-HAP/PLLA and g-HAP/PLLA composite implants was investigated. The mechanical properties, molecular weight, thermal properties as well as crystallinity of the implants were measured. The bending strength of the n- and g-HAP/PLLA composites showed a marked reduction from an initial value of 102 and 114 MPa to 33 and 24 MPa at 36 weeks, respectively. While the bending strength of PLLA was maintained at 80 MPa at 36 weeks compared with initial value of 107 MPa. The impact strength increased over time especially for the composites. Significant differences in the molecular weight were seen among all the materials and g-HAP/PLLA appeared the fastest rate of decrease than others. Environmental scanning electron microscope (ESEM) results demonstrated that an apparently porous morphology full of pores and hollows were formed in the composites. The results indicated that the in vivo degradation of PLLA could be accelerated by the g-HAP nanoparticles. It implied that g-HAP/PLLA composites might be a candidate for human non-load bearing bone fracture fixation which needs high initial strength and fast degradation rate.

  14. Traumatic Partial Aniridia and Cataract after Iris-Fixated Foldable Phakic Intraocular Lens Implantation

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    Joo Hyun

    2013-10-01

    Full Text Available We present the first case of partial aniridia, traumatic cataract, and peripapillary subretinal hemorrhage after blunt trauma to an eye containing a foldable iris-fixated phakic intraocular lens (pIOL. Although the patient experienced visual loss because of considerable corneal astigmatism and a traumatic cataract, vision was recovered by a 2-stage primary corneal repair and cataract surgery with a toric intraocular lens. This case exhibits clinical manifestations that differ from previously reported trauma of a non-foldable iris-fixated pIOL. A relatively small corneal incision and a large optic diameter of Artiflex pIOLs may prevent posttraumatic total expulsion of intraocular tissues and present different clinical features from the case of non-foldable pIOLs (Artisan. Although the extent of the damage is different, the possibility of aniridia and traumatic cataract exists in eyes with both foldable and non-foldable iris-fixated pIOLs.

  15. Irreversibly increased nitrogen fixation in Trichodesmium experimentally adapted to elevated carbon dioxide.

    Science.gov (United States)

    Hutchins, David A; Walworth, Nathan G; Webb, Eric A; Saito, Mak A; Moran, Dawn; McIlvin, Matthew R; Gale, Jasmine; Fu, Fei-Xue

    2015-09-01

    Nitrogen fixation rates of the globally distributed, biogeochemically important marine cyanobacterium Trichodesmium increase under high carbon dioxide (CO2) levels in short-term studies due to physiological plasticity. However, its long-term adaptive responses to ongoing anthropogenic CO2 increases are unknown. Here we show that experimental evolution under extended selection at projected future elevated CO2 levels results in irreversible, large increases in nitrogen fixation and growth rates, even after being moved back to lower present day CO2 levels for hundreds of generations. This represents an unprecedented microbial evolutionary response, as reproductive fitness increases acquired in the selection environment are maintained after returning to the ancestral environment. Constitutive rate increases are accompanied by irreversible shifts in diel nitrogen fixation patterns, and increased activity of a potentially regulatory DNA methyltransferase enzyme. High CO2-selected cell lines also exhibit increased phosphorus-limited growth rates, suggesting a potential advantage for this keystone organism in a more nutrient-limited, acidified future ocean.

  16. A review of improved fixation methods for dental implants. Part II: biomechanical integrity at bone-implant interface.

    Science.gov (United States)

    Shibata, Yo; Tanimoto, Yasuhiro; Maruyama, Noriko; Nagakura, Manamu

    2015-04-01

    The purpose of this article is to review the mechanical requirements of the tissue-implant interface and analyze related theories. The osseointegration capacity of titanium implants has been investigated over the past 50 years. We considered the ultimate goal of osseointegration to which form a desirable interfacial layer and a bone matrix with adequate biomechanical properties. Occasionally, the interface comprises porous titanium and bone ingrowth that enables a functionally graded Young's modulus, thereby allowing reduction of stress shielding. However, the optimal biomechanical connection at the interface has not yet been fully clarified. There have been publications supporting several universal mechanical testing technologies in terms of bone-titanium bonding ability, although the separation of newly formed bone quality is unlikely. The understanding of complex mechanical bone behavior and size-dependent properties ranging from a nano- to a macroscopic level are essential in the biomechanical optimization of implants. The requirements of regenerated tissue at the interface include high strength, fracture toughness related to ductility, and time-dependent energy dissipation and/or elastic-plastic stress distribution. Moreover, a strong relationship between strain signals and peri-implant tissue turnover could be expected, so that ideal implant biomechanics may enable longevity via adaptive bone remodeling. Copyright © 2015 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  17. Experimental and Numerical Analysis of Screw Fixation in Anterior Cruciate Ligament Reconstruction

    Science.gov (United States)

    Chizari, Mahmoud; Wang, Bin; Snow, Martyn; Barrett, Mel

    2008-09-01

    This paper reports the results of an experimental and finite element analysis of tibial screw fixation in anterior cruciate ligament (ACL) reconstruction. The mechanical properties of the bone and tendon graft are obtained from experiments using porcine bone and bovine tendon. The results of the numerical study are compared with those from mechanical testing. Analysis shows that the model may be used to establish the optimum placement of the tunnel in anterior cruciate ligament reconstruction by predicting mechanical parameters such as stress, strain and displacement at regions in the tunnel wall.

  18. Implant-free press-fit fixation for bone-patellar tendon-bone ACL reconstruction: 10-year results.

    Science.gov (United States)

    Felmet, Gernot

    2010-08-01

    The aim of this study is to determine the outcome of anterior cruciate ligament (ACL) reconstruction without foreign material with patellar tendon bone graft in the fixation with bone dowels near the native insertion. Between 1998 and 1999, 189 patients were operated with ACL reconstruction with BTB patellar tendon graft. In a prospective study, 148 (78%) (91M, 57F) patients could be seen for a mean follow-up of 10.3 years. All had foreign material-free press-fit and a bottom-to-top (BTT) fixation in 120 degrees knee flexion. All patients were evaluated with detailed history, clinical examinations, radiographic examination with weight bearing which could be compared to the time of surgery in 64 (43%) patients. Laxity testing was performed in Lachman position with the Rolimeter and pivot shift. All patients were graded according to the IKDC and Tegner activity score. 87% of the patients achieved an IKDC score of A/B. The subjective IKDC score was A/B in 94.6% of the subjects. The average side-to-side difference was 1.42 +/- 0.88 mm for the Lachman test, 97% of the patients were rated between 0 and 2 mm. The pivot-shift test was negative in 90% and was observed with a glide in 7% of the patients. Radiological joint space narrowing was found in the medial compartment in 8 (12.4%) cases, and laterally in 9 (14.1%) cases. All these patients had partial or total meniscus resections. The patello-femoral joint space was reduced in 21 (23%) cases. The Tegner activity score changed from 6.9 pre-injury to 5.0 at the 10-year follow-up. The implant-free fixation of the graft with bone dowels and BTT implantation has good and excellent results after 10 years in more than 80% of the patients. Loss of the meniscus is a main factor contributing to osteoarthritis. Advantages of patellar tendon bone press-fit fixation include anatomical positioning and fast bone-to-bone healing, ease for revision surgery and cost effectiveness.

  19. Estudo mecânico de implante para fixação do segmento lombossacro da coluna vertebral Mechanical study of implant for lumbossacral spinal fixation

    Directory of Open Access Journals (Sweden)

    Afrane Serdeira

    2000-09-01

    Full Text Available Foram estudados, do ponto de vista mecânico, a rigidez e os pontos críticos de um implante para fixação interna da coluna lombossacra. Aplicou-se o implante sobre um modelo de madeira simulando o segmento lombossacro da coluna. Realizamos sete ensaios de flexo-compressão, sete de rigidez axial, sete de rigidez radial e um ensaio destrutivo. Os resultados demonstraram que o implante foi eficiente e seguro para uso em seres humanos.This work consists of a mechanical analysis of the resistance and critical points of a stainless steel device for lumbossacral spinal fixation. The device was fixed into a wooden model representing the spinal lumbossacral segment. The experiment comprised seven tests of flexo-compression, seven tests of axial rigidity, seven tests of radial rigidity, and one destructive test. The critical points are the intersection of the pedicular screws threads and the attrition rate between the vise and the rod. The results demonstrated the device to be efficient and safe when used in human beings.

  20. An experimental study on initial fixation strength in transpedicular screwing augmented with calcium phosphate cement.

    Science.gov (United States)

    Masaki, Taiga; Sasao, Yutaka; Miura, Takehiko; Torii, Yoshiaki; Kojima, Atsushi; Aoki, Haruhito; Beppu, Moroe

    2009-09-15

    An experimental study. To clarify the optimal insertion timing of transpedicular screws when the initial fixation strength reaches in maximum as calcium phosphate cement (CPC) hardens, in cases augmented by CPC to the vertebrae. CPC goes easily into the bone trabeculae and excels in the bone compatibility. However, it is still unknown as for differences of fixation effects by CPC hardening time at actual insertion of the pedicle screw. Fifty-seven vertebrae obtained from 11 human cadavers. The CPC and titanium pedicle screws were used. Experimental groups were decided as follows. (1) Control group (without CPC). (2) CPC group (augmented with CPC); the mixed CPC infused into the screw hole, afterwards the pedicle screw inserted at a set time (passage time from the initiation of powder and liquid agent mixing). The CPC group was further divided into 3 subgroups, with respect to insertion time of the pedicle screws: 2, 5, and 10 minute subgroups. Maximum pull-out strength was compared, and cross sectioned specimens of the 5 and 10 minute groups were prepared and observed. CPC group showed a pull-out strength of about 177% that of the control group. For inserting timing of the pedicle screw and pull-out strength, no apparent statistically significant difference was found between each subgroups, although the 10-minute group showed the lowest. Cross sectional observations revealed that the CPC diffused deeper into the bone trabeculae in the 5-minute group than in the 10 minutes. CPC augmentation enabled an average 77% increase of the maximum pull-out strength compared to the control group. The study of screw insertion timing augmented with CPC was indicative of the fact that an increase in the initial fixation of the pedicle screw can be achieved when the screw is inserted before initiation of CPC hardening.

  1. Influence of the fixation region of a press-fit hip endoprosthesis on the stress-strain state of the "bone-implant" system.

    Science.gov (United States)

    Levadnyi, Ievgen; Awrejcewicz, Jan; Goethel, Márcio Fagundes; Loskutov, Alexander

    2017-05-01

    Although significant progress has been made in the development of total hip replacement, behaviour of the femoral component of an endoprosthesis in relation to the type of its fixation in the bone is still not fully understood. In this paper, behaviour of the femoral bone and the stem prosthesis is studied taking into account different types of prosthesis fixation in the medullary canal of the femur under the action of functional loads. For an analysis, a three-dimensional model of a femur has been developed based on the results of a computed tomography. The stress-strain state governing behaviour of the femoral bone and the stem prosthesis has been estimated with the use of the finite element method (FEM). The FEM analysis has shown that for the diaphyseal fixation, the area of contact between the surface of the endoprosthesis and the bone is insufficient and leads to large stresses in the implant accompanied by stress concentration in the distal femur. An increase in the area of contact between the implant and the bone raises the stiffness of the "bone-implant" system, which, in turn, reduces stresses in the implant. The applied metaphyseal-type fixation yielded an improvement of results regarding behaviour of the femoral bone and the stem prosthesis. Namely, the study yielded the distribution of stress in the bone similar to the physiological stress state. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Plate fixation of extra-articular fractures of the proximal phalanx: do new implants cause less problems?

    Science.gov (United States)

    Brei-Thoma, Pascale; Vögelin, Esther; Franz, Torsten

    2015-03-01

    Limited range of finger motion is a frequent complication after plate fixation of phalangeal fractures. The purpose of this study was to evaluate the results of plate fixation of extra-articular fractures of the proximal phalanx using current low-profile mini-fragment-systems. From 2006 to 2012, 32 patients with 36 extra-articular fractures of the proximal phalanx of the triphalangeal fingers were treated with open reduction and plate fixation (ORPF) using 1.2 and 1.5 mm mini-fragment systems. Patients presenting with open fractures grade 2 and 3 or relevant laceration of adjacent structures were excluded from the study. We retrospectively evaluated the rate of mal-union or non-union after ORPF, the need for revision surgery, for plate removal, and for tenolysis. Data were analyzed for further complications with regard to infections or complex regional pain syndrome (CRPS). No infections were noted. Five patients developed transient symptoms of CRPS. Six weeks postoperatively, total active finger motion (TAM) averaged 183°, and all 32 patients underwent formal hand therapy. At the latest follow-up or at the time of plate removal, respectively, the mean TAM improved to 213°. Extension lag of proximal interphalangeal joints was found in 67 % of all fractured fingers. Secondary surgery was necessary in 14 of 32 patients (2 corrective osteotomies, 12 plate removals including 7 procedures explicitly because of reduced mobility). Despite of new implant designs significant problems persist. Adhesions of extensor tendons leading to limited range of finger motion are still the most frequent complications after ORPF of proximal phalangeal fractures, even in absence of significant soft-tissue damage. Therapeutic, Retrospective, Level IV.

  3. Experimental characterization of monocrystalline Si targets implanted with Sb + ions

    Science.gov (United States)

    Labbani, R.; Serrar, H.; Baouni, L.

    2010-02-01

    Monocrystalline silicon targets were submitted to a beam of antimony ions. The Si(1 1 1) substrates were implanted at an energy of 120 keV, at room temperature, to a dose varying from 1×10 15 to 5×10 15 Sb + cm -2. To recover the radiation defects generated by Sb + ions, a thermal annealing was performed, at 900 °C for 30 min under very high vacuum. The study of antimony ion implantation in the monocrystalline silicon targets was performed by means of different experimental techniques: X-ray diffraction, optical and electrical measurements. The perturbations enhanced by Sb + ion implantation and the recovery of the damage were investigated with great interest. Although the selected techniques are not frequently applied to investigate such phenomena, they have provided important results. In as-implanted specimens, it was found that the radiation damage increased with the increase of antimony dose. After the annealing treatment, a good recovery of defects was obtained especially in the samples implanted with the low dose (i.e. 1×10 15 Sb + cm -2).

  4. Experimental studies of irradiated and hydrogen implantation damaged reactor steels

    Energy Technology Data Exchange (ETDEWEB)

    Slugeň, Vladimír, E-mail: vladimir.slugen@stuba.sk; Pecko, Stanislav; Sojak, Stanislav

    2016-01-15

    Radiation degradation of nuclear materials can be experimentally simulated via ion implantation. In our case, German reactor pressure vessel (RPV) steels were studied by positron annihilation lifetime spectroscopy (PALS). This unique non-destructive method can be effectively applied for the evaluation of microstructural changes and for the analysis of degradation of reactor steels due to neutron irradiation and proton implantation. Studied specimens of German reactor pressure vessel steels are originally from CARINA/CARISMA program. Eight specimens were measured in as-received state and two specimens were irradiated by neutrons in German experimental reactor VAK (Versuchsatomkraftwerk Kahl) in the 1980s. One of the specimens which was in as-received and neutron irradiated condition was also used for simulation of neutron damage by hydrogen nuclei implantation. Defects with the size of about 1–2 vacancies with relatively small contribution (with intensity on the level of 20–40 %) were observed in “as-received” steels. A significant increase in the size of the induced defects due to neutron damage was observed in the irradiated specimens resulting in 2–3 vacancies. The size and intensity of defects reached a similar level as in the specimens irradiated in the nuclear reactor due to the implantation of hydrogen ions with energies of 100 keV (up to the depth <500 nm).

  5. Experimental studies of irradiated and hydrogen implantation damaged reactor steels

    Science.gov (United States)

    Slugeň, Vladimír; Pecko, Stanislav; Sojak, Stanislav

    2016-01-01

    Radiation degradation of nuclear materials can be experimentally simulated via ion implantation. In our case, German reactor pressure vessel (RPV) steels were studied by positron annihilation lifetime spectroscopy (PALS). This unique non-destructive method can be effectively applied for the evaluation of microstructural changes and for the analysis of degradation of reactor steels due to neutron irradiation and proton implantation. Studied specimens of German reactor pressure vessel steels are originally from CARINA/CARISMA program. Eight specimens were measured in as-received state and two specimens were irradiated by neutrons in German experimental reactor VAK (Versuchsatomkraftwerk Kahl) in the 1980s. One of the specimens which was in as-received and neutron irradiated condition was also used for simulation of neutron damage by hydrogen nuclei implantation. Defects with the size of about 1-2 vacancies with relatively small contribution (with intensity on the level of 20-40 %) were observed in "as-received" steels. A significant increase in the size of the induced defects due to neutron damage was observed in the irradiated specimens resulting in 2-3 vacancies. The size and intensity of defects reached a similar level as in the specimens irradiated in the nuclear reactor due to the implantation of hydrogen ions with energies of 100 keV (up to the depth <500 nm).

  6. Endothelial Cell Implantation and Survival within Experimental Gliomas

    Science.gov (United States)

    Lal, Bachchu; Indurti, Ravi R.; Couraud, Pierre-Olivier; Goldstein, Gary W.; Laterra, John

    1994-10-01

    The delivery of therapeutic genes to primary brain neoplasms opens new opportunities for treating these frequently fatal tumors. Efficient gene delivery to tissues remains an important obstacle to therapy, and this problem has unique characteristics in brain tumors due to the blood-brain and blood-tumor barriers. The presence of endothelial mitogens and vessel proliferation within solid tumors suggests that genetically modified endothelial cells might efficiently transplant to brain tumors. Rat brain endothelial cells immortalized with the adenovirus E1A gene and further modified to express the β-galactosidase reporter were examined for their ability to survive implantation to experimental rat gliomas. Rats received 9L, F98, or C6 glioma cells in combination with endothelial cells intracranially to caudate/putamen or subcutaneously to flank. Implanted endothelial cells were identified by β-galactosidase histochemistry or by polymerase chain reaction in all tumors up to 35 days postimplantation, the latest time examined. Implanted endothelial cells appeared to cooperate in tumor vessel formation and expressed the brain-specific endothelial glucose transporter type 1 as identified by immunohistochemistry. The proliferation of implanted endothelial cells was supported by their increased number within tumors between postimplantation days 14 and 21 (P = 0.015) and by their expression of the proliferation antigen Ki67. These findings establish that genetically modified endothelial cells can be stably engrafted to growing gliomas and suggest that endothelial cell implantation may provide a means of delivering therapeutic genes to brain neoplasms and other solid tumors. In addition, endothelial implantation to brain may be useful for defining mechanisms of brain-specific endothelial differentiation.

  7. The effect of Hydroxyapatite/collagen I composites, bone marrow aspirate and bone graft on fixation of bone implants in sheep

    DEFF Research Database (Denmark)

    Babiker, Hassan

      The effect of Hydroxyapatite/collagen I composites, bone marrow aspirate and bone graft on fixation of bone implants IN SHEEP   Ph.D. Student, Hassan Babiker; Associate Professor, Ph.D. Ming Ding; Professor, dr.med., Soren Overgaard. Department of Orthopaedic Surgery, Odense University Hospital......, Odense, Denmark   Background: Hydroxyapatite and collagen composites (HA/coll) have the potential in mimicking and replacing skeletal bones. This study attempted to determine the effect of newly developed HA/coll-composites with and without bone marrow aspirate (BMA) in order to enhance the fixation...

  8. The evaluation criteria for selecting the type of fixation implant for total hip replacement

    Directory of Open Access Journals (Sweden)

    V. N. Chornyi

    2013-02-01

    Full Text Available Osteoarthrosis is a chronic disease of joints. Endoprosthetics is one of the methods of treatment of osteoarthrosis. A choice of method of fixing of implant is one of the important questions in the preoperative planning. In a clinic «Motor-Sich» conducted the analysis of operative treatment of a 41 patients. The use of cortical index and criterias of ultrasonic densitometry is described in the choice of type of endoprosthesis.

  9. Required minimum primary stability and torque values for immediate loading of mini dental implants: an experimental study in nonviable bovine femoral bone.

    Science.gov (United States)

    Dilek, Ozkan; Tezulas, Emre; Dincel, Mert

    2008-02-01

    Immediate loading of implants decreases the period a patient has to remain edentulous. However, for successful immediate loading in clinical practice, a strong initial fixation with bone is a prerequisite. In the present study, it is aimed to measure the primary stability, minimum placement, and removal torque values of mini dental implants which were originally designed for immediate loading. Therefore, mini dental implants (10, 13, 15, and 18 mm length and 1.8 and 2.4 mm diameter) were inserted into nonviable femoral bovine bone with a physiodispenser which can show the torque values digitally. After the implants were inserted, the primary stability values were measured with Periotest. Then the implants were removed from the bone using the same physiodispenser and the removal torque values of the implants were measured. Finally, 3 related tables were created, which show the match of the 3 different values (primary stability, placement, and removal torque) for each implant. The best Periotest values are -8 to +9, which reveal the best primary fixation range. In the tables, placement and removal torque values that correspond to this range are observed. In conclusion, it is believed that the results will aid the dentists in their decision for the selection of the Periotest value ranges and their related placement and removal torque values to decide for immediate loading of the mini dental implants. Mini dental implants, which are especially designed for immediate loading, can only be loaded immediately if their Periotest values (and their related placement and removal torque values) are measured to be between the range of -8 to +9. It is believed that the placement and removal torque values below the -8 to +9 Periotest range are not suitable for immediate loading procedure. Because this study concentrates only on experimental results, further clinical research is needed to be made in order to draw more definite conclusions about immediate loading of the mini dental

  10. Experimental and failure analysis of the prosthetic finger joint implants

    Science.gov (United States)

    Naidu, Sanjiv H.

    Small joint replacement arthroplasty of the hand is a well accepted surgical procedure to restore function and cosmesis in an individual with a crippled hand. Silicone elastomers have been used as prosthetic material in various small hand joints for well over three decades. Although the clinical science aspects of silicone elastomer failure are well known, the physical science aspects of prosthetic failure are scant and vague. In the following thesis, using both an animal model, and actual retrieved specimens which have failed in human service, experimental and failure analysis of silicone finger joints are presented. Fractured surfaces of retrieved silicone trapezial implants, and silicone finger joint implants were studied with both FESEM and SEM; the mode of failure for silicone trapezium is by wear polishing, whereas the finger joint implants failed either by fatigue fracture or tearing of the elastomer, or a combination of both. Thermal analysis revealed that the retrieved elastomer implants maintained its viscoelastic properties throughout the service period. In order to provide for a more functional and physiologic arthroplasty a novel finger joint (Rolamite prosthesis) is proposed using more recently developed thermoplastic polymers. The following thesis also addresses the outcome of the experimental studies of the Rolamite prosthesis in a rabbit animal model, in addition to the failure analysis of the thermoplastic polymers while in service in an in vivo synovial environment. Results of retrieved Rolamite specimens suggest that the use for thermoplastic elastomers such as block copolymer based elastomers in a synovial environment such as a mammalian joint may very well be limited.

  11. Screw augmentation reduces motion at the bone-implant interface: a biomechanical study of locking plate fixation of proximal humeral fractures.

    Science.gov (United States)

    Schliemann, Benedikt; Seifert, Robert; Rosslenbroich, Steffen B; Theisen, Christina; Wähnert, Dirk; Raschke, Michael J; Weimann, Andre

    2015-12-01

    Shear forces at the bone-implant interface lead to a loss of reduction after locking plate fixation of proximal humeral fractures. The aim of the study was to analyze the roles of medial support screws and screw augmentation in failure loads and motion at the bone-implant interface after locking plate fixation of proximal humeral fractures. Unstable 3-part fractures were simulated in 6 pairs of cadaveric humeri and were fixed with a DiPhos-H locking plate (Lima Corporate, Udine, Italy). An additional medial support screw was implanted in 1 humerus of every donor. The opposite humerus was stabilized with a medial support screw and additional bone cement augmentation of the 2 anteriorly directed head screws. Specimens were loaded in the varus bending position. Stiffness, failure loads, plate bending, and the motion at the bone-implant interface were evaluated using an optical motion capture system. The mean load to failure was 669 N (standard deviation [SD], 117 N) after fixation with medial support screws alone and 706 N (SD, 153 N) after additional head screw augmentation (P = .646). The initial stiffness was 453 N/mm (SD, 4.16 N/mm) and 461 N/mm (SD, 64.3 N/mm), respectively (P = .594). Plate bending did not differ between the 2 groups. However, motion at the bone-implant interface was significantly reduced after head screw augmentation (P < .05). The addition of bone cement to augment anteriorly directed head screws does not increase stiffness and failure loads but reduces motion at the bone-implant interface. Thus, the risk of secondary dislocation of the head fragment may be reduced. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  12. Estudo macroscópico e dinamométrico comparativo de implantes (ímãs recobertos e de suas técnicas de fixação em órbitas de coelhas Comparative macroscopic and dynamometric study of implants (covered magnets and techniques of their fixation in orbits of female rabbits

    Directory of Open Access Journals (Sweden)

    Elcio Roque Kleinpaul

    2004-06-01

    Full Text Available OBJETIVOS: Avaliação clínica dos sinais da reação inflamatória de fixação de implante orbitário (ímã recoberto por ouro e avaliação macroscópica de sua resistência aos fluidos orgânicos. MÉTODOS: Estudo experimental em 54 coelhas adultas, divididas em três grupos de 18, com 3 subgrupos de 6 de acordo com o material usado para fixação, avaliação com uma, três e seis semanas de pós-operatório. Fixação, no rebordo inferior da órbita, de implante (ímã e ouro por meio de cola ou parafuso ou fio inabsorvível (Mersilene 5.0®. As órbitas contralaterais (sem implante compuseram o grupo-controle. Medidas da resistência à tração tangencial do implante fixado. RESULTADOS: Sinais clínicos de reação inflamatória à fixação orbitária do implante foram observados com cianoacrilato, parafuso, ou sutura inabsorvível (Mersilene 5.0®, até a sexta semana de pós-operatório, sendo mais intensa no grupo F (fixação com fio. A força de tração de 80 gf, independentemente do tipo de fixação, não produziu arrancamentos em 94,5% dos implantes na primeira semana, 100% na terceira semana e em 94,5% dos casos na sexta semana. CONCLUSÃO: Sinais clínicos de reação inflamatória do implante e sua fixação foram observados com cianoacrilato ou parafuso ou sutura inabsorvível (Mersilene 5.0® até a sexta semana pós-operatória, sendo mais intensa no grupo F (fio. A resistência do implante aos fluídos orgânicos mostrou falha em 9,3% (implante com dano.PURPOSE: To evaluate the clinical signs of inflammatory reaction in the fixation of an orbitary implant (magnet, covered by gold, and to evaluate the macroscopic resistance to organic fluids of the used implants. METHODS: An experimental study was performed in 54 adult female rabbits, divided into 3 groups of eighteen with 3 subgroups of 6 according to the material used for fixation; the implants were evaluated at weeks 1, 3 and 6 after surgery. An implant (magnet

  13. Stable fixation of an osseointegated implant system for above-the-knee amputees: titel RSA and radiographic evaluation of migration and bone remodeling in 55 cases.

    Science.gov (United States)

    Nebergall, Audrey; Bragdon, Charles; Antonellis, Anne; Kärrholm, Johan; Brånemark, Rickard; Malchau, Henrik

    2012-04-01

    Rehabilitation of patients with transfemoral amputations is particularly difficult due to problems in using standard socket prostheses. We wanted to assess long-term fixation of the osseointegrated implant system (OPRA) using radiostereometric analysis (RSA) and periprosthetic bone remodeling. 51 patients with transfemoral amputations (55 implants) were enrolled in an RSA study. RSA and plain radiographs were scheduled at 6 months and at 1, 2, 5, 7, and 10 years after surgery. RSA films were analyzed using UmRSA software. Plain radiographs were graded for bone resorption, cancellization, cortical thinning, and trabecular streaming or buttressing in specifically defined zones around the implant. At 5 years, the median (SE) migration of the implant was -0.02 (0.06) mm distally. The rotational movement was 0.42 (0.32) degrees around the longitudinal axis. There was no statistically significant difference in median rotation or migration at any follow-up time. Cancellization of the cortex (plain radiographic grading) appeared in at least 1 zone in over half of the patients at 2 years. However, the prevalence of cancellization had decreased by the 5-year follow-up. The RSA analysis for the OPRA system indicated stable fixation of the implant. The periprosthetic bone remodeling showed similarities with changes seen around uncemented hip stems. The OPRA system is a new and promising approach for addressing the challenges faced by patients with transfemoral amputations.

  14. Incidence and predictors of clinically relevant cardiac perforation associated with systematic implantation of active-fixation pacing and defibrillation leads: a single-centre experience with over 3800 implanted leads.

    Science.gov (United States)

    Cano, Óscar; Andrés, Ana; Alonso, Pau; Osca, Joaquín; Sancho-Tello, María-José; Olagüe, José; Martínez-Dolz, Luis

    2017-01-01

    Active-fixation leads have been associated with higher incidence of cardiac perforation. Large series specifically evaluating this complication are lacking. We sought to evaluate the incidence and predictors of clinically relevant cardiac perforation in a consecutive series of patients implanted with active-fixation pacing and defibrillation leads. We conducted a retrospective observational study including all consecutive patients implanted with an active-fixation pacing/defibrillation lead at our institution from July 2008 to July 2015. The incidence of clinically relevant cardiac perforation and cardiac tamponade was evaluated. Univariate and multivariate analyses were used to identify predictors of cardiac perforation. Acute and long-term management of these patients was also investigated. A total of 3822 active-fixation pacing (n = 3035) and defibrillation (n = 787) leads were implanted in 2200 patients. Seventeen patients (0.8%) had clinically relevant cardiac perforation (13 acute and 4 subacute perforations), and 13 (0.5%) had cardiac tamponade resolved with pericardiocentesis. None of the patients with cardiac perforation required surgical treatment. In multivariate analysis, an age >80 years (OR 3.84, 95% CI 1.14-12.87, P = 0.029), female sex (OR 3.14, 95% CI 1.07-9.22, P = 0.037), and an apical position of the right ventricular lead (OR 3.37, 95% CI 1.17-9.67, P = 0.024) were independent predictors of cardiac perforation. Implantation of active-fixation leads is associated with a low incidence of clinically relevant cardiac perforation. Older and female patients have a higher risk of perforation as well as those patients receiving the ventricular lead in an apical position. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

  15. Biomechanical comparison of tension band- and interfragmentary screw fixation with a new implant in transverse patella fractures.

    Science.gov (United States)

    Dargel, J; Gick, S; Mader, K; Koebke, J; Pennig, D

    2010-02-01

    The aim of the present study was to compare the primary fixation stability and initial fixation stiffness of two established fixation techniques, the tension band wiring technique and interfragmentary screw fixation, with a mini-screw fragment fixation system in a model of transverse patella fracture. It was hypothesised that the biomechanical loading performance of the fragment fixation system would not significantly differ from the loading characteristics of the two established methods currently investigated. Ninety-six calf patellae were used in this biomechanical model. A standardized transverse patella fracture was induced and three different fixation methods, including the modified tension band wiring technique, interfragmentary screw fixation, and the mini-screw fragment fixation system, were used for fragment fixation. Specimens were mounted to a loading rig which was secured within a material testing machine. In each fixation group, eight specimens were loaded to failure at a simulated knee angle of either 0 degrees or 45 degrees . Another eight specimens were submitted to a polycyclic loading protocol consisting of 30 cycles between 20N and 300N at a simulated knee angle of 0 degrees or 45 degrees . The residual displacement between the first and the last cycle was recorded. Differences in the biomechanical performance between the three fixation groups were evaluated. No significant differences between the three fixation groups were observed in the parameters maximum load to failure and linear fixation stiffness with monocyclic loading. Specimens being loaded at 45 degrees showed significantly lower maximum failure loads and linear stiffness when compared with 0 degrees . During polycyclic loading, no significant differences in the residual displacement were observed between the groups at 0 degrees loading angle, while at 45 degrees , residual displacement was significantly higher with tension band fixation when compared with interfragmentary screw

  16. Novel external fixation fracture method with circular locking mechanism compared with the application of dynamic axial external fixator on experimental tibial model ensures better stability in bending and favourable performance in dynamic loads.

    Science.gov (United States)

    Pavic, Arsen; Kodvanj, Janos; Sabalic, Srecko; Cukelj, Fabijan; Bakota, Bore

    2013-09-01

    The aim of this study was to compare the biomechanical properties of a novel tibial external bone fracture fixator with a circular locking mechanism with standard dynamic axial external fixator. In order to investigate the prototype usability in experimental conditions, a biomechanical study was performed in which 42 polyacetal tubes set in 14 experimental groups and subgroups represented the fractured tibia that were fixed by a standard dynamic axial external fixator and a novel fixator. Displacements under static and dynamic loads were measured, with static ones corresponding to three directions of fragment movement and dynamic simulating the human gait. Analysis was performed in SPSS v13, with significance set at Pexternal fixator outperformed the novel one in the situations of bending with "fragments in contact" study groups. There were no significant differences in dynamic load, despite better numerical result of the novel fixator. The novel fixator is expectedly faster applicable and offers greater extent of external fixation flexibility. Further developments of this model thus seems justified in both construction improvement and on clinical application. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Exploring the Boundaries of N2-Fixation in Cereals and Grasses: A Hypothetical and Experimental Framework

    NARCIS (Netherlands)

    Giller, K.E.; Merckx, R.

    2003-01-01

    Despite more than 40 years of research on free-living and endophytic bacteria associated with cereals and grasses, conclusive examples of impacts of non-symbiotic N2-fixation in agriculture are lacking. All available methods for measurement of N2-fixation associated with cereals and grasses have

  18. Laparoscopic intraperitoneal mesh fixation with fibrin sealant (Tisseel) vs. titanium tacks: a randomised controlled experimental study in pigs.

    Science.gov (United States)

    Eriksen, J R; Bech, J I; Linnemann, D; Rosenberg, J

    2008-10-01

    the laparoscopic fixation of an intraperitoneal mesh with Tisseel is safe and technically feasible in a pig model. There is still no evidence that fibrin-sealing alone is appropriate for intraperitoneal mesh fixation in hernia repair, but the technique might become an alternative or supplement to mechanical mesh fixation. Until then, further experimental research in animal hernia models with larger meshes is needed, especially with a focus on mesh folding and displacement.

  19. Implant stability and marginal bone level of microgrooved zirconia dental implants: A 3-month experimental study on dogs

    Directory of Open Access Journals (Sweden)

    Delgado-Ruíz Rafael Arcesio

    2014-01-01

    Full Text Available Background/Aim. The modification of implant surfaces could affect mechanical implant stability as well as dynamics and quality of peri-implant bone healing. The aim of this 3-month experimental study in dogs was to investigate implant stability, marginal bone levels and bone tissue response to zirconia dental implants with two laser-micro-grooved intraosseous surfaces in comparison with nongrooved sandblasted zirconia and sandblasted, high-temperature etched titanium implants. Methods. Implant surface characterization was performed using optical interferometric profilometry and energy dispersive X-ray spectroscopy. A total of 96 implants (4 mm in diameter and 10 mm in length were inserted randomly in both sides of the lower jaw of 12 Fox Hound dogs divided into groups of 24 each: the control (titanium, the group A (sandblasted zirconia, the group B (sandblasted zirconia plus microgrooved neck and the group C (sandblasted zirconia plus all microgrooved. All the implants were immediately loaded. Insertion torque, periotest values, radiographic crestal bone level and removal torque were recorded during the 3-month follow-up. Qualitative scanning electon micro-scope (SEM analysis of the bone-implant interfaces of each group was performed. Results. Insertion torque values were higher in the group C and control implants (p the control > the group B > the group A (p the control > the group B > the group A (p < 0.05. SEM showed that implant surfaces of the groups B and C had an extra bone growth inside the microgrooves that corresponded to the shape and direction of the microgrooves. Conclusion. The addition of micro-grooves to the entire intraosseous surface of zirconia dental implants enhances primary and secondary implant stability, promotes bone tissue ingrowth and preserves crestal bone levels.

  20. Re-osseointegration after treatment of peri-implantitis at different implant surfaces. An experimental study in the dog.

    Science.gov (United States)

    Persson, L G; Berglundh, T; Lindhe, J; Sennerby, L

    2001-12-01

    Peri-implantitis is a condition that includes soft tissue inflammation and rapid loss of bone. Treatment of peri-implantitis includes both antimicrobial and bone augmenting methods. The question of whether true re-osseointegration may occur following treatment of peri-implantitis is controversial. The aim of this study was to investigate whether the character of the implant surface was of importance for the occurrence of re-osseointegration following treatment of peri-implantitis. Four beagle dogs were used. The mandibular premolars were extracted. After 12 months, 3 ITI(R) solid screw dental implants were placed in each side of the mandible. In the left side, implants with a turned surface (Turned sites) were used, while in the right side implants with a SLA surface (SLA sites) were placed. After 3 months of healing, peri-implantitis was induced by ligature placement and plaque accumulation. When about 50% of the initial bone support was lost, the ligatures were removed. Five weeks later, treatment was initiated. Each animal received tablets of Amoxicillin and Metronidazole for a period of 17 days. Three days after the start of the antibiotic regimen, one implant site (experimental site) in each quadrant was exposed to local therapy. Following flap elevation, the exposed titanium surface was cleaned with the use of cotton pellets soaked in saline. The implants were submerged. Six months later, biopsies were obtained. Treatment resulted in a 72% bone fill of the bone defects at Turned sites and 76% at SLA sites. The amount of re-osseointegration was 22% at Turned sites and 84% at SLA sites. A treatment regimen that included (i) systemic administration of antibiotics combined with (ii) granulation tissue removal and implant surface cleaning resulted in resolution of peri-implantitis and bone fill in adjacent bone defects. Further, while substantial "re-osseointegration" occurred to an implant with a rough surface (SLA), bone growth on a previously exposed smooth

  1. Effect of Pentoxifylline Administration on an Experimental Rat Model of Femur Fracture Healing With Intramedullary Fixation

    Science.gov (United States)

    Vashghani Farahani, Mohammad Mahdi; Masteri Farahani, Reza; Mostafavinia, Ataroalsadat; Abbasian, Mohammad Reza; Pouriran, Ramin; Noruzian, Mohammad; Ghoreishi, Seyed Kamran; Aryan, Arefe; Bayat, Mohammad

    2015-01-01

    Background: Globally, musculoskeletal injuries comprise a major public health problem that contributes to a large burden of disability and suffering. Pentoxifylline (PTX) has been originally used as a hemorheologic drug to treat intermittent claudication. Previous test tube and in vivo studies reported the beneficial effects of PTX on bony tissue. Objectives: This study aims to evaluate the effects of different dosages of PTX on biomechanical properties that occur during the late phase of the fracture healing process following a complete femoral osteotomy in a rat model. We applied intramedullary pin fixation as the treatment of choice. Materials and Methods: This experimental study was conducted at the Shahid Beheshti University of Medical Sciences, Tehran, Iran. We used the simple random technique to divide 35 female rats into five groups. Group 1 received intraperitoneal (i.p.) PTX (50 mg/kg, once daily) injections, starting 15 days before surgery, and group 2, group 3, and group 4 received 50 mg/kg, 100 mg/kg, and 200 mg/kg i.p. PTX injections, respectively, once daily after surgery. All animals across groups received treatment for six weeks (until sacrificed). Complete surgical transverse osteotomy was performed in the right femur of all rats. At six weeks after surgery, the femurs were subjected to a three-point bending test. Results: Daily administration of 50 mg/kg PTX (groups 1 and 2) decreased the high stress load in repairing osteotomized femurs when compared with the control group. The highest dose of PTX (200 mg/kg) significantly increased the high stress load when compared with the control group (P = 0.030), group 1 (P = 0.023), group 2 (P = 0.008), and group 3 (P = 0.010), per the LSD findings. Conclusions: Treatment with 200 mg/kg PTX accelerated fracture healing when compared with the control group. PMID:26756019

  2. Experimental Fracture Model versus Osteotomy Model in Metacarpal Bone Plate Fixation

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    S. Ochman

    2011-01-01

    Full Text Available Introduction. Osteotomy or fracture models can be used to evaluate mechanical properties of fixation techniques of the hand skeleton in vitro. Although many studies make use of osteotomy models, fracture models simulate the clinical situation more realistically. This study investigates monocortical and bicortical plate fixation on metacarpal bones considering both aforementioned models to decide which method is best suited to test fixation techniques. Methods. Porcine metacarpal bones (=40 were randomized into 4 groups. In groups I and II bones were fractured with a modified 3-point bending test. The intact bones represented a further control group to which the other groups after fixation were compared. In groups III and IV a standard osteotomy was carried out. Bones were fixated with plates monocortically (group I, III and bicortically (group II, IV and tested for failure. Results. Bones fractured at a mean maximum load of 482.8 N ± 104.8 N with a relative standard deviation (RSD of 21.7%, mean stiffness was 122.3 ± 35 N/mm. In the fracture model, there was a significant difference (=0.01 for maximum load of monocortically and bicortically fixed bones in contrast to the osteotomy model (=0.9. Discussion. In the fracture model, because one can use the same bone for both measurements in the intact state and the bone-plate construct states, the impact of inter-individual differences is reduced. In contrast to the osteotomy model there are differences between monocortical and bicortical fixations in the fracture model. Thus simulation of the in vivo situation is better and seems to be suitable for the evaluation of mechanical properties of fixation techniques on metacarpals.

  3. Osseointegration at implants placed into delayed reimplanted roots: an experimental study in dogs.

    Science.gov (United States)

    de Carvalho Cardoso, Leandro; Poi, Wilson Roberto; Botticelli, Daniele; Junior, Idelmo Rangel Garcia; Pantani, Fabio; Pereira, Cassiano Costa Silva

    2014-05-01

    To evaluate peri-implant bone repair of implants placed into the roots of delayed reimplanted teeth, in a process of ankylosis and external replacement resorption. The third and fourth mandibular premolars of four (4) beagle dogs were used as experimental sites. The study was divided into three stages: stage 1 - endodontic and extraction/reimplantation session, stage 2 - decrowning session and stage 3 - implant placement. Two groups were identified: (I) immediate implants, including implants installed in fresh extraction sockets of the distal roots, and (II) experimental implants, including implants installed into the retained ankylotic mesial roots. In each group, 16 implants were planned to be inserted, but only 9 immediate implants and 12 experimental implants were used for analyses. Implants were intended to heal in a submerged mode. After 4 months of healing, the animals were sacrificed and ground sections were obtained for histomorphometric evaluation. Eleven of the twelve implants in the experimental group were found successful regarding clinical and radiographic aspects. For immediate implants, a lower BIC% was found at the coronal portion (BIC% 1 = 42.2%) compared with the three most coronal threads portion (BIC% 2 = 55.1). Also, experimental implants presented a lower BIC% at the coronal portion (BIC% 1 = 36.9%) compared with the three most coronal threads portion (BIC% 2 = 45.3). Comparison between groups showed a higher degree of BIC% and mineralization in immediate group compared with experimental group. The differences, however, did not yield statistical significance. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  4. Experimental investigation of commercial small diameter dental implants in porcine mandibular segments.

    Science.gov (United States)

    Hasan, Istabrak; Heinemann, Friedhelm; Schwegmann, Monika; Keilig, Ludger; Stark, Helmut; Bourauel, Christoph

    2017-02-01

    Small diameter (mini) dental implants have become more popular in recent years as alternatives to classical implant treatment in clinical cases with critical bony situations. However, an in-depth scientific analysis of the mechanical and biomechanical effects of small diameter implants has not yet been published. The aim of the present study was to investigate experimentally different commercial mini implants by measuring their displacements under immediate loading. Twelve commercially available mini implants were measured. Implants were inserted into porcine mandibular segments and loaded by means of a predefined displacement of 0.5 mm of the loading system. The implants were loaded at an angle of 30° to the implant long axis using the self-developed biomechanical hexapod measurement system. Implant displacements were registered. The experimental results were compared to the numerical ones from a previous study. Measured implant displacements were within the range of 39-194 μm. A large variation in the displacements was obtained among the different implant systems due to the different designs and thread profiles. Comparing experimental and numerical results, the displacements that were obtained numerically were within the range of 79-347 μm. The different commercial mini implants showed acceptable primary stability and could be loaded immediately after their insertion.

  5. Effects of low-dose microwave on healing of fractures with titanium alloy internal fixation: an experimental study in a rabbit model.

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    Dongmei Ye

    Full Text Available BACKGROUND: Microwave is a method for improving fracture repair. However, one of the contraindications for microwave treatment listed in the literature is surgically implanted metal plates in the treatment field. The reason is that the reflection of electromagnetic waves and the eddy current stimulated by microwave would increase the temperature of magnetic implants and cause heat damage in tissues. Comparing with traditional medical stainless steel, titanium alloy is a kind of medical implants with low magnetic permeability and electric conductivity. But the effects of microwave treatment on fracture with titanium alloy internal fixation in vivo were not reported. The aim of this article was to evaluate the security and effects of microwave on healing of a fracture with titanium alloy internal fixation. METHODS: Titanium alloy internal fixation systems were implanted in New Zealand rabbits with a 3.0 mm bone defect in the middle of femur. We applied a 30-day microwave treatment (2,450MHz, 25W, 10 min per day to the fracture 3 days after operation. Temperature changes of muscle tissues around implants were measured during the irradiation. Normalized radiographic density of the fracture gap was measured on the 10th day and 30th day of the microwave treatment. All of the animals were killed after 10 and 30 days microwave treatment with histologic and histomorphometric examinations performed on the harvested tissues. FINDINGS: The temperatures did not increase significantly in animals with titanium alloy implants. The security of microwave treatment was also supported by histology of muscles, nerve and bone around the implants. Radiographic assessment, histologic and histomorphometric examinations revealed significant improvement in the healing bone. CONCLUSION: Our results suggest that, in the healing of fracture with titanium alloy internal fixation, a low dose of microwave treatment may be a promising method.

  6. Effect of Intraoperative Three-Dimensional Imaging During the Reduction and Fixation of Displaced Calcaneal Fractures on Articular Congruence and Implant Fixation

    DEFF Research Database (Denmark)

    Eckardt, Henrik; Lind, Marianne

    2015-01-01

    BACKGROUND: Operative treatment of displaced calcaneal fractures should restore joint congruence, but conventional fluoroscopy is unable to fully visualize the subtalar joint. We questioned whether intraoperative 3-dimensional (3D) imaging would aid in the reduction of calcaneal fractures......, resulting in improved articular congruence and implant positioning. METHOD: Sixty-two displaced calcaneal fractures were operated on using standard fluoroscopic views. When the surgeon had achieved a satisfactory reduction, an intraoperative 3D scan was conducted, malreductions or implant imperfections were......: Intraoperative 3D imaging improved the articular reduction of the posterior facet and secured optimal implant position in displaced calcaneal fractures. Radiation dose to the patient was less than that of a normal foot computed tomography scan. LEVEL OF EVIDENCE: Level IV, case series....

  7. [Experimental study of delayed implantation on bone grafts].

    Science.gov (United States)

    Zhang, Guo-Zhi; Zhang, Guo-Quan

    2007-05-01

    To explore the feasibility of transplantation of frozen autogenous mandible with delayed implantation. Operations were performed to create two defects in the bilateral mandible of 16 dogs. The left defect was grafted by composite transplantation of frozen autogenous mandible (immersed in -196 degrees C liquid nitrogen) with fresh cancellous ilium (composite transplantation group, CTG). The right defect was grafted by fresh ilium (iliac transplantation group, ITG). Three months after transplantation one IMZ TPS dental implant was placed into the graft of each side. At 3, 6, 9, 12 weeks postoperatively, 4 animals were sacrificed respectively and the grafts with dental implant were harvested for gross observation, X-Ray examination and histological evaluation to compare peri-implant bone healing between composite transplantation group and iliac transplantation group. There was no absorbing bone density reducing image of peri-implant at each stage. The quantified X-Ray gray extent displayed obvious variation of interfacial bone density between two kinds of grafts at 3 weeks, 6 weeks and 9 weeks after implantation. The composite transplantation group obviously surpassed the iliac transplantation group. At 12 weeks after the implantation, there was no significant difference between the peri-implant bones of both sides. There was satisfactory osseointegration between the implants and the two kinds of grafts. The healing style of peri-implant bone was similar. Good osseointegration was performed between the implant and the composite transplantation of frozen autogenous mandible following delayed implantation.

  8. Evaluation of bone loss in antibacterial coated dental implants: An experimental study in dogs.

    Science.gov (United States)

    Godoy-Gallardo, Maria; Manzanares-Céspedes, Maria Cristina; Sevilla, Pablo; Nart, José; Manzanares, Norberto; Manero, José M; Gil, Francisco Javier; Boyd, Steven K; Rodríguez, Daniel

    2016-12-01

    The aim of this study was to evaluate the in vivo effect of antibacterial modified dental implants in the first stages of peri-implantitis. Thirty dental implants were inserted in the mandibular premolar sites of 5 beagle dogs. Sites were randomly assigned to Ti (untreated implants, 10units), Ti_Ag (silver electrodeposition treatment, 10units), and Ti_TSP (silanization treatment, 10units). Coated implants were characterized by scanning electron microscopy, interferometry and X-ray photoelectron spectroscopy. Two months after implant insertion, experimental peri-implantitis was initiated by ligature placement. Ligatures were removed 2months later, and plaque formation was allowed for 2 additional months. Clinical and radiographic analyses were performed during the study. Implant-tissue samples were prepared for micro computed tomography, backscattered scanning electron microscopy, histomorphometric and histological analyses and ion release measurements. X-ray, SEM and histology images showed that vertical bone resorption in treated implants was lower than in the control group (Pimplant surface. Histological analysis suggested an increase of peri-implant bone formation on silanized implants. However, the short post-ligature period was not enough to detect differences in clinical parameters among implant groups. Within the limits of this study, antibacterial surface treatments have a positive effect against bone resorption induced by peri-implantitis. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Fixation-Dependent Memory for Natural Scenes: An Experimental Test of Scanpath Theory

    Science.gov (United States)

    Foulsham, Tom; Kingstone, Alan

    2013-01-01

    Many modern theories propose that perceptual information is represented by the sensorimotor activity elicited by the original stimulus. Scanpath theory (Noton & Stark, 1971) predicts that reinstating a sequence of eye fixations will help an observer recognize a previously seen image. However, the only studies to investigate this are…

  10. Trauma to an implant-supported crown that was saved by the fixation screw : A case report

    NARCIS (Netherlands)

    den Hartog, Laurens; Meijer, Henny J. A.; Stellingsma, Kees; Santing, Hendrik J.; Raghoebar, Gerry M.

    A traumatic impact to an implant-supported crown might damage the implant, restoration and peri-implant tissues. Ideally, only a small prosthetic retreatment is needed for restoration, as complicated prosthetic retreatments or surgical retreatments in particular, could be very inconvenient for the

  11. Effect of formalin fixation on the immunohistochemical detection of PRRS virus antigen in experimentally and naturally infected pigs.

    Science.gov (United States)

    Van Alstine, W G; Popielarczyk, M; Albregts, S R

    2002-11-01

    The purpose of this study was to determine the effect of formalin fixation on the immunohistochemical detection of porcine reproductive and respiratory syndrome (PRRS) viral antigen in lungs of experimentally and naturally infected pigs. In separate trials, five 24-day-old pigs and six 10-day-old pigs were housed as separate groups in isolation and inoculated intranasally with 10(5.5) TCID50 of an isolate of PRRS virus (PRRSV; P129). The older and younger pigs were euthanatized at 7 and 10 days post inoculation (dpi), respectively. At necropsy, all pigs had gross and microscopic lung lesions typical of PRRS, and PRRSV was isolated from all pigs. To insure uniform fixation, lungs from each pig were cut into 1-cm-thick slices and immersed into 10% neutral-buffered formalin. After fixation in formalin for 8 hours or 1, 2, 3, 5, 6, 8, 10, and 15 days, 3 lung sections from some or all pigs were processed for histological examination using routine methods. Immunohistochemical staining for PRRSV antigen was positive at the following times (days unless otherwise stated) after fixation (percentage of pigs staining positive for PRRSV in parentheses): 8 hours (100); 1 (100); 2 (100); 3 (80); 5 (33); and 6, 8, 10, and 15 (0-all negative). To further evaluate the effects of formalin fixation on PRRSV immunodetection, 31 field cases of PRRS were selected for immunohistochemistry (IHC). Over a 3-month period, submitted cases were selected from the Purdue University Animal Disease Diagnostic Laboratory, W. Lafayette, Indiana, for IHC if 1) the clinical history included respiratory disease, 2) PRRSV was isolated from lung and/or serum from the submitted pigs or tissues, 3) at least 1 section of lung fixed in 10% neutral-buffered formalin was submitted for IHC, and 4) the duration of fixation could be accurately determined from the case history. Of the 31 PRRSV-infected pig cases meeting the selection criteria, 23 were fixed in formalin for 4 days or less. Twenty-one of these 23 (91

  12. A Case Report of Implant Fracture of Extensively Porous-Coated, Distally Fixated Cementless Long Stem: Detailed Course of Stem Bending Development.

    Science.gov (United States)

    Mimura, Tomohiro

    2015-01-01

    We report the fracture of a cementless long stem in a distally fixated, extensively porous-coated femoral prosthesis used for revisional total hip arthroplasty (THA) 9 years previously in a 48-year-old woman, measuring 58 kg in weight and 155 cm in height. Following resolution of an infection 7 years after the revisional THA, a series of posterior dislocations occurred up until 7 months before sudden stem fracture. Extensive radiographic imaging evidence indicated a gradual progression of bending in the stem, and scanning electron microscope energy dispersive X-ray spectroscopy revealed oxygen in the medial and lateral sections, suspecting in vivo corrosion. We retrospectively examined the detailed course of stem bending development prior to stem fracture. The stem bending immediately after the revisional THA, at the first dislocation, and immediately before the stem fracture was 0°, 1.9°, and 5.2°, respectively. We consider that the cyclic loading with poor proximal bone support, distal fixation, and small diameter were the potential risk of this implant fracture. However, the course of stem bending development suggested that repeated operations and several dislocations might have aggravated the implant fatigue in the present case.

  13. A Case Report of Implant Fracture of Extensively Porous-Coated, Distally Fixated Cementless Long Stem: Detailed Course of Stem Bending Development

    Directory of Open Access Journals (Sweden)

    Tomohiro Mimura

    2015-01-01

    Full Text Available We report the fracture of a cementless long stem in a distally fixated, extensively porous-coated femoral prosthesis used for revisional total hip arthroplasty (THA 9 years previously in a 48-year-old woman, measuring 58 kg in weight and 155 cm in height. Following resolution of an infection 7 years after the revisional THA, a series of posterior dislocations occurred up until 7 months before sudden stem fracture. Extensive radiographic imaging evidence indicated a gradual progression of bending in the stem, and scanning electron microscope energy dispersive X-ray spectroscopy revealed oxygen in the medial and lateral sections, suspecting in vivo corrosion. We retrospectively examined the detailed course of stem bending development prior to stem fracture. The stem bending immediately after the revisional THA, at the first dislocation, and immediately before the stem fracture was 0°, 1.9°, and 5.2°, respectively. We consider that the cyclic loading with poor proximal bone support, distal fixation, and small diameter were the potential risk of this implant fracture. However, the course of stem bending development suggested that repeated operations and several dislocations might have aggravated the implant fatigue in the present case.

  14. Immunological aspects of clinical and experimental cardiac valve allograft implantation

    NARCIS (Netherlands)

    F.B.S. Oei (Frank)

    2001-01-01

    textabstractThe documented history of allogeneic cardiac valve implantation began in 1952. In that year, the first successful implantation of an canine aortic valve in the descendlng aorta of another dog, was carried out by Conrad Lam etal. Driven by the succes seen in this animal model Murray et

  15. High speed insertion of bone fracture fixation pins: a finite element penetration model with experimental comparisons.

    Science.gov (United States)

    Prygoski, Matthew P; Pasang, Timotius; Schmid, Steven R; Lozier, Antony J

    2011-12-01

    A new method of bone fracture fixation is considered in which small pins/darts are dynamically inserted into bone to prevent translation and rotation at the fracture site. An ABAQUS model was developed to analyze dart penetration in cortical and cancellous bone for varying dart diameter, material, and velocity, and cortical thickness. The method is advocated for bioresorbable darts, so polylactide (PLA) and magnesium are the materials examined in this study. Numerical results showed that magnesium darts can achieve full penetration in bone while suffering little damage. The PLA darts penetrated thin bone well, but substantial deformation was seen as the cortical thickness increased, especially for small diameter darts. As partial validation, prototype PLA fixation darts were fired into cadaveric bone with a custom nailer. As in the model, the PLA darts could penetrate thin cortices but saw gross deformation when impacted against thicker bone.

  16. Impact of dental implant insertion method on the peri-implant bone tissue: Experimental study

    Directory of Open Access Journals (Sweden)

    Stamatović Novak

    2013-01-01

    Full Text Available Background/Aim. The function of dental implants depends on their stability in bone tissue over extended period of time, i.e. on osseointegration. The process through which osseointegration is achieved depends on several factors, surgical insertion method being one of them. The aim of this study was to histopathologically compare the impact of the surgical method of implant insertion on the peri-implant bone tissue. Methods. The experiment was performed on 9 dogs. Eight weeks following the extraction of lower premolars implants were inserted using the one-stage method on the right mandibular side and two-stage method on the left side. Three months after implantation the animals were sacrificed. Three distinct regions of bone tissue were histopathologically analyzed, the results were scored and compared. Results. In the specimens of one-stage implants increased amount of collagen fibers was found in 5 specimens where tissue necrosis was also observed. Only moderate osteoblastic activity was found in 3 sections. The analysis of bone-to-implant contact region revealed statistically significantly better results regarding the amount of collagen tissue fibers for the implants inserted in the two-stage method (Wa = 59 105, α = 0.05. No necrosis and osteoblastic activity were observed. Conclusion. Better results were achieved by the two-stage method in bone-to-implant contact region regarding the amount of collagen tissue, while the results were identical regarding the osteoblastic activity and bone tissue necrosis. There was no difference between the methods in the bone-implant interface region. In the bone tissue adjacent to the implant the results were identical regarding the amount of collagen tissue, osteoblastic reaction and bone tissue necrosis, while better results were achieved by the two-stage method regarding the number of osteocytes.

  17. Time-dependent cytokine expression in bone of experimental animals after hydroxyapatite (Hap) implantation

    Energy Technology Data Exchange (ETDEWEB)

    Pilmane, M [Riga Stradins University, Institute of Anatomy and Anthropology, Dzirciema 16, LV-1007, Riga (Latvia); Salms, G; Salma, I; Skagers, A [Riga Stradins University, Department of Oral and Maxillofacial Surgery, Dzirciema 20. LV-1007, Riga (Latvia); Locs, J; Loca, D; Berzina-Cimdina, L, E-mail: pilmane@latnet.lv [Riga Technical University, Riga Biomaterials innovation and development centre, Pulka 3/3, LV-1007, Riga (Latvia)

    2011-06-23

    Proinflammatory cytokines mediate bone loss around the implants in patients with peri-implant disease. However, there is no complete data about the expression of cytokines into the bone around the implants. The aim of this work was to investigate the distribution and appearance of inflammatory cytokines and anti-inflammatory proteins in the bone of jaw of experimental rabbits in different time periods after HAp implantation. Material was obtained from 8 rabbits in lower jaw 6 and 8 months after HAp implants were placed. Tissues were processed for immunohistochemical detection of tumor necrosis factor alfa (TNF{alpha}), Interleukin 1, 6, 8, 10 (IL-1, IL-6, IL-8, IL-10) and defensin 2. Results demonstrated practically unchanged expression of IL-6 and IL-10 between both - experimental and control side 6 months after implantation, while IL-1 and IL-8 notably increased in control side. IL-1 and IL-10 expression did not change in either the experimental side nor the controle side after 8 months HAP implantation, but IL-6 and IL-8 demonstrated a decrease in the control sites. Only IL-8 was elevated with time in experimental sites, while IL-10 showed individual variations in 2 cases.

  18. Time-dependent cytokine expression in bone of experimental animals after hydroxyapatite (Hap) implantation

    Science.gov (United States)

    Pilmane, M.; Salms, G.; Salma, I.; Skagers, A.; Locs, J.; Loca, D.; Berzina-Cimdina, L.

    2011-06-01

    Proinflammatory cytokines mediate bone loss around the implants in patients with peri-implant disease. However, there is no complete data about the expression of cytokines into the bone around the implants. The aim of this work was to investigate the distribution and appearance of inflammatory cytokines and anti-inflammatory proteins in the bone of jaw of experimental rabbits in different time periods after HAp implantation. Material was obtained from 8 rabbits in lower jaw 6 and 8 months after HAp implants were placed. Tissues were processed for immunohistochemical detection of tumor necrosis factor alfa (TNFα), Interleukin 1, 6, 8, 10 (IL-1, IL-6, IL-8, IL-10) and defensin 2. Results demonstrated practically unchanged expression of IL-6 and IL-10 between both - experimental and control side 6 months after implantation, while IL-1 and IL-8 notably increased in control side. IL-1 and IL-10 expression did not change in either the experimental side nor the controle side after 8 months HAP implantation, but IL-6 and IL-8 demonstrated a decrease in the control sites. Only IL-8 was elevated with time in experimental sites, while IL-10 showed individual variations in 2 cases.

  19. Experimental verification of using nanostructured ceramic implants and osteograft

    Science.gov (United States)

    Rerikh, V. V.; Lastevskiy, A. D.; Sadovoy, M. A.; Zaidman, A. M.; Bataev, A. V.; Predein, Yu. A.; Avetisyan, A. R.; Romanenko, V. V.; Mamonova, E. V.; Nikulina, A. A.; Semantsova, E. S.; Smirnov, A. I.

    2017-09-01

    Ventral interbody fusion was carried out in 8 mini pigs in order to determine the effectiveness of anterior stabilization of the vertebral unit with implants made of nanostructured alumina ceramics using cellular technologies to form a bone block. A ceramic cage with a through cylindrical orifice in the center was implanted into the interbody gap; either cellular osteograft (group 1) or cellular autograft (group 2) was placed in it. The adjacent vertebrae were fixed anteriorly with a ceramic plate containing 4 screws. Bone block formation was studied radiographically, morphologically, and by MSCT. The signs of osteointegration of ceramic implants were observed in both groups after 90 days. MSCT and morphological analysis revealed the formation of the osteoceramic block and completed osteogenesis in the bone-graft contact region in group 1 compared to the control group (p < 0.05).

  20. Corneal Collagen Cross-Linking Combined with an Artiflex Iris-Fixated Anterior Chamber Phakic Intraocular Lens Implantation in a Patient with Progressive Keratoconus

    Directory of Open Access Journals (Sweden)

    Sharif Hashmani

    2017-10-01

    Full Text Available We present here the case of a 24-year-old male who experienced progressive keratoconus and vision loss which adversely affected his ability to carry out everyday tasks. This landed him in the Hashmanis Hospital for consultation. He had a preoperative best corrected visual acuity of 6/12. He underwent multiple Oculus Pentacam examinations, which showed progressive keratoconus. Corneal collagen cross-linking (CXL was performed to stabilize his cornea and, subsequently, an Artiflex anterior chamber iris-fixated phakic intraocular lens (ACIF-PIOL was implanted to alleviate his refractive errors. The patient achieved a postoperative uncorrected visual acuity of 6/12. This report shows that CXL combined with ACIF-PIOL can be safe and effective in those with progressive keratoconus.

  1. [Anterior cruciate ligament reconstruction with hamstring tendons preserved tibial insertion and an implant fixation technique of hamstring tendon knot and bone bolt press-fit].

    Science.gov (United States)

    Song, Guang-hu

    2008-10-01

    To evaluate the feasibility of hamstring autograft anterior cruciate ligament reconstruction with hamstring tendons insertion on tibia preserved and an implant fixation technique of hamstring tendons knot and bone bolt press-fit. Twenty cases of injured anterior cruciate ligament were reconstructed. There were 15 males and 5 females with the average age of 22 years old. Ten left knees and 10 right knees were involved. Hamstring tendons were taken, and pretension was performed. Tibial tunnel and femoral tunnel were prepared,and the femoral tunnel was a frame of narrow inside and wide outside. The hamstring tendons knot and bone bolt were pulled inside of femoral tunnel. The tendons distal of tendons knot were brought to pass the femoral tunnel, joint capsule and another tibial tunnel. Then, the tendons distal of tendons knot were tightened together with the part of hamstring tendons of which the insertion were on tibia. After the operation, the knee was fixed at a flexion of 45 degrees by brace. The patients were followed up for 8 to 24 months. The function of troubled knees was evaluated by Lysholm knee functional scale. The average knee score were 61.5 +/- 4.6 and 92.5 +/- 3.7 respectively before and after operation, and the difference was statistically significant (P anterior cruciate ligament reconstruction with hamstring. The advantage of this method was avoidance of using high cost material for fixation,which lessened spending for the patients. And it was also benefit for tendon-bone healing.

  2. Development of a Patient-Specific Finite Element Model for Predicting Implant Failure in Pelvic Ring Fracture Fixation

    Directory of Open Access Journals (Sweden)

    Vickie Shim

    2017-01-01

    Full Text Available Introduction. The main purpose of this study is to develop an efficient technique for generating FE models of pelvic ring fractures that is capable of predicting possible failure regions of osteosynthesis with acceptable accuracy. Methods. Patient-specific FE models of two patients with osteoporotic pelvic fractures were generated. A validated FE model of an uninjured pelvis from our previous study was used as a master model. Then, fracture morphologies and implant positions defined by a trauma surgeon in the preoperative CT were manually introduced as 3D splines to the master model. Four loading cases were used as boundary conditions. Regions of high stresses in the models were compared with actual locations of implant breakages and loosening identified from follow-up X-rays. Results. Model predictions and the actual clinical outcomes matched well. For Patient A, zones of increased tension and maximum stress coincided well with the actual locations of implant loosening. For Patient B, the model predicted accurately the loosening of the implant in the anterior region. Conclusion. Since a significant reduction in time and labour was achieved in our mesh generation technique, it can be considered as a viable option to be implemented as a part of the clinical routine to aid presurgical planning and postsurgical management of pelvic ring fracture patients.

  3. Experimental acrylonitrile butadiene styrene and polyamide evisceration implant: a rabbit clinical and histopathology study

    Directory of Open Access Journals (Sweden)

    D.C. Gomes Júnior

    Full Text Available ABSTRACT The purpose of this study was to evaluate acrylonitrile butadiene styrene (ABS and polyamide implants in rabbits submitted to evisceration at the macroscopic and microstructure level and to assess clinical response and histopathological changes as well. For the experimental study implants of 12mm diameter were prepared by rapid prototyping, weighed and the outer and inner surfaces evaluated macroscopically and by electron microscopy. In addition, a compression test was performed and ultrastructural damage was then determined. After evisceration of the left eyeball, nine New Zealand rabbits received ABS implants and nine others received polyamide implants. The animals were assessed daily for 15 days after surgery and every seven days until the end of the study (90 days. Histopathological evaluation was performed at 15, 45 and 90 days after surgery. The ABS implants weighed approximately 0.44g, while the polyamide ones weighed 0.61g. Scanning electron microscopy demonstrated that the ABS implants had regular-sized, equidistant micropores, while the polyamide ones showed micropores of various sizes. The force required to fracture the ABS implant was 14.39 ±0.60 Mpa, while for the polyamide one, it was 16.80 ±1.05 Mpa. Fifteen days after surgery, we observed centripetal tissue infiltration and scarce inflammatory infiltrate. Implants may be used in the filling of anophthalmic cavities, because they are inert, biocompatible and allow tissue integration.

  4. [Implantation of a sulcus-fixated toric additive intraocular lens in a case of high astigmatism after a triple procedure].

    Science.gov (United States)

    Linz, K; Auffarth, G U; Kretz, F T A

    2014-08-01

    Residual refractive errors, especially high-grade astigmatism after penetrating keratoplasty, often lead to a significant loss of vision. If high anismetropia could not be corrected with glasses or contact lenses, different kinds of surgical procedures are available for visual rehabilitation (intraocular lens exchange, astigmatic keratotomy, Excimer laser treatment, intrastromal corneal ring segment implantation and additive intraocular lens implantation). Toric add-on IOLs are especially designed for sulcus implantation and correcting high astigmatism in pseudophakic eyes. All toric IOLs are individually manufactured according to subjective refraction and biometry. Depending on the underlying manufacturer high-grade astigmatism can be corrected with a cylindrical power up to + 30.0 D. A 74-year-old patient presented with endothelial decompensation and an uncorrected distance visual acuity (UDVA) of 1.0 logMAR for penetrating keratoplasty on the right eye due to a Fuchs endothelial dystrophy. Postoperatively, the uncorrected distance visual acuity improved to 0.8 logMAR, with pinhole correction to 0.5 logMAR. After removing the sutures a high and irregular corneal astigmatism of 21.0 D was found. The corrected distance visual acuity (CDVA) with a refraction of + 5.5 D sph, - 21.0 D cyl 90° was 0.24 logMAR. Therefore an individually manufactured toric additive intraocular lens of + 25.0 D cylindrical and - 18.0 D spherical power for sulcus implantation was chosen and implanted uneventfully. Eight months after surgery refractive astigmatism was reduced significantly to - 0.75 D with an UDVA of 0.08 logMAR and a CDVA of 0.02 logMAR. During the 8-months follow-up period the additive IOL remained centered and no IOL rotation could be observed. Toric add-on IOLs are a safe and successful method for reducing high astigmatism and anisometropia after penetrating keratoplasty. One of the main advantages is the reversibility of the procedure by an explantation of

  5. Shock-implanted noble gases. II - Additional experimental studies and recognition in naturally shocked terrestrial materials

    Science.gov (United States)

    Bogard, Donald; Horz, Friedrich; Johnson, Pratt

    1989-01-01

    The process by which ambient gases can be implanted into silicates by shocks was investigated by analyzing the noble-gas content of several experimentally and naturally shocked silicate samples. The retentivity of shock-implanted gas during stepwise heating in the laboratory was defined in terms of two parameters, namely, the activation energy for diffusion and the extraction temperature at which 50 percent of the gas is released, both of which correlate with the shock pressure. The experiments indicate that, with increasing shock pressure, gas implantation occurs through an increasing production of microcracks/defects in the silicate lattice. The degree of annealing of these defects control the degree of diffusive loss of implanted gas.

  6. Bone healing and mineralization, implant corrosion, and trace metals after nickel-titanium shape memory metal intramedullary fixation.

    Science.gov (United States)

    Ryhänen, J; Kallioinen, M; Serlo, W; Perämäki, P; Junila, J; Sandvik, P; Niemelä, E; Tuukkanen, J

    1999-12-15

    Its shape memory effect, superelasticity, and good wear and damping properties make the NiTi shape memory alloy a material with fascinating potential for orthopedic surgery. It provides a possibility for making self-locking, self-expanding, and self-compressing implants. Problems, however, may arise because of its high nickel content. The purpose of this work was to determine the corrosion of NiTi in vivo and to evaluate the possible deleterious effects of NiTi on osteotomy healing, bone mineralization, and the remodeling response. Femoral osteotomies of 40 rats were fixed with either NiTi or stainless steel (StSt) intramedullary nails. The rats were killed at 2, 4, 8, 12, 26, and 60 weeks. Bone healing was examined with radiographs, peripheral quantitative computed tomography, (pQCT) and histologically. The corrosion of the retrieved implants was analyzed by electron microscopy (FESEM). Trace metals from several organs were determined by graphite furnace atomic absorption spectrometry (GF-AAS) or by inductively coupled plasma-atomic emission spectrometry (ICP-AES). There were more healed bone unions in the NiTi than in the StSt group at early (4 and 8 weeks) time points. Callus size was equal between the groups. The total and cortical bone mineral densities did not differ between the NiTi and StSt groups. Mineral density in both groups was lower in the osteotomy area than in the other areas along the nail. Density in the nail area was lower than in the proximal part of the operated femur or the contralateral femur. Bone contact to NiTi was close. A peri-implant lamellar bone sheet formed in the metaphyseal area after 8 weeks, indicating good tissue tolerance. The FESEM assessment showed surface corrosion changes to be more evident in the StSt implants. There were no statistically significant differences in nickel concentration between the NiTi and StSt groups in any of the organs. NiTi appears to be an appropriate material for further intramedullary use because it

  7. Histopathological comparative analysis of peri-implant soft tissue response after dental implant placement with flap and flapless surgical technique. Experimental study in pigs.

    Science.gov (United States)

    Vlahovic, Zoran; Markovic, Aleksa; Golubovic, Mileta; Scepanovic, Miodrag; Kalanovic, Milena; Djinic, Ana

    2015-11-01

    The aim of this study was comparing the effect of flapless vs. flap technique of implant placement on inflammation degree of peri-implant soft tissue, through histopathological analysis. The experiment was conducted on five domestic pigs. Nine weeks after tooth extraction, implants were installed. Each animal received six implants in mandible. According to split-mouth design, randomly one side was used for flapless technique using mini-incision, while on the other side, flap was raised. After 7, 14, 21, 28, and 90 days, the experimental animals were sacrificed. Samples for histopathological analyzes were taken from the buccal side of peri-implant mucosa next to the neck of implants, from three levels. The degree of inflammatory response in the peri-implant soft tissue was estimated through ordinal scores from 0 to 3. In the flap group Score 3 indicating high degree of inflammation was present from day 7 to day 21, in contrast to flapless group where Score 3 was not recorded during the entire follow-up. Three months after implantation, there were no signs of inflammation neither around flap nor around flapless implants. Flapless surgical implantation technique using mini-incision decreases peri-implant soft tissue inflammatory reaction compared with flap surgery. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. Novel posterior fixation keratoprosthesis

    Science.gov (United States)

    Lacombe, Emmanuel

    1992-08-01

    The keratoprosthesis is the last solution for corneally blind patients that cannot benefit from corneal transplants. Keratoprostheses that have been designed to be affixed anteriorly usually necessitate multi-step surgical procedures and are continuously subjected to the extrusion forces generated by the positive intraocular pressure; therefore, clinical results in patients prove inconsistent. We proposed a novel keratoprosthesis concept that utilizes posterior corneal fixation which `a priori' minimizes the risk of aqueous leakage and expulsion. This prosthesis is implanted in a single procedure thereby reducing the number of surgical complications normally associated with anterior fixation devices. In addition, its novel design makes this keratoprosthesis implantable in phakic eyes. With an average follow-up of 13 months (range 3 to 25 months), our results on 21 cases are encouraging. Half of the keratoprostheses were implanted in severe burn cases, with the remainder in cases of pseudo- pemphigus. Good visual results and cosmetic appearance were obtained in 14 of 21 eyes.

  9. EXPERIMENTAL STUDY OF OSTEOINTERGRATION OF SYNTHETIC MATERIAL POLYTETRAFLUOROETHYLENE IMPLANTED IN BONE

    Directory of Open Access Journals (Sweden)

    V. N. Trezubov

    2010-01-01

    Full Text Available The authors presented the results of experimental study devoted the examination of features of synthetic polymer polytetrafluoroethylene (ePTFE implanted in the bone. It was determined that ePTFE with 70% porosity has the more marked osteointegration and can be recommended for clinical use.

  10. Regression of experimental endometriotic implants in a rat model with the angiotensin II receptor blocker losartan.

    Science.gov (United States)

    Cakmak, Bulent; Cavusoglu, Turker; Ates, Utku; Meral, Ayfer; Nacar, Mehmet Can; Erbaş, Oytun

    2015-04-01

    Endometriosis is a common disease in women of reproductive age, and many different treatments have been developed, although none has provided a cure. In this study, the efficacy of losartan, an angiotensin II type 1 receptor blocker and an antiangiogenic and anti-inflammatory agent, on regression of experimental endometriotic implants in a rat model was investigated. Peritoneal endometriosis was surgically induced in 16 mature female Sprague-Dawley rats. The peritoneal endometriotic implant was confirmed after 28 days, and the animals were divided randomly into two groups. The control group (n = 8) was given 4 mL/day tap water by oral gavage, and the losartan group (n = 8) was given 20 mg/kg per day losartan p.o. We compared endometriotic implant size, extent and severity of adhesion, as well as plasma and peritoneal lavage fluid cytokine levels including vascular endothelial growth factor (VEGF) and tumor necrosis factor (TNF)-α, plasma inflammatory factor pentraxin-3 (PTX-3) and C-reactive protein (CRP) between the treatment groups. Mean surface endometriotic area, histological score of implants, adhesion formation, plasma VEGF, TNF, PTX-3 and CRP levels were significantly lower in the losartan group compared with control (P losartan group than in the control group (P 0.05). Losartan suppressed the implant surface area of experimental endometriosis in rats and reduced the levels of plasma VEGF, TNF-α, PTX-3 and CRP. © 2014 The Authors. Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology.

  11. Comparative radiographic and resonance frequency analyses of the peri-implant tissue after dental implants placement using flap and flapless techniques: an experimental study on domestic pigs.

    Science.gov (United States)

    Vlahović, Zoran; Mihailović, Branko; Lazić, Zoran; Golubović, Mileta

    2013-06-01

    Flapless implant surgery has become very important issue during recent years, mostly thanks to computerization of dentistry and software planning of dental implants placements. The aim of this study was to compare flap and flapless surgical techniques for implant placement through radiographic and radiofrequency analyses. The experiment was made in five domestic pigs. Nine weeks following domestic pigs teeth extraction, implants were placed, on the right side using surgical technique flap, and flapless on the left side. Digital dental Xrays were applied to determine primary dental implant stability quality (ISQ). At certain intervals, not later than three months, the experimental animals were sacrificed, and just before it, control X-rays were applied to measure dental implants stability. Radiographic analysis showed that peri-implant bone resorption in the first 4 weeks following placement implants with flap and flapless surgical techniques was negligible. After the 3 months, mean value of peri-implant bone resorption of the implants placed using flap tehnique was 1.86 mm, and of those placed using flapless tehnique was 1.13 mm. In relation to the primary dental implant stability in the first and second week there was an expected decrease in ISQ values, but it was less expressed in the dental implants placed using the flapless technique. In the third week the ISQ values were increased in the dental implants placed by using both techniques, but the increase in flapless implant placement was higher (7.4 ISQ) than in flap implant placement (1.5 ISQ). The upward trend continued in a 4-week period, and after 3 months the dental implant stability values in the implants placed using flap technique were higher than the primary stability for 7.1 ISQ, and in the implants placed using flapless technique were higher comparing to the primary stability for 10.1 ISQ units. Based on the results of radiographic and resonance frequency analyses it can be concluded that the flapless

  12. Comparative radiographic and resonance frequency analyses of the peri-implant tissue after dental implants placement using flap and flapless techniques: An experimental study on domestic pigs

    Directory of Open Access Journals (Sweden)

    Vlahović Zoran

    2013-01-01

    Full Text Available Background/Aim. Flapless implant surgery has become very important issue during recent years, mostly thanks to computerization of dentistry and software planning of dental implants placements. The aim of this study was to compare flap and flapless surgical techniques for implant placement through radiographic and radiofrequency analyses. Methods. The experiment was made in five domestic pigs. Nine weeks following domestic pigs teeth extraction, implants were placed, on the right side using surgical technique flap, and flapless on the left side. Digital dental Xrays were applied to determine primary dental implant stability quality (ISQ. At certain intervals, not later than three months, the experimental animals were sacrificed, and just before it, control X-rays were applied to measure dental implants stability. Results. Radiographic analysis showed that peri-implant bone resorption in the first 4 weeks following placement implants with flap and flapless surgical techniques was negligible. After the 3 months, mean value of peri-implant bone resorption of the implants placed using flap technique was 1.86 mm, and of those placed using flapless technique was 1.13 mm. In relation to the primary dental implant stability in the first and second week there was an expected decrease in ISQ values, but it was less expressed in the dental implants placed using the flapless technique. In the third week the ISQ values were increased in the dental implants placed by using both techniques, but the increase in flapless implant placement was higher (7.4 ISQ than in flap implant placement (1.5 ISQ. The upward trend continued in a 4- week period, and after 3 months the dental implant stability values in the implants placed using flap technique were higher than the primary stability for 7.1 ISQ, and in the implants placed using flapless technique were higher comparing to the primary stability for 10.1 ISQ units. Conclusion. Based on the results of radiographic and

  13. Human fetal osteoblast behavior on zirconia dental implants and zirconia disks with microstructured surfaces. An experimental in vitro study.

    Science.gov (United States)

    Delgado-Ruíz, Rafael Arcesio; Gomez Moreno, Gerardo; Aguilar-Salvatierra, Antonio; Markovic, Aleksa; Mate-Sánchez, Jose Eduardo; Calvo-Guirado, José Luis

    2016-11-01

    To measure the lateral surface area of microgrooved zirconia implants, to evaluate the cell geometry and cell density of human fetal osteoblasts seeded on zirconia microgrooved implants, to describe the surface roughness and chemistry, and to evaluate the activity of human fetal osteoblasts seeded on zirconia microgrooved disks. This experimental in vitro study used 62 zirconia implants and 130 zirconia disks. Two experimental groups were created for the implants: 31 non-microgrooved implants (Control) and 31 microgrooved implants (Test); two experimental groups were created for the disks: 65 non-microgrooved disks (Control) and 65 microgrooved disks (Test). The following evaluations of the implants were made: lateral surface area (LSA), cell morphology, and density of human fetal osteoblasts seeded on implant surfaces. On the disks, surface parameters (roughness and chemistry) and cell activity (alkaline phosphatase - ALP and alizarin red - ALZ) were evaluated at 7 and 15 days. LSA was lower for control implants (62.8 mm) compared with test implants (128.74 mm) (P implants presented cells rich in lamellipodia prolongations, attached to the inner walls or to the borders of the microgrooves and in the flat areas between the microgrooves. Cell density was higher in the test group compared with controls (P implants with microgrooves. (ii) The LSA of microgrooved zirconia implants is greater and provides more available surface compared with implants of the same dimensions without microgrooves. (iii) Microgrooves on zirconia implants modify the morphology and guide the size and alignment of human fetal osteoblasts. (iv) Zirconia surfaces with microgrooves of 30 μm width and 70 μm separation between grooves enhance ALP and ALZ expression by human fetal osteoblasts. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Experimentally induced peri-implant mucositis. A clinical study in humans.

    Science.gov (United States)

    Pontoriero, R; Tonelli, M P; Carnevale, G; Mombelli, A; Nyman, S R; Lang, N P

    1994-12-01

    The purpose of this study was to compare the clinical and microbiological (microscopic) parameters during the development of experimental gingivitis and experimental peri-implant mucositis. Twenty partially edentulous patients were treated for moderate to advanced periodontal disease. Following active periodontal therapy consisting of motivation, instruction in oral hygiene practices, scaling and root planing and periodontal surgery where indicated, IMZ oral implants were incorporated in posterior edentulous areas. After 3 months of healing, the prosthetic abutments were connected, and the patients were closely supervised for another 2 months of healing. At this time, baseline data were obtained. Re-examinations were scheduled at 3 and 6 months. Following this, the patients were asked to refrain from oral hygiene practices for 3 weeks. At all examinations including the end of the period of no oral hygiene, the following clinical parameters were obtained: Plaque Index, Gingival Index and Sulcus Bleeding Index, all modified by Mombelli et al. (1987), probing pocket depths and recession in mm. Furthermore, submucosal/subgingival plaque samples were obtained and analyzed using phase contrast microscopy. At the end of the 3-week period of plaque accumulation, optimal oral hygiene was reinstituted. There were no statistically significant differences between the mean values of all parameters at implant compared to tooth sites at any observation periods. The period of no oral hygiene demonstrated a similar cause-effect relationship between the accumulation of bacterial plaque and the development of peri-implant mucositis as established for the gingival units by the experimental gingivitis model.

  15. Prediction of bone density around orthopedic implants delivering bisphosphonate.

    Science.gov (United States)

    Stadelmann, Vincent A; Terrier, Alexandre; Gauthier, O; Bouler, J-M; Pioletti, Dominique P

    2009-06-19

    The fixation of an orthopedic implant depends strongly upon its initial stability. Peri-implant bone may resorb shortly after the surgery. This resorption is directly followed by new bone formation and implants fixation strengthening, the so-called secondary fixation. If the initial stability is not reached, the resorption continues and the implant fixation weakens, which leads to implant loosening. Studies with rats and dogs have shown that a solution to prevent peri-implant resorption is to deliver bisphosphonate from the implant surface. The aims of the study were, first, to develop a model of bone remodeling around an implant delivering bisphosphonate, second, to predict the bisphosphonate dose that would induce the maximal peri-implant bone density, and third to verify in vivo that peri-implant bone density is maximal with the calculated dose. The model consists of a bone remodeling equation and a drug diffusion equation. The change in bone density is driven by a mechanical stimulus and a drug stimulus. The drug stimulus function and the other numerical parameters were identified from experimental data. The model predicted that a dose of 0.3 microg of zoledronate on the implant would induce a maximal bone density. Implants with 0.3 microg of zoledronate were then implanted in rat femurs for 3, 6 and 9 weeks. We measured that peri-implant bone density was 4% greater with the calculated dose compared to the dose empirically described as best. The approach presented in this paper could be used in the design and analysis processes of experiments in local delivery of drug such as bisphosphonate.

  16. Deproteinized bovine bone mineral particles and osseointegration of implants without primary bone contact: an experimental study in dogs.

    Science.gov (United States)

    Sivolella, Stefano; Bressan, Eriberto; Salata, Luiz A; Quiñones, Maria E; Lang, Niklaus P; Botticelli, Daniele

    2014-03-01

    To evaluate the influence on osseointegration of Deproteinized bovine bone mineral (DBBM) particles used to fill defects of at least 1 mm around implants having no primary contact with bone. Premolars and first molars were extracted bilaterally from the mandible of six Labrador dogs. After 3 months of healing, mucoperiosteal full-thickness flaps were elevated, and one recipient site was prepared in the molar region of each hemi-mandible to place implants. These were installed with a deliberate circumferential and periapical space to the bone walls of 1.2 mm. All implants were stabilized with passive fixation plates to maintain the implants in situ and without any contact with the implant bed. The control sites were left to be filled with coagulum, while at the test sites, the residual gap was filled with DBBM. After 3 months of submerged healing, the animals were sacrificed. Ground sections were prepared and analyzed histomorphometrically. Mineralized bone-to-implant contact was 4.0% and 3.9% for control and test sites, respectively. The width of the residual defects was 0.48 mm and 0.88 mm at the control and test sites, respectively. The percentage of implant surface covered by a layer of dense connective tissue of 0.12 mm of width on average was 84.9% and 88.5% at the control and test sites, respectively. A minor and not predictable degree of contact or distance osteogenesis was obtained on the implant surface when primary contact of the implant surface with the implant bed had deliberately been avoided. DBBM grafting of the artificial gap did not favor osseointegration. Neither did it enhance the ability to bridge the gap with newly formed bone in an artificial defect wider than 1 mm. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  17. The effect of the local use of chlorhexidine in surgical treatment of experimental peri-implantitis in dogs.

    Science.gov (United States)

    Carcuac, Olivier; Abrahamsson, Ingemar; Charalampakis, Georgios; Berglundh, Tord

    2015-02-01

    To evaluate the effect of surgical treatment of experimental peri-implantitis at implants with different surface characteristics using different anti-infective procedures. Four implants with different surface characteristics (A: TiOblast, B: OsseoSpeed, C: AT-I, D: TiUnite) were installed in a randomized order in each side of the mandible in 6 labrador dogs 3 months after tooth extraction. Experimental peri-implantitis was induced 3 months later. Surgical treatment of peri-implantitis was performed. The implants were cleaned with gauze soaked in either saline (control) or chlorhexidine (test). Clinical and radiographical examinations were performed and microbiological samples were taken during a 6-month period after surgery. Biopsies were obtained and prepared for histological analysis. Clinical signs of soft tissue inflammation were reduced after surgical therapy in most test and control sites. While the analysis of bone level alterations in radiographs together with histological and microbiological assessments of resolution of peri-implantitis lesions failed to demonstrate statistically significant differences between test and control procedures, the evaluations disclosed significant differences between implant D and implants A, B and C on treatment outcome. It is suggested that (i) the local use of chlorhexidine has minor influence on treatment outcome, (ii) resolution of peri-implantitis following surgical treatment without the adjunctive use of local and systemic antimicrobial agents is possible and (iii) the results are influenced by implant surface characteristics. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Development and experimental study of large size composite plasma immersion ion implantation device

    Science.gov (United States)

    Falun, SONG; Fei, LI; Mingdong, ZHU; Langping, WANG; Beizhen, ZHANG; Haitao, GONG; Yanqing, GAN; Xiao, JIN

    2018-01-01

    Plasma immersion ion implantation (PIII) overcomes the direct exposure limit of traditional beam-line ion implantation, and is suitable for the treatment of complex work-piece with large size. PIII technology is often used for surface modification of metal, plastics and ceramics. Based on the requirement of surface modification of large size insulating material, a composite full-directional PIII device based on RF plasma source and metal plasma source is developed in this paper. This device can not only realize gas ion implantation, but also can realize metal ion implantation, and can also realize gas ion mixing with metal ions injection. This device has two metal plasma sources and each metal source contains three cathodes. Under the condition of keeping the vacuum unchanged, the cathode can be switched freely. The volume of the vacuum chamber is about 0.94 m3, and maximum vacuum degree is about 5 × 10‑4 Pa. The density of RF plasma in homogeneous region is about 109 cm‑3, and plasma density in the ion implantation region is about 1010 cm‑3. This device can be used for large-size sample material PIII treatment, the maximum size of the sample diameter up to 400 mm. The experimental results show that the plasma discharge in the device is stable and can run for a long time. It is suitable for surface treatment of insulating materials.

  19. Fracture fixation.

    Science.gov (United States)

    Taljanovic, Mihra S; Jones, Marci D; Ruth, John T; Benjamin, James B; Sheppard, Joseph E; Hunter, Tim B

    2003-01-01

    The basic goal of fracture fixation is to stabilize the fractured bone, to enable fast healing of the injured bone, and to return early mobility and full function of the injured extremity. Fractures can be treated conservatively or with external and internal fixation. Conservative fracture treatment consists of closed reduction to restore the bone alignment. Subsequent stabilization is then achieved with traction or external splinting by slings, splints, or casts. Braces are used to limit range of motion of a joint. External fixators provide fracture fixation based on the principle of splinting. There are three basic types of external fixators: standard uniplanar fixator, ring fixator, and hybrid fixator. The numerous devices used for internal fixation are roughly divided into a few major categories: wires, pins and screws, plates, and intramedullary nails or rods. Staples and clamps are also used occasionally for osteotomy or fracture fixation. Autogenous bone grafts, allografts, and bone graft substitutes are frequently used for the treatment of bone defects of various causes. For infected fractures as well as for treatment of bone infections, antibiotic beads are frequently used. Copyright RSNA, 2003

  20. Effect of alpha-lipoic acid on endometrial implants in an experimental rat model.

    Science.gov (United States)

    Pınar, Neslihan; Soylu Karapınar, Oya; Özcan, Oğuzhan; Özgür, Tümay; Bayraktar, Suphi

    2017-10-01

    To investigate the antioxidant and anti-inflammatory effects of alpha-lipoic acid (ALA) in the treatment of endometriosis in an experimental rat model by evaluating biochemical and histopathologic parameters. Experimental endometriosis was induced by the peritoneal implantation of autologous endometrial tissue. The rats were randomly divided into two groups with eight rats each. Group I was intraperitoneally administered ALA 100 mg/kg/day for 14 days. Group II was intraperitoneally administered saline solution at the same dosage and over the same period. Endometrial implant volume was measured in both groups both pre- and post-treatment. Tumor necrosis factor alpha (TNF-α) was measured in peritoneal fluid. Total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) were assessed in serum. The implants were histopathologically evaluated. In the ALA group, the serum TOS and OSI levels, the endometrial implant volumes, the TNF-α levels in serum and peritoneal fluid, and the histopathologic scores were significantly lower compared to the control group (P Alpha-lipoic acid may have a therapeutic potential in the treatment of endometriosis due to its antioxidant and anti-inflammatory effects. © 2017 Société Française de Pharmacologie et de Thérapeutique.

  1. An improved cochlear implant electrode array for use in experimental studies

    Science.gov (United States)

    Shepherd, Robert; Verhoeven, Kristien; Xu, Jin; Risi, Frank; Fallon, James; Wise, Andrew

    2012-01-01

    Experimental studies play an important role in establishing the safety and efficacy of cochlear implants and they continue to provide insight into a new generation of electrode arrays and stimulation strategies. One drawback has been the limited depth of insertion of an electrode array in experimental animals. We compared the insertion depth and trauma associated with the insertion of Cochlear Ltd’s Hybrid-L (HL) array with a standard 8 ring array in cat cochleae. Both arrays were inserted into cadaver cochleae and an X-ray recorded their anatomical location. The implanted cochlea was serially sectioned and photographed at 300µm intervals for evidence of electrode insertion trauma. Subsequently two cats were chronically implanted with HL arrays and electrically-evoked potentials recorded over a three month period. Mean insertion depth for the HL arrays was 334.8° (SD = 21°; n=4) versus 175.5°(SD = 6°; n=2) for the standard array. This relates to ~10.5 mm and 6 mm respectively. A similar insertion depth was measured in a chronically implanted animal with a HL array. Histology from each cadaver cochleae showed that the electrode array was always located in the scala tympani; there was no evidence of electrode insertion trauma to the basilar membrane, the osseous spiral lamina or the spiral ligament. Finally, evoked potential data from the chronically implanted animals exhibited significantly lower thresholds compared with animals implanted with a standard 8 ring array, with electrical thresholds remaining stable over a three month observation period. Cochlear Ltd’s HL electrode array can be safely inserted ~50% of the length of the cat scala tympani, placing the tip of the array close to the 4 kHz place. This insertion depth is considerably greater than is routinely achieved using a standard 8-ring electrode array (~12 kHz place). The HL array evokes low thresholds that remain stable over three months of implantation. This electrode array has potential

  2. Alendronate treatment in the revision setting, with and without controlled implant motion

    DEFF Research Database (Denmark)

    Søballe, Kjeld; Chen, Xinqian; Jensen, Thomas B

    2007-01-01

    Introduction Bisphosphonates have been proposed to delay or prevent loosening of joint replacement implants by reducing bone resorption. It is known, however, that implant motion prevents the bone anchorage necessary to maintain secure implant fixation. Methods We used our experimental implant...... conditions, even with alendronate. With alendronate and stabilized implants, increased bone was observed near the sclerotic shell of the revision cavity, but it was reduced with alendronate when the implant was unstable. Interpretation Our findings suggest that it may be difficult for alendronate...

  3. Spontaneous progression of ligature induced peri-implantitis at implants with different surface roughness: an experimental study in dogs

    DEFF Research Database (Denmark)

    Berglundh, T; Gotfredsen, K; Zitzmann, N U

    2007-01-01

    : The aim of the current experiment was to study the progression of peri-implantitis around implants with different surface roughness. MATERIAL AND METHODS: In five beagle dogs, three implants with either a sandblasted acid-etched surface (SLA) or a polished surface (P) were installed bilaterally...

  4. Histopathology of experimental myiasis in mice as a result of infestation and experimental implantation of Dermatobia hominis larvae.

    Science.gov (United States)

    Leite, A C R; Nascimento, M F A; Leite, L H R; Leite, V H R

    2011-05-01

    A laboratory model of myiasis as a result of Dermatobia hominis (L.) larvae was developed using mice as hosts. Mice in three groups were each infested with one newly hatched larva and skin biopsies processed for histopathology at 4, 12, and 20 d postinfestation (dpi). Mice in three other groups were each subjected to implantation of one larva collected from an infested (donor) mouse at 4, 12, and 20 dpi. Skin lesions of these receptor mice were then assessed at 10, 14, and 6 d postimplantation (dpimp), respectively. The inflammatory process in infested mice at 4 dpi was discrete, consisting of a thin necrotic layer around the larva, edema, many neutrophils, few eosinophils, mast cells, and proliferation of fibroblasts. At 12 dpi, there was a thicker necrotic layer, edema, many neutrophils and eosinophils, few mast cells, neoformation of capillaries, proliferation of the endothelium and fibroblasts, and early stages of fibrosis. These histopathological characteristics together with fibrosis were observed over a large area of the lesion at 20 dpi. Mice submitted to larval implantations demonstrated similar skin histopathology to that seen in the infested rodents, 10 dpimp corresponding to 12 dpi and 6 or 14 dpimp to 20 dpi. In all mice, the progressive acute inflammatory process followed a sequence linked to factors such as size of larvae and presence of secretory-excretory products. Both infested mice and those implanted experimentally with D. hominis larvae were shown to be suitable models for the study of the parasite-host relationship in this important zoonotic myiasis.

  5. Intravitreal implantation of the biodegradable cyclosporin A drug delivery system for experimental chronic uveitis.

    Science.gov (United States)

    Dong, Xiaoguang; Shi, Weiyun; Yuan, Gongqiang; Xie, Lixin; Wang, Shenguo; Lin, Ping

    2006-04-01

    The purpose was to evaluate the efficacy of the intravitreal implantation of the biodegradable cyclosporin A (CsA) drug delivery system (DDS) for experimental chronic uveitis. The DDS was prepared by formulating CsA into glycolide-co-lactide-co-caprolactone copolymer (PGLC). Right eyes of 30 New Zealand white rabbits were used to establish a model of uveitis and randomized into control, intravitreal non-medicated DDS, oral CsA (15 mg/kg daily), and intravitreal CsA-PGLC DDS (each containing 2 mg CsA) groups. The progress of ocular inflammation, results of electroretinography, and histopathological examination of ocular, renal, and hepatic functions were recorded. Intravitreal CsA levels were measured in another 13 rabbits receiving an implant of the CsA-PGLC DDS. Chronic uveitis was successfully induced in all 30 eyes. The inflammation in the eyes with no treatment, non-medicated implant, and oral CsA was more severe than those with the CsA-PGLC DDS at each timepoint. The electroretinography b-wave was depressed much less in the CsA-PGLC DDS group than in the other three groups (ptoxicity was detected. Intravitreal implantation of the biodegradable CsA-PGLC DDS may effectively reduce the intraocular inflammation in rabbits with no toxicity, which provides a potentially safe and convenient approach for the treatment of chronic uveitis.

  6. Design Fixation

    Science.gov (United States)

    Kelley, Todd R.; Sung, Euisuk

    2017-01-01

    The purpose of this article is to provide awareness of the danger of design fixation and promote the uses of brainstorming early in the design process--before fixation limits creative ideas. The authors challenged technology teachers to carefully limit the use of design examples too early in the process and provided suggestions for facilitating…

  7. Experimental study of bone response to hydroxyapatite coating implants: bone-implant contact and removal torque test.

    Science.gov (United States)

    Eom, Tae-Gwan; Jeon, Gyeo-Rok; Jeong, Chang-Mo; Kim, Young-Kyun; Kim, Su-Gwan; Cho, In-Hee; Cho, Yong-Seok; Oh, Ji-Su

    2012-10-01

    The objective of this study was to evaluate the early osseointegration of hydroxyapatite (HA)-coated implant. Twelve adult male miniature pigs were used in this study. The removal torque of implants placed in the tibia of miniature pigs was measured. For implants placed in the mandible, histomorphometric evaluation was performed for the evaluation of the bone-implant contact (BIC) ratio. After 4, 8, and 12 weeks, removal torque values were increased. Among the 3 groups, the HA-coated group showed the highest values (P < .05). At 4 and 8 weeks, the BIC ratio of HA was significantly higher than that of resorbable blast medium or sand blasted with alumina and acid etched (P < .05). It was concluded that HA-coated implants are relatively favorable in early loading stages. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Healing of experimental femoral defects in rats after implantation of collagen-calcium phosphate biocomposites

    Directory of Open Access Journals (Sweden)

    O. V. Korenkov

    2017-06-01

    Full Text Available The aim of this study was to investigate the healing process of experimental defects of the femoral shaft diaphysis of rats after implantation of osteoplastic material Collapan into its cavity. In experi-mental animals, a perforated defect with diameter of 2.5 mm was created in the medullary canal of the femoral shaft and filled with osteoplastic material Collapan. In control rats, the defect was left un-filled. The bone fragments were examined on the 15th and 30th day by light microscopy morphometry and scanning electron microscopy. It was found that application of osteoplastic material Collapan in the femoral diaphysis defect optimised reparative osteogenesis, showed high biocompatibility, osteo-conductive properties, resorption ability and good integration with tissue-specific structures of the regenerate

  9. The influence of Young's modulus of loaded implants on bone remodeling: an experimental and numerical study in the goat knee.

    NARCIS (Netherlands)

    Stoppie, N.; Oosterwyck, H. Van; Jansen, J.A.; Wolke, J.G.C.; Wevers, M.; Naert, I.

    2009-01-01

    The aim of this study was to examine the influence of the Young's modulus of the implant material on the bone remodeling in a loaded condition. A combined animal experimental and computational study was set up. The animal experimental group comprised of 16 Saanen goats, each receiving one titanium

  10. Evaluation of bone loss in antibacterial coated dental implants: An experimental study in dogs

    DEFF Research Database (Denmark)

    Gallardo, Maria Godoy; Manzanares-Céspedes, Maria Cristina; Sevilla, Pablo

    2016-01-01

    The aim of this study was to evaluate the in vivo effect of antibacterial modified dental implants in the first stages of peri-implantitis. Thirty dental implants were inserted in the mandibular premolar sites of 5 beagle dogs. Sites were randomly assigned to Ti (untreated implants, 10 units), Ti...

  11. Blood clearance of Howell-Jolly bodies in an experimental autogenic splenic implant model.

    Science.gov (United States)

    Marques, R G; Lucena, S B S G; Caetano, C E R; de Sousa, V Oliveira; Portela, M C; Petroianu, A

    2014-06-01

    Autogenic splenic implant (ASI) is one of the few alternatives for preservation of splenic tissue when total splenectomy is inevitable. The aim of this study was to determine the morphological and functional regeneration of ASIs, as indicated by the clearance of Howell-Jolly (HJ) bodies, in an experimental model. Ninety-nine male Wistar rats were divided into three groups: sham-operated (group 1), total splenectomy alone (group 2), and total splenectomy combined with ASI (group 3). Animals in group 3 were further allocated to nine subgroups of nine rats each, and analysed at different time points (1, 4, 8, 12, 16, 20, 24, 28 and 32 weeks after surgery). Blood smears were prepared at predetermined times for detection of HJ bodies. Morphological regeneration of tissue in the ASI was analysed by histology. At 1 week, the regenerated mass corresponded to about 7 per cent of the tissue implanted, reaching approximately 54 per cent at 24 weeks. The HJ body levels were increased in groups 2 and 3 until 8 weeks after surgery, following which levels in the ASI group became similar to those in the sham-operated group. HJ bodies were difficult to detect when a level of 22.5 per cent of regenerated ASI mass was reached. Functional regeneration of ASIs occurred from 8 weeks after surgery. When 22.5 per cent of regenerated ASI mass was reached almost no HJ bodies could be observed in the bloodstream, resembling a spleen in situ. Splenectomy has been practised routinely, both in the emergency setting and as a therapeutic elective procedure. There is a correlation between asplenia/hyposplenia and the occurrence of fulminant sepsis, underlining the importance of developing surgical methods for preserving splenic function. Both clinical and experimental studies have shown at least partial morphological and functional regeneration of autogenic splenic implants (ASIs). Experimental studies investigating the immunoprotective effect of ASIs, based mostly on exposure of animals to

  12. Peri-implant tissue reactions to immediate nonocclusal loaded implants with different collar design: an experimental study in dogs.

    Science.gov (United States)

    Negri, Bruno; Calvo Guirado, José L; Maté Sánchez de Val, José E; Delgado Ruíz, Rafael A; Ramírez Fernández, María P; Barona Dorado, Cristina

    2014-02-01

    The aim of this study was to evaluate bone remodelling and soft tissue reactions around immediate nonocclusal loaded implants with different collar configuration in beagle dogs. The mandibular bilateral second, third and fourth premolars of six beagle dogs were extracted. After 3 months of healing, four implants were placed in the mandibles of each dog. Randomly, two implants with a 1.5 mm polished surface collar (TSA, control group) and two implants with a 0.7 mm polished surface collar and 2.5 mm microthreaded area (TSAA, test group) were inserted. Both groups were treated with a minimal mucoperiosteal flap elevation approach. Impressions were taken and two single screw-retained restorations were inserted in each hemi-mandible 2 days after the implant placement. The animals were sacrificed at 1, 2 and 3 months (two specimens each), and biopsies were obtained. Samples were processed for ground sectioning. Histomorphometric analysis was carried out to compare buccal and lingual bone height loss and soft tissue behaviour between the two groups. Crestal bone resorption was significantly higher in the control group (P > 0.05). The establishment of the biological width showed similar outcomes for both groups. Only the distance from the top of the peri-implant mucosa to the apical portion of the barrier epithelium at lingual aspect was significantly more pronounced in the control group (P > 0.05). The alterations that occurred in the peri-implant tissues were related to the adaptation that occurred after the loading conditions in both groups. The microthread design might have an effect in maintaining the marginal bone loss against loading. © 2012 John Wiley & Sons A/S.

  13. Results of bone regenerate study after osteosynthesis with bioinert and calcium phosphate-coated bioactive implants in experimental femoral neck fractures (experimental study

    Directory of Open Access Journals (Sweden)

    K. S. Kazanin

    2015-01-01

    Full Text Available Objective - to analyze the results of X-ray, cytomorphometric and immunohistochemistry experimental studies of bone regenerates after osteosynthesis with bioinert and calcium phosphate-coated bioactive implants. Material and methods. The study was conducted on experimental femoral neck fractures in rabbit males. Reparative osteogenesis processes were studied in groups of bioinert titanium implant osteosynthesis and calcium phosphate-coated bioactive titanium implant osteosynthesis. The animals were clinically followed-up during the postoperative period. X-ray, cytomorphometric and immunohistochemistry studies of samples extracted from femoral bones were conducted over time on days 1, 7, 14, 30 and 60. The animal experiments were kept and treated according to recommendations of international standards, Helsinki Declaration on animal welfare and approved by the local ethics committee. All surgeries were performed under anesthesia, and all efforts were made to minimize the suffering of the animals. Results. In the animal group without femoral neck fracture osteosynthesis, femoral neck pseudoarthrosis was observed at the end of the experiment. The results of cytomorphometric and immunohistochemistry studies conducted on day 60 of the experiment confirmed that the cellular composition of the bone regenerate in the group of calcium phosphate-coated bioactive titanium implants corresponded to a more mature bone tissue than in the group of bioinert titanium implants. Conclusion. The results of the statistical analysis of cytomorphometric and immunohistochemistry data show that the use of calcium phosphate-coated bioactive titanium implants allows to achieve significantly earlier bone tissue regeneration.

  14. [Case-control study on Zero-profile implant for anterior cervical discectomy and fusion and conventional cage plate internal fixation for the treatment of single segmental cervical intervertebral disc herniation].

    Science.gov (United States)

    Shao, Hai-yu; Zhang, Jun; Yang, Di; Chen, Jin-ping; Huang, Ya-zeng

    2016-06-01

    To compare clinical efficacy of Zero-profile implant for anterior cervical discectomy and fusion and conventional titanium plate with cage internal fixation for the treatment of single segmental cervical intervertebral disc herniation. From August 2011 to March 2014, clinical data of 139 patients with single cervical disc herniation treated with anterior cervical discectomy and interbody fusion with internal fixation were retrospectively analyzed. The patients were divided into two groups according to its operation method. There were 63 patients in group A which performed anterior discectomy and interbody fusion with Zero-profile;76 patients in group B which performed anterior cervical discectomy and cage plate internal fixation. JOA score and Odom functional rating between two groups were compared before and after operation. Videofluorographic swallowing study (VFSS) were used to evaluate thickness of prevertebral soft tissue. Bazaz dysphagia score were used to assess incidence of dysphagia. Postoperative AP X-ray and CT of cervical vertebra at 12 months were applied for evaluating bone graft fusion. Postoperative MRI was applied for evaluating the incidence of adjacent segment degeneration. Blood loss,operative time, preoperative and postoperative JOA score, Odom functional rating and VFSS score, Bazaz score, fusion rate between vertebral bodies and incidence of adjacent segment degeneration were compared between two groups. There were no statistical meaning between two groups in JOA score, Odom functional rating before and after operation (P > 0.05); and no significant meaning in VFSS score between two groups before operation (P > 0.05); There were no significant difference in operative time and blood loss. There was statistical meaning in VFSS, Bazaz dysphagia score at 2 days, and 6 months after operation (P 0.05). Eight patients (12.7%) in group A occurred adjacent segment degeneration and 19 patients (25%) in group B occurred adjacent segment degeneration

  15. Biodegradable interlocking nails for fracture fixation

    NARCIS (Netherlands)

    van der Elst, M.; Bramer, J. A.; Klein, C. P.; de Lange, E. S.; Patka, P.; Haarman, H. J.

    1998-01-01

    Serious problems such as stress shielding, allergic reactions, and corrosion are associated with the use of metallic fracture fixation devices in fractured long bones. Metal implants often are removed during a second retrieval operation after fracture healing has completed. A biocompatible implant

  16. Effect of glenoid implant design on glenohumeral stability: an experimental study.

    Science.gov (United States)

    Sins, Lauranne; Tétreault, Patrice; Petit, Yvan; Nuño, Natalia; Billuart, Fabien; Hagemeister, Nicola

    2012-10-01

    Though several glenoid implants were developed over the past years, a high rate of glenoid loosening remains. This complication is linked to the glenohumeral stability, defined as humeral head translation. In an intact shoulder, this concept is ensured by all active and passive elements, particularly the labrum. Two features of a glenoid implant can be adjusted to improve the stability, or, in other words, to decrease the translations: the first is the mismatch, defined as the difference of curvature between the prosthetic head and glenoid; the second is the shape of the glenoid component. Therefore, the objective of this study was to compare the performance of 2 glenoid components (Ceraver, Roissy, France): (1) a standard design and (2) a design named "labrum design" with a superior part simulating the anatomic labrum. An experimental device was developed to evaluate forces and kinematics. The device simulated active, dynamic and continuous abduction of an entire arm. It reproduced the Scapulo-Humeral Rhythm. The labrum design was installed first. To evaluate the effect of mismatch on the glenohumeral stability, 3 humeral heads were tested, corresponding to the ones recommended by the company. The experiment was repeated for the standard design. The results obtained show a general decrease of the prosthetic head translation with the labrum design compared to the standard design. No noticeable effect of mismatch was found. A proof of concept of the interest of the artificial labrum was provided since it improved the glenohumeral stability. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Dental implants immediate loading versus the standard 2-staged protocol: an experimental study in dogs.

    Science.gov (United States)

    Rismanchian, Mansour; Attar, Bijan Movahedian; Razavi, Sayed Mohammad; Shamsabad, Ali Nasir; Rezaei, Majid

    2012-02-01

    The endeavors to shorten implant treatment time have led to the concept of immediate loading. This research was designed to compare the immediate loading and the 2-staged methods on implant placement from a clinical, histological, and histomorphometric standpoint. Three months postextraction of 12 premolars of 3 dogs, 12 implants were inserted. Bone-implant contact (BIC), implant stability quotient (ISQ), the bone type in a 2-mm periphery around the implant, and the marginal bone loss (MBL) were recorded for unloaded implants (n  =  6) and immediately loaded ones (n  =  6). BIC, ISQ, MBL in the mesial, and the bone types around the implants were not significantly different in the 2 groups. The distal MBL was higher in the immediately loaded group. Immediate loading does not appear to be perilous for osseointegration, BIC, or new bone type around implants.

  18. Shock-implanted noble gases - An experimental study with implications for the origin of Martian gases in shergottite meteorites

    Science.gov (United States)

    Bogard, Donald D.; Horz, Friedrich; Johnson, Pratt H.

    1986-01-01

    The shock-implantation of gases is studied by artificially shocking whole rock and power samples of terrestrial basalt to pressures of 2-40 GPa. Ar, Kr, Xe, and Ne were implanted into the silicate. It is observed that the amount of implanted gas is linearly proportional to its partial pressure over a pressure range of 0.0001 to 0.1 atmosphere. The fractionation effect in the implanted gas and the gas diffusion properties are examined. The amounts of gas that would have been implanted with 100 percent efficiency are calculated from the measured porosities of the power samples and are compared to observed abundances. It is determined that the implantation efficiencies are approximately 0.5 percent at 2 GPa, 7 percent at 5 GPa, and greater than 50 percent at both 20 and 35 GPa. The experimental data correlate with the shock implantation of Martian gases without mass fractionation into the shock-melted phase of meteorite EETA 79001.

  19. Bone Morphometric Evaluation around Immediately Placed Implants Covered with Porcine-Derived Pericardium Membrane: An Experimental Study in Dogs

    Directory of Open Access Journals (Sweden)

    Ryo Jimbo

    2012-01-01

    Full Text Available Objective. To investigate whether porcine-derived bioresorbable pericardium membrane coverage enhances the osseointegration around implants placed in fresh extraction sockets. Study Design. Twenty-four commercially available endosseous implants were placed in the fresh extraction sockets of the mandibular first molar of mature beagles (. On one side, implants and osteotomy sites were covered with porcine-derived bioresorbable pericardium membranes, whereas on the other side, no membranes were used. After 6 weeks, samples were retrieved and were histologically processed for histomorphometric analysis. Results. The histological observation showed that bone loss and soft tissue migration in the coronal region of the implant were evident for the control group, whereas bone fill was evident up to the neck of the implant for the membrane-covered group. Bone-to-implant contact was significantly higher for the membrane-covered group compared to the control group, 75% and 45% (, respectively. Conclusion. The experimental membranes proved to regenerate bone around implants placed in fresh extraction sockets without soft tissue intrusion.

  20. Effect of titanium dental implants on proton therapy delivered for head tumors: experimental validation using an anthropomorphic head phantom

    Science.gov (United States)

    Oancea, C.; Shipulin, K.; Mytsin, G.; Molokanov, A.; Niculae, D.; Ambrožová, I.; Davídková, M.

    2017-03-01

    A dosimetric experiment was performed at the Medico-Technical Complex in the Joint Institute for Nuclear Research, Dubna, to investigate the effects of metallic dental implants in the treatment of head and neck tumours with proton therapy. The goal of the study was to evaluate the 2D dose distributions of different clinical treatment plans measured in an anthropomorphic phantom, and compare them to predictions from a treatment planning system. The anthropomorphic phantom was sliced into horizontal segments. Two grade 4 Titanium implants were inserted between 2 slices, corresponding to a maxillary area. GafChromic EBT2 films were placed between the segments containing the implants to measure the 2D delivered dose. Two different targets were designed: the first target includes the dental implants in the isocentre, and in the second target, the proton beam is delivered through the implants, which are located at the entrance region of the Bragg curve. The experimental results were compared to the treatment plans made using our custom 3D Treatment Planning System, named RayTreat. To quantitatively determine differences in the isodose distributions (measured and calculated), the gamma index (3 mm, 3%) was calculated for each target for the matrix value in the region of high isodose (> 90%): for the experimental setup, which includes the implants in the SOBP region, the result obtained was 84.3%. When the implants were localised in the entrance region of the Bragg curve, the result obtained was 86.4%. In conclusion, the uncertainties introduced by the clinically planned dose distribution are beyond reasonable limits. The linear energy transfer spectra in close proximity to the implants were investigated using solid state nuclear track detectors (TED). Scattered particles outside the target were detected.

  1. Is Salvage of Recently Infected Breast Implant After Breast Augmentation or Reconstruction Possible? An Experimental Study.

    Science.gov (United States)

    Castus, P; Heymans, O; Melin, P; Renwart, L; Henrist, C; Hayton, E; Mordon, S; Leclère, F M

    2018-01-23

    The reinsertion of an infected implant when peri-prosthetic infection occurs early after breast augmentation or breast reconstruction remains controversial. In this experimental study, the authors tried to remove bacteria, and their biofilm, from the colonized surface of breast prostheses, without damaging their integrity. A total of 112 shell samples of silicone breast prostheses, smooth (SPSS) and textured (TPSS), were colonized by S. epidermidis (SE) or S. aureus (SA) strains, all able to produce biofilms. After 15 days, all the samples were removed from the contaminated culture broth and constituted 4 groups of 20 contaminated samples: SPSS/SE (group I), SPSS/SA (group II), TPSS/SE (group III), TPSS/SE (group IV). In another group-group SEM-, 16 colonized samples were used for documentation with scanning electron microscopy (SEM). The remaining 16 samples were used to test the limits of detection of the sterility test. All samples of groups I-IV and 8 samples of group SEM were « washed » with a smooth brush in a povidone-iodine bath and rinsed with saline solution. A subset of the washed samples was sent for SEM and the others were immersed in sterile broth and were incubated at 35 °C for 3 weeks (groups I-IV). Fifteen days after contamination, all the samples in groups I-IV were colonized. In the SEM group, SEM images attested to the presence of bacteria in biofilm attached to the shells. After cleaning, SEM did not reveal any bacteria and there was no visible alteration in the outer structure of the shell. Sterility tests performed after decontamination in groups I-IV remained negative for all the samples. Breast prostheses recently contaminated with Staphylococci, frequently involved in peri-prosthetic breast implant infection and capable of producing biofilms, can be efficiently decontaminated by the procedure used in this study. Our decontamination procedure did not alter the surface structure of the prostheses. This decontamination procedure

  2. Healing of implants installed in over- or under-prepared sites--an experimental study in dogs.

    Science.gov (United States)

    Rea, Massimiliano; Lang, Niklaus P; Ricci, Sara; Mintrone, Francesco; González González, Gladys; Botticelli, Daniele

    2015-04-01

    To study bone healing at implants installed with different insertion torques. In six Labrador dogs, all mandibular premolars and first molars were extracted. After 4 months of healing, flaps were elevated, and two implant sites were prepared at each side of the mandible. In the right side of the mandible, the distal sites were prepared conventionally, while the mesial sites were over-prepared by 0.2 mm. As a consequence, a final insertion torque of ~30 Ncm at the distal and a minimal insertion torque close to 0 Ncm at the mesial sites were obtained. In the left sides of the mandible, however, the recipient sites were underprepared by 0.3 mm resulting in an insertion torque of ≥ 70 Ncm at both implants. Cover screws were applied, and flaps sutured to fully submerge the experimental sites. After 4 months, the animals were sacrificed and ground sections obtained for histological evaluation. The mineralized bone-to-implant contact was in the range of 55.2-62.1%, displaying the highest value at implants with ~30 Ncm insertion torque and the lowest value at the implant sites with close to 0 Ncm insertion torque. No statistically significant differences were revealed. Bone density was in the range of 43.4-54.9%, yielding the highest value at implants with ≥ 70 Ncm insertion torque and the lowest at the implant sites with close to 0 Ncm insertion torque. The difference between the sites of ~30 Ncm and the corresponding ≥ 70 Ncm insertion torque reached statistical significance. Similar amounts of osseointegration were obtained irrespective of the insertion torque applied. Moreover, implants installed in sites with close to 0 Ncm insertion torque may properly osseointegrate as well. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Experimental total wrapping of breast implants with acellular dermal matrix: a preventive tool against capsular contracture in breast surgery?

    Science.gov (United States)

    Schmitz, Marweh; Bertram, Martin; Kneser, Ulrich; Keller, Andrea K; Horch, Raymund E

    2013-10-01

    Capsular contracture remains a hitherto unsolved complication after implantation of silicone gel-filled breast prostheses. Based on clinical and experimental data, the use of an acellular dermal matrix as a sheath around implants may lead to lesser capsular contracture acting as a proposed biological environment mimicking wound bed tissue. The aim of our study was to analyse the tissue reaction after implantation of silicone prosthesis with and without an envelope of acellular dermal matrix. Implantation of 60 silicone prostheses in the back of Lewis rats were carried out, randomly paired taking one rat from group A and one from group B. Group A included implants completely enveloped with xenogenic acellular dermis and group B undraped silicone implants. At 3, 6 and 12 weeks postoperatively, the samples were explanted and subjected to histological and immunohistochemical evaluation. A new myofibroblast tissue layer was identified in proximity to the implant in both groups. The thickness of the layer in group A was continuously thinner than in group B regarding the different explantation time points. Implants completely wrapped with acellular dermal matrix showed significantly lesser inflammatory signs at 3 and 12 weeks after implantation compared to controls. Cell proliferation after 12 weeks was significantly decreased in group A. The slight myofibroblast layer and reduced rate of inflammation and proliferation in the treatment group show a positive effect of total acellular dermal matrix envelope and hypothesise the decrease of capsular contracture in long-term periods. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  4. Experimental versus computational analysis of micromotions at the implant-bone interface

    NARCIS (Netherlands)

    Tarala, M.; Janssen, D.; Telka, A.; Waanders, D.; Verdonschot, N.J.J.

    2011-01-01

    In total hip arthroplasty, micromotions at the implant-bone interface influence the long-term survival of the prosthesis. These micromotions are often measured using sensors that are fixed to the implant and bone at points that are remote from the interface. Given that the implant-bone system is not

  5. Experimental study on penetration of dental implants into the maxillary sinus in different depths

    Directory of Open Access Journals (Sweden)

    Weijian ZHONG

    2013-12-01

    Full Text Available The exposing of dental implant into the maxillary sinus combined with membrane perforation might increase risks of implant failure and sinus complications. Objective: The purpose of this study was to investigate the effects of the dental implant penetration into the maxillary sinus cavity in different depths on osseointegration and sinus health in a dog model. Material and Methods: Sixteen titanium implants were placed in the bilateral maxillary molar areas of eight adult mongrel dogs, which were randomly divided into four groups according to the different penetrating extents of implants into the sinus cavities (group A: 0 mm; group B: 1 mm; group C: 2 mm; group D: 3 mm. The block biopsies were harvested five months after surgery and evaluated by radiographic observation and histological analysis. Results: No signs of inflammatory reactions were observed in any maxillary sinus of the eight dogs. The tips of the implants with penetrating depth of 1 mm and 2 mm were found to be fully covered with newly formed membrane and partially with new bone. The tips of the implants with penetrating depth over 3 mm were exposed in the sinus cavity and showed no membrane or bone coverage. No significant differences were found among groups regarding implant stability, bone-to-implant contact (BIC and bone area in the implant threads (BA. Conclusions: Despite the protrusion extents, penetration of dental implant into the maxillary sinus with membrane perforation does not compromise the sinus health and the implant osseointegration in canine.

  6. Rapid selective sweep of pre-existing polymorphisms and slow fixation of new mutations in experimental evolution of Desulfovibrio vulgaris.

    Science.gov (United States)

    Zhou, Aifen; Hillesland, Kristina L; He, Zhili; Schackwitz, Wendy; Tu, Qichao; Zane, Grant M; Ma, Qiao; Qu, Yuanyuan; Stahl, David A; Wall, Judy D; Hazen, Terry C; Fields, Matthew W; Arkin, Adam P; Zhou, Jizhong

    2015-11-01

    To investigate the genetic basis of microbial evolutionary adaptation to salt (NaCl) stress, populations of Desulfovibrio vulgaris Hildenborough (DvH), a sulfate-reducing bacterium important for the biogeochemical cycling of sulfur, carbon and nitrogen, and potentially the bioremediation of toxic heavy metals and radionuclides, were propagated under salt stress or non-stress conditions for 1200 generations. Whole-genome sequencing revealed 11 mutations in salt stress-evolved clone ES9-11 and 14 mutations in non-stress-evolved clone EC3-10. Whole-population sequencing data suggested the rapid selective sweep of the pre-existing polymorphisms under salt stress within the first 100 generations and the slow fixation of new mutations. Population genotyping data demonstrated that the rapid selective sweep of pre-existing polymorphisms was common in salt stress-evolved populations. In contrast, the selection of pre-existing polymorphisms was largely random in EC populations. Consistently, at 100 generations, stress-evolved population ES9 showed improved salt tolerance, namely increased growth rate (2.0-fold), higher biomass yield (1.8-fold) and shorter lag phase (0.7-fold) under higher salinity conditions. The beneficial nature of several mutations was confirmed by site-directed mutagenesis. All four tested mutations contributed to the shortened lag phases under higher salinity condition. In particular, compared with the salt tolerance improvement in ES9-11, a mutation in a histidine kinase protein gene lytS contributed 27% of the growth rate increase and 23% of the biomass yield increase while a mutation in hypothetical gene DVU2472 contributed 24% of the biomass yield increase. Our results suggested that a few beneficial mutations could lead to dramatic improvements in salt tolerance.

  7. Experimental validation of 3D printed patient-specific implants using digital image correlation and finite element analysis.

    Science.gov (United States)

    Sutradhar, Alok; Park, Jaejong; Carrau, Diana; Miller, Michael J

    2014-09-01

    With the dawn of 3D printing technology, patient-specific implant designs are set to have a paradigm shift. A topology optimization method in designing patient-specific craniofacial implants has been developed to ensure adequate load transfer mechanism and restore the form and function of the mid-face. Patient-specific finite element models are used to design these implants and to validate whether they are viable for physiological loading such as mastication. Validation of these topology optimized finite element models using mechanical testing is a critical step. Instead of inserting the implants into a cadaver or patient, we embed the implants into the computer-aided skull model of a patient and, fuse them together to 3D print the complete skull model with the implant. Masticatory forces are applied in the molar region to simulate chewing and measure the stress-strain trajectory. Until recently, strain gages have been used to measure strains for validation. Digital Image Correlation (DIC) method is a relatively new technique for full-field strain measurement which provides a continuous deformation field data. The main objective of this study is to validate the finite element model of patient-specific craniofacial implants against the strain data from the DIC obtained during the mastication simulation and show that the optimized shapes provide adequate load-transfer mechanism. Patient-specific models are obtained from CT scans. The principal maximum and minimum strains are compared. The computational and experimental approach to designing patient-specific implants proved to be a viable technique for mid-face craniofacial reconstruction. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Multivariate phenotypic divergence due to the fixation of beneficial mutations in experimentally evolved lineages of a filamentous fungus

    NARCIS (Netherlands)

    Schoustra, S.E.; Punzalan, D.; Dali, R.; Rundle, H.D.; Kassen, R.

    2012-01-01

    The potential for evolutionary change is limited by the availability of genetic variation. Mutations are the ultimate source of new alleles, yet there have been few experimental investigations of the role of novel mutations in multivariate phenotypic evolution. Here, we evaluated the degree of

  9. New means in spinal pedicle hook fixation. A biomechanical evaluation.

    Science.gov (United States)

    Berlemann, U; Cripton, P; Nolte, L P; Lippuner, K; Schläpfer, F

    1995-01-01

    Pedicle hooks which are used as an anchorage for posterior spinal instrumentation may be subjected to considerable three-dimensional forces. In order to achieve stronger attachment to the implantation site, hooks using screws for additional fixation have been developed. The failure loads and mechanisms of three such devices have been experimentally determined on human thoracic vertebrae: the Universal Spine System (USS) pedicle hook with one screw, a prototype pedicle hook with two screws and the Cotrel-Dubousset (CD) pedicle hook with screw. The USS hooks use 3.2-mm self-tapping fixation screws which pass into the pedicle, whereas the CD hook is stabilised with a 3-mm set screw pressing against the superior part of the facet joint. A clinically established 5-mm pedicle screw was tested for comparison. A matched pair experimental design was implemented to evaluate these implants in constrained (series I) and rotationally unconstrained (series II) posterior pull-out tests. In the constrained tests the pedicle screw was the strongest implant, with an average pull-out force of 1650 N (SD 623 N). The prototype hook was comparable, with an average failure load of 1530 N (SD 414 N). The average pull-out force of the USS hook with one screw was 910 N (SD 243 N), not significantly different to the CD hook's average failure load of 740 N (SD 189 N). The result of the unconstrained tests were similar, with the prototype hook being the strongest device (average 1617 N, SD 652 N). However, in this series the difference in failure load between the USS hook with one screw and the CD hook was significant. Average failure loads of 792 N (SD 184 N) for the USS hook and 464 N (SD 279 N) for the CD hook were measured. A pedicular fracture in the plane of the fixation screw was the most common failure mode for USS hooks.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. [Experimental study of dental implants with nanostructured non-resorbable coating integration into bone tissue].

    Science.gov (United States)

    Grigor'ian, A S; Khamraev, T K; Toporkova, A K; Amirov, A R

    2010-01-01

    In 2 dogs on both sides of mandible premolars were removed. In 3 months after dental alveolus healing intraosseous screwdriver dental implants (Konmet, Russia) were installed in the place of the removed teeth. Analogous operation was done on the contralateral side: the same type of implants were installed but with new nanostructured multifunctional biocompatible non-resorbable coating (MBNC) of the Ti-Ca-P-C-O-N composition. The animals were taken out of the experiment in 4 months after implants installation and implant-bone blocks were studied by SEM-method. According to the SEM-data in the region of the contact of implant-bone without new MBNC only fibrous connective tissue was formed. In case when MBNC was used the close welding of bone tissue with implant surface was observed that was considered as sign of osteointegration.

  11. Load-bearing capacity and fracture behavior of glass fiber-reinforced composite cranioplasty implants.

    Science.gov (United States)

    Piitulainen, Jaakko M; Mattila, Riina; Moritz, Niko; Vallittu, Pekka K

    2017-11-10

    Glass fiber-reinforced composites (FRCs) have been adapted for routine clinical use in various dental restorations and are presently also used in cranial implants. The aim of this study was to measure the load-bearing capacity and failure type of glass FRC implants during static loading with and without interconnective bars and with different fixation modes. Load-bearing capacities of 2 types of FRC implants with 4 different fixation modes were experimentally tested. The sandwich-like FRC implants were made of 2 sheets of woven FRC fabric, which consisted of silanized, woven E-glass fiber fabrics impregnated in BisGMA-TEGDMA monomer resin matrix. The space between the outer and inner surfaces was filled with glass particles. All FRC implants were tested up to a 10-mm deflection with load-bearing capacity determined at 6-mm deflection. The experimental groups were compared using nonparametric Kruskal-Wallis analysis with Steel-Dwass post hoc test. FRC implants underwent elastic and plastic deformation until 6-mm deflection. The loading test did not demonstrate any protrusions of glass fibers or cut fiber even at 10-mm deflection. An elastic and plastic deformation of the implant occurred until the FRC sheets were separated from each other. In the cases of the free-standing setup (no fixation) and the fixation with 6 screws, the FRC implants with 2 interconnective bars showed a significantly higher load-bearing capacity compared with the implant without interconnective bars. FRC implants used in this study showed a load-bearing capacity which may provide protection for the brain after cranial bone defect reconstruction.

  12. [The assessment of modification of prosthesis fixation method on visceral interposition during laparoscopic abdominal hernia reconstruction].

    Science.gov (United States)

    Jamry, Andrzej; Jałyński, Marek; Brocki, Marian

    2011-09-01

    During laparoscopic abdominal hernia repair (LAHR) there is a discrepancy in relative position of mesh and fixation points during the procedure (while abdominal cavity is distended with gas) and afterwards. Therefore, after the surgery the prosthesis becomes corrugated, and tension develops in suture anchoring points. One of the proposed solutions of this problem is to place stabilizing sutures outside the mesh edges and to tie them after emptying the abdominal cavity of CO2. However, due to lack of visualization, viscera entrapment between the mesh and integuments may occur during this stage of surgery. The aim of the study was to assess the effect of fixation technique modification on the risk of visceral interposition between the mesh and integuments and deformation of prostheses fixated this way. The study was performed in an experimental animal model (12 pigs) by implanting laparoscopically two 6.6x6 cm mesh fragments per animals and tying fixation sutures after emptying the abdominal cavity of CO2. After 6 weeks, visceral interposition between mesh and integuments and such fixated fragments corrugation were assessed. Visceral dislocation between parietal and visceral surface was absent in all 24 assessed meshes, despite fixation under no visual guidance. There were no mesh deformities between anchoring points. The analysed modification of laparoscopic abdominal hernia repair does not create risk of internal organ interposition between the prosthesis and integuments and prevents mesh from being corrugated.

  13. Comparative analysis of clinical outcomes between zero-profile implant and cages with plate fixation in treating multilevel cervical spondilotic myelopathy: A three-year follow-up.

    Science.gov (United States)

    Chen, Yu; Chen, Huajiang; Wu, Xiaodong; Wang, Xinwei; Lin, Wenbo; Yuan, Wen

    2016-05-01

    This study aimed to figure out three-year clinical outcomes and complications of ACDF with Zero-p in treating multilevel cervical spondylotic myelopathy (MCSM) by comparing with plate fixation. Patients with MCSM caused by degenerative disc herniation only were recruited from April 2010 to December 2010. According to the surgical procedures, the patients were divided into two groups at random, the plate group and Zero-P group. The data was collected before surgery and at three-year follow-up. Clinical parameters, including Japanese orthopedic association (JOA) score, neck disabled index (NDI) were evaluated. Cervical segmental lordosis was calculated and fusion in each level was assessed on lateral radiographs. The Bazaz's criterion and the short Swallowing and Quality of Life (SQOL) questionnaires were used to evaluate the dysphagia incidence and severity respectively. The presence of ALOD was observed and recorded on lateral radiographs. A total of 72 patients (46 men and 26 women) were recruited. The mean age at operation was 52.9±7.9years, ranged from 43 to 69 years. There was no significant difference between two groups preoperatively in age, sex, operative levels, JOA, NDI, cervical lordosis, dysphagia incidence, SQOL and ALOD incidence. JOA, NDI and cervical lordosis improved postoperatively and postoperative SQOL got restitution in both groups. However, no difference was detected. There were 7 patients with ALOD in the plate group after surgeries while there was only 1 patient in Zero-P group. The difference of AOLD incidence between them was significant. Of the 7 patients with ALOD in the plate group, 4 patients developed ALOD in cranial level, 2 in caudal level and 1 in both levels. The patient in Zero-P group developed ALOD in caudal level. Based on the three-year follow-up, we could not conclude that Zero-P was superior to plate fixation in clinical outcomes such as neurological results, cervical lordosis, fusion rate and the incidence and severity of

  14. Theoretical Evaluation and Experimental Validation of Localized Therapeutic Hypothermia Application to Preserve Residual Hearing After Cochlear Implantation.

    Science.gov (United States)

    Tamames, Ilmar; King, Curtis; Huang, Chin-Yuh; Telischi, Fred F; Hoffer, Michael E; Rajguru, Suhrud M

    2017-12-13

    Cochlear implantation surgery has been shown to result in trauma to inner ear sensory structures, resulting in loss of residual hearing. Localized therapeutic hypothermia has been shown in clinical care to be a neuroprotective intervention. Previously, we have shown in an experimental model that localized hypothermia protects cochlear hair cells and residual hearing function against surgical and cochlear implantation trauma. Using experimental temperature measurements carried out in human cadaver temporal bones and a finite element model of the inner ear, the present study examined the temperature distribution of a custom-designed hypothermia delivery system in the human inner ear organs. The efficacy of the hypothermia probe and resulting heat distribution across human cochlea and surrounding tissues were modeled in three-dimensional in COMSOL. The geometry and dimensions of inner ear and temporal bones were derived from computed tomographic and magnetic resonance imaging images. Model predictions were compared with experimental observations from five human temporal bones. In both the modeling and experimental studies, the cochlear temperature was lowered by 4 to 6 °C on the round window from a baseline of 37 °C within 16 to 18 minutes. The model simulations showed uniformly distributed cooling across the cochlea. This study provides insight for design, operation, and protocols for efficacious delivery of mild therapeutic hypothermia to the human cochlea that may significantly benefit patients undergoing surgical cochlear implantation by preserving residual hearing. There was a close correlation between the results of the numerical simulations and experimental observations in this study. Our custom-designed system is capable of effectively providing mild therapeutic hypothermia locally to the human cochlea. When combined with results from in vivo animal experiments, the present study suggests that the application of localized therapeutic hypothermia may hold

  15. The effect of anterior cruciate ligament resection and immediate or delayed implantation of a meniscus prosthesis on knee joint biomechanics and cartilage. An experimental study in rabbits.

    Science.gov (United States)

    Sommerlath, K G; Gillquist, J

    1993-04-01

    In a rabbit experiment with anterior cruciate ligament (ACL) resection, immediate substitution of the medial meniscus with a prosthesis was compared with delayed prosthetic implantation after a postmeniscectomy period of three weeks. The knees with a prosthetic implant were compared with their contralateral joints as well as to joints with an intact ACL and menisci. Anterior cruciate ligament resection alone led to disturbed biomechanics and cartilage degeneration. Anterior cruciate ligament resection in combination with meniscus resection increased cartilage degeneration and led to more inferior biomechanics. Ingrowth and stable fixation was less frequent when the prosthesis was inserted three weeks after meniscus resection than when inserted immediately. Furthermore, in knees with delayed prosthetic implantation, only minor improvement in terms of cartilage protection was shown when compared with knees with resection only. In contrast, knees with immediate meniscus replacement demonstrated similar joint stiffness and stress relaxation characteristics and similar cartilage protection effects as knees with a nonresected medial meniscus.

  16. Pectin nanocoating of titanium implant surfaces - an experimental study in rabbits

    DEFF Research Database (Denmark)

    Gurzawska, Katarzyna Aleksandra; Dirscherl, Kai; Jørgensen, Bodil

    2017-01-01

    that may increase adhesion of bone proteins, and bone cells at the implant surface. Nanocoating with pectins, plant cell wall-derived polysaccharides, is frequently done using rhamnogalacturonan-I (RG-I). AIM: The aim of the study was to evaluate the effect of nanocoating titanium implants with plant cell......) into the left and right tibia of rabbits. Machined titanium implants without RG-I nanocoating were used as controls (n = 32). Total number of 128 implants was placed in tibias of 16 rabbits. Fluorochrome bone labels, calcein green and alizarin red S were given intravenously after 9 and 12 days, respectively....... The bone response to the nanocoated implants was analyzed qualitatively and quantitatively after 2, 4, 6, and 8 weeks of healing using light microscopy and histomorphometric methods. RESULTS: The RG-I coating influenced the surface chemical composition; wettability and roughness, making the surface more...

  17. Comparison of the mechanical behaviors of semicontoured, locking plate-rod fixation and anatomically contoured, conventional plate-rod fixation applied to experimentally induced gap fractures in canine femora.

    Science.gov (United States)

    Goh, Clara S S; Santoni, Brandon G; Puttlitz, Christian M; Palmer, Ross H

    2009-01-01

    To compare the mechanical behaviors of a semicontoured, locking compression plate-rod (LCP-rod) construct and an anatomically contoured, limited-contact dynamic compression plate-rod (LC-DCP-rod) construct applied to experimentally induced gap fractures in canine femora. 16 femora from 8 cadaveric dogs. 8 limbs from 8 dogs were assigned to the LCP-rod construct group or the LC-DCP-rod construct group. In each femur, a 39-mm mid-diaphyseal ostectomy was performed at the same plate location and the assigned construct was applied. Construct stiffness and ostectomy gap subsidence were determined before and after cyclic axial loading (6,000 cycles at 20%, 40%, and 60% of live body weight [total, 18,000 cycles]). Three constructs from each group further underwent 45,000 cycles at 60% of body weight (total, 63,000 cycles). Following cyclic loading, mode of failure during loading to failure at 5 mm/min was recorded for all constructs. After 18,000 or 63,000 cycles, construct stiffness did not differ significantly between construct groups. No implant failure occurred in any construct that underwent 63,000 cycles. In both construct groups, ostectomy gap subsidence similarly increased as axial load increased but did not change after 18,000 cycles. Mean +/- SEM loads at failure in the LCP-rod (1,493.83 +/- 200.12 N) and LC-DCP-rod (1,276.05 +/- 156.11 N) construct groups were not significantly different. The primary failure event in all constructs occurred at the screw hole immediately distal to the ostectomy. Biomechanically, the semicontoured LCP-rod construct is similar to the anatomically contoured LC-DCP-rod system.

  18. Integration of fluoridated implants in onlay autogenous bone grafts - an experimental study in the rabbit tibia.

    Science.gov (United States)

    Dasmah, Amir; Kashani, Hossein; Thor, Andreas; Rasmusson, Lars

    2014-09-01

    Bone augmentation before treatment with endosseous implants is a common procedure for rehabilitation of the edentulous jaw. Both machined and surface modified implants have been used in one-stage and two-stage surgery protocols with varying results and survival rates. The influence of surface modification on the integration of implants has been documented in both non-grafted and grafted bone. The aim of this study was to compare the integration and stability of surface modified fluoridated vs. machined implants when placed simultaneously with an onlay bone graft. Eight rabbits were used in this study. A disc shaped bone graft was harvested from each side of the sagittal suture of the calvarial bone and fixed bi-cortically to the proximal tibial metaphysis by means of a dental implant, 9 mm long and 3.5 mm in diameter with a smooth machined surface as control and a blasted, fluoridated surface as test. Test and control sides were randomised. After a healing time of 8 weeks, the rabbits were sacrificed and the implants were removed en block for light microscopic analysis. Bone to implant contact (BIC) was registered as well as the amount of bone filling a rectangle indicating a region of interest (ROI) in the grafted area. Resonance frequency analysis (RFA) was conducted both at the time of surgery and at the end of the study. Our results showed statistically significant differences in BIC within the grafted area and the total bone to implant contact between the test and control sides in favour of the surface modified implants. The bone area filling the threads within a region of interest showed no statistically significant difference between the test and control sides. RFA showed higher implant stability with significant differences at the time of sacrifice in favour of the fluoridated implants. Surface modified fluoridated implants showed a higher degree of osseointegration and stability in onlay bone grafts compared with control implants with machined surface

  19. Functionality Evaluation of a Novel Smart Expandable Pedicle Screw to Mitigate Osteoporosis Effect in Bone Fixation: Modeling and Experimentation

    Directory of Open Access Journals (Sweden)

    Ahmadreza Eshghinejad

    2013-01-01

    Full Text Available This paper proposes a novel expandable-retractable pedicle screw and analyzes its functionality. A specially designed pedicle screw is described which has the ability to expand and retract using nitinol elements. The screw is designed to expand in body temperature and retract by cooling the screw. This expansion-retraction function is verified in an experiment designed in larger scale using a nitinol antagonistic assembly. The results of this experiment are compared to the results of a finite element model developed in Abaqus in combination with a user material subroutine (UMAT. This code has been developed to analyze the nonlinear thermomechanical behavior of shape memory alloy materials. The functionality of the proposed screw is evaluated with simulation and experimentation in a pullout test as well. The pullout force of a normal screw inserted in a normal bone was simulated, and the result is compared with the results of the expandable screw in osteoporotic bone. Lastly, strength of the designed pedicle screw in a foam block is also verified with experiment. The reported finite element simulations and experiments are the proof for the concept of nitinol expandable-retractable elements on a pedicle screw which validate the functionality in a pullout test.

  20. The Effect of Simplifying Dental Implant Drilling Sequence on Osseointegration: An Experimental Study in Dogs

    Directory of Open Access Journals (Sweden)

    Gabriela Giro

    2013-01-01

    Full Text Available Objectives. To test the hypothesis that there would be no differences in osseointegration by reducing the number of drills for site preparation relative to conventional drilling sequence. Methods. Seventy-two implants were bilaterally placed in the tibia of 18 beagle dogs and remained for 1, 3, and 5 weeks. Thirty-six implants were 3.75 mm in diameter and the other 36 were 4.2 mm. Half of the implants of each diameter were placed under a simplified technique (pilot drill + final diameter drill and the other half were placed under conventional drilling where multiple drills of increasing diameter were utilized. After euthanisation, the bone-implant samples were processed and referred to histological analysis. Bone-to-implant contact (BIC and bone-area-fraction occupancy (BAFO were assessed. Statistical analyses were performed by GLM ANOVA at 95% level of significance considering implant diameter, time in vivo, and drilling procedure as independent variables and BIC and BAFO as the dependent variables. Results. Both techniques led to implant integration. No differences in BIC and BAFO were observed between drilling procedures as time elapsed in vivo. Conclusions. The simplified drilling protocol presented comparable osseointegration outcomes to the conventional protocol, which proved the initial hypothesis.

  1. Morphological Changes in Blood Cells After Implantation of Titanium and Plastic Clips in the Neurocranium - Experimental Study on Dogs

    OpenAIRE

    Katica, Muhamed; Celebicic, Mirza; Gradascevic, Nedzad; Obhodzas, Muamer; Sulji?, Enra; Ocuz, Muhamed; Delibegovic, Samir

    2017-01-01

    Introduction: Various studies confirm the biocompatibility and efficacy of clips for certain target tissues, but without any comparative analysis of hematological parameters. Therefore, we conducted a study to assess the possible association of the implantation of titanium and plastic clips in the neurocranium with possible morphological changes in the blood cells of experimental animals. Materials and Methods: As a control, the peripheral blood smears were taken before surgery from 12 adult ...

  2. Bone conditioning to enhance implant osseointegration: an experimental study in pigs.

    Science.gov (United States)

    Schlegel, Karl Andreas; Kloss, Frank Rudolf; Kessler, Peter; Schultze-Mosgau, Stefan; Nkenke, Emeka; Wiltfang, Joerg

    2003-01-01

    Osseointegration of implants depends on time and the local bone conditions regarding quality and quantity. This led to the bone classification by Lekholm and Zarb. The aim of the present study was to enhance osseointegration of implants through conditioning of the bone bed and to compare in this context the efficacy of bone condensation, an osteoinductive collagen (Colloss), and platelet-rich plasma (PRP). Porcine frontal skull bone was used for the preparation of Identical-size implant beds. Before placement of the implants (Ankylos, 3.5 x 4 mm), the implant beds were untreated (control) or conditioned with condensation, Colloss, or PRP. The animals were sacrificed after 2, 4, and 8 weeks. The specimens were then compared and analyzed by microradiography, and statistical analysis was performed using the Wilcoxon signed rank test. At the early observation times, significant effects on the sites of topical bone conditioning in comparison to the control group could be seen regarding the implant-bone interface (2 weeks: control 31%, Colloss 60%, condensation 73%, PRP 47%; 4 weeks: control 39%, Colloss 51%, condensation 40%, PRP 42%) and peri-implant bone density (2 weeks: control 31%, Colloss 48%, condensation 59%, PRP 39%; 4 weeks: control 47%, Colloss 53%, condensation 41%, PRP 50%). A leveling of the results between groups was found at 8 weeks (implant-bone interface: control 51%, Colloss 58%, condensation 55%, PRP 62%; peri-implant bone density: control 50%, Colloss 55%, condensation 51%, PRP 51%). Overall, bone condensation and Colloss apparently influenced bone formation process from the onset, but over the entire 8-week healing period, differences in bone formation were not significant It can be stated that, in the initial healing phase, an effect of topical bone conditioning may be achieved by the different described methods.

  3. HA-Coated Implant

    DEFF Research Database (Denmark)

    Daugaard, Henrik; Søballe, Kjeld; Bechtold, Joan E

    2014-01-01

    The goal of osseointegration of orthopedic and dental implants is the rapid achievement of a mechanically stable and long lasting fixation between living bone and the implant surface. In total joint replacements of cementless designs, coatings of calcium phosphates were introduced as a means...

  4. Influence of Drilling Speed on Stability of Tapered Dental Implants: An Ex Vivo Experimental Study.

    Science.gov (United States)

    Almeida, Karen P; Delgado-Ruiz, Rafael; Carneiro, Leandro G; Leiva, Alberto Bordonaba; Calvo-Guirado, Jose Luis; Gómez-Moreno, Gerardo; Malmström, Hans; Romanos, Georgios E

    2016-01-01

    The aim of this study was to evaluate whether the drilling speed used during implant site preparation influences primary stability. Eighty tapered designed implants (3.8 × 10 mm) were inserted following osteotomies created in solid rigid polyurethane foam (simulating bone type II) and cellular rigid polyurethane foam (simulating bone type IV). Half were prepared using drilling speeds of 800 rpm (low speed), and the other half were prepared using speeds of 1,500 rpm (high speed). Following insertion, implant primary stability was measured using Periotest and Osstell (resonance frequency analysis [RFA]) devices. Two-way analysis of variance (ANOVA) used for this study found that the drilling speed used to create the osteotomies appeared to have no significant impact on primary stability. The bone quality and not the osteotomy drilling speed seems to influence the implant primary stability.

  5. Enhanced osseointegration of titanium implants with nanostructured surfaces: an experimental study in rabbits.

    Science.gov (United States)

    Salou, Laëtitia; Hoornaert, Alain; Louarn, Guy; Layrolle, Pierre

    2015-01-01

    Titanium and its alloys are commonly used for dental implants because of their good mechanical properties and biocompatibility. The surface properties of titanium implants are key factors for rapid and stable bone tissue integration. Micro-rough surfaces are commonly prepared by grit-blasting and acid-etching. However, proteins and cells interact with implant surfaces in the nanometer range. The aim of this study was to compare the osseointegration of machined (MA), standard alumina grit-blasted and acid-etched (MICRO) and nanostructured (NANO) implants in rabbit femurs. The MICRO surface exhibited typical random cavities with an average roughness of 1.5 μm, while the NANO surface consisted of a regular array of titanium oxide nanotubes 37±11 nm in diameter and 160 nm thick. The MA and NANO surfaces had a similar average roughness of 0.5 μm. The three groups of implants were inserted into the femoral condyles of New Zealand White rabbits. After 4 weeks, the pull-out test gave higher values for the NANO than for the other groups. Histology corroborated a direct apposition of bone tissue on to the NANO surface. Both the bone-to-implant contact and bone growth values were higher for the NANO than for the other implant surfaces. Overall, this study shows that the nanostructured surface improved the osseointegration of titanium implants and may be an alternative to conventional grit-blasted and acid-etched surface treatments. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  6. A review on the wettability of dental implant surfaces I: theoretical and experimental aspects.

    Science.gov (United States)

    Rupp, Frank; Gittens, Rolando A; Scheideler, Lutz; Marmur, Abraham; Boyan, Barbara D; Schwartz, Zvi; Geis-Gerstorfer, Jürgen

    2014-07-01

    The surface wettability of biomaterials determines the biological cascade of events at the biomaterial/host interface. Wettability is modulated by surface characteristics, such as surface chemistry and surface topography. However, the design of current implant surfaces focuses mainly on specific micro- and nanotopographical features, and is still far from predicting the concomitant wetting behavior. There is an increasing interest in understanding the wetting mechanisms of implant surfaces and the role of wettability in the biological response at the implant/bone or implant/soft tissue interface. Fundamental knowledge related to the influence of surface roughness (i.e. a quantification of surface topography) on titanium and titanium alloy surface wettability, and the different associated wetting regimes, can improve our understanding of the role of wettability of rough implant surfaces on the biological outcome. Such an approach has been applied to biomaterial surfaces only in a limited way. Focusing on titanium dental and orthopaedic implants, the present study reviews the current knowledge on the wettability of biomaterial surfaces, encompassing basic and applied aspects that include measurement techniques, thermodynamic aspects of wetting and models predicting topographical and roughness effects on the wetting behavior. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  7. A new floating piezoelectric microphone for the implantable middle ear microphone in experimental studies.

    Science.gov (United States)

    Jia, Xian-Hao; Gao, Na; Xu, Xin-da; Wu, Yong-Zhen; Kang, Hou-Yong; Chi, Fang-Lu

    2016-12-01

    The new floating piezoelectric microphone is feasible for use as an implantable middle ear microphone in a totally implantable cochlear implant. A piezoelectric sensor that is driven by the acoustic vibration of the ossicles is one possible design for a microphone for a totally implantable cochlear implant. Such a new floating piezoelectric microphone has been manufactured in the lab. The purpose of this article was to study the frequency response of the new floating piezoelectric microphone in the intact ossicular chain and to identify whether it is usable and implantable. The frequency response of the new floating piezoelectric microphone was analyzed using in vitro testing of fresh cadaveric heads. The microphone, which was designed with an integrated unibody structure to ensure good biocompatibility and capsulation, was attached to the long process of the incus by a titanium clip, or placed in the tympanic cavity and stimulated with pure tones of different frequencies. The new floating piezoelectric microphone can pick up the vibration of the long process of the incus and convert it into electrical signals sensitively and flatly.

  8. 21 CFR 888.3010 - Bone fixation cerclage.

    Science.gov (United States)

    2010-04-01

    ...) Identification. A bone fixation cerclage is a device intended to be implanted that is made of alloys, such as cobalt-chromium-molybdenum, and that consists of a metallic ribbon or flat sheet or a wire. The device is...

  9. Estudo tomográfico do atlas relacionado com a inserção de implantes na massa lateral Tomographic study of the atlas concerning screw fixation on lateral mass

    Directory of Open Access Journals (Sweden)

    Max Franco de Carvalho

    2009-01-01

    Full Text Available INTRODUÇÃO: A técnica de Harms para a realização da artrodese atlantoaxial possibilita o uso de manobras de redução transoperatória da subluxação atlantoaxial e facilita a fixação dessa articulação, principalmente nos pacientes hipercifóticos e nas situações em que há impossibilidade da fixação com o parafuso transarticular C1-C2. OBJETIVOS: descrever os parâmetros morfométricos do atlas relacionados à técnica de Harms para a artrodese C1-C2, o trajeto ideal e o corredor de segurança da inserção do parafuso na massa lateral do atlas mensurados através de imagens de reconstrução multiplanar com tomografia computadorizada helicoidal nos planos. MATERIAIS E MÉTODOS: trinta atlas de origem local foram submetidos a tomografia computadorizada e mensurados com cursor digital. RESULTADOS: o comprimento posteroanterior do implante mediu 16,5 mm à direita e 16,3mm à esquerda. Quando utilizando como ponto de entrada na porção central da massa lateral imediatamente inferior ao arco posterior, o trajeto deve ter uma congruência de 15º no plano coronal e uma angulação superior de 20º no plano sagital. CONCLUSÃO: O corredor de segurança para um parafuso na massa lateral teria uma inclinação inferior de 22º e superior de 33º no plano sagital e no plano axial de 36º medial e 26º lateral.INTRODUCTION: Harms's technique for atlanto-axial arthrodesis fusion makes possible the use of intraoperative reduction maneuvers of the atlanto-axial dislocation and facilitates the fixation of this joint, especially in hiperkyphotic patients and in situations where the fixation with transarticular screw on C1-C2 segment is impossible. OBJECTIVE: to describe the morphometric parameters of atlases related to the Harms's technique for atlanto-axial arthrodesis, the optimal path and the safety aisle for screw insertion into atlas' lateral mass measured with multiplanar reconstruction imaging with helical computed tomography scan at

  10. Experimental and computational analysis of micromotions of an uncemented femoral knee implant using elastic and plastic bone material models.

    Science.gov (United States)

    Berahmani, Sanaz; Janssen, Dennis; Verdonschot, Nico

    2017-08-16

    It is essential to calculate micromotions at the bone-implant interface of an uncemented femoral total knee replacement (TKR) using a reliable computational model. In the current study, experimental measurements of micromotions were compared with predicted micromotions by Finite Element Analysis (FEA) using two bone material models: linear elastic and post-yield material behavior, while an actual range of interference fit was simulated. The primary aim was to investigate whether a plasticity model is essential in order to calculate realistic micromotions. Additionally, experimental bone damage at the interface was compared with the FEA simulated range. TKR surgical cuts were applied to five cadaveric femora and micro- and clinical CT- scans of these un-implanted specimens were made to extract geometrical and material properties, respectively. Micromotions at the interface were measured using digital image correlation. Cadaver-specific FEA models were created based on the experimental set-up. The average experimental micromotion of all specimens was 53.1±42.3µm (mean±standard deviation (SD)), which was significantly higher than the micromotions predicted by both models, using either the plastic or elastic material model (26.5±23.9µm and 10.1±10.1µm, respectively; p-valuematerial models). The difference between the two material models was also significant (p-value<0.001). The predicted damage had a magnitude and distribution which was comparable to the experimental bone damage. We conclude that, although the plastic model could not fully predict the micro motions, it is more suitable for pre-clinical assessment of a press-fit TKR implant than using an elastic bone model. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Histomorphometric and removal torque analysis for TiO2-blasted titanium implants. An experimental study on dogs

    DEFF Research Database (Denmark)

    Gotfredsen, K; Nimb, L; Hjörting-Hansen, E

    1992-01-01

    bilaterally and 24 commercial pure titanium implants were placed immediately in extraction sockets and covered with mucoperiosteum. Each dog had inserted 4 implants: 1 screw implant and 1 cylindrical implant blasted with titanium-dioxide-particles; 1 screw implant and 1 cylindrical implant with machine......-produced (m.p.) surface (controls). After a healing period of 12 weeks, 16 implants from 4 animals were used for removal torque test, which demonstrated that significantly higher removal torque force was needed to unscrew the implants blasted with titanium-dioxide-particles, than the normal m.p. implants......-blasted implants and the control implants. The implants blasted with titanium-dioxide-particles in this study showed a better anchorage than implants with a machine-produced surface. The screw implants showed a better anchorage than the cylindrical implants....

  12. Bone healing at implants with different surface configurations: an experimental study in dogs.

    Science.gov (United States)

    Beolchini, Marco; Lang, Niklaus P; Gómez Moreno, Gerardo; Iezzi, Giovanna; Botticelli, Daniele; Calvo Guirado, José Luis

    2016-02-01

    To study osseointegration of implants with surface modifications by the use of fluoroboric acid and/or H2 O2 installed in conventional sites or sites with circumferential marginal defects. Four implants with different surfaces were used. One basic surface (ZirTi(®)) was sandblasted with zirconium microspheres and acid etched additionally with hydrofluoric acid. A second surface was treated with fluoroboric acid instead of hydrofluoric acid. The remainder of the other two surfaces was additionally treated with H2O2. The edentulous mandibles of 6 foxhound dogs were used to randomly install 8.5-mm-long implants with the different surfaces and to study the histological healing after 1 and 3 months. To study osteoconductivity, additional four recipient sites were prepared with the coronal region being widened so that a 4 mm deep and 0.85 mm wide marginal defect resulted after the placement of the four implants with different surfaces. No filler material or membranes were used, and a fully submerged healing was allowed for 3 months. At the conventional sites, new bone formation ranged between 68.5% and 74.9% after 1 month. After 3 months, bone-to-implant contact ranged from 72.6% at the ZirTi(®) surface to 84.1% at the fluoroboric acid-treated implants, the difference being statistically significant. At the sites with marginal defects, bone formation ranged from 0.77 mm at the surface treated with fluoroboric acid and H2O2 , to 1.93 mm at the surface treated with fluoroboric acid alone. Fluoroboric acid treatment alone of titanium implant surfaces resulted in improved osseointegration and osteoconductivity after 3 months. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. A Comparative Study of Densitometric Parameters of the Bone Tissue Under Transosseous Osteosynthesis by Using Experimental Implants Coated with Superhard Compounds

    Directory of Open Access Journals (Sweden)

    Galimzyan KABIROV

    2015-07-01

    Full Text Available By X-ray computed tomography (CT, density characteristics of the tibiae bones in 25 experimental adult male rats were studied after their tibiae bones have experimentally fractured and then repaired by osteosynthesis using different implants. According to the data that was obtained by computed tomography, it has been defined that bone densities depend on the type of the implant and the chemical composition of the coating which is applied on the surface of the implant. Thus, average values of the density of the tibiae bones in the experimental rats with implants coated with a combination of titanium and hafnium nitrides were not different from the density values of the intact bones. At the same time, the densities of the tibiae in rats with implants made of copper and implants coated with a combination of titanium and zirconium nitrides were 1.5-2 times lower than those of the intact bones. This leads us to conclude that implants coated with titanium and hafnium nitrides are biologically and chemically inert because less pathologic changes in the bone tissue were observed, in contrast to the copper-based implants and those where the coating contains zirconium.

  14. Implante Autólogo Ovariano no Omento Maior: Estudo Experimental Ovarian Autotransplantation to the Greater Omentum: Experimental Model

    Directory of Open Access Journals (Sweden)

    Luiz Ronaldo Alberti

    2002-01-01

    Full Text Available Objetivos: avaliar os aspectos morfofuncionais de ovários implantados no omento maior, bem como a melhor técnica para implantação do ovário: se íntegro ou fatiado. Métodos: foram divididas aleatoriamente 40 ratas Wistar com ciclos estrais normais em quatro grupos: Grupo I (n = 5, controle - laparotomia; Grupo II (n = 5, ooforectomia total bilateral; Grupo III (n = 15, implante autólogo íntegro no omento maior e Grupo IV (n = 15, implante autólogo fatiado no omento maior. Realizaram-se esfregaços vaginais nos 3º e 6º mes pós-operatório e estudos histológicos dos implantes ovarianos, avaliando-se: degeneração, fibrose, reação inflamatória, angiogênese, cistos foliculares, desenvolvimento folicular e corpos lúteos. Resultados: os animais do Grupo I ciclaram normalmente. As ratas do Grupo II não apresentaram ciclo, permanecendo em diestro. No Grupo III, 11 ratas permaneceram em diestro, três apresentaram ciclos incompletos e apenas uma ciclou normalmente. No Grupo IV, três animais não ciclaram, oito tiveram esfregaços vaginais incompletos e quatro ciclaram normalmente. Os achados histológicos dos animais pertencentes ao Grupo III evidenciaram histoarquitetura normal em dez ratas, porém nas outras cinco, houve degeneração ovariana. No Grupo IV, 14 ratas tiveram ovários com histoarquitetura preservada e em apenas uma houve sinais de degeneração. Conclusões: o implante autólogo ovariano no omento maior foi viável, obtendo-se melhor preservação morfofuncional com a implantação de fatias.Purpose: in order to maintain the gonadal function after oophorectomy, morphofunctional aspects of ovarian autotransplantation to the greater omentum and the best kind of implantation, intact or sliced, were investigated. Methods: forty cycling female Wistar rats were randomly divided into four groups: Group I (n = 5, control - laparotomy; Group II (n = 5, bilateral oophorectomy; Group III (n = 10, intact ovarian

  15. Estudo experimental da biocompatibilidade de novo material para implante orbitário

    Directory of Open Access Journals (Sweden)

    Rodrigo Beraldi Kormann

    2013-06-01

    Full Text Available OBJETIVO:Avaliar a biocompatibilidade de material FullCure 720®, que é uma resina, na confecção de implante orbitário. Avaliou-se a resposta clínica dos animais, toxicidade sistêmica e a resposta inflamatória crônica. Os animais foram pesados, exames bioquímicos e resposta inflamatória foram avaliados. Foi efetuada evisceração e colocado implante esférico orbitário. Os animais foram acompanhados durante o período de 60 dias, onde se avaliou o comportamento clínico e sinais locais. Após este período, procedeu-se a eutanásia seguida da enucleação. Foi realizada análise macroscópica e histomorfométrica. Os resultados revelaram comportamento normal dos animais, com ausência de exposição ou extrusão dos implantes, morte de algum animal e ausência de toxicidade sistêmica. Houve formação de uma cápsula fibrosa entre a capa escleral e o implante orbitário, resposta inflamatória considerada normal quando em contato com o tecido do coelho. A resina FullCure 720® utilizada como implante orbitário, mostrou-se biocompatível neste estudo.

  16. An experimental examination of mutimodal imagine system for implant site assessment

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang Seo; Kim, Kee Deog [Dept. of Dental Radiology, College of Dentistry, Yonsei University, Seoul (Korea, Republic of)

    1998-02-15

    The scanora X-ray unit uses the principles of narrow beam radiography and spiral tomography. Starting with a panoramic overview as a scout image, multiple tomographic projection could be selected. This study evaluated the accuracy of spiral tomography in comparison to routine panoramic radiography for dental implant treatment planing. An experimental study was performed on a cadaver mandible to assess the accuracy of panoramic radiography and spiral tomography film images for measurement of metallic spheres. After radiographic images of the metallic spheres on the surgical stent were measured and corrected for a fixed magnification of radiographic images, following results were obtained. 1. In the optimal position of the mandible, the minimal horizontal and vertical distortion was evident in the panoramic radiography images. The mean horizontal and vertical magnification error in anterior sites was 5.25% and 0.75%, respectively. The mean horizontal and vertical magnification error in posterior sites was 0.50% and 1.50%, respectively. 2. In the displaced forward or in and eccentric position of the mandible, the magnification error of the panoramic radiography images increased significantly over the optimal position. Overall, the mean horizontal magnification error of the anterior site in the different position changed dramatically within a range of -17.25% to 39.00%, compared to the posterior range of -5.25% to 8.50%. However, the mean vertical magnification error stayed with the range of 0.5% to 3.75% for all the mandibular positions. 3. The magnification effects in the tomographic scans were nearly identical for the anterior and posterior with a range of 2.00% to 5.75% in the horizontal and 4.50% to 5.50% in the vertical dimension, respectively. 4. A statistically significant difference between the anterior and posterior measurements was found in the horizontal measurements of the panoramic radiography images of the displaced dorward and backward position of the

  17. Reliable experimental setup to test the pressure modulation of Baerveldt Implant tubes for reducing post-operative hypotony

    Science.gov (United States)

    Ramani, Ajay

    Glaucoma encompasses a group of conditions that result in damage to the optic nerve and can cause loss of vision and blindness. The nerve is damaged due to an increase in the eye's internal (intraocular) pressure (IOP) above the nominal range of 15 -- 20 mm Hg. There are many treatments available for this group of diseases depending on the complexity and stage of nerve degradation. In extreme cases where drugs or laser surgery do not create better conditions for the patient, ophthalmologists use glaucoma drainage devices to help alleviate the IOP. Many drainage implants have been developed over the years and are in use; but two popular implants are the Baerveldt Glaucoma Implant and the Ahmed Glaucoma Valve Implant. Baerveldt Implants are non-valved and provide low initial resistance to outflow of fluid, resulting in post-operative complications such as hypotony, where the IOP drops below 5 mm of Hg. Ahmed Glaucoma Valve Implants are valved implants which initially restrict the amount of fluid flowing out of the eye. The long term success rates of Baerveldt Implants surpass those of Ahmed Valve Implants because of post-surgical issues; but Baerveldt Implants' initial effectiveness is poor without proper flow restriction. This drives the need to develop new ways to improve the initial effectiveness of Baerveldt Implants. A possible solution proposed by our research team is to place an insert in the Baerveldt Implant tube of inner diameter 305 microns. The insert must be designed to provide flow resistance for the early time frame [e.g., first 30 -- 60 post-operative days] until sufficient scar tissue has formed on the implant. After that initial stage with the insert, the scar tissue will provide the necessary flow resistance to maintain the IOP above 5 mm Hg. The main objective of this project was to develop and validate an experimental apparatus to measure pressure drop across a Baerveldt Implant tube, with and without inserts. This setup will be used in the

  18. Anchorage of titanium implants with different surface characteristics: an experimental study in rabbits

    DEFF Research Database (Denmark)

    Gotfredsen, K; Berglundh, T; Lindhe, J

    2000-01-01

    ) TiO2-blasted with particles of grain size 10 to 53 microns; (3) TiO2-blasted, grain size 63 to 90 microns; (4) TiO2-blasted, grain size 90 to 125 microns; (5) titanium plasma-sprayed (TPS). The surface topography was determined by the use of an optical instrument. Twelve rabbits, divided into two...... groups, had a total of 120 implants inserted in the tibiae. One implant from each of the five surface categories was placed within the left tibia of each rabbit. By a second operation, implants were installed in the right tibia, after 2 weeks in group A and after 3 weeks in group B. Fluorochrome labeling...

  19. Latarjet Fixation

    Science.gov (United States)

    Alvi, Hasham M.; Monroe, Emily J.; Muriuki, Muturi; Verma, Rajat N.; Marra, Guido; Saltzman, Matthew D.

    2016-01-01

    Background: Attritional bone loss in patients with recurrent anterior instability has successfully been treated with a bone block procedure such as the Latarjet. It has not been previously demonstrated whether cortical or cancellous screws are superior when used for this procedure. Purpose: To assess the strength of stainless steel cortical screws versus stainless steel cannulated cancellous screws in the Latarjet procedure. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen matched-pair shoulder specimens were randomized into 2 separate fixation groups: (1) 3.5-mm stainless steel cortical screws and (2) 4.0-mm stainless steel partially threaded cannulated cancellous screws. Shoulder specimens were dissected free of all soft tissue and a 25% glenoid defect was created. The coracoid process was osteomized, placed at the site of the glenoid defect, and fixed in place with 2 parallel screws. Results: All 10 specimens failed by screw cutout. Nine of 10 specimens failed by progressive displacement with an increased number of cycles. One specimen in the 4.0-mm screw group failed by catastrophic failure on initiation of the testing protocol. The 3.5-mm screws had a mean of 274 cycles (SD, ±171 cycles; range, 10-443 cycles) to failure. The 4.0-mm screws had a mean of 135 cycles (SD, ±141 cycles; range, 0-284 cycles) to failure. There was no statistically significant difference between the 2 types of screws for cycles required to cause failure (P = .144). Conclusion: There was no statistically significant difference in energy or cycles to failure when comparing the stainless steel cortical screws versus partially threaded cannulated cancellous screws. Clinical Relevance: Latarjet may be performed using cortical or cancellous screws without a clear advantage of either option. PMID:27158630

  20. EXPERIMENTAL SUBSTANTIATION OF APPLICATION GEL IMPLANT «SFERO®GEL» AND FILM IMPLANT «ELASTOPOB»® AT A TRAUMA OF PERIPHERAL NERVOUS SYSTEM IN EXPERIMENT

    Directory of Open Access Journals (Sweden)

    A. G. Fedyakov

    2009-01-01

    Full Text Available The purpose of the present work was the experimental substantiation of application of new biodegraded materials: gel implant «Sfero®Gel» and a film membrane of «ElastoPOB»® a domestic production, in surgery of defeats of peripheral nerves. Experimental researches carried out on females of nonlinear rats, is powerful 200–250 gramme. In experience 10 animals are used, 20 operative interventions on sciatic nerves are executed. Morphological studying of the received material in 101 days after operation was carried out. At application of a membrane «ElastoPOB»® it was defined delimitin of peripheral nerves from surrounding tissue. A film membrane of «ElastoPOB»® is perspective to apply at traumas of a nervous fabric for the purpose of formation of a friable hem in a damage zone. On the basis of the received experimental data it is possible to make the conclusion about possibility and expediency of application of biodegraded materials in surgical treatment of defeats of peripheral nervous system. 

  1. Noun plural production in preschoolers with early cochlear implantation: an experimental study of Dutch and German.

    Science.gov (United States)

    Laaha, Sabine; Blineder, Michaela; Gillis, Steven

    2015-04-01

    Studies investigating language skills of children after cochlear implantation usually present general measures of expressive/receptive vocabulary and grammar and rarely tackle the acquisition of specific language phenomena (word classes, grammatical constructions, word forms, etc.). Furthermore, research is largely restricted to children acquiring English. Cross-linguistic comparisons among children acquiring different languages are almost inexistent. The present study targets the acquisition of noun plurals (e.g., dogs, balls) by Dutch- and German-speaking children implanted before their second birthday. Given its structural complexity and irregularity, noun plural formation is a good indicator of grammatical proficiency in children at risk for a developmental delay. The study sample consisted of 14 cochlear-implanted (CI) children (M=55 months of age), 80 age-matched normally hearing (NH) controls, and 40 normally hearing controls matched by Hearing Age (HA). The children were administered an elicitation task in which they had to provide plural forms to a set of singular nouns. The analysis focussed on the following variables: Hearing status (CI, NH), Language (Dutch, German), and Suffix Predictability/Stem Transparency of the plural words. There was no significant difference between children with CI and their NH peers in correct plural production. In both child groups, plural responses followed the predicted pattern of Suffix Predictability/Stem Transparency. However, children with CI significantly more frequently replied to the test item with a recast of the singular noun instead of the plural, and the probability of these responses increased with later age of CI implantation. Furthermore, Dutch-speaking children showed an overall better performance than German-speaking children. The findings suggest that after 3 years of implant use, preschoolers with early cochlear implantation show age-appropriate patterns of noun plural formation, but still have to catch up

  2. Implante Autólogo Ovariano no Omento Maior: Estudo Experimental

    OpenAIRE

    Alberti,Luiz Ronaldo; Vasconcellos,Leonardo de Souza; Barbosa,Juliano Ferreira; Petroianu,Andy

    2002-01-01

    Objetivos: avaliar os aspectos morfofuncionais de ovários implantados no omento maior, bem como a melhor técnica para implantação do ovário: se íntegro ou fatiado. Métodos: foram divididas aleatoriamente 40 ratas Wistar com ciclos estrais normais em quatro grupos: Grupo I (n = 5), controle - laparotomia; Grupo II (n = 5), ooforectomia total bilateral; Grupo III (n = 15), implante autólogo íntegro no omento maior e Grupo IV (n = 15), implante autólogo fatiado no omento maior. Realizaram-se esf...

  3. Technical developments: use of targeting guide wire in left subclavian puncture during percutaneous implantation of port-catheter systems using the catheter tip fixation method

    Energy Technology Data Exchange (ETDEWEB)

    Yamagami, Takuji; Kato, Takeharu; Nakamura, Toshiyuki; Iida, Shigeharu; Tanaka, Osamu; Nishimura, Tsunehiko [Department of Radiology, Kyoto Prefectural University of Medicine, 465 Kajii, Kawaramachi-Hirokoji, Kamigyo, Kyoto 602-8566 (Japan)

    2003-04-01

    Our objective was to evaluate the feasibility and safety of a new method in approaching the access route percutaneously for the implantable port-catheter system for repeated hepatic arterial infusion chemotherapy. Fifteen patients underwent port-catheter system placement via the left subclavian artery with the catheter tip fixed within the gastroduodenal artery with embolic materials and a catheter side hole opening to the common hepatic artery. Before port-catheter placement, the right gastric artery was embolized via the femoral catheter access. Then a 0.035-in. guide wire was inserted from the right femoral artery to the left subclavian artery. The guide wire was left in place during puncture by the needle as an access route for catheter placement. At the time of puncture, the tip of the puncture needle was aimed at the guide wire placed in the subclavian artery beforehand. In all 15 patients the procedure was successfully completed in a reasonable time (mean time 95.0 min, range 50-240 min). Complications occurred in two patients: a transient numbness of the arm in 1 patient and a mild hematoma detected in the subcutaneous pocket in another patient. This experience indicates the possibility of using a targeting guide wire in puncture of the subclavian artery as an access route for catheter placement. (orig.)

  4. Comparative radiographic and resonance frequency analyses of the peri-implant tissue after dental implants placement using flap and flapless techniques: An experimental study on domestic pigs

    OpenAIRE

    Vlahović Zoran; Mihailović Branko; Lazić Zoran; Golubović Mileta

    2013-01-01

    Background/Aim. Flapless implant surgery has become very important issue during recent years, mostly thanks to computerization of dentistry and software planning of dental implants placements. The aim of this study was to compare flap and flapless surgical techniques for implant placement through radiographic and radiofrequency analyses. Methods. The experiment was made in five domestic pigs. Nine weeks following domestic pigs teeth extraction, implants were placed, on the right side us...

  5. Bone tissue engineering for spine fusion : An experimental study on ectopic and orthotopic implants in rats

    NARCIS (Netherlands)

    van Gaalen, SM; Dhert, WJA; van den Muysenberg, A; Oner, FC; van Blitterswijk, C; Verbout, AJ; de Bruijn, J.D.

    2004-01-01

    Alternatives to the use of autologous bone as a bone graft in spine surgery are needed. The purpose of this study was to examine tissue-engineered bone constructs in comparison with control scaffolds without cells in a posterior spinal implantation model in rats. Syngeneic bone marrow cells were

  6. Design and experimental study of joint torque balance mechanism of seed implantation articulated robot

    Directory of Open Access Journals (Sweden)

    Zhang Yongde

    2015-06-01

    Full Text Available This article discusses several new mechanisms that may be used in prostate cancer seed implant robotics. We have developed relatively simple but effective mathematical models of multi-needle puncture prostate using nonlinear spring–damper model; based on Automatic Dynamic Analysis of Mechanical Systems or dynamics module, displacement simulation for prostate is performed, and simulation results indicate that the multi-needle puncture mechanism could reduce prostate displacement in the y- or z-direction. Then aiming at the limitation of human body structure space and seed implant needle insertion path, a revolute-revolute-translational-type prostate seed implantation robot with three-dimensional transrectal ultrasound navigation is designed. It is noteworthy that drive torque fluctuation is caused by the center of gravity change of revolute-revolute tandem cantilever structure; an elastic balance mechanism is designed to realize the complete balance of cantilever weight. Based on Automatic Dynamic Analysis of Mechanical Systems or dynamics module, static drive torque simulation of 2-revolute tandem cantilever structure is performed. Finally, we manufacture the robot prototype and make verification experiment to the cantilever balancing device, and the experiment results provide evidence that elastic balance mechanism can realize the complete balance of cantilever weight, improve the fluctuation in the amplitude value of driving torque, and increase its operation stationary of seed implantation robot system.

  7. Expression of bone matrix proteins during the osseus healing of topical conditioned implants: an experimental study.

    Science.gov (United States)

    Schlegel, Karl Andreas; Thorwarth, Michael; Plesinac, Alexandra; Wiltfang, Joerg; Rupprecht, Stephan

    2006-12-01

    Osseointegration of implants depends on time and local bone conditions regarding quality and quantity. This led to the bone classification by Lekholm et al. The aim of the present study was to follow the expression of bone matrix proteins during the phase of osseointegration after conditioning of the bone bed by means of immunohistochemistry. In the porcine frontal skull, implant beds of identical size were created. Before placement of the implants (Ankylos 4 x 3.5 mm), the implant beds were conditioned using bone condensation (cond), an osteoinductive collagen (Co) and platelet-rich plasma (PRP). These conditioning methods were compared with standard procedure. The animals were sacrificed after 2, 4 and 8 weeks. The specimens were then analyzed by light microcopy and immunohistochemistry for expression of bone morphogenic proteins (BMP)2, procollagen I and osteocalcin (OC). Light microscopy revealed an initial effect of condensation and the bovine collagen at 2 weeks in comparison with the standard group. The PRP did not achieve a significant effect. At 8 weeks, the results of the standard, bone condensation and the bovine collagen group had aligned. The PRP group showed a significantly lower bone-implant contact (BIC) (P=0.003) compared with the standard group. BMP2 expression was significantly higher in all evaluated test groups at 4 and 8 weeks, as well as at 2 weeks in the condensation group. The procollagen I expression at 2 weeks was significantly increased for PRP and lower in the collagen and condensation group compared with standard procedure. Values for 4 and 8 weeks were slightly higher than in the standard group. No significant differences were obvious in the OC group at any time. During the initial healing phase, an effect of the evaluated methods of topical bone conditioning can be demonstrated by differences in the expression of BMP2 and procollagen I. These findings had leveled at 8 weeks and were, in contrast, not detectable in the expression of

  8. EXPERIMENTAL RESEARCH OF REGENERATIVE FEATURES IN BONE TISSUES AROUND IMPLANTS AFTER ONE-STAGE BILATERAL TOTAL HIP REPLACEMENT

    Directory of Open Access Journals (Sweden)

    V. M. Mashkov

    2012-01-01

    Full Text Available Objective: to research the specific features of regenerative processes of bone tissue around implants after one-stage bilateral total hip replacement in experiment. Material and methods: 27 total hip replacement operations have been performed in 18 rabbits of breed "chinchilla" to which bipolar femoral endoprosthesis made of titanic alloy PT-38, one type-size, with friction pair metal-on-metal and neck-shaft angle 165 degrees have been implanted: total unilateral hip replacement operations have been performed in 9 animals (control group, one-stage bilateral total hip replacement operations have been performed in 9 animals (experimental group. During research they have been on radiological and clinical checking-up. After the experiment the animals had histological tests of the tissues around endoprosthesis components. Results and conclusions: After one-stage bilateral total hip replacement in early terms of research more expressed changes of bone tissue in the form of its thinning and decompaction were found around implants. One-stage bilateral total hip replacement did not essentially influence on the speed of osteogenesis around endoprothesis components in comparison with unilateral total hip replacement, so in late terms of observation in both groups the fixing of endoprothesis components did not differ.

  9. Experimental substantiation of the design of a prosthetic heart valve for «valve-in-valve» implantation

    Directory of Open Access Journals (Sweden)

    K. Yu. Klyshnikov

    2017-01-01

    Full Text Available The aim of the study was to perform a series of in vitro tests of a prototype of the developing heart valve prosthesis to evaluate its functional characteristics. Materials and methods. In this work we have used the frames and full prototypes of the prosthesis, consisting of a stent-like stainless steel support frame with mounted biological leaflets and cover. The authors evaluated the calculated and experimental forces necessary for the displacement of the sutureless implanted prosthesis using the test machine under uniaxial tension. The risk of defects and damages to the supporting framework as a result of implantation was evaluated by scanning electron microscopy. The hydrodynamic characteristics of the prosthesis were investigated under physiological conditions and «valvein-valve» implantation. Evaluation of the ergonomics and applicability of the proposed construction on the cadaver heart model of cattle was carried out. Results. As a result of the forces assessment, it was found that the force required to shear the prosthesis was 3.12 ± 0.37 N, while the calculated value was 1.7 N, which is significantly lower than the obtained value. The comparison of the images obtained with small and large magnifications demonstrated the absence of critical surface defects. Additional analysis under the super-large magnifications also did not reveal problem areas. During the hydrodynamic study, it was shown that the average transplant gradient increased slightly from 2.8–3.4 to 3.2–4.5 mm Hg for the initial prosthesis and the «valve-in-valve» complex, respectively. The decrease of the effective orifice area was 6–9% relative to the initial one. Evaluation of the implantation technique demonstrated the consistency of the approach: the use of the developed holder in combination with the balloon implantation system made it possible to position the prosthesis throughout the procedure. Conclusion. The series of tests demonstrates the consistency

  10. Experimental evaluation of tooth movement in the beagle dog with the mini-screw implant for orthodontic anchorage.

    Science.gov (United States)

    Owens, Shannon E; Buschang, Peter H; Cope, Jason B; Franco, Pedro F; Rossouw, P Emile

    2007-11-01

    The purposes of this study were to evaluate the stability of mini-screw implants (MSIs) and tooth movements in relation to the timing, amount, and location of force application. Additionally, clinical measurements of peri-implant health were recorded to determine predictors for MSI failure. A randomized split-mouth design was used in 7 skeletally mature male beagle dogs. All third premolars were extracted to facilitate retraction of the second premolars via sectional orthodontic appliances. In the maxilla, the effect of delayed vs immediate loading was tested under constant force (25 g). In the mandible, the effect of force level (25 vs 50 g) was tested on immediately loaded MSIs. All experimental MSIs had a corresponding unloaded control. Clinical records and measurements of tooth movement were taken at specified intervals. The overall success rate of the implants was 93% with no significant effects of timing, amount, or location of force applied. Peri-implant tissue health was not predictive of MSI failure. The maxillary and the mandibular second premolars were moved 3.3 +/- 1.0 and 3.8 +/- 1.3 mm, respectively. No significant differences in tooth movement were observed between immediate and delayed loading, at either 25 or 50 g or force, or between the maxilla and the mandible. These results support the notion that immediate MSI loading with light forces (25 and 50 g) can be accomplished with high rates of success, producing clinically relevant amounts of tooth movement that are not influenced by the amount of force or the location at which they are applied.

  11. Histological and Histomorphometric Evaluation of Zirconia Dental Implants Modified by Femtosecond Laser versus Titanium Implants: An Experimental Study in Fox Hound Dogs.

    Science.gov (United States)

    Calvo-Guirado, Jose Luis; Aguilar-Salvatierra, Antonio; Delgado-Ruiz, Rafael Arcesio; Negri, Bruno; Fernández, María Piedad Ramírez; Maté Sánchez de Val, José Eduardo; Gómez-Moreno, Gerardo; Romanos, Georgios E

    2015-06-01

    This study applied femtosecond laser technology to zirconia dental implants (Bredent GmbH & Co.KG, Senden, Germany) to generate a surface texture of microgrooves over the entire intraosseous surface, analyzing its behavior in an in vivo model in comparison with titanium implants with sandblasted and acid-etched surfaces. The study used six American Fox Hound dogs. Each received four implants per hemi-mandible, making a total of eight implants per animal. The 48 immediate loaded implants were divided into two groups of 24 titanium implants (control group) and 24 zirconia implants (study/test group), distributed randomly. Bone-to-implant contact (BIC) values and crestal resorption were determined at 1 and 3 months, also measuring calcium, phosphorous, and carbon concentrations by means of energy dispersive x-ray. BIC percentages after 30 days were 51.36% for titanium implants and 44.68% for zirconia implants. After 90 days, values increased to 61.73% in titanium and 47.94% in zirconia implants. After 30 days, there was more crestal bone lost in the titanium group (0.77 mm) compared with the zirconia group (0.01 mm). After 90 days, zirconia implants showed greater marginal bone resorption (1.25 mm) compared with the titanium group (0.37 mm). The present study shows that zirconia implants with modified surfaces can produce good osseointegration values when compared with titanium implants in terms of BIC and crestal bone resorption at 1 and 3 months. © 2013 Wiley Periodicals, Inc.

  12. Histomorphometric and removal torque analysis for TiO2-blasted titanium implants. An experimental study on dogs

    DEFF Research Database (Denmark)

    Gotfredsen, K; Nimb, L; Hjörting-Hansen, E

    1992-01-01

    The aim of the present study was to compare the anchorage of TiO2-blasted screw and cylindrical implants with conventionally used machine-produced screw and cylindrical implants inserted immediately in extraction sockets on dogs. 6 adult mongrel dogs had 3rd and 4th mandibular premolars extracted...... bilaterally and 24 commercial pure titanium implants were placed immediately in extraction sockets and covered with mucoperiosteum. Each dog had inserted 4 implants: 1 screw implant and 1 cylindrical implant blasted with titanium-dioxide-particles; 1 screw implant and 1 cylindrical implant with machine...

  13. Is montelukast effective in regression of endometrial implants in an experimentally induced endometriosis model in rats?

    Science.gov (United States)

    Kiykac Altinbas, Sadiman; Tapisiz, Omer Lutfi; Cavkaytar, Sabri; Simsek, Gulcin; Oguztuzun, Serpil; Goktolga, Umit

    2015-01-01

    Montelukast, a selective antagonist of Type 1 cysteinyl leukotriene receptors (CysLT1Rs), antagonizes the proinflammatory and proasthmatic activities of CysLT1Rs. We investigated the effect of montelukast on a surgically induced endometriosis rat model. Thirty-two sexually mature, cycling, female Wistar-Albino rats, in which endometriotic implants were surgically induced, were randomly divided into three groups. Group I [Montelukast (M), 10 rats)] was given 1.6 mg/kg/day of oral montelukast sodium. Group II [Leuprolide acetate (L), 11 rats] was given 1 mg/kg single dose of s.c.leuprolide acetate. Group III [Control (C), 11 rats] received saline solution through an orogastric tube and served as controls. After a 3-weeks medication, the rats were sacrificed to investigate the endometriotic implants for size and morphological and histological characteristics, including immunoreactivity of MMP-2 and VEGF. The mean area of implants decreased from 48.2 ± 24.7 to 29.3 ± 15.8mm(2) in Group I (M) (P = 0.008) and from 62 ± 32.1 to 39.9 ± 18.1mm(2) in Group II (L) (P=0.003). In Group III (C), the mean area increased from 41.1 ± 31.1 to 60.4 ± 37.1mm(2) (P = 0.025). Histopathological analysis showed statistically significant lower scores in rats treated with montelukast compared to leuprolide and controls. MMP H scores were not different between the groups in both epithelial and stromal MMP-2 immunostaining. VEGF H scores were statistically lower in Group 1 (M) in epithelial VEGF immunostaining when compared to Group II (L) and Group III (C) (P=0.006). Montelukast may effectively cause a significant decrease in the area of endometriotic implants. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  14. A Psychophysics experimental software to evaluate electrical pitch discrimination in Nucleus cochlear implanted patients

    Science.gov (United States)

    Pérez Zaballos, M. T.; Ramos de Miguel, A.; Killian, M.; Ramos Macías, A.

    2016-02-01

    Multichannel electrode array design in cochlear implants has evolved into two major categories: straight and perimodiolar electrodes. When implanted, the former lies along the outer wall of the scala tympani, while the later are located closer to the modiolus, where the neural ends are. Therefore, a perimodiolar position of the electrode array could be expected to result in reduced stimulus thresholds and stimulating currents, increased dynamic range, and more localized stimulation of the neural elements. However, their advantage for pitch discrimination has not been conclusively stated. Therefore, in order to study electrode independence, a psychophysical software has been developed, making use of Nucleus Implant Communicator tools provided by Cochlear company under a research agreement. The application comprises a graphical interface to facilitate its use, since previous software has always required some type of computer language skills. It allows for customization of electrical pulse parameters, measurement of threshold and comfort levels, loudness balancing and alternative forced choice experiments to determine electrode discrimination in Nucleus© users.

  15. Experimental formation of periodontal structure around titanium implants utilizing bone marrow mesenchymal stem cells: a pilot study.

    Science.gov (United States)

    Marei, Mona K; Saad, Manal M; El-Ashwah, Adham M; El-Backly, Rania M; Al-Khodary, Mohammed A

    2009-01-01

    Tissue engineering in the head and neck area, presents numerous advantages. One of the most remarkable advantages is that regeneration of only a small amount of tissue can be highly beneficial to the patient, particularly in the field of periodontal tissue regeneration. For decades, successful osseointegration has provided thousands of restorations that maintain normal function. With the increasing need to utilize dental implants for growing patients and enhance their function to simulate normal tooth physiology and proprioception, there appears to be an urgent need for t concept of periodontal tissue regeneration around dental implants. In the present work, 5 goats wer used for immediate implant placement post canine teeth extraction. Each goat received 2 implan fixtures; the control side received a porous hollow root-form poly (DL-Lactide-co-Glycolide) scaf around the titanium fixture, and the experimental side received the same scaffold but seeded with autogenous bone marrow-derived mesenchymal stem cells. One animal was killed 10 days postoperatively, and the others were killed after 1 month. The results showed that on th experimental side, periodontal-like tissue with newly formed bone was demonstrated both at 1 days and after 1 month, while the control specimens showed early signs of connective tissue regeneration around the titanium fixture at 10 days, but was not shown in the 1 month specimens. I can be concluded that undifferentiated mesenchymal stem cells were capable of differentiating t provide the 3 critical tissues required for periodontal tissue regeneration: cementum, bone, a periodontal ligament. This work may provide a new approach for periodontal tissue regeneration.

  16. Design and Optimization of Resorbable Silk Internal Fixation Devices

    Science.gov (United States)

    Haas, Dylan S.

    Limitations of current material options for internal fracture fixation devices have resulted in a large gap between user needs and hardware function. Metal systems offer robust mechanical strength and ease of implantation but require secondary surgery for removal and/or result in long-term complications (infection, palpability, sensitivity, etc.). Current resorbable devices eliminate the need for second surgery and long-term complications but are still associated with negative host response as well as limited functionality and more difficult implantation. There is a definitive need for orthopedic hardware that is mechanically capable of immediate fracture stabilization and fracture fixation during healing, can safely biodegrade while allowing complete bone remodeling, can be resterilized for reuse, and is easily implantable (self-tapping). Previous work investigated the use of silk protein to produce resorbable orthopedic hardware for non- load bearing fracture fixation. In this study, silk orthopedic hardware was further investigated and optimized in order to better understand the ability of silk as a fracture fixation system and more closely meet the unfulfilled market needs. Solvent-based and aqueous-based silk processing formulations were cross-linked with methanol to induce beta sheet structure, dried, autoclaved and then machined to the desired device/geometry. Silk hardware was evaluated for dry, hydrated and fatigued (cyclic) mechanical properties, in vitro degradation, resterilization, functionalization with osteoinductive molecules and implantation technique for fracture fixation. Mechanical strength showed minor improvements from previous results, but remains comparable to current resorbable fixation systems with the advantages of self-tapping ability for ease of implantation, full degradation in 10 months, ability to be resterilized and reused, and ability to release molecules for osteoinudction. In vivo assessment confirmed biocompatibility, showed

  17. Histopathological comparative analysis of periimplant bone inflammatory response after dental implant insertion using flap and flapless surgical technique. An experimental study in pigs.

    Science.gov (United States)

    Vlahović, Zoran; Marković, Aleksa; Lazić, Zoran; Šćepanović, Miodrag; Đinić, Ana; Kalanović, Milena

    2017-09-01

    To evaluate by histopathological analysis the peri-implant bone inflammation degree, in certain time intervals (7, 14, 21 and 28 days), following mini-incision flapless and flap implant placement. The experiment was conducted on four domestic pigs. Nine weeks prior to implant insertion, second and third mandibular premolars were extracted. Each animal received six implants in lower jaw. On one randomly chosen side of jaw flapless technique using mini-incision was performed, while on the other side implants were inserted after flap raising. After 7, 14, 21, and 28 days, the experimental animals were sacrificed. Following mandibular resection and decalcification, the samples for histopathological analysis of the peri-implant bone were obtained in the empty implant bed area, from the buccal side of the mandible, adjacent to implant neck region and parallel to crestal edge of implant bed. The degree of inflammatory response of the peri-implant bone was estimated through ordinal scores from 0 to 2. Seven days after the surgery all samples in the flap group had score 2 indicating high inflammation degree, in contrast to lower inflammatory reaction in flapless group. On the 14th and 21st postoperative day decreasing of inflammation degree was noted in all samples of the flapless group (score 1), while in flap group samples presented scores 1 and 2. Twenty-eight days after the implant placement, further reduction of inflammation in the flapless group (33% of samples had score 0) was observed. Flapless technique in comparison to conventional flap procedure minimizes postoperative bone inflammatory reactions. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Linear and Angular Deviations of Implants Placed in Experimental Casts with Stereolithographic Drill Guides Fixed by O'ring Ortho Implant Devices

    OpenAIRE

    Novellino,Marcelo Michele; Sesma,Newton; Lagana,Dalva Cruz; Ferrari, Glais

    2013-01-01

    The aim of this study was to evaluate whether the introduction of a device, resulting from the combination of an o'ring attachment with an orthodontic implant (o'ring ortho implant, O'ROI), to affix the surgical template of CAD/CAM-guided implant surgery contribute to minimizing the deviations in the position and inclination of implants at the time of their placement. Ten models simulating bone tissue were fabricated and randomly divided into 2 groups: 5 with the scanning and surgical templat...

  19. Anchorage of TiO2-blasted, HA-coated, and machined implants: an experimental study with rabbits

    DEFF Research Database (Denmark)

    Gotfredsen, K; Wennerberg, A; Johansson, C

    1995-01-01

    The purpose of this study was to evaluate the histometrical and biomechanical anchorage of TiO2-blasted implants and TiO2-blasted implants coated with hydroxyapatite. The control implants were machined. Twenty-six rabbits had a total of 156 implants placed in the proximal part of the tibia. Each ...

  20. Is There an Impact of Concomitant Injuries and Timing of Fixation of Major Fractures on Fracture Healing? A Focused Review of Clinical and Experimental Evidence.

    Science.gov (United States)

    Hildebrand, Frank; van Griensven, Martijn; Huber-Lang, Markus; Flohe, Stefanie B; Andruszkow, Hagen; Marzi, Ingo; Pape, Hans-Christoph

    2016-03-01

    This review aims to summarize current knowledge regarding the underlying patho-mechanisms of delayed fracture healing in polytraumatized patients. The following search terms were used: "fracture", "hemorrhage," "chest trauma," "inflammation," "inflammatory response," "fracture healing," "delayed healing," "nonunion," "fracture stabilisation," "intramedullary nailing," "external fixation," "early total care," and "damage control." Medline, Embase, and Cochrane Library were searched for studies published between January 1, 1990 through March 30, 2014. Of 1322 publications, 68 were included in the current summary. Concomitant injuries and the strategy for fracture stabilization seem to affect bone metabolism and fracture healing. Among the relevant patho-mechanisms, interactions between the local and systemic inflammatory response seem to play a role. However, the consequences of fracture fixation strategies in case of severe concomitant injuries on local inflammation and bone healing remain unknown. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

  1. Reduction and fixation capabilities of different plate designs for pubic symphysis disruption: a biomechanical comparison.

    Science.gov (United States)

    Pizanis, Antonius; Garcia, Patric; Santelmann, Maike; Culemann, Ulf; Pohlemann, Tim

    2013-02-01

    Typical stabilisation of pelvic open book injuries consists in plate fixation of the symphysis, leading to many different plate designs and procedures that have evolved. However, implant loosening and development of chronic instability are still evident and represent major complications after plate fixation of the symphysis. The aim of this study was to analyse reduction and fixation capabilities of different classical plate techniques with dynamic compression (DC), prebending or modern interlocking screws. Compression injuries (OTA B1.1) were simulated on synthetic composite pelvises. Sensor films placed in the disrupted symphysis allowed assessment of reduction and compression forces, as well as contact characteristics by implants at defined time points under static non loaded conditions. The commercially available steel plates used in our study differed in curved design, prebending and DC- or locking screw capabilities, as narrow large fragment (4.5) or small fragment plates (3.5). DC procedure clearly increased the compressive force in the symphysis and improved the reduction by enhanced contact areas. These effects were preserved to the end of the experiments only when the plates were prebended (10°). Anatomically contoured and prebended 3.5 plates had a similar effect, but the contact area was even more pronounced. Best results were observed using the "3.5 symphyseal plate" with DC-effect medially and locking screws laterally. Purely interlocking screw plates by themselves allowed an optimal contact area, yet failed to preserve the initial compressive reduction force. The experimental results suggest a biomechanical advantage in using prebended plates for symphysis fixation compared to non-bended plates. Best results with regard to compression and increased contact area can be achieved by anatomically contoured plates with combined DC and locking screw capabilities. These findings are of special interest in pelvic surgery for choosing the right implant in

  2. Influence of surgical technique in the peritoneal carcinomatosis surgical wound implant: experimental model in mice.

    Science.gov (United States)

    Rosa, Roberto Maranhão; Caiado, Rafael Coelho; Reis, Paulo Roberto de Melo; Lacerda, Elisângela de Paula Silveira; Sugita, Denis Masashi; Mrué, Fátima

    2015-01-01

    The number of malignancies increased alarmingly. Surgery constitutes one of the most efficient therapeutic modalities for the treatment of solid tumors. The neoplastic implant in surgical wound is a complication whose percentage of occurrence reported in the literature is variable, but sets with high morbidity and therapeutic difficulties. Protecting the wound is one of the recommended principles of oncologic surgery. To evaluate the influence of wound protection in the development of tumor implantation. Sarcoma 180 tumor cells were used, with intraperitoneal inoculation in Swiss mice. After the establishment of neoplastic ascites, animals were randomized into two groups of 10, each group consisting of five males and five females. In both groups, laparotomy and manipulation of intra-abdominal organs was performed. In a group laparotomy was performed using the protection of the abdominal wound and the other group without it. On the 9th postoperative day macroscopic evaluation of the operative scar was performed, which was later removed for microscopic evaluation. There was microscopic infiltration of tumor cells in the wound of all animals. However, the group that held the protection, infiltration was less intense when compared to the group without it. The infiltration was also more severe in females than in males of the same group. Tumor infiltration into the wound was more intense in the group in which the protection of the surgical site was not performed, and in females when compared to males of the same group.

  3. Intramedullary Fixation of Clavicle Fractures: Anatomy, Indications, Advantages, and Disadvantages.

    Science.gov (United States)

    Eichinger, Josef K; Balog, Todd P; Grassbaugh, Jason A

    2016-07-01

    Historically, management of displaced midshaft clavicle fractures has consisted of nonsurgical treatment. However, recent literature has supported surgical repair of displaced and shortened clavicle fractures. Several options exist for surgical fixation, including plate and intramedullary (IM) fixation. IM fixation has the potential advantages of a smaller incision and decreased dissection and soft-tissue exposure. For the last two decades, the use of Rockwood and Hagie pins represented the most popular form of IM fixation, but concerns exist regarding stability and complications. The use of alternative IM implants, such as Kirschner wires, titanium elastic nails, and cannulated screws, also has been described in limited case series. However, concerns persist regarding the complications associated with the use of these implants, including implant failure, migration, skin complications, and construct stability. Second-generation IM implants have been developed to reduce the limitations of earlier IM devices. Although anatomic and clinical studies have supported IM fixation of midshaft clavicle fractures, further research is necessary to determine the optimal fixation method.

  4. The role of fixation and bone quality on the mechanical stability of tibial knee components.

    Science.gov (United States)

    Lee, R W; Volz, R G; Sheridan, D C

    1991-12-01

    Tibial component loosening remains one of the major causes of failure of cemented and noncemented total knee arthroplasties. In this study, the authors identified the role of implant design, method of fixation, and bone density as it related to implant stability. The physical properties of "good" and "bad" bone were simulated using a "good" and "bad" foam model of the proximal tibia, fabricated in the laboratory from DARO RF-100 foam. A generic tibial component permitting various fixation designs was implanted into "good" and "bad" variable density foam tibial models in both cemented and noncemented modes. The mechanical stability of the implants was determined using a Materials Testing Machine by the application of an eccentrically applied cyclic load. The micromotion (subsidence and lift-off) of the tibial implants was recorded using two Linear Variable Differential Transformers. Statistically significant differences in implant stability were recorded as a function of fixation method. The most rigid implant fixation was achieved using four peripherally placed, 6.5-mm cancellous screws. The addition of a central stem added stability only in the case of "poor" quality foam. The mechanical stability of noncemented implants related directly to the density of the foam. Implant stability was greatly enhanced in "poor" quality foam by the use of cement. The method of implant fixation and bone density are critical determinants to tibial implant stability.

  5. Implantable synthetic cytokine converter cells with AND-gate logic treat experimental psoriasis.

    Science.gov (United States)

    Schukur, Lina; Geering, Barbara; Charpin-El Hamri, Ghislaine; Fussenegger, Martin

    2015-12-16

    Psoriasis is a chronic inflammatory skin disease characterized by a relapsing-remitting disease course and correlated with increased expression of proinflammatory cytokines, such as tumor necrosis factor (TNF) and interleukin 22 (IL22). Psoriasis is hard to treat because of the unpredictable and asymptomatic flare-up, which limits handling of skin lesions to symptomatic treatment. Synthetic biology-based gene circuits are uniquely suited for the treatment of diseases with complex dynamics, such as psoriasis, because they can autonomously couple the detection of disease biomarkers with the production of therapeutic proteins. We designed a mammalian cell synthetic cytokine converter that quantifies psoriasis-associated TNF and IL22 levels using serially linked receptor-based synthetic signaling cascades, processes the levels of these proinflammatory cytokines with AND-gate logic, and triggers the corresponding expression of therapeutic levels of the anti-inflammatory/psoriatic cytokines IL4 and IL10, which have been shown to be immunomodulatory in patients. Implants of microencapsulated cytokine converter transgenic designer cells were insensitive to simulated bacterial and viral infections as well as psoriatic-unrelated inflammation. The designer cells specifically prevented the onset of psoriatic flares, stopped acute psoriasis, improved psoriatic skin lesions and restored normal skin-tissue morphology in mice. The antipsoriatic designer cells were equally responsive to blood samples from psoriasis patients, suggesting that the synthetic cytokine converter captures the clinically relevant cytokine range. Implanted designer cells that dynamically interface with the patient's metabolism by detecting specific disease metabolites or biomarkers, processing their blood levels with synthetic circuits in real time, and coordinating immediate production and systemic delivery of protein therapeutics may advance personalized gene- and cell-based therapies. Copyright © 2015

  6. Porous metal for orthopedics implants

    OpenAIRE

    Matassi, Fabrizio; Botti, Alessandra; Sirleo, Luigi; Carulli, Christian; Innocenti, Massimo

    2013-01-01

    Porous metal has been introduced to obtain biological fixation and improve longevity of orthopedic implants. The new generation of porous metal has intriguing characteristics that allows bone healing and high osteointegration of the metallic implants. This article gives an overview about biomaterials properties of the contemporary class of highly porous metals and about the clinical use in orthopaedic surgery.

  7. Avaliação experimental de novo eletrodo para implante de marca-passo em fetos Experimental assessment of a new electrode for fetal pacing

    Directory of Open Access Journals (Sweden)

    Renato Samy Assad

    2006-09-01

    sensed fetal R wave was 8.6 ± 5.6 mV. Fetal heart rate bellow 60 bpm was associated to low cardiac output and low blood pressure (p<0.05. Fetal bradycardia also determined oxygen saturation drop parallel to low cardiac output, with severe hypoxia below 60 bpm. CONCLUSION: The new lead allows for a less invasive procedure and stable fixation to the myocardium that may prevent lead dislodgement after fetal recovery. It seems to be compatible with safe chronic stimulation. This study suggests that a gradual increase in the fetal rate beginning on 80 bpm after implantation would be more adaptive and adequately augment fetal cardiac output.

  8. On Fixation of Hip Prostheses

    OpenAIRE

    Palm, Lars

    2007-01-01

    This thesis, comprising 5 separate studies, is concerned with fixation of prosthetic components in total hip arthroplasty. The results and conclusions of the studies fol-low; The initial stability of femoral revision components, the long cementless PCA stem and the Exeter standard stem cemented in a bed of impacted bone graft, was com-pared in an experimental study. The PCA stem was more stable than the Exeter stem. However, for both stems initial stability may not be sufficient to allow bone...

  9. Magnesium-based implants: Beyond fixators

    Directory of Open Access Journals (Sweden)

    Xiaodan Chen

    2017-07-01

    The translational potential of this article: For the first time, magnesium is shown to be beneficial for fracture healing at the weight-bearing site. In addition, calcitonin gene-related peptide-delivery system will also be another translational direction, as the promotive role of calcitonin gene-related peptide in fracture healing is supportive. These cost-effective and innovative treatment approaches will definitely bring a reduction not only in the suffering of patients, but also in the economic burden for their families and our society.

  10. Estudo experimental da aplicação do ventrículo artificial eletromecânico pulsátil implantável Experimental study of pulsatile implantable electromechanical artificial ventricle

    Directory of Open Access Journals (Sweden)

    Jarbas Jakson Dinkhuysen

    2011-03-01

    Full Text Available OBJETIVO: Apresentar os resultados da aplicação deste dispositivo em animais de experimentação, promovendo auxílio hemodinâmico apenas ao ventrículo esquerdo (VE. MÉTODOS: Entre junho 2002 e outubro 2009, foram implantados em 27 bezerros com idade 2½ a 4 meses e peso 80/100 kg e, por meio de anestesia geral e ventilação controlada e de toracotomia lateral esquerda, era introduzida cânula no ápice do VE e anastomose término/lateral de tubo vascular de politetrafluoretileno (PTFE com a porção descendente da aorta torácica, ambos interligados ao dispositivo implantado no subcutâneo abaixo do diafragma (24 e intratorácico (três. Em cinco bezerros, o dispositivo foi aplicado com auxílio de circulação extracorpórea (CEC e, em 22, sem CEC. RESULTADOS: Ocorreram dois óbitos durante o implante e três por causas diversas nas primeiras horas de pós-operatório (PO, sendo um relacionado ao dispositivo. A sobrevivência entre o 1º e 6º dia de PO ocorreu em 17 animais e entre o 8º e 31º dia de PO em cinco, com causas determinantes diversas, não só por problemas clínico/cirúrgicos, mas também relacionados ao dispositivo. O impacto hemodinâmico avaliado pela análise da pressão sistêmica mostrou incremento que variou de 20 a 40 mmHg e os dados laboratoriais analisados demonstraram baixos impactos traumáticos à crase sanguínea e boa biocompatibilidade. CONCLUSÃO: Trata-se de pesquisa árdua e complexa onde a cada experimento são identificados problemas não só de implantabilidade, mas também relacionados ao dispositivo, que vão sendo sistematicamente corrigidos, tornando-o cada vez mais seguro e eficaz.OBJECTIVE: The objective is to present the results of the application this device in experimental animals unloading only the left ventricle. METHODS: Between June 2002 and October 2009, were implanted in 27 calfs with age between 2½ to 4 months and 80 to 100 kg of weight, with general anaesthesia and controled

  11. Tissue state of anterior abdominal wall in rats after implantation of alloplastic material, processed with collagen, in the abdominal cavity and in contact with hollow organs

    OpenAIRE

    Belyanskyi L.S.; Svisenko O.V.

    2010-01-01

    A research purpose was to investigate the tissue reactions on implantation of polypropylene mesh, processed withcollagen, after the plastic of experimental defect at rats at intraperitoneal localization of prosthesis in contact with holloworgans. Research was performed in two experimental groups. Group 1 – at 27 rats an experimental defect of of anterior abdominalwall of size 3 cm, with further transabdominal fixation of the polypropylene mesh of size 1×1,5 cm on parietal peritoneumin contact...

  12. Histologic and histomorphometric evaluation of peri-implant bone subjected to immediate loading: an experimental study with Macaca fascicularis.

    Science.gov (United States)

    Romanos, George E; Toh, Chooi Gait; Siar, Chong Huat; Swaminathan, Dasan

    2002-01-01

    Immediately loaded splinted implants can become osseointegrated when they are placed in the anterior part of the mandible. The concept of immediate loading has not been well examined in the posterior mandible. The aim of this study was to evaluate the hard tissue reactions around immediately loaded implants placed in the posterior mandible in the monkey model. Six adult M. fascicularis monkeys were used in this study. Thirty-six Ankylos implants (Degussa Dental, Hanau-Wolfgang, Germany) were placed after extraction of the second premolar, first, and second molar teeth and complete healing of the sockets. Control (C) group implants were placed and, after osseointegration, were loaded for 1 month using temporary acrylic resin prostheses and later for 2 months using splinted metal crowns. In the contralateral region of the mandible, test (T) group implants were placed and loaded immediately with the same sequence as carried out for the C implants. After sacrifice of the animals, specimens were examined histologically and evaluated histomorphometrically. All implants were osseointegrated. Compact, cortical bone in contact with the implant surface without any gaps or connective tissue formation was demonstrated. Histomorphometric findings of the bone-implant-contacts showed no significant differences between the T and C group implants. Peri-implant mineralized bone areas presented statistically significant differences and showed a higher density of bone between the threads of immediately loaded implants (P < .05). Immediately loaded splinted implants in the posterior mandible can become osseointegrated with a hard tissue peri-implant response similar to that of delayed loaded implants. Moreover, immediate loading seems to increase the ossification of the alveolar bone around endosseous implants.

  13. Cochlear Implants

    Science.gov (United States)

    ... implant procedure Welcome to the Food and Drug Administration (FDA) website on cochlear implants. Cochlear implants are electronic hearing devices. Doctors implant cochlear implants into people ...

  14. A new material to prevent urethral damage after implantation of artificial devices: an experimental study

    Directory of Open Access Journals (Sweden)

    Salvador Vilar Correia Lima

    Full Text Available ABSTRACT Objective To validate the application of the bacterial cellulose (BC membrane as a protecting barrier to the urethra. Materials and Methods Forty female Wistar rats (four groups of 10: Group 1 (sham, the urethra was dissected as in previous groups and nothing applied around; Group 2, received a 0.7cm strip of the BC applied around the urethra just below the bladder neck; Group 3, received a silicon strip with the same dimensions as in group 2; Group 4, had a combination of 2 and 3 groups being the silicon strip applied over the cellulosic material. Half of the animals in each group were killed at 4 and 8 months. Bladder and urethra were fixed in formalin for histological analysis. Results Inflammatory infiltrates were more intense at 4 months at lymphonodes (80% Grade 2, statistically different in the group 2 compared with groups 1 (p=0.0044 and 3 (p=0.0154. At 8 months, all samples were classified as grade 1 indicating a less intense inflammatory reaction in all groups. In group 2, at 8 months, there was a reduction in epithelial thickness (30±1μm when com-pared to groups 1 (p=0.0001 and 3 (p<0.0001. Angiogenesis was present in groups 2 and 4 and absent in group 3. In BC implant, at 4 and 8 months, it was significant when comparing groups 4 with 1 (p=0.0159. Conclusion BC membrane was well integrated to the urethral wall promoting tissue remodeling and strengthening based on morphometric and histological results and may be a future option to prevent urethral damage.

  15. Validation of an experimental polyurethane model for biomechanical studies on implant supported prosthesis - tension tests

    Directory of Open Access Journals (Sweden)

    Mariane Miyashiro

    2011-06-01

    Full Text Available OBJECTIVES: The complexity and heterogeneity of human bone, as well as ethical issues, frequently hinder the development of clinical trials. The purpose of this in vitro study was to determine the modulus of elasticity of a polyurethane isotropic experimental model via tension tests, comparing the results to those reported in the literature for mandibular bone, in order to validate the use of such a model in lieu of mandibular bone in biomechanical studies. MATERIAL AND METHODS: Forty-five polyurethane test specimens were divided into 3 groups of 15 specimens each, according to the ratio (A/B of polyurethane reagents (PU-1: 1/0.5, PU-2: 1/1, PU-3: 1/1.5. RESULTS: Tension tests were performed in each experimental group and the modulus of elasticity values found were 192.98 MPa (SD=57.20 for PU-1, 347.90 MPa (SD=109.54 for PU-2 and 304.64 MPa (SD=25.48 for PU-3. CONCLUSION: The concentration of choice for building the experimental model was 1/1.

  16. Mechanical, histological and histomorphometric evaluation of modified by femtosecond laser zirconia implants versus titanium implants. An experimental study in dogs at three months

    Directory of Open Access Journals (Sweden)

    J.L. Calvo-Guirado

    2013-06-01

    Full Text Available Aim The present study was aimed at quantifying implant´s stability and elemental composition by Periotest® and evaluating bone to implant contact (BIC and crestal bone loss of modified by femtosecond laser zirconia and titanium implants.Materials and methods Forty-eight implants were divided into 2 groups: titanium (control and modified by femtosecond laser zirconia (test and then inserted in 6 American Foxhound dogs. Primary stability and secondary stability were measured by Periotest, BIC was evaluated by histomorphometry at 1 and 3 months, elemental composition of the surrounding bone in both groups after 1 and 3 months was assessed.Results Differences between groups regarding primary stability and secondary stability were not significant (p>0.05. The Carbon ratio at zirconia (12.529% was significantly lower (p0.05 regarding BIC for titanium vs modified zirconia were observed. Crestal bone loss at 3 months was significantly (p<0.05 lower (0.07 ±0.34 mm in titanium group than in zirconia (1.25 ± 1.73 mm.Conclusion Surface treatment by using femtosecond laser equalizes osseointegration of zirconia implants.

  17. Dinitrogen fixation in aphotic oxygenated marine environments

    Directory of Open Access Journals (Sweden)

    Eyal eRahav

    2013-08-01

    Full Text Available We measured N2 fixation rates from oceanic zones that have traditionally been ignored as sources of biological N2 fixation; the aphotic, fully oxygenated, nitrate (NO3--rich, waters of the oligotrophic Levantine Basin (LB and the Gulf of Aqaba (GA. N2 fixation rates measured from pelagic aphotic waters to depths up to 720 m, during the mixed and stratified periods, ranged from 0.01 nmol N L-1 d-1 to 0.38 nmol N L-1 d-1. N2 fixation rates correlated significantly with bacterial productivity and heterotrophic diazotrophs were identified from aphotic as well as photic depths. Dissolved free amino acid amendments to whole water from the GA enhanced bacterial productivity by 2to 3.5 and N2 fixation rates by ~ 2 fold in samples collected from aphotic depths while in amendments to water from photic depths bacterial productivity increased 2 to 6 fold while N2 fixation rates increased by a factor of 2 to 4 illustrating that both BP an heterotrophic N2 fixation are carbon limited. Experimental manipulations of aphotic waters from the LB demonstrated a significant positive correlation between transparent exopolymeric particles (TEP concentration and N2 fixation rates. This suggests that sinking organic material and high carbon (C: nitrogen (N micro-environments (such as TEP-based aggregates or marine snow could support high heterotrophic N2 fixation rates in oxygenated surface waters and in the aphotic zones. Indeed, our calculations show that aphotic N2 fixation accounted for 37 to 75 % of the total daily integrated N2 fixation rates at both locations in the Mediterranean and Red Seas with rates equal or greater to those measured from the photic layers. Moreover, our results indicate that that while N2 fixation may be limited in the surface waters, aphotic, pelagic N2 fixation may contribute significantly to new N inputs in other oligotrophic basins, yet it is currently not included in regional or global N budgets.

  18. Mesh-fixation method and pain and quality of life after laparoscopic ventral or incisional hernia repair: a randomized trial of three fixation techniques

    NARCIS (Netherlands)

    Wassenaar, E.; Schoenmaeckers, E.; Raymakers, J.; van der Palen, Jacobus Adrianus Maria; Rakic, S.

    2010-01-01

    BackgroundPersistent, activity-limiting pain after laparoscopic ventral or incisional hernia repair (LVIHR) appears to be related to fixation of the implanted mesh. A randomized study comparing commonly used fixation techniques with respect to postoperative pain and quality of life has not

  19. Intraocular lens fixation with Dacron mesh: Part II.

    Science.gov (United States)

    Peyman, G A; Koziol, J; Janevicius, R

    1977-08-01

    We studied the feasibility of fixation of an intraocular lens in the posterior chamber by utilizing Dacron mesh to stimulate cellular ingrowth from the posterior iris surface. Tissue ingrowth into the Dacron mesh occurred five days after Dacron implantation and a firm adhesion between Dacron and the iris developed in a consistent and localized manner. Dacron fibers, when placed in contact with the posterior iris surface, induce fibroblastic and pigmented epithelial tissue ingrowth around the fibers. Fixation of the lens with and without the posterior lens capsule and vitreous is compared in vitrectomized and nonvitrectomized eyes. It is possible to achieve fixation without support from the posterior lens capsule and vitreous.

  20. Osteoporotic rat models for evaluation of osseointegration of bone implants

    NARCIS (Netherlands)

    Alghamdi, H.S.A.; Beucken, J.J.J.P van den; Jansen, J.A.

    2014-01-01

    Osseointegration of dental and orthopedic bone implants is the important process that leads to mechanical fixation of implants and warrants implant functionality. In view of increasing numbers of osteoporotic patients, bone implant surface optimization strategies with instructive and drug-loading

  1. Osteogenic protein-1 increases the fixation of implants grafted with morcellised bone allograft and ProOsteon bone substitute: an experimental study in dogs

    DEFF Research Database (Denmark)

    Jensen, T B; Overgaard, S; Lind, M

    2007-01-01

    Impacted bone allograft is often used in revision joint replacement. Hydroxyapatite granules have been suggested as a substitute or to enhance morcellised bone allograft. We hypothesised that adding osteogenic protein-1 to a composite of bone allograft and non-resorbable hydroxyapatite granules (...

  2. Effects of substitute coated with hyaluronic acid or poly-lactic acid on implant fixation. Experimental study in ovariectomized and glucocorticoid treated sheep

    DEFF Research Database (Denmark)

    Andreasen, Christina M; Ding, Ming; Andersen, Thomas L

    2018-01-01

    Investigated in healthy animal models, hyaluronic acid (HyA) and poly-D,L -lactic acid (PDLLA) demonstrate osteoconductive properties when coated onto hydroxyapatite (HA) and β-tricalcium phosphate (βTCP) scaffolds. In this study, we examined the efficacy of HA/βTCP granules coated with Hy...

  3. Morphological Changes in Blood Cells After Implantation of Titanium and Plastic Clips in the Neurocranium - Experimental Study on Dogs.

    Science.gov (United States)

    Katica, Muhamed; Celebicic, Mirza; Gradascevic, Nedzad; Obhodzas, Muamer; Suljić, Enra; Ocuz, Muhamed; Delibegovic, Samir

    2017-04-01

    Various studies confirm the biocompatibility and efficacy of clips for certain target tissues, but without any comparative analysis of hematological parameters. Therefore, we conducted a study to assess the possible association of the implantation of titanium and plastic clips in the neurocranium with possible morphological changes in the blood cells of experimental animals. As a control, the peripheral blood smears were taken before surgery from 12 adult dogs that were divided into two experimental groups. After placing titanium and plastic clips in the neurocranium, the peripheral blood of the first group was analyzed on the seventh postoperative day, while the peripheral blood of the second group was analyzed on the sixtieth day. By microscopy of the blood smears, the following parameters were analyzed: the presence of poikilocytosis of the red blood cells, degenerative changes in the leukocytes and leukogram. There were no statistically significant differences between the mean values of the groups. Monocytosis was detected (first group 22.83 % and second 16.30 %), as well as neutropenia (46.80 %, in the second group). Degenerative changes to neutrophils and the occurrence of atypical lymphocytes were observed in the second experimental group (60th postoperative day). A mild adverse effect from the biomaterials present in the neurocranium of dogs was detected, affecting the majority of leukocytic cells. A chronic recurrent inflammatory process was caused by the presence of the plastic and titanium clips in the brain tissue. No adverse effect of biomaterials on erythrocytes in the neurocranium was detected in the dogs studied. Further studies are necessary to explain the occurrence of degenerative changes in the neutrophils and lymphocytes.

  4. Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys.

    Science.gov (United States)

    Upadhyaya, Suraj; Pullela, Mythri; Ramachandran, Santoshi; Adade, Samuel; Joshi, Anand C; Das, Vallabh E

    2017-11-01

    To evaluate the contribution of fixational saccades toward fixation instability in strabismic monkeys. Binocular eye movements were measured as six experimental monkeys (five strabismic monkeys and one monkey with downbeat nystagmus) and one normal monkey fixated targets of two shapes (Optotype, Disk) and two sizes (0.5°, 2°) during monocular and binocular viewing. Fixational saccades were detected using an unsupervised clustering algorithm. When compared with the normal monkey, amplitude and frequency of fixational saccades in both the viewing and nonviewing eye were greater in 3 of 5 strabismic monkeys (1-way ANOVA on ranks P saccades was largely due to quick phases of ongoing nystagmus. Fixational saccade amplitude was increased significantly (3-way ANOVA; P saccade amplitude and the Bivariate Contour Ellipse Area (BCEA) was nonlinear, showing saturation of saccade amplitude. Fixation instability in depth was significantly greater in strabismic monkeys (vergence BCEA: 0.63 deg2-2.15 deg2) compared with the normal animal (vergence BCEA: 0.15 deg2; P saccades. Target parameter effects on fixational saccades are similar to previous findings of target effects on BCEA.

  5. Experimental and computational investigation of Morse taper conometric system reliability for the definition of fixed connections between dental implants and prostheses.

    Science.gov (United States)

    Bressan, Eriberto; Lops, Diego; Tomasi, Cristiano; Ricci, Sara; Stocchero, Michele; Carniel, Emanuele Luigi

    2014-07-01

    Nowadays, dental implantology is a reliable technique for treatment of partially and completely edentulous patients. The achievement of stable dentition is ensured by implant-supported fixed dental prostheses. Morse taper conometric system may provide fixed retention between implants and dental prostheses. The aim of this study was to investigate retentive performance and mechanical strength of a Morse taper conometric system used as implant-supported fixed dental prostheses retention. Experimental and finite element investigations were performed. Experimental tests were achieved on a specific abutment-coping system, accounting for both cemented and non-cemented situations. The results from the experimental activities were processed to identify the mechanical behavior of the coping-abutment interface. Finally, the achieved information was applied to develop reliable finite element models of different abutment-coping systems. The analyses were developed accounting for different geometrical conformations of the abutment-coping system, such as different taper angle. The results showed that activation process, occurred through a suitable insertion force, could provide retentive performances equal to a cemented system without compromising the mechanical functionality of the system. These findings suggest that Morse taper conometrical system can provide a fixed connection between implants and dental prostheses if proper insertion force is applied. Activation process does not compromise the mechanical functionality of the system. © IMechE 2014.

  6. Nutrient feedbacks to soil heterotrophic nitrogen fixation in forests

    Science.gov (United States)

    Perakis, Steven; Pett-Ridge, Julie C.; Catricala, Christina E.

    2017-01-01

    Multiple nutrient cycles regulate biological nitrogen (N) fixation in forests, yet long-term feedbacks between N-fixation and coupled element cycles remain largely unexplored. We examined soil nutrients and heterotrophic N-fixation across a gradient of 24 temperate conifer forests shaped by legacies of symbiotic N-fixing trees. We observed positive relationships among mineral soil pools of N, carbon (C), organic molybdenum (Mo), and organic phosphorus (P) across sites, evidence that legacies of symbiotic N-fixing trees can increase the abundance of multiple elements important to heterotrophic N-fixation. Soil N accumulation lowered rates of heterotrophic N-fixation in organic horizons due to both N inhibition of nitrogenase enzymes and declines in soil organic matter quality. Experimental fertilization of organic horizon soil revealed widespread Mo limitation of heterotrophic N-fixation, especially at sites where soil Mo was scarce relative to C. Fertilization also revealed widespread absence of P limitation, consistent with high soil P:Mo ratios. Responses of heterotrophic N-fixation to added Mo (positive) and N (negative) were correlated across sites, evidence that multiple nutrient controls of heterotrophic N-fixation were more common than single-nutrient effects. We propose a conceptual model where symbiotic N-fixation promotes coupled N, C, P, and Mo accumulation in soil, leading to positive feedback that relaxes nutrient limitation of overall N-fixation, though heterotrophic N-fixation is primarily suppressed by strong negative feedback from long-term soil N accumulation.

  7. The Role of Biomimetic Incubation of Sandblasted Titanium Implants in the Process of Osseointegration: An Experimental Study in Dogs

    Directory of Open Access Journals (Sweden)

    Nigmon L. Khabilov

    2015-03-01

    Full Text Available The aim of the present study was to examine the surface characteristics and values of removal torque of an implant surface subjected to sandblasting with 125µm Al2O3 particles with a following immersion in biomimetic fluid and to compare that surface with a machined implant surface. Study protocol: Forty-eight conical implants were initially made of second-grade titanium alloy. The diameter of implants was 4mm at the head and 2.6 at the apex, all implants were of 8 mm length and of large variable thread design. Half of them were subjected to sand blasting and immersion in biomimetic fluid at 37 ⁰C for four weeks with daily replenishment of solution until the moment of placement; another 24 implants were left with untreated machined surface. Three-dimensional roughness values were obtained with the help of confocal laser scanning microscope. Forty-eight implants were implanted in 12 dogs. Twenty-four implants were retrieved after a 6-week healing period following installation, and the remaining 24 were removed upon the completion of 16 weeks, using a torque calibrator ((BTG150CN-S TOHNICHI with a 20 cN•m - 150 cN•m scale of force registration was applied for the measurements of the removal torque. Results: The mean 3-dimensional roughness value of biomimetically treated implant surfaces was 1.34±0.24µm and the mean roughness value measured for the machined surfaces was 0.33±0.04µm (P<0.05. As to the average parameters of maximum peak-trough distance, these were equal to 2.85 for machined and 24.25 for incubated sandblasted implants. Machined implants demonstrated 49.5±10.3 removal torque values after the 6-week healing period. But for the immersed sandblasted implants the same parameter was equal to 72.7±15.98 Ncm. During a 16-week recovery period, these values increased up to 77.5±15.16 Ncm and 89.7±11.83 Ncm for machined and biomimetically treated sandblasted implants, respectively, P<0.05. Conclusion: The present study

  8. Guided tissue regeneration ensures osseointegration of dental implants placed into extraction sockets. An experimental study in monkeys

    DEFF Research Database (Denmark)

    Warrer, L; Gotfredsen, K; Hjørting-Hansen, E

    1991-01-01

    The aim of the present study was to explore the possibility of achieving osseointegration of dental titanium implants, inserted into alveoli immediately after tooth extraction, by covering the recipient site with a teflon membrane. In each of 7 monkeys, mucoperiosteal flaps were raised...... present between the implant and the socket walls. In one side of the jaw, a membrane (Gore-Tex Augmentation Material) was adjusted to cover the implant. The implant in the other side of the jaw served as control and was only covered by the tissue flaps. Microscopic analysis after 3 months of healing...... on the buccal and palatal aspects of the maxillary molars in both sides of the jaw. The second molars were then extracted and self tapping titanium implants of the screw type (Astra Dental Implants) were inserted into the sockets of the largest roots. In the coronal portion of the sockets, a void was always...

  9. Influence of microgap location and configuration on radiographic bone loss in nonsubmerged implants: an experimental study in dogs.

    Science.gov (United States)

    Weng, Dietmar; Nagata, Maria Jose Hitomi; Leite, Christiane Mota; de Melo, Luiz Gustavo Nascimento; Bosco, Alvaro Francisco

    2011-01-01

    The implant-abutment connection (microgap) influences the peri-implant bone morphology. However, it is unclear if different microgap configurations additionally modify bone reactions. This preliminary study aimed to radiographically monitor peri-implant bone levels in two different microgap configurations during 3 months of nonsubmerged healing. Six dogs received two implants with internal Morse taper connection (INT group) on one side of the mandible and two implants with external-hex connection (EXT group) on the other side. One implant on each side was positioned at bone level (equicrestal); the second implant was inserted 1.5 mm below the bone crest (subcrestal). Healing abutments were attached directly after implant insertion, and the implants were maintained for 3 months without prosthetic loading. At implant placement and 1, 2, and 3 months, standardized radiographs were taken to monitor peri-implant bone levels. All implants osseointegrated. A total bone loss of 0.48 ± 0.66 mm was measured in the equicrestal INT group, 0.69 ± 0.43 mm in the equicrestal EXT group, 0.79 ± 0.93 mm in the subcrestal INT group, and 1.56 ± 0.53 mm in the subcrestal EXT group (P > .05, paired t tests). Within the four groups, bone loss over time became significantly greater in the EXT groups than in the INT groups. The greatest bone loss was noted in the subcrestal EXT group. Within the limits of this animal study, it seems that even without prosthetic loading, different microgap configurations exhibit different patterns of bone loss during nonsubmerged healing. Subcrestal positioning of an external butt joint microgap may lead to faster radiographic bone loss.

  10. Comparison of Lyophilized Glutaraldehyde-Preserved Bovine Pericardium with Different Vascular Prostheses for Use as Vocal Cords Implants: Experimental Study

    Science.gov (United States)

    Olmos-Zuñiga, J. Raúl; Jasso-Victoria, Rogelio; Gaxiola-Gaxiola, Miguel; Sotres-Vega, Avelina; Hernández-Jiménez, Claudia; Baltazares-Lipp, Matilde; Arredondo del Bosque, Fernando; Santillan-Doherty, Patricio

    2015-01-01

    This study compared the use of lyophilized glutaraldehyde-preserved bovine pericardium (LGPBP), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), and Teflon felt (TF) as implants for vocal cords (VC) medialization and aimed to assess the endoscopic, macroscopic, and microscopic VC changes after medialization in a canine model. In 18 mongrel dogs, the right VC were medialized with LGPBP and the left were implanted as follows: Group I (n = 6): LGPBP and PTFE; Group II (n = 6): LGPBP and PET; Group III (n = 6): LGPBP and TF. Surgical handling of the implants was compared. Three months after surgery, macroscopic and microscopic changes of VC and implants were evaluated. LGPBP offered the best surgical handling (p = 0.005, Kruskal-Wallis). TF implants showed extrusion (p = 0.005, Kruskal-Wallis) and severe inflammation. All VC formed fibrous capsules around the implants; the ones developed by LGPBP implants were thinner (p = 0.001, ANOVA, Tukey). VC implanted with synthetic materials showed eosinophilic infiltration (p = 0.01, Kruskal-Wallis). We concluded that the LGPBP could be used as an implant for VC medialization because it is biocompatible, easy to handle and remove during surgical procedures, and nonabsorbable or extrudable and produces an inflammatory reaction similar to PTFE and PET. PMID:26075232

  11. Submerged flapless technique vs. conventional flap approach for implant placement: experimental domestic pig study with 12-month follow-up.

    Science.gov (United States)

    Pérez-Albacete Martínez, Carlos; Vlahović, Zoran; Šćepanović, Miodrag; Videnović, Goran; Barone, Antonio; Calvo-Guirado, José Luis

    2016-08-01

    The aim of our study was to compare osseointegration and peri-implant crestal bone resorption in submerged flapless and conventional flap surgery over a 12-month follow-up. The study used five domestic pigs. Implants were inserted 9 weeks after tooth extraction. Each animal received six implants in the mandible, following a split-mouth design: one side was treated using a flapless technique using mini-incisions, while a flap was raised on the other. The animals were sacrificed at 2 weeks, 1, 3, 6 and 12 months after implant placement. Radiographic images were taken to analyze crestal bone loss, and samples were extracted for histopathological and bone-to-implant contact (BIC) analyses. Significantly, greater crestal bone loss (P = 0.005) was obtained in the flap group compared with the flapless group. The flapless group presented significantly higher percentages of BIC (P surgery (flap or flapless) affects peri-implant bone preservation and osseointegration of regular platform implants. Flapless surgery is associated with peri-implant crestal bone preservation. Flapless surgery in combination with submerged implants allows higher osseointegration values. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. Experimental model of biofilm implant-related osteomyelitis to test combination biomaterials using biofilms as initial inocula.

    Science.gov (United States)

    Williams, Dustin L; Haymond, Bryan S; Woodbury, Kassie L; Beck, J Peter; Moore, David E; Epperson, R Tyler; Bloebaum, Roy D

    2012-07-01

    Currently, the majority of animal models that are used to study biofilm-related infections use planktonic bacterial cells as initial inocula to produce positive signals of infection in biomaterials studies. However, the use of planktonic cells has potentially led to inconsistent results in infection outcomes. In this study, well-established biofilms of methicillin-resistant Staphylococcus aureus were grown and used as initial inocula in an animal model of a Type IIIB open fracture. The goal of the work was to establish, for the first time, a repeatable model of biofilm implant-related osteomyelitis, wherein biofilms were used as initial inocula to test combination biomaterials. Results showed that 100% of animals that were treated with biofilms developed osteomyelitis, whereas 0% of animals not treated with biofilm developed infection. The development of this experimental model may lead to an important shift in biofilm and biomaterials research by showing that when biofilms are used as initial inocula, they may provide additional insights into how biofilm-related infections in the clinic develop and how they can be treated with combination biomaterials to eradicate and/or prevent biofilm formation. Copyright © 2012 Wiley Periodicals, Inc.

  13. The influence of external ultrasound on the histologic architecture of the organic capsule around smooth silicone implants: experimental study in rats.

    Science.gov (United States)

    Mendes, F H; Viterbo, F; DeLucca, L

    2008-05-01

    Capsular contracture is the main complication related to breast silicone implants, and its prevention remains a medical challenge. The authors present experimental research examining the effect of external ultrasound on the formation and contracture of peri-implant capsules. In this study, 42 male Wistar rats had a 2-mm smooth surface implant placed in a dorsal submuscular pocket. They then were separated into "ultrasound" and "control" groups that received repeated external applications either with or without the ultrasound power on. Ultrasound applications were given three times a week for a period of 90 days. After that, both groups were housed under the same conditions with no application scheduled. Five animals of each group, killed at 30, 60, 90, and 180 days, had their implants removed along with the capsule, which received a special histologic preparation via annular sectioning that provided wide circumferential observation of the capsular tissue. Sections were stained with hematoxylin/eosin stain, Masson's trichrome stain, and Pricrosirius Red stain for regular microscopic evaluation under normal and polarized light. Histologic data showed that capsules from the ultrasound and control groups had statistically significant differences. Ultrasound application developed a capsular architecture similar to that shown within textured silicone implants, and its effect had an early definition with subsequent stabilization. The authors conclude that early and repeated external ultrasound application enhances the thickness, cellular count, and vascularity of smooth silicone capsular tissue, whereas it diminishes the pattern of parallel orientation of collagen fibers.

  14. The effect of injectable calcium phosphate cement on bone anchorage of titanium implants: an experimental feasibility study in dogs.

    NARCIS (Netherlands)

    Arisan, V.; Anil, A.; Wolke, J.G.C.; Ozer, K.

    2010-01-01

    Calcium phosphate has high osteotransductive potential. The injectable form of calcium phosphate cement (ICAP) can be used as an adjunctive supportive agent for dental implants. The aim of this study was to assess the effect of an ICAP on the reverse torque resistance of titanium implants. Two

  15. Adipose-Derived Stem Cells as a Tool for Dental Implant Osseointegration: an Experimental Study in the Dog.

    Science.gov (United States)

    Bressan, Eriberto; Botticelli, Daniele; Sivolella, Stefano; Bengazi, Franco; Guazzo, Riccardo; Sbricoli, Luca; Ricci, Sara; Ferroni, Letizia; Gardin, Chiara; Velez, Joaquin Urbizo; Zavan, Barbara

    2015-01-01

    The biological interaction between the jaw bones and dental implant is fundamental for the long-term success of dental implant placement. Nevertheless, the insufficient bone volume remains a major clinical problem, especially in case of immediate dental implant. Using a canine model, the present study proves the regenerative potential of adipose- derived stem cells (ADSCs) to repair peri-implant bone defects occurring in immediate dental implant placement. In six labradors, all mandibular premolars and the first molars were extracted bilaterally and three months later dental implants were installed with a marginal gap. The marginal defects were filled with hydroxyapatite (HA)-based scaffolds previously seeded with ADSCs. After one month of healing, specimens were prepared for histological and histomorphometric evaluations. Histological analyses of ground sections show that ADSCs significantly increase bone regeneration. Several new vessels, osteoblasts and new bone matrix were detected. By contrast, no inflammatory cells have been revealed. ADSCs could be used to accelerate bone healing in peri- implant defects in case of immediate dental implant placement.

  16. Monitoring in vivo load transmission through an external fixator.

    Science.gov (United States)

    Grasa, J; Gómez-Benito, M J; González-Torres, L A; Asiaín, D; Quero, F; García-Aznar, J M

    2010-03-01

    This work presents a portable non-invasive external fixator to assess and monitor fracture healing in real time. To evaluate the potential of this fixator, a transverse osteotomy was performed in the tibia of six adult sheep (mean age 3+/-0.5 years and weight 63+/-5 kg). The fractures were stabilized by a specially designed unilateral external fixator, which was instrumented by means of a set of strain gauges. Strains in the external surface of the fixator were monitored during all the healing process. A wireless, remote monitoring of the implant was developed through a specially designed external telemetric device. The strain gauges were arranged in two different half-bridge Wheatstone configurations, allowing easy post-processing of the signal. Thus, bending loads were measured in two planes of the external fixator acting as a load cell. The load through the fixator was evaluated for the gait cycle during all the healing process. Full weight bearing of the injured leg was observed from the beginning. The load transmission mechanism in the fixator was quite similar in all operated tibias and radiographic images showed a successful healing in all animals. Although the fixator has only been tested in an animal model, after further testing this system may have clinical potential.

  17. Evaluation of guided bone generation around implants placed into fresh extraction sockets: an experimental study in dogs

    DEFF Research Database (Denmark)

    Gotfredsen, K; Nimb, L; Buser, D

    1993-01-01

    . The objective of this study was to evaluate the crestal bone healing response adjacent to implants placed immediately into fresh extraction sockets with and without covering membranes. Eight adult mongrel dogs had the third and fourth mandibular premolars extracted bilaterally. Thirty-two submerged titanium...... hollow-screw implants were inserted immediately into the extraction sockets. On the right side, the implants were covered with an expanded polytetrafluorethylene membrane, whereas the left side served as a control. One dog was killed after 2 weeks, one after 4 weeks, and six after 12 weeks. Soft tissue...... dehiscence developed over 10 implants (12-week dogs) covered with membranes. Dehiscence was noted histologically over three contralateral control implants. When soft tissue dehiscence occurred and the membrane was left exposed without oral hygiene during healing, the degree of bone integration...

  18. Immediate implant placement using a biodegradable barrier, polyhydroxybutyrate-hydroxyvalerate reinforced with polyglactin 910. An experimental study in dogs

    DEFF Research Database (Denmark)

    Gotfredsen, K; Nimb, L; Hjørting-Hansen, E

    1994-01-01

    The purpose of this study was to evaluate the use of a biodegradable membrane of polyhydroxybutyrate-hydroxyvalerate copolymer reinforced with polyglactin 910 fibers, as an occlusive barrier over implants placed into fresh extraction sockets. Ten dogs had the 3rd and 4th mandibular premolars...... extracted bilaterally. Each dog had 4 Astra Dental Implants placed directly into the fresh extraction sockets. The top of the fixtures was placed at the same level as the top of the buccal cortical bone. The two implants in the right side were covered with the hydrolyzable polyester material...... (polyhydroxybutyrate-hydroxyvalerate reinforced with polyglactin 910 fibers; PHB-HV/PG), and the 2 implants in the left side were controls without occlusive membranes. Soft tissue dehiscences were registered for half of the implants in the test side but were not noted in the control side. The histomorphological...

  19. Comparative experimental re-evaluation of the two implanting methods of silicone gel testicular prostheses in beagle dogs

    Directory of Open Access Journals (Sweden)

    Chen Peng

    2011-04-01

    Full Text Available Abstract Background Testicular prosthesis has been applied clinically for decades, and implantation of testis prosthesis under the tunica albuginea has been considered to be the standard method in the most of the reports. However, postoperative scrotal appearance, the mobilization and the palpitation of the prosthesis are not always satisfactory to all the patients. Modifications in surgical techniques might be necessary to bring improvements to the clinical outcomes in testicular prosthesis implantation. Findings In a group of 9 beagle dogs in this study, an orchiectomy succeeded with a testicular prosthesis implantation under the tunica vaginalis, and a complete mechanical denudation of the testicular parenchyma succeeded with an implantation under the tunica albuginea were performed, respectively. Histopathological evaluations of the scrotal tissues and the implants, which were made at the end of the follow-up, showed that all the tested animals lived uneventful lives during the follow-up period, and no rejections or infections were found. Prostheses implanted under the tunica vaginalis showed a more satisfying mobilization and palpation than those implanted under the tunica albuginea. Chronic inflammation in the para-prosthesis tissues with vascular proliferation and fibrinogenesis were more common in the "under tunica albuginea" group than that in the "under tunica vaginalis" group, although differences in fibrinogenesis between the two groups were found to be statistically insignificant. Conclusions In this comparative study, we have re-evaluated the two most popular implantation methods of testicular prosthesis, the "under the tunica albuginea" and the "under the tunica vaginalis" pathways, in animal models. We found that the testicular prosthesis were all well tolerated, but the prosthesis implanted under the tunica vaginalis showed a more satisfying result concerning appearance, palpability, and histopathological findings than that of

  20. Comparative experimental re-evaluation of the two implanting methods of silicone gel testicular prostheses in beagle dogs.

    Science.gov (United States)

    Hao, Tong-Li; Chen, Peng

    2011-04-02

    Testicular prosthesis has been applied clinically for decades, and implantation of testis prosthesis under the tunica albuginea has been considered to be the standard method in the most of the reports. However, postoperative scrotal appearance, the mobilization and the palpitation of the prosthesis are not always satisfactory to all the patients. Modifications in surgical techniques might be necessary to bring improvements to the clinical outcomes in testicular prosthesis implantation. In a group of 9 beagle dogs in this study, an orchiectomy succeeded with a testicular prosthesis implantation under the tunica vaginalis, and a complete mechanical denudation of the testicular parenchyma succeeded with an implantation under the tunica albuginea were performed, respectively. Histopathological evaluations of the scrotal tissues and the implants, which were made at the end of the follow-up, showed that all the tested animals lived uneventful lives during the follow-up period, and no rejections or infections were found. Prostheses implanted under the tunica vaginalis showed a more satisfying mobilization and palpation than those implanted under the tunica albuginea. Chronic inflammation in the para-prosthesis tissues with vascular proliferation and fibrinogenesis were more common in the "under tunica albuginea" group than that in the "under tunica vaginalis" group, although differences in fibrinogenesis between the two groups were found to be statistically insignificant. In this comparative study, we have re-evaluated the two most popular implantation methods of testicular prosthesis, the "under the tunica albuginea" and the "under the tunica vaginalis" pathways, in animal models. We found that the testicular prosthesis were all well tolerated, but the prosthesis implanted under the tunica vaginalis showed a more satisfying result concerning appearance, palpability, and histopathological findings than that of the "under the tunica albuginea" group. The "under the tunica

  1. Comparative experimental re-evaluation of the two implanting methods of silicone gel testicular prostheses in beagle dogs

    Science.gov (United States)

    2011-01-01

    Background Testicular prosthesis has been applied clinically for decades, and implantation of testis prosthesis under the tunica albuginea has been considered to be the standard method in the most of the reports. However, postoperative scrotal appearance, the mobilization and the palpitation of the prosthesis are not always satisfactory to all the patients. Modifications in surgical techniques might be necessary to bring improvements to the clinical outcomes in testicular prosthesis implantation. Findings In a group of 9 beagle dogs in this study, an orchiectomy succeeded with a testicular prosthesis implantation under the tunica vaginalis, and a complete mechanical denudation of the testicular parenchyma succeeded with an implantation under the tunica albuginea were performed, respectively. Histopathological evaluations of the scrotal tissues and the implants, which were made at the end of the follow-up, showed that all the tested animals lived uneventful lives during the follow-up period, and no rejections or infections were found. Prostheses implanted under the tunica vaginalis showed a more satisfying mobilization and palpation than those implanted under the tunica albuginea. Chronic inflammation in the para-prosthesis tissues with vascular proliferation and fibrinogenesis were more common in the "under tunica albuginea" group than that in the "under tunica vaginalis" group, although differences in fibrinogenesis between the two groups were found to be statistically insignificant. Conclusions In this comparative study, we have re-evaluated the two most popular implantation methods of testicular prosthesis, the "under the tunica albuginea" and the "under the tunica vaginalis" pathways, in animal models. We found that the testicular prosthesis were all well tolerated, but the prosthesis implanted under the tunica vaginalis showed a more satisfying result concerning appearance, palpability, and histopathological findings than that of the "under the tunica

  2. Cochlear implant

    Science.gov (United States)

    Hearing loss - cochlear implant; Sensorineural - cochlear; Deaf - cochlear; Deafness - cochlear ... of the cochlear implant. WHO USES A COCHLEAR IMPLANT? Cochlear implants allow deaf people to receive and process ...

  3. Photographic fixative poisoning

    Science.gov (United States)

    Photographic fixatives are chemicals used to develop photographs. This article discusses poisoning from swallowing such chemicals. This article is for information only. DO NOT use it to treat or manage an ...

  4. Biomechanical evaluation of three fixation modalities for preperitoneal inguinal hernia repair: a 24-hour postoperative study in pigs.

    Science.gov (United States)

    Guérin, Gaëtan; Bourges, Xavier; Turquier, Frédéric

    2014-01-01

    Tacks and sutures ensure a strong fixation of meshes, but they can be associated with pain and discomfort. Less invasive methods are now available. Three fixation modalities were compared: the ProGrip™ laparoscopic self-fixating mesh; the fibrin glue Tisseel™ with Bard™ Soft Mesh; and the SorbaFix™ absorbable fixation system with Bard™ Soft Mesh. Meshes (6 cm ×6 cm) were implanted in the preperitoneal space of swine. Samples were explanted 24 hours after surgery. Centered defects were created, and samples (either ten or eleven per fixation type) were loaded in a pressure chamber. For each sample, the pressure, the mesh displacement through the defect, and the measurements of the contact area were recorded. At all pressures tested, the ProGrip™ laparoscopic self-fixating mesh both exhibited a significantly lower displacement through the defect and retained a significantly higher percentage of its initial contact area than either the Bard™ Soft Mesh with Tisseel™ system or the Bard™ Soft Mesh with SorbaFix™ absorbable fixation system. Dislocations occurred with the Bard™ Soft Mesh with Tisseel™ system and with the Bard™ Soft Mesh with SorbaFix™ absorbable fixation system at physiological pressure (,225 mmHg). No dislocation was recorded for the ProGrip™ laparoscopic self-fixating mesh. At 24 hours after implantation, the mechanical fixation of the ProGrip™ laparoscopic self-fixating mesh was found to be significantly better than the fixation of the Tisseel™ system or the SorbaFix™ absorbable fixation system.

  5. The prediction of cyclic proximal humerus fracture fixation failure by various bone density measures.

    Science.gov (United States)

    Varga, Peter; Grünwald, Leonard; Windolf, Markus

    2018-02-22

    Fixation of osteoporotic proximal humerus fractures has remained challenging, but may be improved by careful pre-operative planning. The aim of this study was to investigate how well the failure of locking plate fixation of osteoporotic proximal humerus fractures can be predicted by bone density measures assessed with currently available clinical imaging (realistic case) and a higher resolution and quality modality (theoretical best-case). Various density measures were correlated to experimentally assessed number of cycles to construct failure of plated unstable low-density proximal humerus fractures (N = 18). The influence of density evaluation technique was investigated by comparing local (peri-implant) versus global evaluation regions; HR-pQCT-based versus clinical QCT-based image data; ipsilateral versus contralateral side; and bone mineral content (BMC) versus bone mineral density (BMD). All investigated density measures were significantly correlated with the experimental cycles to failure. The best performing clinically feasible parameter was the QCT-based BMC of the contralateral articular cap region, providing significantly better correlation (R 2  = 0.53) compared to a previously proposed clinical density measure (R 2  = 0.30). BMC had consistently, but not significantly stronger correlations with failure than BMD. The overall best results were obtained with the ipsilateral HR-pQCT-based local BMC (R 2  = 0.74) that may be used for implant optimization. Strong correlations were found between the corresponding density measures of the two CT image sources, as well as between the two sides. Future studies should investigate if BMC of the contralateral articular cap region could provide improved prediction of clinical fixation failure compared to previously proposed measures. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  6. Improving Saliency Models by Predicting Human Fixation Patches

    KAUST Repository

    Dubey, Rachit

    2015-04-16

    There is growing interest in studying the Human Visual System (HVS) to supplement and improve the performance of computer vision tasks. A major challenge for current visual saliency models is predicting saliency in cluttered scenes (i.e. high false positive rate). In this paper, we propose a fixation patch detector that predicts image patches that contain human fixations with high probability. Our proposed model detects sparse fixation patches with an accuracy of 84 % and eliminates non-fixation patches with an accuracy of 84 % demonstrating that low-level image features can indeed be used to short-list and identify human fixation patches. We then show how these detected fixation patches can be used as saliency priors for popular saliency models, thus, reducing false positives while maintaining true positives. Extensive experimental results show that our proposed approach allows state-of-the-art saliency methods to achieve better prediction performance on benchmark datasets.

  7. A chlorhexidine-releasing epoxy-based coating on titanium implants prevents Staphylococcus aureus experimental biomaterial-associated infection.

    Science.gov (United States)

    Riool, M; Dirks, A J; Jaspers, V; de Boer, L; Loontjens, T J; van der Loos, C M; Florquin, S; Apachitei, I; Rijk, L N; Keul, H A; Zaat, S A

    2017-02-14

    Prevention of biomaterial-associated infections (BAI) remains a challenging problem, in particular due to the increased risk of resistance development with the current antibiotic-based strategies. Metallic orthopaedic devices, such as non-cemented implants, are often inserted under high mechanical stress. These non-cemented implants cannot be protected by e.g. antibioticreleasing bone cement or other antimicrobial approaches, such as the use of bioactive glass. Therefore, in order to avoid abrasion during implantation procedures, we developed an antimicrobial coating with great mechanical stability for orthopaedic implants, to prevent Staphylococcus aureus BAI. We incorporated 5 and 10 wt % chlorhexidine in a novel mechanically stable epoxy-based coating, designated CHX5 and CHX10, respectively. The coatings displayed potent bactericidal activity in vitro against S. aureus, with over 80 % of the release (19 µg/cm2 for CHX5 and 41 µg/cm2 for CHX10) occurring within the first 24 h. In mice, the CHX10 coating significantly reduced the number of CFU (colony forming units), both on the implants and in the peri-implant tissues, 1 d after S. aureus challenge. The CHX10-coated implants were well-tolerated by the animals, with no signs of toxicity observed by histological analysis. Moreover, the coating significantly reduced the frequency of culture-positive tissues 1 d, and of culture-positive implants 1 and 4 d after challenge. In summary, the chlorhexidine-releasing mechanically stable epoxy-based CHX10 coating prevented implant colonisation and S. aureus BAI in mice and has good prospects for clinical development.

  8. A Novel Anterior Transpedicular Screw Artificial Vertebral Body System for Lower Cervical Spine Fixation: A Finite Element Study.

    Science.gov (United States)

    Wu, Weidong; Chen, Chun; Ning, Jinpei; Sun, Peidong; Zhang, Jinyuan; Wu, Changfu; Bi, Zhenyu; Fan, Jihong; Lai, Xianliang; Ouyang, Jun

    2017-06-01

    A finite element model was used to compare the biomechanical properties of a novel anterior transpedicular screw artificial vertebral body system (AVBS) with a conventional anterior screw plate system (ASPS) for fixation in the lower cervical spine. A model of the intact cervical spine (C3-C7) was established. AVBS or ASPS constructs were implanted between C4 and C6. The models were loaded in three-dimensional (3D) motion. The Von Mises stress distribution in the internal fixators was evaluated, as well as the range of motion (ROM) and facet joint force. The models were generated and analyzed by mimics, geomagic studio, and ansys software. The intact model of the lower cervical spine consisted of 286,382 elements. The model was validated against previously reported cadaveric experimental data. In the ASPS model, stress was concentrated at the connection between the screw and plate and the connection between the titanium mesh and adjacent vertebral body. In the AVBS model, stress was evenly distributed. Compared to the intact cervical spine model, the ROM of the whole specimen after fixation with both constructs is decreased by approximately 3 deg. ROM of adjacent segments is increased by approximately 5 deg. Facet joint force of the ASPS and AVBS models was higher than those of the intact cervical spine model, especially in extension and lateral bending. AVBS fixation represents a novel reconstruction approach for the lower cervical spine. AVBS provides better stability and lower risk for internal fixator failure compared with traditional ASPS fixation.

  9. Immediate implant placement using a biodegradable barrier, polyhydroxybutyrate-hydroxyvalerate reinforced with polyglactin 910. An experimental study in dogs

    DEFF Research Database (Denmark)

    Gotfredsen, K; Nimb, L; Hjørting-Hansen, E

    1994-01-01

    The purpose of this study was to evaluate the use of a biodegradable membrane of polyhydroxybutyrate-hydroxyvalerate copolymer reinforced with polyglactin 910 fibers, as an occlusive barrier over implants placed into fresh extraction sockets. Ten dogs had the 3rd and 4th mandibular premolars...... extracted bilaterally. Each dog had 4 Astra Dental Implants placed directly into the fresh extraction sockets. The top of the fixtures was placed at the same level as the top of the buccal cortical bone. The two implants in the right side were covered with the hydrolyzable polyester material...

  10. Surface modification of implants in long bone

    Science.gov (United States)

    Förster, Yvonne; Rentsch, Claudia; Schneiders, Wolfgang; Bernhardt, Ricardo; Simon, Jan C.; Worch, Hartmut; Rammelt, Stefan

    2012-01-01

    Coatings of orthopedic implants are investigated to improve the osteoinductive and osteoconductive properties of the implant surfaces and thus to enhance periimplant bone formation. By applying coatings that mimic the extracellular matrix a favorable environment for osteoblasts, osteoclasts and their progenitor cells is provided to promote early and strong fixation of implants. It is known that the early bone ongrowth increases primary implant fixation and reduces the risk of implant failure. This review presents an overview of coating titanium and hydroxyapatite implants with components of the extracellular matrix like collagen type I, chondroitin sulfate and RGD peptide in different small and large animal models. The influence of these components on cells, the inflammation process, new bone formation and bone/implant contact is summarized. PMID:23507866

  11. 915 MHz microwave ablation with implanted internal cooled-shaft antenna: Initial experimental study in in vivo porcine livers

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Zhigang, E-mail: qlczg@yahoo.cn [Department of Interventional Ultrasound, Chinese PLA General Hospital, 28, Fuxing Road, Haidian District, Beijing 100853 (China); Xiao Qiujin, E-mail: xiaoqj@hotmail.com [Department of Ultrasound, Chinese PLA Ninety-fourth Hospital, Nanchang, Jiangxi Province 330000 (China); Wang Yang, E-mail: wangyang301@sohu.com [Department of Ultrasound, Chinese PLA General Hospital, 28, Fuxing Road, Haidian District, Beijing 100853 (China); Sun Yuanyuan, E-mail: qlczg@sina.com [Department of Interventional Ultrasound, Chinese PLA General Hospital, 28, Fuxing Road, Haidian District, Beijing 100853 (China); Lu Tong, E-mail: lutong_java@yahoo.com.cn [Department of Interventional Ultrasound, Chinese PLA General Hospital, 28, Fuxing Road, Haidian District, Beijing 100853 (China); Liang Ping, E-mail: liangping301@yahoo.com.cn [Department of Interventional Ultrasound, Chinese PLA General Hospital, 28, Fuxing Road, Haidian District, Beijing 100853 (China)

    2011-07-15

    Purpose: To explore a preferred power output for further clinical application based on the ablated lesions induced by the four power outputs of 915 MHz microwave in experimental study of in vivo porcine livers. Materials and methods: A KY2000-915 microwave ablation system with an implanted 915 MHz internal cooled-shaft antenna was used in this study. A total of 24 ablations were performed in eight in vivo porcine livers. The energy was applied for 10 min at microwave output powers of 50 W, 60 W, 70 W, and 80 W. Long-axis and short-axis diameters of the coagulation zone were measured on all gross specimens. Results: The shapes of the 915 MHz microwave ablation lesions were elliptical commonly. As the power increased, the long-axis and short-axis diameters of the coagulation zone had a tendency to rise. But the long-axis diameter of the ablated lesion at 50 W was not significantly smaller than that of the ablated lesion at 60 W (P > 0.05) and there were no statistical differences in short-axis diameters of the ablated lesion among the three power outputs of 60 W, 70 W and 80 W (P > 0.05). After 10 min irradiation of 60 W, the long-axis and short-axis diameters of the coagulation zone were 5.02 {+-} 0.60 cm and 3.65 {+-} 0.46 cm, respectively. Conclusions: For decreasing the undesired damages of liver tissues along the shaft and the number of antenna in further clinically percutaneous microwave ablation treatment, the power of 60 W may be a preferred setting among the four power outputs used in present study.

  12. Resorbable screws for fixation of autologous bone grafts

    NARCIS (Netherlands)

    Raghoebar, GM; Liem, RSB; Bos, RRM; van der Wal, JE; Vissink, A

    The aim of this study was to evaluate the suitability of resorbable screws made of poly (D,L-lactide) acid (PDLLA) for fixation of autologous bone grafts related to graft regeneration and osseointegration of dental implants. In eight edentulous patients suffering from insufficient retention of their

  13. [Complex reconstruction with internal locking plate fixation for Charcot arthropathy].

    Science.gov (United States)

    Ramadani, F; Härägus, H; Radu, P; Trieb, K; Hofstaetter, S

    2015-01-01

    Osteosynthesis and reposition of the Charcot foot is challenging with respect to choice of a proper implant. There is currently no international consensus regarding the optimal implant. Locking plates seem to be an innovative and stable method for reconstruction. The aim of this work is to analyze bone fusion, complications, pseudoarthrosis, and patient satisfaction. This paper presents a retrospective analysis of 63 consecutive Charcot feet treated between 2004 and 2014. The mean follow-up time was 2.4 years. All Charcot feet treated between 2004 and 2014 were Sanders type II or III. A bony fusion was achieved in 50 % of the cases, 26 % had a functional pseudoarthrosis with intact implants and pain-free mobility, and 22 % showed no healing with broken implants. Conclusion Internal fixation with locking plates is superior to screw fixation only with regard to biomechanics. We prefer internal fixation plates to external fixation because of stability even in the case of pseudoathrosis and because of the learning curve.

  14. Effect of intraarticular stainless steel implants on the health of the rabbit knee joint: an experimental study.

    Science.gov (United States)

    Stubbs, M; Zhang, H; Vrahas, M S; Baratta, R V; Zieske, A

    2000-11-01

    This study was designed to investigate the histologic changes to the knee joints of rabbits after insertion of a metal implant in retrograde fashion. Eighteen rabbits had a modified stainless steel screw implanted in one knee, with the other knee serving as a sham-operated control. The animals were killed after two, six, or twelve months. The histologic status of the cartilage and synovium were graded by the Modified Mankin and Mirra criteria, respectively. At the time of killing, every insertion site was covered by fibrous tissue. Statistical analysis showed no significant differences in histologic scores between implanted and control knees. Insertion of a stable, well-fixed implant results in no deleterious effect to the knee joint.

  15. An Experimental Study to Determine the Role of Inferior Vena Cava Filter in Preventing Bone Cement Implantation Syndrome

    OpenAIRE

    Guo, Wangang; Zheng, Qiangsun; Li, Bingling; Shi, Xiaoqin; Xiang, Dingcheng; Wang, Chen

    2015-01-01

    Background: Inferior vena cava filters (IVCF) are frequently used for preventing pulmonary embolism (PE) following deep venous thromboembolism. Objectives: The present study was designed to investigate whether IVCF could prevent or impede the occurrence of bone cement implantation syndrome (BCIS), since PE is considered as the central mechanism of BCIS. Materials and Methods: Fifteen sheep were divided into three groups: bone cement free (BCF) group, cement implantation (CI) group and IVCF gr...

  16. Deflections of an implant-supported cantilever beam subjected to vertically directed loads: in vitro measurements in three dimensions using an optoelectronic method. I. Experimental set-up.

    Science.gov (United States)

    Cassel, Björn; Lundgren, Dan; Karlsson, Dan

    2011-03-01

    The aim of this in vitro study was to develop and test an experimental set-up consisting of a video camera and computer-based optoelectronic motion analysis system, synchronized with a loading device, for studying load-dependent deflections in three dimensions of single implant-supported cantilever beams. One Brånemark System implant was tightly screwed into a steel plate so that the entire implant became submerged. An abutment was attached to the implant and a cast 22-mm-long cantilever gold alloy beam incorporating a prefabricated gold cylinder was attached to the abutment with a prosthetic gold screw. A force transducer was glued on the upper surface of the beam end with its centre 19.4 mm from the centre of the implant abutment gold cylinder unit to register the applied load. A specially designed loading device was used to apply increasing vertical loads of the beam end via the transducer. The motion analysis system was synchronized with the transducer to enable measurements of three-dimensional positional changes of the beam end related to known loads. Vertical loads from 15.7 to 40.4 N were applied resulting in vertical positional changes of the beam end ranging from 40.8 to 225.2 μm (z-axis). The corresponding horizontal changes perpendicular to the long axis of the beam (y-axis) due to counterclockwise horizontal rotation of the beam around the abutment- and prosthetic cylinder threads varied from 7.4 to 77.4 μm. This rotation changed the position of the beam end from 11.9 to 49.3 μm along the x-axis of the coordinate system toward the supporting implant. It was possible to arrange an experimental set-up for optoelectronic 3-D measurements within such a limited measurement volume that would permit satisfactory registrations of small load-dependent deflections of the prosthetic beam and implant components. © 2010 John Wiley & Sons A/S.

  17. Experimental and numerical optical characterization of plasmonic copper nanoparticles embedded in ZnO fabricated by ion implantation and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Le, Khai Q. [Faculty of Science and Technology, Hoa Sen University, Ho Chi Minh City (Viet Nam); Department of Physics, Faculty of Science, Jazan University, P.O. Box 114, 45142 Jazan (Saudi Arabia); Nguyen, Hieu P.T. [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, NJ 07102 (United States); Ngo, Quang Minh [Institute of Material Sciences, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi (Viet Nam); Canimoglu, Adil [Nigde University, Faculty of Arts and Sciences, Physics Department, Nigde (Turkey); Can, Nurdogan, E-mail: cannurdogan@yahoo.com [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Department of Physics, Faculty of Science, Jazan University, P.O. Box 114, 45142 Jazan (Saudi Arabia)

    2016-06-05

    Here we describe the successfully fabrication of metal nanoparticle crystals by implanting copper (Cu) ions into single zinc oxide (ZnO) crystals with ion energy of 400 keV at ion doses of 1 × 10{sup 16} to 1 × 10{sup 17} ions/cm{sup 2}. After implantation and post-annealing treatment, the Cu implanted ZnO produces a broad range of luminescence emissions, ranging from green to yellow. A green luminescence peak at 550 nm could be ascribed to the isolated Cu ions. The changes in luminescence emission bands between the initial implant and annealed suggest that the implants give rise to clustering Cu nanoparticles in the host matrix but that the annealing process dissociates these. Numerical modelling of the Cu nanoparticles was employed to simulate their optical properties including the extinction cross section, electron energy loss spectroscopy and cathodoluminescence. We demonstrate that the clustering of nanoparticles generates Fano resonances corresponding to the generation of multiple resonances, while the isolation of nanoparticles results in intensity amplification. - Highlights: • We present the fabrication of metal nanoparticle crystals by implanting Cu into ZnO. • The luminescence properties were studied at different annealing temperature. • Numerical modelling of the Cu nanoparticles was employed. • We demonstrate that the clustering of nanoparticles generates Fano resonances.

  18. kgp, rgpA, and rgpB DNA vaccines induce antibody responses in experimental peri-implantitis.

    Science.gov (United States)

    Guo, Meihua; Wang, Zhifeng; Fan, Xin; Bian, Yuanyuan; Wang, Tiantian; Zhu, Lina; Lan, Jing

    2014-11-01

    Peri-implantitis is the key factor for implant failure. This study aims to evaluate kgp, rgpA, and rgpB DNA vaccines to induce an immune response and prevent peri-implantitis. The kgp, rgpA, and rgpB genes were amplified by polymerase chain reaction (PCR) from Porphyromonas gingivalis (Pg) ATCC 33277 and cloned into the pVAX1 vector. Titanium implants were placed into the mandibular bone of dogs. Three months later, the animals were divided into four groups, immunized with pVAX1-kgp, pVAX1-rgpA, pVAX1-rgpB, or pVAX1. Cotton ligatures infiltrated with Pg were tied around the neck of the implants. Immunoglobulin (Ig)G and IgA antibodies were detected by enzyme-linked immunosorbent assay before and after immunization. The kgp, rgpA, and rgpB genes were successfully cloned into the pVAX1 plasmid. Animals immunized with pVAX1-kgp and pVAX1-rgpA showed higher titers of IgG and IgA antibodies compared to those before immunization (P implantitis animal models, whereas pVAX1-rgpB was ineffective.

  19. Transcatheter implantation of self-expandable valved prosthesis in outlet right ventricle an experimental study in pigs.

    Science.gov (United States)

    Guilhen, José Cícero Stocco; Palma, José Honório; Gaia, Diego Felipe; Araujo, Andre Telis Vilela de; Teles, Carlos Alberto; Branco, João Nelson; Buffolo, Enio

    2011-01-01

    Patients with congenital heart disease who underwent pulmonary valvotomy or surgery to open the pulmonary valve ring are prone to develop residual pulmonary insufficiency or stenosis that may lead to right heart failure with clinical deterioration. These children require multiple interventions throughout their lives, which impose a high rate of morbidity and mortality. To develop a less invasive technique for implantation of a valved prosthesis through the right ventricle. The valved prosthesis consists of an auto expanding metal stent built with nitinol, surrounded with polyester, where the three leaflets of bovine pericardium were mounted. Twelve pigs were used to perform the implants. Echocardiographic control was performed immediately after implantation and one, four, eight and 12 weeks. One animal showed reflux of moderate to severe and three mild reflux. Transvalvular gradients measured before implantation ranged from 3 to 6 mmHg and that soon after the implant was increased, ranging from 7 to 45 mmHg. There was a decrease in these gradients during follow up and in only four of the twelve animals the gradients were above 20 mmHg. Thrombus formation occurred in the prosthesis of six animals, and this was the most frequent complication. These findings highlight the need for studies with the use of anticoagulants and antiplatelet, an attempt to reduce this event. The study aims to contribute for the start of the use of prosthetic heart valves that could be implanted through minimally invasive techniques without the use of cardiopulmonary bypass.

  20. Interpretation of Post-operative Distal Humerus Radiographs After Internal Fixation: Prediction of Later Loss of Fixation

    NARCIS (Netherlands)

    Claessen, Femke M. A. P.; Stoop, Nicky; Doornberg, Job N.; Guitton, Thierry G.; van den Bekerom, Michel P. J.; Ring, David; Spoor, A. B.; Chauhan, A.; Wahegaonkar, A. L.; Shafritz, A. B.; Garcia G, A. E.; Miller, A. N.; Barquet, A.; Kristan, A.; Apard, T.; Armstrong, A. D.; Berner, A.; Jubel, A.; Kreis, B. E.; Babis, C. G.; Sutker, B.; Sears, B. W.; Nolan, B. M.; Crist, B. D.; Cross, B. J.; Wills, B. P.; Barreto, C. J.; Ekholm, C.; Swigart, C.; Oliveira Miranda, C. D.; Manke, C.; Zalavras, C.; Goldfarb, C. A.; Cassidy, C.; Walsh, C. J.; Jones, C. M.; Garnavos, C.; Young, C.; Moreno-Serrano, C. L.; Lomita, C.; Klostermann, C.; van Deurzen, D. F.; Rikli, D. A.; Polatsch, D.; Beingessner, D.; Drosdowech, D.; Eygendaal, D.; Patel, M.; Brilej, D.; Walbeehm, E. T.; Ballas, E. G.; Ibrahim, E. F.; Melamed, E.; Stojkovska Pemovska, E.; Hofmeister, E.; Hammerberg, E. M.; Kaplan, F. T.; Suarez, F.; Fernandes, C. H.; Lopez-Gonzalez, F.; Walter, F. L.; Frihagen, F.; Kraan, G. A.; Kontakis, G.; Dyer, G. S.; Kohut, G.; Panagopoulos, G.; Hernandez, G. R.; Porcellini, G.; Bayne, G. J.; Merrell, G.; DeSilva, G.; Della Rocca, G. J.; Bamberger, H. B.; Broekhuyse, H.; Durchholz, H.; Kodde, I. F.; McGraw, I.; Harris, I.; Pountos, I.; Wiater, J. M.; Choueka, J.; Kazanjian, J. E.; Gillespie, J. A.; Biert, J.; Fanuele, J. C.; Johnson, J. W.; Greenberg, J. A.; Abrams, J.; Hall, J.; Fischer, J.; Scheer, J. H.; Itamura, J.; Capo, J. T.; Braman, J.; Rubio, J.; Ortiz, J. A.; Filho, J. E.; Nolla, J.; Abboud, J.; Conflitti, J. M.; Abzug, J. M.; Patiño, J. M.; Rodríguez Roiz, J. M.; Adams, J.; Bishop, J.; Kabir, K.; Chivers, K.; Prommersberger, K.; Egol, K.; Rumball, K. M.; Dickson, K.; Jeray, K.; Poelhekke, L. M.; Campinhos, L. A.; Mica, L.; Borris, L. C.; Adolfsson, L. E.; Schulte, L. M.; Elmans, L.; Lane, L. B.; Paz, L.; Taitsman, L.; Guenter, L.; Austin, L. S.; Waseem, M.; Palmer, M. J.; Abdel-Ghany, M. I.; Richard, M. J.; Rizzo, M.; Pirpiris, M.; Di Micoli, M.; Bonczar, M.; Loebenberg, M. I.; Richardson, M.; Mormino, M.; Menon, M.; Soong, M.; Wood, M. M.; Meylaerts, S. A.; Darowish, M.; Nancollas, M.; Prayson, M.; Grafe, M. W.; Kessler, M. W.; Kaminaris, M. D.; Pirela-Cruz, M. A.; McKee, M.; Merchant, M.; Tyllianakis, M.; Shafi, M.; Powell, A. J.; Shortt, N. L.; Felipe, N. E.; Parnes, N.; Bijlani, N.; Elias, N.; Akabudike, N. M.; Rossiter, N.; Lasanianos, N. G.; Kanakaris, N. K.; Brink, O.; van Eerten, P. V.; Paladini, P.; Martineau, P. A.; Appleton, P.; Levin, P.; Althausen, P.; Evans, P. J.; Jebson, P.; Krause, P.; Schandelmaier, P.; Peters, A.; Dantuluri, P.; Blazar, P.; Andreas, P.; Inna, P.; Quell, M.; Ramli, R. M.; de Bedout, R.; Ranade, A. B.; Ashish, S.; Smith, R. M.; Babst, R. H.; Omid, R.; Buckley, R.; Jenkinson, R.; Gilbert, R. S.; Page, R. S.; Papandrea, R.; Zura, R. D.; Gray, R. L.; Wagenmakers, R.; Pesantez, R.; van Riet, R.; Calfee, R. P.; van Helden, S. H.; Bouaicha, S.; Kakar, S.; Kaplan, S.; Scott, F. D.; Kaar, S. G.; Mitchell, S.; Rowinski, S.; Dodds, S.; Kennedy, S. A.; Beldner, S.; Schepers, T.; Guitton, T. G.; Gosens, T.; Baxamusa, T.; Taleb, C.; Tosounidis, T.; Wyrick, T.; Begue, T.; DeCoster, T.; Dienstknecht, T.; Varecka, T. F.; Mittlmeier, T.; Fischer, T. J.; Chesser, T.; Omara, T.; Bafus, T.; Siff, T.; Havlicek, T.; Sabesan, V. J.; Nikolaou, V. S.; Philippe, V.; Giordano, V.; Vochteloo, A. J.; Batson, W. A.; Hammert, W. C.; Satora, W.; Weil, Y.; Ruch, D.; Marsh, L.; Swiontkowski, M.; Hurwit, S.

    2016-01-01

    Purpose Stable fixation of distal humerus fracture fragments is necessary for adequate healing and maintenance of reduction. The purpose of this study was to measure the reliability and accuracy of interpretation of postoperative radiographs to predict which implants will loosen or break after

  1. Role of toll-like receptor 2 in inflammation and alveolar bone loss in experimental peri-implantitis versus periodontitis.

    Science.gov (United States)

    Yu, X; Hu, Y; Freire, M; Yu, P; Kawai, T; Han, X

    2017-09-05

    Peri-implantitis and periodontitis are different entities in immune characteristics even though they share similar features in clinical and radiologic signs. Toll-like receptor 2 (TLR-2), one of the key pathogen-recognition receptors in the innate immune system, plays an important role in the progression of periodontitis. However, the role of TLR-2 in peri-implantitis remains unclear. The objective of this study was to investigate the role of TLR-2 in inflammation and alveolar bone loss in a murine model of ligature-induced peri-implantitis and to compare it with ligature-induced periodontitis. Smooth-surface titanium implants were placed in the alveolar bone of the left maxillary molars of wild-type (WT) and Tlr2 knockout (Tlr2-KO) mice 6 weeks after tooth extraction. Silk ligatures were applied to the left implant fixtures and the right maxillary second molars to induce peri-implantitis and periodontitis 4 weeks after implant placement. Two weeks after ligation, bone loss around the implants and maxillary second molars was analysed by micro-computed tomography (micro-CT), and inflammation around the implants and maxillary second molars was assessed at the same time point using histology and TRAP staining, respectively. Expression of mRNA for proinflammatory cytokines (interleukin-1β [Il1β], tumor necrosis factor-α [Tnfα]), an anti-inflammatory cytokine (interleukin-10 [Il10]) and osteoclastogenesis-related cytokines (Rankl, osteoprotegerin [Opg]) were evaluated, in gingival tissue, using real-time quantitative PCR (RT-qPCR). The success rate of implant osseointegration was significantly higher in Tlr2-KO mice (85.71%) compared with WT mice (53.66%) (P = .0125). Micro-CT revealed significantly decreased bone loss in Tlr2-KO mice compared with WT mice (P = .0094) in peri-implantitis. The levels of mRNA for Il1β (P = .0055), Tnfα (P = .01) and Il10 (P = .0019) in gingiva were significantly elevated in the peri-implantitis tissues of WT mice, but

  2. Sub-crestal positioning of implants results in higher bony crest resorption: an experimental study in dogs.

    Science.gov (United States)

    Cesaretti, Gianfranco; Lang, Niklaus P; Salata, Luiz A; Schweikert, Michael T; Gutierrez Hernandez, Maria Elena; Botticelli, Daniele

    2015-12-01

    To compare peri-implant soft- and hard-tissue integration at implants installed juxta- or sub-crestally. Furthermore, differences in the hard and soft peri-implant tissue dimensions at sites prepared with drills or sonic instruments were to be evaluated. Three months after tooth extraction in six dogs, recipient sites were prepared in both sides of the mandible using conventional drills or a sonic device (Sonosurgery(®)). Two implants with a 1.7-mm high-polished neck were installed, one with the rough/smooth surface interface placed at the level of the buccal bony crest (control) and the second placed 1.3 mm deeper (test). After 8 weeks of non-submerged healing, biopsies were harvested and ground sections prepared for histological evaluation. The buccal distances between the abutment/fixture junction (AF) and the most coronal level of osseointegration (B) were 1.6 ± 0.6 and 2.4 ± 0.4 mm; between AF and the top of the bony crest (C), they were 1.4 ± 0.4 and 2.2 ± 0.2 mm at the test and control sites, respectively. The top of the peri-implant mucosa (PM) was located more coronally at the test (1.2 ± 0.6 mm) compared to the control sites (0.6 ± 0.5 mm). However, when the original position of the bony crest was taken into account, a higher bone loss and a more apical position of the peri-implant mucosa resulted at the test sites. The placement of implants into a sub-crestal location resulted in a higher vertical buccal bone resorption and a more apical position of the peri-implant mucosa in relation to the level of the bony crest at implant installation. Moreover, peri-implant hard-tissue dimensions were similar at sites prepared with either drills or Sonosurgery(®). © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Superelastic Orthopedic Implant Coatings

    Science.gov (United States)

    Fournier, Eric; Devaney, Robert; Palmer, Matthew; Kramer, Joshua; El Khaja, Ragheb; Fonte, Matthew

    2014-07-01

    The demand for hip and knee replacement surgery is substantial and growing. Unfortunately, most joint replacement surgeries will fail within 10-25 years, thereby requiring an arduous, painful, and expensive revision surgery. To address this issue, a novel orthopedic implant coating material ("eXalt") has been developed. eXalt is comprised of super elastic nitinol wire that is knit into a three-dimensional spacer fabric structure. eXalt expands in vivo to conform to the implantation site and is porous to allow for bone ingrowth. The safety and efficacy of eXalt were evaluated through structural analysis, mechanical testing, and a rabbit implantation model. The results demonstrate that eXalt meets or exceeds the performance of current coating technologies with reduced micromotion, improved osseointegration, and stronger implant fixation in vivo.

  4. Soft tissue dimensions in flapless immediate implants with and without immediate loading: an experimental study in the beagle dog.

    Science.gov (United States)

    Blanco, Juan; Carral, Cristina; Liñares, Antonio; Pérez, Javier; Muñoz, Fernando

    2012-01-01

    The aim of the present study was to evaluate the peri-implant soft tissue dimensions in flapless immediate implants with and without immediate loading. This study was carried out on six beagle dogs. Four implants were placed (two per side) immediately after tooth extraction (third and fourth premolars). Flapless immediate implant placement was performed in one hemimandible (control). The same procedure was performed in the contralateral side and immediate prosthesis was connected (test). After 3 months of healing, the dogs were sacrificed. None of the implants and prosthesis were lost. Barrier epithelium in the loaded group was 2.51 mm at the buccal and 2.34 mm at the lingual aspect. In the no loaded group, the results were similar, 2.54 and 2.2 mm at the buccal and lingual side, respectively. Connective tissue in the loaded group was 1.38 mm at the buccal and 0.65 mm at the lingual aspect, and in the no loaded group 1.48 mm at the buccal and 0.53 mm at the lingual side. Biological width dimensions were 3.9 mm at the buccal and 2.95 mm at the lingual aspect for the loaded group, and 4.01 and 2.64 mm at the buccal and lingual aspect for the no loaded group. The results of the present study suggested that soft tissues dimensions around immediate implants with immediate loading were similar to immediate implants without loading. © 2011 John Wiley & Sons A/S.

  5. [A new implant system for orbital prosthetic rehabilitation: "epiplating mono"].

    Science.gov (United States)

    Schneider, M; Federspil, P A; Neumann, A; Schick, B

    2014-06-01

    A New Implant System for Orbital Prosthetic Rehabilitation: "Epiplating Mono" Prosthetic or episthetic rehabilitation of ear, eye and nose are currently most common performed using magnetic fixation. While at the beginning single implants have been used, now-a-days a more extended approach with plate fixation are recommended to enhance the stability of the anchored magnets. A newly designed implant system epiplating mono is presented that combines the structure of a single implant with additional fixation elements. In a pilot study this new implant system was used in 4 patients for prosthetic orbital rehabilitation. Further experiences with this new implant system are required necessitating long-term experiences of implant stability to define the value of the presented epiplating mono system for prosthetic rehabilitation. © Georg Thieme Verlag KG Stuttgart · New York.

  6. Dimensional changes in soft tissues around dental implants following free gingival grafting: an experimental study in dogs.

    Science.gov (United States)

    Bengazi, Franco; Lang, Niklaus P; Caroprese, Marino; Urbizo Velez, Joaquin; Favero, Vittorio; Botticelli, Daniele

    2015-02-01

    To study the buccal dimensional tissue changes at oral implants following free gingival grafting, with or without including the keratin layer, performed at the time of implant installation into alveolar mucosa. The mandibular premolars and first molars were extracted bilaterally in six Beagle dogs. In the right side of the mandible (Test), flaps were first elevated, and the buccal as well as part of the lingual masticatory mucosa was removed. An incision of the periosteum at the buccal aspect was performed to allow the flap to be coronally repositioned. Primary wound closure was obtained. In the left side, the masticatory (keratinized) mucosa was left in situ, and no sutures were applied (Control). After 3 months of healing, absence of keratinized mucosa was confirmed at the test sites. Two recipient sites were prepared at each side of the mandible in the region of the third and fourth premolars. All implants were installed with the shoulder placed flush with the buccal alveolar bony crest, and abutments were connected to allow a non-submerged healing. Two free gingival mucosal grafts were harvested from the buccal region of the maxillary canines. One graft was left intact (gingival mucosal graft), while for the second, the epithelial layer was removed (gingival connective tissue graft). Subsequently, the grafts were fixed around the test implants in position of the third and fourth premolars, respectively. After 3 months, the animals were euthanized and ground sections obtained. Similar bony crest resorption and coronal extension of osseointegration were found at test and control sites. Moreover, similar dimensions of the peri-implant soft tissues were obtained at test and control sites. The increase in the alveolar mucosal thickness by means of a gingival graft affected the peri-implant marginal bone resorption and soft tissue recession around implants. This resulted in outcomes that were similar to those at implants surrounded by masticatory mucosa, indicating

  7. Healing at implant sites prepared conventionally or by means of Sonosurgery ®. An experimental study in dogs.

    Science.gov (United States)

    Viganò, Paolo; Botticelli, Daniele; Salata, Luiz A; Schweikert, Michael T; Urbizo Velez, Joaquin; Lang, Niklaus P

    2015-04-01

    To compare peri-implant tissue healing at implants installed in sites prepared with conventional drills or a sonic device. In six Beagle dogs, the mandibular premolars and first molars were extracted bilaterally. After 3 months, full-thickness muco-periosteal flaps were elevated and recipient sites were prepared in both sides of the mandible. In the right side (control), the osteotomies were prepared using conventional drills, while, at the left side (test), a sonic device (Sonosurgery(®)) was used. Two implants were installed in each side of the mandible. After 8 weeks of non-submerged healing, biopsies were harvested and ground sections prepared for histological evaluation. The time consumed for the osteotomies at the test was more than double compared to the conventional control sites. No statistically significant differences were found for any of the histological variables evaluated for hard and soft tissue dimensions. Although not statistically significant, slightly higher mineralized bone-to-implant contact was found at the test (65.4%) compared to the control (58.1) sites. Similar healing characteristics in osseointegration and marginal hard tissue remodeling resulted at implants installed into osteotomies prepared with conventional drills or with the sonic instrument (Sonosurgery(®)). © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. Effects of artificial tracheal fixation on tracheal epithelial regeneration and prevention of tracheal stenosis.

    Science.gov (United States)

    Nakaegawa, Yuta; Nakamura, Ryosuke; Tada, Yasuhiro; Suzuki, Ryo; Takezawa, Toshiaki; Nakamura, Tatsuo; Omori, Koichi

    2017-06-01

    Tight fixation of the artificial trachea is important for epithelialization and tracheal stenosis. The authors have developed an artificial trachea and have used it for tracheal reconstruction. Although various studies on tracheal reconstruction have been conducted, no studies have examined the effect of artificial tracheal fixation on tracheal stenosis and regeneration. Therefore, the purpose of the present study was to evaluate the effect of artificial tracheal fixation. Preliminary animal experiment. Artificial tracheae were implanted into rabbits with partial tracheal defects. Tracheal stenosis and regeneration of the tracheal epithelium on the artificial tracheae were evaluated by endoscopic examination, scanning electron microscopic analysis, and histological examination. The artificial tracheae fixed to the tracheal defects were classified into three groups (0-point, 4-point, and 8-point) by the number of fixation points. At 14 and 28 days post-implantation, the luminal surface of the implantation area was mostly covered with epithelium in all fixation groups. However, a small amount of granulation tissue was observed in the 0-point fixation group at 14 days post-implantation. Moreover, tracheal stenosis did not occur in the 8-point fixation group, but stenosis was detected in the other groups.

  9. Success and High Predictability of Intraorally Welded Titanium Bar in the Immediate Loading Implants

    National Research Council Canada - National Science Library

    Fogli, Vaniel; Camerini, Michele; Lauritano, Dorina; Carinci, Francesco

    2014-01-01

    .... This concept is especially true in case of implants placed in atrophic ridges. So the primary stabilization and fixation of implants are an important goal that can also allow immediate loading and oral rehabilitation on the same day of surgery...

  10. Success and high predictability of intraorally welded titanium bar in the immediate loading implants

    National Research Council Canada - National Science Library

    Fogli, Vaniel; Camerini, Michele; Lauritano, Dorina; Carinci, Francesco

    2014-01-01

    .... This concept is especially true in case of implants placed in atrophic ridges. So the primary stabilization and fixation of implants are an important goal that can also allow immediate loading and oral rehabilitation on the same day of surgery...

  11. Effect of membranes and porous hydroxyapatite on healing in bone defects around titanium dental implants. An experimental study in monkeys

    DEFF Research Database (Denmark)

    Gotfredsen, K; Warrer, K; Hjørting-Hansen

    1991-01-01

    The purpose of the present study was to examine the effect of treating bony craters around titanium dental implant with polytetrafluoroethylene membranes (PTFE), with and without grafting of hydroxyapatite (HA), and with HA alone. 4 standardized bone defects were prepared in the alveolar ridge...... of edentulous areas in each of 7 monkeys. A titanium implant was then placed centrally in each defect, and in each monkey, the defects were treated with 1 of the following 4 treatment modalities: (1) coverage with PTFE membrane; (2) grafting of HA and covering with a PTFE membrane; (3) HA grafting; (4......) no treatment. Following a healing period of 12 weeks, all animals were sacrificed and mesio-distal ground sections of the treated areas were prepared. The histological analysis showed that all bone defects around the implants treated with PTFE membranes and 5 of the defects treated with HA and PTFE membranes...

  12. Novel intramedullary-fixation technique for long bone fragility fractures using bioresorbable materials.

    Directory of Open Access Journals (Sweden)

    Takanobu Nishizuka

    Full Text Available Almost all of the currently available fracture fixation devices for metaphyseal fragility fractures are made of hard metals, which carry a high risk of implant-related complications such as implant cutout in severely osteoporotic patients. We developed a novel fracture fixation technique (intramedullary-fixation with biodegradable materials; IM-BM for severely weakened long bones using three different non-metallic biomaterials, a poly(l-lactide (PLLA woven tube, a nonwoven polyhydroxyalkanoates (PHA fiber mat, and an injectable calcium phosphate cement (CPC. The purpose of this work was to evaluate the feasibility of IM-BM with mechanical testing as well as with an animal experiment. To perform mechanical testing, we fixed two longitudinal acrylic pipes with four different methods, and used them for a three-point bending test (N = 5. The three-point bending test revealed that the average fracture energy for the IM-BM group (PLLA + CPC + PHA was 3 times greater than that of PLLA + CPC group, and 60 to 200 times greater than that of CPC + PHA group and CPC group. Using an osteoporotic rabbit distal femur incomplete fracture model, sixteen rabbits were randomly allocated into four experimental groups (IM-BM group, PLLA + CPC group, CPC group, Kirschner wire (K-wire group. No rabbit in the IM-BM group suffered fracture displacement even under full weight bearing. In contrast, two rabbits in the PLLA + CPC group, three rabbits in the CPC group, and three rabbits in the K-wire group suffered fracture displacement within the first postoperative week. The present work demonstrated that IM-BM was strong enough to reinforce and stabilize incomplete fractures with both mechanical testing and an animal experiment even in the distal thigh, where bone is exposed to the highest bending and torsional stresses in the body. IM-BM can be one treatment option for those with severe osteoporosis.

  13. Update: Biological Nitrogen Fixation.

    Science.gov (United States)

    Wiseman, Alan; And Others

    1985-01-01

    Updates knowledge on nitrogen fixation, indicating that investigation of free-living nitrogen-fixing organisms is proving useful in understanding bacterial partners and is expected to lead to development of more effective symbioses. Specific areas considered include biochemistry/genetics, synthesis control, proteins and enzymes, symbiotic systems,…

  14. Sacroiliac Screw Fixation

    NARCIS (Netherlands)

    E.W. van den Bosch

    2003-01-01

    textabstractThe aim of this thesis is to evaluate three major aspects of the use of sacroiliac screws in patients with unstable pelvic ring fractures: the optimal technique for sacroiliac screw fixation, the reliability of peroperative fluoroscopy and the late results. We focused on the questions

  15. A CHLORHEXIDINE-RELEASING EPOXY-BASED COATING ON TITANIUM IMPLANTS PREVENTS STAPHYLOCOCCUS AUREUS EXPERIMENTAL BIOMATERIAL-ASSOCIATED INFECTION

    NARCIS (Netherlands)

    Riool, M.; Dirks, A. J.; Jaspers, V.; de Boer, L.; Loontjens, T. J.; van der Loos, C. M.; Florquin, S.; Apachitei, I.; Rijk, L. N.; Keul, H. A.; Zaat, S. A.

    2017-01-01

    Prevention of biomaterial-associated infections (BAI) remains a challenging problem, in particular due to the increased risk of resistance development with the current antibiotic-based strategies. Metallic orthopaedic devices, such as non-cemented implants, are often inserted under high mechanical

  16. An experimental intraarticular implantation of woven carbon fiber pad into osteochondral defect of the femoral condyle in rabbit.

    Science.gov (United States)

    Kang, H J; Han, C D; Kang, E S; Kim, N H; Yang, W I

    1991-06-01

    The defects of the articular cartilage structure are not replaced unless the subchondral plate has been breached. However, following the creation of a defect in the subchondral plate, the area is filled in with a fibrous tissue which gradually transforms to hyaline cartilage. The porous nontoxic materials of both biologic and synthetic origin have reportedly been used as matrices for repairing bone and cartilage. Following implantation, carbon fibre, chemically inert and well-tolerated by the body, induces a proliferation of ordered fibrous tissue. We implanted carbon fiber pads in osteochondral defects in rabbits. Those repairs were compared to control holes with no implants. The pads appeared to induce the gross appearance of a restored joint surface, mechanically strong to loading for periods from 2 to 6 weeks. Also, carbon fiber pads promoted the healing of the osteochondral defects in the rabbit femoral condyle, supplying well-organized cartilagenous tissue over repaired subchondral bone. The use of carbon fiber pads as implant material is suggested for the restoration of articular surface in osteoarthritis and osteochondritis dissecans.

  17. An Experimental Study to Determine the Role of Inferior Vena Cava Filter in Preventing Bone Cement Implantation Syndrome

    OpenAIRE

    Guo; Zheng,; Li; Shi; Xiang; Wang,

    2015-01-01

    Background Inferior vena cava filters (IVCF) are frequently used for preventing pulmonary embolism (PE) following deep venous thromboembolism. Objectives The present study was designed to investigate whether IVCF could prevent or impede the occurrence of bone cement implantation syndrome (BCIS), since PE is considered as the central mechanism of BCIS. Materials and Methods Fifteen ...

  18. VENTRAL SPONDYLODESIS BYTITAN IMPLANTS AT SPINE TUMORS

    Directory of Open Access Journals (Sweden)

    A. V. Babkin

    2010-01-01

    Full Text Available At RSPC of traumatology and orthopaedic surgery and Institute of powders metallurgic porous implants are working out which allow complitely replace alio- and autotranplants and improve the surgical technology of interbody spondylodesis. Porous implants, made from mechanic durabilities, are bioinert or biocompatible materials, provide durabilities prime spondylodesis. It doesn't need an additional fixation, realize a possibility to grow a bone matter in powder structure of implants.

  19. Percutaneous implantation of an intraventricular device for the treatment of heart failure: experimental results and proof of concept.

    Science.gov (United States)

    Nikolic, Serjan D; Khairkhahan, Alex; Ryu, Miho; Champsaur, Gerard; Breznock, Eugene; Dae, Michael

    2009-11-01

    A percutaneous system to implant a ventricular partitioning device (VPD) has been developed to partition the left ventricular (LV) cavity for treating regional wall motion abnormalities associated with post-left anterior descending (LAD) infarction, dilated left ventricle, and systolic dysfunction. The hemodynamic effects of this novel approach were evaluated in an ovine model with an anteroapical infarction created by a coil placed in the LAD. LV anteroapical infarction (MI) was induced in 10 animals. The VPD device was implanted at 6 weeks after MI in 5 animals. The hemodynamic status of each animal was evaluated at 30 weeks post-MI in treated ("VPD+MI" group, n=5) and nontreated ("MI" group, n=5). The comparison of end-point hemodynamic variables shows a significantly smaller end-systolic LV volume in the animals receiving the implant (70.1+/-9.0 mL in "VPD+MI" group vs. 102.9+/-10.3 mL in "MI" group, P < .02), improved ejection fraction (46.9+/-5.2% in "VPD+MI" group vs. 34.7+/-6.8% in "MI" group, P < .04) and preserved cardiac output (5.2+/-0.7 L/min in "VPD+MI" group vs. 5.0+/-1.8 L/min in "MI" group, P=NS), suggesting more efficient mechanical performance of the LV with the implanted VPD. A significant reduction in LV volumes and corresponding improvement in LV function occurred after device implantation indicating a potential beneficial effect of this new device in treatment of post MI LV dilation.

  20. [Regeneration processes in bone defects after implantation of composite material of different density of polylactide origin filled with HAP (experimental-morphological study)].

    Science.gov (United States)

    Kulakov, A A; Grigor'ian, A S; Krotova, L I; Popov, V K; Volozhin, A I; Losev, V F

    2009-01-01

    In experimental-morphological study on 6 dogs the dynamics of regenerate formation in ulna and mandible defects after implantation in them composite material of different density (0.46-0.50 and 0.38-0.42 g/cm(3)) of polylactide (PL) origin filled with HAP was followed at the terms of 6 and 9 months. Histologic study and structural determinant distribution analysis in the content of regenerate showed that optimal results according to the bone defect substitution by bone regenerate criterion at 9th month of the experiment were received after composite material from PL and HAP with the density of 0.38-0.42 g/cm(3) implantation. Newly formed trabecular bone tissue was seen in the regenerate and as well as strong tendency for bone matrix maturation. It was confirmed by the appearance of lamellar structures in newly formed bone trabecules situated in peripheral zones of bone defect. In bone mandible defects the substitution process of the implants from PL with HAP by the bone tissue was much slower than in ulna defects.

  1. [Experimental study of transforming growth factor-β3 combined with dental pulp stem cells in promoting the implant's osseointegration].

    Science.gov (United States)

    Wang, T; Muhetaer, Huojia; Li, J

    2017-06-09

    Objective: To investigate the effect of transforming growth factor-β3 (TGF-β3) and dental pulp stem cells (DPSC) in promoting the implant's osteointegration. Methods: Thirty-three New Zealand white rabbits were randomly divided into phosphate buffer saline (PBS) group, DPSC group and TGF-β3 + DPSC group (12 rabbits/group). Two teeth from the rabbits's mandibular incisors or molars were pulled out randomly, then implant were placed in the tooth extraction site immediately. In PBS group, the implant area was filled with Bio-Oss powder 0.30 g mixed by PBS 20 μl only; while the implant area was filled with Bio-oss powder 0.30 g and 1×10(8)/L DPSC 20 μl in DPSC group; in the the TGF-β3+DPSC group the implant area was filled with Bio-Oss powder 0.30 g mixed with 1×10(8)/L DPSC 20 μl and 80 μg/L TGF-β3 20 μl. Eighteen New Zealand rabbits were executed in the 4 weeks and 8 weeks respectively. The treated alveolar bone tissue and implant were collected for plastic section. Alizarin red staining (ARS), immunohistochemical detection (IHC) of bone sialoprotein (BSP), osteocalcin (OC) and type Ⅰ collagen (COL-Ⅰ) were performed after 4 weeks and 8 weeks. Combined bone lamelta width (CBLW) and implant bone contact rate (IBCR), trabecular width (TW) and trabecular area percentage (TA) were observed by histomorphometric measurement. Results: ARS staining: 4 weeks after the operation, the TGF-β3+ DPSC group showed more red calcified nodules than the other two groups; 8 weeks after operation, the red calcified nodule was further increased. 4 weeks after the operation, the expression of BSP, OC and COL-Ⅰ was (0.35± 0.04), (0.36 ± 0.03) and (0.39 ± 0.01) respectively in TGF-β3+ DPSC group, (0.27 ± 0.02), (0.24 ± 0.01) and (0.28±0.03) respectively in DPSC group, and (0.13±0.03), (0.15±0.02) and (0.16±0.02) respectively in PBS group. Eight weeks after operation, the expression of BSP, OC and COL-Ⅰ was (0.51±0.02), (0.49±0.03) and (0.53±0.02) respectively

  2. Posterior transodontoid fixation: A new fixation (Kotil technique

    Directory of Open Access Journals (Sweden)

    Kadir Kotil

    2011-01-01

    Full Text Available Anterior odontoid screw fixation or posterior C1-2 fusion techniques are routinely used in the treatment of Type II odontoid fractures, but these techniques may be inadequate in some types of odontoid fractures. In this new technique (Kotil technique, through a posterior bilateral approach, transarticular screw fixation was performed at the non-dominant vertebral artery (VA side and posterior transodontoid fixation technique was performed at the dominant VA side. C1-2 complex fusion was aimed with unilateral transarticular fixation and odontoid fixation with posterior transodontoid screw fixation. Cervical spinal computed tomography (CT of a 40-year-old male patient involved in a motor vehicle accident revealed an anteriorly dislocated Type II oblique dens fracture, not reducible by closed traction. Before the operation, the patient was found to have a dominant right VA with Doppler ultrasound. He was operated through a posterior approach. At first, transarticular screw fixation was performed at the non-dominant (left side, and then fixation of the odontoid fracture was achieved by directing the contralateral screw (supplemental screw medially and toward the apex. Cancellous autograft was scattered for fusion without the need for structural bone graft or wiring. Postoperative cervical spinal CT of the patient revealed that stabilization was maintained with transarticular screw fixation and reduction and fixation of the odontoid process was achieved completely by posterior transodontoid screw fixation. The patient is at the sixth month of follow-up and complete fusion has developed. With this new surgical technique, C1-2 fusion is maintained with transarticular screw fixation and odontoid process is fixed by concomitant contralateral posterior transodontoid screw (supplemental screw fixation; thus, this technique both stabilizes the C1-2 complex and fixes the odontoid process and the corpus in atypical odontoid fractures, appearing as an

  3. A mechanical evaluation of implants placed with different surgical techniques into the trabecular bone of goats.

    NARCIS (Netherlands)

    Shalabi, M.M.; Wolke, J.G.C.; Ruijter, A.J. de; Jansen, J.A.

    2007-01-01

    The aim of the study was to assess the effects of surgical technique and implant surface roughness on implant fixation. A total of 48 screw implants with machined or etched surface topographies were placed into the femoral condyles of goats. The implant sites were prepared by a conventional

  4. Consensus report - reconstructions on implants. The Third EAO Consensus Conference 2012

    DEFF Research Database (Denmark)

    Gotfredsen, Klaus; Wiskott, Anselm

    2012-01-01

    This group was assigned the task to review the current knowledge in the areas of implant connections to abutments/reconstructions, fixation methods (cement vs. screw retained) for implant-supported reconstructions, as well as the optimal number of implants for fixed dental prosthesis and implant...

  5. Light microscopic identification and semiquantification of polyethylene particles in methylmethacrylate and paraffin-embedded experimental bone implant specimens

    DEFF Research Database (Denmark)

    Rahbek, O; Kold, S; Overgaard, S

    2005-01-01

    The aim of this study was to evaluate the identification of polyethylene (PE) particles in relatively thick methylmethacrylate (MMA) sections widely used in bone implant research. The sensitivity and specificity were compared between decalcified paraffin-embedded oil red O (ORO) stained and MMA......-embedded sections using polarized light. Furthermore, we introduced a grading system to semiquantify the level of PE particles in peri-implant tissue. Paraffin-embedded and MMA-embedded sections were compared concerning intra-observer agreement of the grading system. Moreover, the semiquantitative assessment...... of particle level was compared between the two section types. We found a sensitivity and specificity of polarized light of 100% for both paraffin ORO-stained and MMA sections. The intra-observer agreement on both types was comparable and acceptable. The ratings of differently processed blocks (MMA...

  6. On guided bone reformation in the maxillary sinus to enable placement and integration of endosseous implants. Clinical and experimental studies.

    OpenAIRE

    Cricchio, Giovanni

    2011-01-01

    Dental caries and periodontal disease are the major causes for tooth loss. While dental caries commonly involve the posterior teeth in both jaws, the teeth most commonly lost due to periodontal problems are the first and second molars in the maxilla. As a consequence, the upper posterior jaw is frequently edentulous. Implant therapy today is a predictable treatment modality for prosthetic reconstruction of edentulous patient. Insufficient amounts of bone, due to atrophy following loss of teet...

  7. Comparative experimental re-evaluation of the two implanting methods of silicone gel testicular prostheses in beagle dogs

    OpenAIRE

    Chen Peng; Hao Tong-li

    2011-01-01

    Abstract Background Testicular prosthesis has been applied clinically for decades, and implantation of testis prosthesis under the tunica albuginea has been considered to be the standard method in the most of the reports. However, postoperative scrotal appearance, the mobilization and the palpitation of the prosthesis are not always satisfactory to all the patients. Modifications in surgical techniques might be necessary to bring improvements to the clinical outcomes in testicular prosthesis ...

  8. Influence of immediate loading on healing of implants installed with different insertion torques--an experimental study in dogs.

    Science.gov (United States)

    Rea, Massimiliano; Botticelli, Daniele; Ricci, Sara; Soldini, Claudio; González, Gladys González; Lang, Niklaus P

    2015-01-01

    To evaluate the influence of different insertion torques on healing of implants loaded immediately or left unloaded. In six Labrador dogs, all mandibular premolars and molars were extracted. After 4 months of healing, flaps were elevated, and two implant sites were prepared at each side of the mandible. The distal sites were prepared conventionally while the mesial sites were underprepared by 0.3 mm. As a consequence, different final insertion torques of about 30 Ncm at the distal and >70 Ncm at the mesial sites were recorded. Healing abutments were applied to the left and transmucosal abutments to the right side. Flaps were sutured, crown preparation of the upper right second and third premolars was performed, and impressions were taken. Within 24 h, crowns were cemented both to implants and teeth in the right side of the mouth. After 4 months, the animals were sacrificed and ground sections obtained for histological evaluation. A higher buccal bony crestal resorption and a more apical position of the coronal level of osseointegration were found at the loaded compared with the unloaded sites. MBIC% and percentages of peri-implant mineralized tissue (MB%) were higher at the loaded compared with the unloaded sites. Moreover, a higher MBIC% was found at the lower compared with the higher final insertion torque. Immediate loading does not seem to have a negative effect on osseointegration. High torque values for the immediate loading procedures were not necessary. Probably, low torque values, were sufficient to obtain primary stability and hence may provide better osseointegration than high torque value. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Bone Ceramic® at Implants Installed Immediately into Extraction Sockets in the Molar Region: An Experimental Study in Dogs.

    Science.gov (United States)

    Pereira, Flávia Priscila; Hochuli-Vieira, Eduardo; Maté Sánchez de Val, José E; De Santis, Enzo; Salata, Luiz Antonio; Botticelli, Daniele

    2016-04-01

    The aim of this paper was to study the healing of 1-1.4 mm wide buccal defects at implants placed immediately into extraction sockets (IPIES) filled with a mixture of synthetic hydroxyapatite (HA) 60% and beta-tricalciumphosphate (TCP) 40% or left with the clot alone and both covered with collagen membranes. Eight Labrador dogs were used and implants were placed immediately into the extraction sockets of the first molar bilaterally. A mixture of synthetic HA 60% and beta-TCP 40% at the test or the clot alone at the control sites were used to fill the defects. All surgical sites were subsequently covered by a resorbable collagen membrane and a non-submerged healing was allowed. After 4 months, the animals were euthanized, biopsies harvested and processed for histomorphometric analysis. At the time of installation, residual buccal defects occurred that were 1.1 mm and 1.4 mm wide and 3 mm and 4 mm deep at the control and test sites, respectively. After 4 months of healing, the top of the bony crest and the coronal level of osseointegration were located respectively at 0.1 ± 1.8 mm and 1.5 ± 1.8 mm at the test, and 0.6 ± 1.6 mm and 1.2 ± 0.7 mm at the control sites apically to the implant shoulder. Bone-to-implant contact at the buccal aspect was 34.9 ± 25.9% and 36.4 ± 17.3% at the test and control sites, respectively. No statistically significant differences were found between test and control sites for any of the variables analyzed at the buccal aspects. The use of a mixture of synthetic HA 60% and beta-TCP 40% to fill residual buccal defects 1-1.4 mm wide at IPIES did not improve significantly the results of healing. © 2015 Wiley Periodicals, Inc.

  10. Estudo experimental da influência da altura do enxerto ósseo intersomático na estabilidade da fixação monossegmentar anterior da coluna cervical Experimental study of the impact of intersomatic bone graft height on the stability of anterior monosegmental fixation of the cervical spine

    Directory of Open Access Journals (Sweden)

    Jorge Alfredo Léo

    2008-06-01

    Full Text Available OBJETIVO: Estudar experimentalmente a influência da altura do enxerto ósseo intersomático da coluna cervical na estabilidade mecânica da fixação cervical anterior. MÉTODOS: Foram realizados ensaios mecânicos utilizando a coluna cervical de suínos (C3-C4. Foram formados três grupos experimentais compostos por 20 segmentos da coluna cervical (C3-C4, de acordo com o grau de instabilidade produzido e a fixação do segmento vertebral. Grupo I: retirada do disco intervertebral e colocação de enxerto intersomático. Grupo II: retirada do disco intervertebral, colocação de enxerto intersomático e fixação anterior com placa. Grupo III: retirada do disco intervertebral, secção dos ligamentos posteriores e cápsulas articulares bilateralmente, colocação do enxerto intersomático e fixação anterior com placa. Cada grupo experimental foi dividido em dois subgrupos, de acordo com a altura do enxerto ósseo utilizado (3,0mm ou 6,0mm. Os segmentos vertebrais foram submetidos a ensaios mecânicos de flexão, flexão lateral e torção em máquina universal de ensaio. Os parâmetros analisados foram força máxima (N e o momento (Nm para produzir uma deflexão preestabelecida. RESULTADOS: Não foi observada em todos os grupos experimentais diferença estatística dos valores da força máxima (N e do momento (Nm, entre as diferentes alturas (3,0mm e 6,0mm do enxerto ósseo intersomático. Conclusões: A estabilidade mecânica imediata da artrodese cervical monossegmentar anterior não sofreu influência da altura do enxerto ósseo intersomático nos ensaios de flexão, flexão lateral e torção.OBJECTIVE: To perform an experimental study of the impact of intersomatic bone graft height of the cervical spine on the mechanical stability of anterior cervical fixation. METHODS: Mechanical assays were performed using swine cervical spine (C3-C4. Three experimental groups were formed with 20 cervical spine segments (C3-C4 according to the degree

  11. Biomechanical evaluation of three fixation modalities for preperitoneal inguinal hernia repair: a 24-hour postoperative study in pigs

    Directory of Open Access Journals (Sweden)

    Guérin G

    2014-12-01

    Full Text Available Gaëtan Guérin, Xavier Bourges, Frédéric Turquier Covidien-Surgical Solutions, Research and Development, Trévoux, France Purpose: Tacks and sutures ensure a strong fixation of meshes, but they can be associated with pain and discomfort. Less invasive methods are now available. Three fixation modalities were compared: the ProGrip™ laparoscopic self-fixating mesh; the fibrin glue Tisseel™ with Bard™ Soft Mesh; and the SorbaFix™ absorbable fixation system with Bard™ Soft Mesh. Materials and methods: Meshes (6 cm ×6 cm were implanted in the preperitoneal space of swine. Samples were explanted 24 hours after surgery. Centered defects were created, and samples (either ten or eleven per fixation type were loaded in a pressure chamber. For each sample, the pressure, the mesh displacement through the defect, and the measurements of the contact area were recorded. Results: At all pressures tested, the ProGrip™ laparoscopic self-fixating mesh both exhibited a significantly lower displacement through the defect and retained a significantly higher percentage of its initial contact area than either the Bard™ Soft Mesh with Tisseel™ system or the Bard™ Soft Mesh with SorbaFix™ absorbable fixation system. Dislocations occurred with the Bard™ Soft Mesh with Tisseel™ system and with the Bard™ Soft Mesh with SorbaFix™ absorbable fixation system at physiological pressure (<225 mmHg. No dislocation was recorded for the ProGrip™ laparoscopic self-fixating mesh. Conclusion: At 24 hours after implantation, the mechanical fixation of the ProGrip™ laparoscopic self-fixating mesh was found to be significantly better than the fixation of the Tisseel™ system or the SorbaFix™ absorbable fixation system. Keywords: hernia, mesh, fixation, ProGrip™ laparoscopic self-fixating mesh

  12. Chronic implantation of newly developed suprachoroidal-transretinal stimulation prosthesis in dogs.

    Science.gov (United States)

    Morimoto, Takeshi; Kamei, Motohiro; Nishida, Kentaro; Sakaguchi, Hirokazu; Kanda, Hiroyuki; Ikuno, Yasushi; Kishima, Haruhiko; Maruo, Tomoyuki; Konoma, Kunihiko; Ozawa, Motoki; Nishida, Kohji; Fujikado, Takashi

    2011-08-29

    To investigate the feasibility of implanting a newly developed suprachoroidal-transretinal stimulation (STS) prosthesis in dogs and to determine its biocompatibility and stability over a 3-month period. The STS prosthesis system consisted of an array of 49 electrodes (nine were active), an intravitreal return electrode, and an extraocular microstimulator. The 49-electrode array was implanted into a scleral pocket of each of three healthy beagle dogs. Color fundus photography, fluorescein angiography, electroretinography, and functional testing of the STS system were performed postoperatively. The dogs were euthanatized 3 months after the implantation, and the retinas were evaluated histologically. All the prostheses were successfully implanted without complications, and no serious complications occurred during the 3-month postoperative period. The fixation of the implant was stable throughout the experimental period. Fluorescein angiography showed that the entire retina, including the area on the electrode array, remained well perfused without intraocular inflammation. Electroretinograms recorded from the eyes with the prosthesis did not differ significantly from those recorded from control eyes. Functional testing of the STS system showed that this system performed well for the 3-month experimental period. Histologic evaluations showed good preservation of the retina over the electrode array. Implantation of a newly developed STS retinal prosthesis into a scleral pocket of beagle dogs is surgically feasible and can be performed without significant damage to the retina or the animal. The biocompatibility and stability of the system were good for the 3-month observation period.

  13. Modulation of Abnormal Metabolic Brain Networks by Experimental Therapies in a Nonhuman Primate Model of Parkinson Disease: An Application to Human Retinal Pigment Epithelial Cell Implantation.

    Science.gov (United States)

    Peng, Shichun; Ma, Yilong; Flores, Joseph; Cornfeldt, Michael; Mitrovic, Branka; Eidelberg, David; Doudet, Doris J

    2016-10-01

    Abnormal covariance pattern of regional metabolism associated with Parkinson disease (PD) is modulated by dopaminergic pharmacotherapy. Using high-resolution (18)F-FDG PET and network analysis, we previously derived and validated a parkinsonism-related metabolic pattern (PRP) in nonhuman primate models of PD. It is currently not known whether this network is modulated by experimental therapeutics. In this study, we examined changes in network activity by striatal implantation of human levodopa-producing retinal pigment epithelial (hRPE) cells in parkinsonian macaques and evaluated the reproducibility of network activity in a small test-retest study. (18)F-FDG PET scans were acquired in 8 healthy macaques and 8 macaques with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced bilateral nigrostriatal dopaminergic lesions after unilateral putaminal implantation of hRPE cells or sham surgery. PRP activity was measured prospectively in all animals and in a subset of test-retest animals using a network quantification approach. Network activity and regional metabolic values were compared on a hemispheric basis between animal groups and treatment conditions. All individual macaques showed clinical improvement after hRPE cell implantation compared with the sham surgery. PRP activity was elevated in the untreated MPTP hemispheres relative to those of the normal controls (P therapy and other symptomatic interventions. With further validation in large samples, (18)F-FDG PET imaging with network analysis may provide a viable biomarker for assessing treatment response in animal models of PD after experimental therapies. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  14. Removal of internal fixation--the effect on patients' complaints: a study of 66 cases of removal of internal fixation after malleolar fractures

    DEFF Research Database (Denmark)

    Jacobsen, S; Honnens de Lichtenberg, M; Jensen, C M

    1994-01-01

    To estimate the effect of removal of internal fixation after treatment of malleolar fractures on postoperatively presented complaints, we retrospectively evaluated 66 patients by their records and by personal questionnaires. Of all the patients, 89.4% had one or more complaints. These were...... typically soreness over implant and cicatrix, reduced movement of the ankle joint, and strain-related pain. About 75% of these patients reported improvement after removal. The AO mode of fixation, i.e., typically by lateral semitubular plating and transsyndesmotic screw and a medial screw or pins...... period. We conclude that removal of internal fixation after malleolar fractures is indicated when common types of complaints are presented....

  15. [Improvement of Hoffmann external fixation apparatus].

    Science.gov (United States)

    Niimura, T

    1984-05-01

    The resurgence of external fixators for the management of skeletal and joint injuries has generated an increasing number of reports. In addition, many types of fixators have been developed in the last ten years. Of these, the Hoffmann external fixator is the most popular one. Is it possible for the patient with a tibial comminuted fracture to walk with the fixator? This study has been pursued to investigate this question and to improve on the fixator. Bone models were made from tubed polyester resin strengthened by glass fiber (elastic module: 9.46 kg/mm2, outside diameter: 35 mm, inside diameter: 30 mm). Each bone model was transfixed by two Steinmann pins (phi: 4.5 mm) with 43 mm between, and a pair of models was framed with two straight bars, with 30 mm from model to bar. The Steinmann pins and straight bars were connected to each attachment. The experiment focused on four main studies: Measurement of the Young's modulus of the Steinmann pin. Compression load test and bending load test framed bone models with each attachment. Observation and measurement of the ground reaction force of ambulation on stilt framed with experimental external fixator. Determination of S-N curve of the Steinmann pin. Results were as follows: The Young's modulus of the Steinmann pin were 1.8 X 10(4) kg/mm2. 0.2% proof of the pin was 110 kg/mm2. The bone models framed with the conventional method were destructed at the universal ball joint at 68 kgf in the compression load test, and 6.8 kgf in the bending load test. The models framed with the conventional method fitted with spring washers at ball joints were not destructed until 203 kgf in compression load, but after several trials the spring washers were crushed. The models fabricated by using a vice with rods and articulation coupling were not damaged until 210 kgf in compression load and were not damaged until 15 kgf in bending load even after several trials. The displacement between the models were 2.8 mm at 80 kgf and 8.5 mm at 210

  16. The Impact of Force Transmission on Narrow-Body Dental Implants Made of Commercially Pure Titanium and Titanium Zirconia Alloy with a Conical Implant-Abutment Connection: An Experimental Pilot Study.

    Science.gov (United States)

    Nelson, Katja; Schmelzeisen, Rainer; Taylor, Thomas D; Zabler, Simon; Wiest, Wolfram; Fretwurst, Tobias

    2016-01-01

    The purpose of this study was to visualize the mode and impact of force transmission in narrowdiameter implants with different implant-abutment designs and material properties and to quantify the displacement of the abutment. Narrow-diameter implants from two manufacturers were examined: Astra 3.0-mm-diameter implants (Astra OsseoSpeed TX; n = 2) and Straumann Bone Level implants with a 3.3-mm diameter made of commercially pure titanium (cpTi) Gr. 4 (n = 2) and 3.3-mm TiZr-alloy (n = 2; Bone Level, Straumann) under incremental force application using synchrotron radiography (absorption and inline x-ray phase-contrast) and tomography. During loading (250 N), Astra 3.0 and Bone Level 3.3- mm implants showed a deformation of the outer implant shoulder of 61.75 to 95 μm independent of the implant body material; the inner implant diameter showed a deformation of 71.25 to 109.25 μm. A deformation of the implant shoulder persisted after the removal of the load (range, 42.75 to 104.5 μm). An angulated intrusion of the abutment (maximum, 140 μm) into the implant body during load application was demonstrated; this spatial displacement persisted after removal of the load. This study demonstrated a deformation of the implant shoulder and displacement of the abutment during load application in narrow-diameter implants.

  17. Comparison and evaluation of experimental mediastinitis models: precolonized foreign body implants and bacterial suspension inoculation seems promising

    Directory of Open Access Journals (Sweden)

    Kose Necmi

    2006-04-01

    Full Text Available Abstract Background Post-sternotomy mediastinitis (PSM is a devastating surgical complication affecting 1–3% of patients that undergo cardiac surgery. Staphylococcus aureus is one of the most commonly encountered bacterial pathogen cultured from mediastinal samples obtained from patients with PSM. A component of the membrane of the gram positive bacteria, lipoteichoic acid, stimulates the blood monocytes and macrophages to secrete cytokines, radicals and nitrogen species leading to oxido-inflammatory damage. This seems to be responsible for the high mortality rate in PSM. For the evaluation of the pathogenesis of infection or for the investigation of alternative treatment models in infection, no standard model of mediastinitis seems to be available. In this study, we evaluated four mediastinitis models in rats. Methods The rats were divided into four groups to form different infection models. Group A: A suspension of 1 × 107 colony-forming units Staphylococcus aureus in 0,5 mL was inoculated from the right second intercostal space into the mediastinum. Group B: A hole was created in the right second intercostal space and a piece of stainless-steel implant with a length of 0.5 cm was inserted into the mediastinum and a suspension of 1 × 107 cfu bacteria in 0,5 mL was administered via the tail vein. Group C: Precolonized stainless-steel implant was inserted into the mediastinum. Group D: Precolonized stainless-steel implant was inserted into the mediastinum and the bacteria suspension was also injected into the mediastinum. On the 10th day, rats were sacrificed and the extension of infection in the mediastenae was evaluated by quantitative cultures. Myeloperoxidase activity (MPO and malondialdehyde (MDA levels were determined in the sera to evaluate the neutrophil activation and assess the inflammatory oxidation. Results The degree of infection in group C and D were 83.3% and 100% respectively (P P Conclusion Infected implants and high

  18. Sequential Healing at Calcium- versus Calcium Phosphate-Modified Titanium Implant Surfaces: An Experimental Study in Dogs.

    Science.gov (United States)

    Favero, Riccardo; Botticelli, Daniele; Antunes, Antonio A; Martinez Sanchez, Roxanna; Caroprese, Marino; Salata, Luiz A

    2016-04-01

    The aim of this paper was to study the sequential healing of bone tissues at implants with different configuration and different modified surfaces. Twelve Beagle dogs were used. Extractions of all teeth from the second premolar to the first molar were performed in both sides of the mandible. After 3 months, full-thickness flaps were elevated and two implants of different systems and with different surfaces were randomly installed in the premolar region in one side of the mandible. One surface was acid etched and further modified with calcium ions (BTI unicCa®), the other was sandblasted and acid etched plus a nanometer calcium phosphate deposition (3i T3®). The flaps were sutured to allow a fully submerged healing. The surgery on the other side of the mandible and the sacrifices were planned in such a way to obtain biopsies representing the healing after 1, 2, 4, and 8 weeks (n = 6 per period). After 1 and 2 weeks of healing, the mean values of new bone apposition on the implant surfaces were 5.9 ± 3.3% and 29.8 ± 16.0% at BTI unicCa and 4.6 ± 3.3% and 12.4 ± 5.6% at 3i T3, respectively. After 4 and 8 weeks, the percentage increased, being 49.4 ± 8.1% and 63.6 ± 7.3% at BTI unicCa and 40.3 ± 10.0% and 47.3 ± 20.2 at 3i T3, respectively. Differences statistically significant between the two surfaces were found only at the 2- and 4-week observation periods. Concomitantly, the old bone was resorbed at both surfaces from about 15-17% after 1 week to about 4-6% after 8 weeks of healing. Moderately rough surfaces modified with calcium ions or discrete calcium phosphate nanocrystalline deposition showed similar patterns of sequential healing. Higher new bone percentages were found at BTI unicCa compared with the 3i T3 implants, the difference being statistically significant at 2 and 4 weeks observation. © 2015 Wiley Periodicals, Inc.

  19. In vivo monitoring of bone-implant bond strength by microCT and finite element modelling.

    Science.gov (United States)

    Stadelmann, Vincent A; Conway, Carl M; Boyd, Steven K

    2013-01-01

    Immediately after implantation, a dynamic process of bone formation and resorption takes place around an orthopaedic implant, influencing its mechanical fixation. The delay until complete fixation depends on local bone architecture and metabolism. Despite its importance, the temporal pattern of implant fixation is still unknown. The optimal duration of post-operative care is therefore difficult to establish for an individual situation, and a method to evaluate non-invasively the evolution of the mechanical stability would be a significant asset in a clinical environment. The aim of this study was to evaluate the potential of micro-finite element modelling based on in vivo micro-computed tomography to monitor longitudinally the contact between bone and implant and the implant strength in vivo. The model was first validated for screw pull-out in synthetic bone surrogate. Correlation coefficients of R(2) = 0.94 and 0.85 (p < 0.01) were measured between experimental and numerical results for stiffness and failure loads, respectively. Then, the mechanical integration of screws in the proximal tibia of 12 rats was monitored at seven time points over a period of 1 month. We observed significant increases (p < 0.05) of bone-screw contact (+28%), stiffness (+93%) and failure load (+71%) over the course of the experiment, and more than 75% of these changes occurred during the first 2 weeks. Limitations, such as image artefacts and radiation, still compromise the immediate clinical application of this method, but it has a promising potential in preclinical animal studies, as it provides very valuable data about the dynamic aspect of implant integration with considerably reduced animal resources.

  20. Gamma and other cephalocondylic intramedullary nails versus extramedullary implants for extracapsular hip fractures in adults.

    Science.gov (United States)

    Parker, Martyn J; Handoll, Helen H G

    2008-07-16

    . Single trials compared the Targon PF nail versus SHS (60 participants); experimental mini-invasive static intramedullary nail versus SHS (60 participants); Kuntscher-Y nail versus SHS (230 participants); Gamma nail versus Medoff sliding plate (217 participants); and PFN versus Medoff sliding plate (203 participants). These trials provided insufficient evidence to establish differences between these implants. Two trials (65 participants with reverse and transverse fractures at the level of the lesser trochanter) found intramedullary nails (Gamma nail or PFN) were associated with better intra-operative results and fewer fracture fixation complications than extramedullary implants (a 90-degree blade plate or dynamic condylar screw) for these fractures. Given the lower complication rate of the SHS in comparison with intramedullary nails, SHS appears superior for trochanteric fractures. Further studies are required to determine if different types of intramedullary nail produce similar results, or if intramedullary nails have advantages for selected fracture types (for example, subtrochanteric fractures).

  1. Scleral Fixation of Intraocular Lens with Ab Interno Technique.

    Science.gov (United States)

    Gurung, N K; Rijal, R; Thapa, B B; Gurung, S

    2017-01-01

    Implantation of scleral fixation intraocular lens for the surgical management of aphakia cases without capsular support is a safe procedure. Prospective study was carried out at Lumbini Eye Institute, Bhairahawa. A total of 32 patients underwent scleral fixation intraocular lens implantation within a period of two years from February 2014 to February 2016. The age range was from 15 to 79 years; mean age was 47.56 ± 20.16 SD. Among them 14 (43.75%) were male and 18 (56.25%) were female. The follow-up lasted for 24 months. SFIOL for the surgical management of aphakia in the absence of capsular support is a safe procedure. The long-term follow-up is needed for an accurate evaluation of outcomes.

  2. A Novel Shape Memory Plate Osteosynthesis for Noninvasive Modulation of Fixation Stiffness in a Rabbit Tibia Osteotomy Model

    Directory of Open Access Journals (Sweden)

    Christian W. Müller

    2015-01-01

    Full Text Available Nickel-titanium shape memory alloy (NiTi-SMA implants might allow modulating fracture healing, changing their stiffness through alteration of both elastic modulus and cross-sectional shape by employing the shape memory effect (SME. Hypotheses: a novel NiTi-SMA plate stabilizes tibia osteotomies in rabbits. After noninvasive electromagnetic induction heating the alloy exhibits the SME and the plate changes towards higher stiffness (inverse dynamization resulting in increased fixation stiffness and equal or better bony healing. In 14 rabbits, 1.0 mm tibia osteotomies were fixed with our experimental plate. Animals were randomised for control or induction heating at three weeks postoperatively. Repetitive X-ray imaging and in vivo measurements of bending stiffness were performed. After sacrifice at 8 weeks, macroscopic evaluation, µCT, and post mortem bending tests of the tibiae were carried out. One death and one early implant dislocation occurred. Following electromagnetic induction heating, radiographic and macroscopic changes of the implant proved successful SME activation. All osteotomies healed. In the treatment group, bending stiffness increased over time. Differences between groups were not significant. In conclusion, we demonstrated successful healing of rabbit tibia osteotomies using our novel NiTi-SMA plate. We demonstrated shape-changing SME in-vivo through transcutaneous electromagnetic induction heating. Thus, future orthopaedic implants could be modified without additional surgery.

  3. A Novel Shape Memory Plate Osteosynthesis for Noninvasive Modulation of Fixation Stiffness in a Rabbit Tibia Osteotomy Model.

    Science.gov (United States)

    Müller, Christian W; Pfeifer, Ronny; Meier, Karen; Decker, Sebastian; Reifenrath, Janin; Gösling, Thomas; Wesling, Volker; Krettek, Christian; Hurschler, Christof; Krämer, Manuel

    2015-01-01

    Nickel-titanium shape memory alloy (NiTi-SMA) implants might allow modulating fracture healing, changing their stiffness through alteration of both elastic modulus and cross-sectional shape by employing the shape memory effect (SME). a novel NiTi-SMA plate stabilizes tibia osteotomies in rabbits. After noninvasive electromagnetic induction heating the alloy exhibits the SME and the plate changes towards higher stiffness (inverse dynamization) resulting in increased fixation stiffness and equal or better bony healing. In 14 rabbits, 1.0 mm tibia osteotomies were fixed with our experimental plate. Animals were randomised for control or induction heating at three weeks postoperatively. Repetitive X-ray imaging and in vivo measurements of bending stiffness were performed. After sacrifice at 8 weeks, macroscopic evaluation, µCT, and post mortem bending tests of the tibiae were carried out. One death and one early implant dislocation occurred. Following electromagnetic induction heating, radiographic and macroscopic changes of the implant proved successful SME activation. All osteotomies healed. In the treatment group, bending stiffness increased over time. Differences between groups were not significant. In conclusion, we demonstrated successful healing of rabbit tibia osteotomies using our novel NiTi-SMA plate. We demonstrated shape-changing SME in-vivo through transcutaneous electromagnetic induction heating. Thus, future orthopaedic implants could be modified without additional surgery.

  4. Hydroxyapatite-lignin composite as a metallic implant-bone tissue osseointegration improver: experimental study in dogs

    Directory of Open Access Journals (Sweden)

    Fabrício Luciani Valente

    2015-01-01

    Full Text Available The study aimed to evaluate biocompatibility, osteoconduction and osseointegration of a pasty composite of hydroxyapatite (20% and lignin (80% as a promoter of metal implant and bone tissue integration. An intramedullary Schanz pin was implanted in both tibias of fifteen bitches. In the left tibia, the pin was coated with the biomaterial at the time of surgery. Marrow cavity was also filled with the biomaterial. Right limb did not receive the biomaterial, then constituting the control group. Tibias were harvested from five animals at 8, 60 and 150 days after surgery; three of them were analyzed by histological and biomechanical assessment and the two remaining tibias by X-ray diffraction. Results showed that the biomaterial is biocompatible, with osteoconductivity and osseointegration properties. Histological analysis and diffractograms showed the presence of hydroxyapatite in samples in all periods, although the presence of organic material of low crystallinity was variable. There was no statistical difference in the forces required for removal of the biocompatibility, osteoconductivity and osseointegration, it was not able to promote a better intramedullary pin anchorage.

  5. Comparative study of bridge plate associated to the intramedullary pin and the dynamic compression plate on the experimental osteotomy fixation of femoral in rabbits (Oryctolagus cuniculus). Clinical, radiographic, histological and scintigraphy analyses; Estudo comparativo da placa em ponte associada ao pino intramedular e da placa de compressao dinamica na fixacao de osteotomia experimental em femur de coelhos (Oryctolagus cuniculus). Analises clinica, radiografica, histologica e cintilografica

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Natalie Ferreira

    2011-07-01

    The objectives were to benchmark and monitor the fracture healing of femoral osteotomy in rabbits after fixation with dynamic compression plate and bridge plate associated with intramedullary pin. Were used 14 New Zealand rabbits, four months old with mean weight of 3.5 pounds, from the Experimental Farm Professor Helio Barbosa of the Veterinary School of Minas Gerais Federal Univ. (UFMG). The animals were randomly divided into two groups (I and II). All rabbits underwent osteotomy across the middle third of right femur. In the group I was made to fix the osteotomy with the bridge plate (BP) associated with intramedullary pin, introduced the technique of minimal invasion. In group II, we used dynamic compression plate (DCP) via the conventional approach. Both groups were evaluated clinical, radiographic, histologic and scintigraphic findings. Clinical assessments were performed weekly until the 12{sup th} postoperative week and radiographic examinations were performed before, immediately after, at 15, 30, 45, 60 and 90 days. The bone scintigraphy were performed before and at 20, 50 and 90 days after surgery to monitor the bone metabolism qualitatively and quantitatively. Observed perfusion and bone healing process. After 90 days of study, there was histopathologic evaluation of the osteotomized area and the insertion of screws. In the region of the osteotomy was observed predominance of trabecular bone in group I and group II, the predominance of bone osteons, compatible with the original bone. On insertion of the screws did not differ between groups and there was cortical discontinuity, little necrosis and local hemorrhage. The two types of fixation have led to consolidation within the scheduled period, maturing in early fixation with DCP fixation compared with BP. Scintigraphy demonstrated by the indices of activity and image characteristics, the process of bone healing was significantly greater in animals undergoing early fixation with DCP. (author)

  6. A physiological perspective on fixational eye movements

    Science.gov (United States)

    Snodderly, D. Max

    2014-01-01

    For a behavioral neuroscientist, fixational eye movements are a double-edged sword. On one edge, they make control of visual stimuli difficult, but on the other edge they provide insight into the ways the visual system acquires information from the environment. We have studied macaque monkeys as models for human visual systems. Fixational eye movements of monkeys are similar to those of humans but they are more often vertically biased and spatially more dispersed. Eye movements scatter stimuli from their intended retinal locations, increase variability of neuronal responses, inflate estimates of receptive field size, and decrease measures of response amplitude. They also bias against successful stimulation of extremely selective cells. Compensating for eye movements reduced these errors and revealed a fine-grained motion pathway from V1 feeding the cortical ventral stream. Compensation is a useful tool for the experimenter, but rather than compensating for eye movements, the brain utilizes them as part of its input. The saccades and drifts that occur during fixation selectively activate different types of V1 neurons. Cells that prefer slower speeds respond during the drift periods with maintained discharges and tend to have smaller receptive fields that are selective for sign of contrast. They are well suited to code small details of the image and to enable our fine detailed vision. Cells that prefer higher speeds fire transient bursts of spikes when the receptive field leaves, crosses, or lands on a stimulus, but only the most transient ones (about one-third of our sample) failed to respond during drifts. Voluntary and fixational saccades had very similar effects, including the presence of a biphasic extraretinal modulation that interacted with stimulus-driven responses. Saccades evoke synchronous bursts that can enhance visibility but these bursts may also participate in the visual masking that contributes to saccadic suppression. Study of the small eye movements

  7. Management of open fractures using a noncontact locking plate as an internal fixator

    Directory of Open Access Journals (Sweden)

    Azad Yildirim

    2017-01-01

    Conclusions: This case series demonstrates that an “internal fixator technique” is an acceptable alternative to the management of open fractures of the femur or tibia in adult patients. The NC-LP method provided opportunities to achieve a stable fixation with noncontact between the implant and the bone tissues, and the fractures were sufficiently stabilized to allow union with a low complication rate.

  8. An Experimental Study to Determine the Role of Inferior Vena Cava Filter in Preventing Bone Cement Implantation Syndrome.

    Science.gov (United States)

    Guo, Wangang; Zheng, Qiangsun; Li, Bingling; Shi, Xiaoqin; Xiang, Dingcheng; Wang, Chen

    2015-07-01

    Inferior vena cava filters (IVCF) are frequently used for preventing pulmonary embolism (PE) following deep venous thromboembolism. The present study was designed to investigate whether IVCF could prevent or impede the occurrence of bone cement implantation syndrome (BCIS), since PE is considered as the central mechanism of BCIS. Fifteen sheep were divided into three groups: bone cement free (BCF) group, cement implantation (CI) group and IVCF group. In all the groups, an osteotomy proximal to the greater trochanter of left femur was carried out. In BCF group, the femoral canal was not reamed out or packed with any bone cement. In CI and IVCF groups, the left femoral canals were packed with bone cement, to simulate the cementing procedures carried out in hip replacement. An OptEase(®) filter was placed and released in inferior vena cava, prior to packing cement in the femoral canal in IVCF group, while the IVCF was not released in the CI group. The BCF group was considered as control. Systolic blood pressure (SBP), saturation of oxygen (SaO2) and partial pressure of carbon dioxide (PaCO2) declined significantly 10 min after the bone cement packing, in CI group, compared to those in BCF group. This was accompanied by a rise in the arterial pH. However, IVCF prevented those changes in the CI group. On ultrasonography, there were dotted echoes in right atrium in the CI group, after bone cement packing, while such echoes were hardly seen in the IVCF group. This study demonstrates that IVCF could prevent BCIS effectively, and, as a corollary, suggests that PE represents the leading cause of the constellation of BCIS symptoms.

  9. Update in dental implant periapical surgery.

    Science.gov (United States)

    Peñarrocha Diago, Miguel; Boronat López, Araceli; Lamas Pelayo, Joana

    2006-08-01

    Implant periapical lesions are infectious-inflammatory alterations surrounding an implant apex, and can be caused by a number of situations--including contamination at instrumentation, overheating of bone, and the prior existence of bone pathology. The diagnosis is based on the clinical manifestations and radiological findings, where a radiotransparency can be seen at periapical level. The lesions are classified according to their evolutive stage as either acute (non-suppurated and suppurated) or chronic (or periapical abscess). The management of implant periapical lesions comprises periapical surgery with curettage and irrigation in the acute phase, or implant extraction when the bone surface is affected and/or primary fixation is lost (chronic phase).

  10. Effect of polychromatic visible light on proliferation of tumor cells under conditions in vitro and in vivo—after implantation to experimental animals

    Science.gov (United States)

    Knyazev, N. A.; Samoilova, K. A.; Filatova, N. A.; Galaktionova, A. A.

    2009-06-01

    The question of the character of effect of visible and near infrared (IR) radiation of Sun and artificial sources on growth of malignant tumors remains open due to controversy and a relatively small amount of available data, which restricts use of this most important environmental and the efficient physiotherapeutic factors at various human pathological states and first of all at the rehabilitation of oncological patients after radical methods of cancer treatment (surgical removal of tumor, intensive medication and radiation therapy), when immunomodulatory antiinflamatory, wound-healing and analgesic properties of visible and near IR light can be drawn. In the present work, using polychromatic visible light, close to this dominant component of the terrestrial solar radiation (380-750 nm, 40 mW/cm2) we irradiated tumor cells of the murine hepatoma (MH-22a line) under conditions in vitro (the monolayer of cells in Petri dishes) and in vivo (after subcutaneous implantation of these cells to mice of the C3HA line). A high resistance of the MH-22a cells to polychromatic visible radiation has been established under conditions in vitro: irradiation at dose 24 J/cm2 did not inhibit their proliferation whereas a dose of 9.6 J/cm2, stimulated statistically significantly proliferation of the cells (by 24-40%). However, stimulation of the tumor cell proliferation, did not develop under conditions in vivo, when mice were irradiated (9.6 J/cm2)—daily for 5 days before the implantation of tumor cells and for 5 days after implantation (in the latter case there was a probability of transcutaneous irradiation of tumor cells). By implanting to the animals of tumor cells at various concentrations (from 2ṡ105 to 25ṡ103 cells per mouse), we did not revealed at any of 10 terms of observations for 41-45 days both an increase of incidence of the tumor development and acceleration of tumor growth as well as a decrease of the animals survival as compared with group of non

  11. Flexible fixation and fracture healing: do locked plating 'internal fixators' resemble external fixators?

    Science.gov (United States)

    Schmal, Hagen; Strohm, Peter C; Jaeger, Martin; Südkamp, Norbert P

    2011-02-01

    External and internal fixators use bone screws that are locked to a plate or bar to prevent periosteal compression and associated impairment of blood supply. Both osteosynthesis techniques rely on secondary bone healing with callus formation with the exception of compression plating of simple, noncomminuted fractures. External fixation uses external bars for stabilization, whereas internal fixation is realized by subcutaneous placement of locking plates. Both of these "biologic" osteosynthesis methods allow a minimally invasive approach and do not compromise fracture hematoma and periosteal blood supply. Despite these similarities, differences between the two fixation methods prevail. Locked plating "internal fixators" allow a combination of biomechanical principles such as buttressing and dynamic compression. Periarticular locking plates are anatomically contoured to facilitate fixation of articular fractures. They allow for subchondral stabilization using small-diameter angular stable screws as well as buttressing of the joint and the metaphyseal component of a fracture. Biomechanically, they can be far stiffer than external fixators, because subcutaneous plates are located much closer to the bone surface than external fixator bars. External fixators have the advantage of being less expensive, highly flexible, and technically less demanding. They remain an integral part of orthopaedic surgery for emergent stabilization, for pediatric fractures, for definitive osteosynthesis in certain indications such as distal radius fractures, and for callus distraction.

  12. Coronary Sinus Lead Removal: A Comparison between Active and Passive Fixation Leads.

    Science.gov (United States)

    Pecha, Simon; Kennergren, Charles; Yildirim, Yalin; Gosau, Nils; Aydin, Ali; Willems, Stephan; Treede, Hendrik; Reichenspurner, Hermann; Hakmi, Samer

    2016-01-01

    Implantation of coronary sinus (CS) leads may be a difficult procedure due to different vein anatomies and a possible lead dislodgement. The mode of CS lead fixation has changed and developed in recent years. We compared the removal procedures of active and passive fixation leads. Between January 2009 and January 2014, 22 patients at our centre underwent CS lead removal, 6 active and 16 passive fixation leads were attempted using simple traction or lead locking devices with or without laser extraction sheaths. Data on procedural variables and success rates were collected and retrospectively analyzed. The mean patient age was 67.2 ± 9.8 years, and 90.9% were male. The indication for lead removal was infection in all cases. All active fixation leads were Medtronic® Attain StarFix™ Model 4195 (Medtronic Inc., Minneapolis, MN, USA). The mean time from implantation for the active and passive fixation leads was 9.9 ± 11.7 months (range 1.0-30.1) and 48.7 ± 33.6 months (range 5.7-106.4), respectively (p = 0.012). Only 3 of 6 StarFix leads were successfully removed (50%) compared to 16 of 16 (100%) of the passive fixation CS leads (p = 0.013). No death or complications occurred during the 30-day follow-up. According to our experience, removal of the Starfix active fixation CS leads had a higher procedural failure rate compared to passive.

  13. Flexible fixation and fracture healing

    DEFF Research Database (Denmark)

    Schmal, Hagen; Strohm, Peter C; Jaeger, Martin

    2011-01-01

    , noncomminuted fractures. External fixation uses external bars for stabilization, whereas internal fixation is realized by subcutaneous placement of locking plates. Both of these "biologic" osteosynthesis methods allow a minimally invasive approach and do not compromise fracture hematoma and periosteal blood...... of articular fractures. They allow for subchondral stabilization using small-diameter angular stable screws as well as buttressing of the joint and the metaphyseal component of a fracture. Biomechanically, they can be far stiffer than external fixators, because subcutaneous plates are located much closer...... to the bone surface than external fixator bars. External fixators have the advantage of being less expensive, highly flexible, and technically less demanding. They remain an integral part of orthopaedic surgery for emergent stabilization, for pediatric fractures, for definitive osteosynthesis in certain...

  14. Eighth international congress on nitrogen fixation

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    This volume contains the proceedings of the Eighth International Congress on Nitrogen Fixation held May 20--26, 1990 in Knoxville, Tennessee. The volume contains abstracts of individual presentations. Sessions were entitled Recent Advances in the Chemistry of Nitrogen Fixation, Plant-microbe Interactions, Limiting Factors of Nitrogen Fixation, Nitrogen Fixation and the Environment, Bacterial Systems, Nitrogen Fixation in Agriculture and Industry, Plant Function, and Nitrogen Fixation and Evolution.

  15. POROUS POLYMER IMPLANTS FOR REPAIR OF FULL-THICKNESS DEFECTS OF ARTICULAR-CARTILAGE - AN EXPERIMENTAL-STUDY IN RABBIT AND DOG

    NARCIS (Netherlands)

    JANSEN, HWB; VETH, RPH; NIELSEN, HKL; DEGROOT, JH; PENNINGS, AJ

    1992-01-01

    Full-thickness defects of articular cartilage were repaired by implantation of porous polymer implants in rabbits and dogs. The quality of the repair tissue was determined by collagen typing with antibodies. Implants with varying pore sizes and chemical composition were used. The effect of loading

  16. Estudo experimental da aplicação das forças de compressão ou distração sobre o sistema de fixação pedicular Compression or distraction forces applied on a pedicular fixation system: an experimental study

    Directory of Open Access Journals (Sweden)

    Helton Luiz Aparecido Defino

    2006-01-01

    Full Text Available Foi realizado estudo experimental com o objetivo de avaliar os efeitos da aplicação da força de compressão e distração (aproximação e afastamento sobre os implantes colocados nos pedículos vertebrais. Foram utilizados no estudo os segmentos vertebrais T8-T9, T10-T11, T12-L1, L2-L3 e L4-L5 de suínos da raça Landsark. Cada segmento vertebral foi fixado com implantes pediculares, tendo sido aplicada força de compressão ou distração com deslocamento que variou de 5,1 mm a 9,35 mm. O deslocamento provocado pela aplicação das forças foi mensurado em quatro pontos do segmento vertebral: A (porção anterior do corpo vertebral, B (porção média do corpo vertebral, C (porção posterior do corpo vertebral e D (processo articular siperior. A força de compressão produziu o afastamento dos pontos localizados nas regiões A e B, e aproximação dos pontos da região D. A força de distração produziu a aproximação dos pontos da região A e B e o afastamento dos pontos da região D.An experimental study was conducted with the objective of evaluating the effects of compression and distraction (approach and deviation forces applied on implants placed at vertebral pedicles. The vertebral segments T8-T9, T10-T11, T12-L1, L2-L3 and L4-L5 of Landsark pigs were used in the study. Each vertebral segment was fixed with pedicular implants, with compression or distraction forces being applied with a displacement that ranged from 5.1 mm to 9.35 mm. Displacement caused by forces application was measured in four points of the vertebral segment: A (anterior portion of the vertebral segment, B (medial portion of the vertebral segment, C (posterior portion of the vertebral segment and D (superior joint process. Compression forces caused the deviation of points located at regions A and B, and the approach of points at region D. Distraction forces caused the approach of points at regions A and B and deviation of the points at region D.

  17. Success and High Predictability of Intraorally Welded Titanium Bar in the Immediate Loading Implants

    OpenAIRE

    Vaniel Fogli; Michele Camerini; Dorina Lauritano; Francesco Carinci

    2014-01-01

    The implants failure may be caused by micromotion and stress exerted on implants during the phase of bone healing. This concept is especially true in case of implants placed in atrophic ridges. So the primary stabilization and fixation of implants are an important goal that can also allow immediate loading and oral rehabilitation on the same day of surgery. This goal may be achieved thanks to the technique of welding titanium bars on implant abutments. In fact, the procedure can be performed ...

  18. Acid etching and plasma sterilization fail to improve osseointegration of grit blasted titanium implants

    DEFF Research Database (Denmark)

    Mortensen, Mikkel Saksø; Jakobsen, Stig Storgaard; Saksø, Henrik

    2012-01-01

    compared with acid etched grit blasted implants. In the second study grit blasted implants were compared with acid etched grit blasted implants that were further treated with plasma sterilization. Implant performance was evaluated by histomorphometrical investigation (tissue-to-implant contact, peri......-implant tissue density) and mechanical push-out testing after four weeks observation time.Neither acid etching nor plasma sterilization of the grit blasted implants enhanced osseointegration or mechanical fixation in this press-fit canine implant model in a statistically significant manner....

  19. [Ear prosthesis anchored on osseointegrated implants. Experience with 9 cases].

    Science.gov (United States)

    Charles, X; Piller, P; Hemar, P; Herman, D; Kennel, P; Riedinger, A M; Conraux, C

    1995-01-01

    The use of osseointegrated titanium implants has improved the quality of auricle prosthesis fixation. Between december 1993 and july 1994, twenty two titanium fixtures have been surgically implanted in nine patients in the Ear Nose Throat department of the university hospital of Strasbourg. This method of auricle amputation repair achieves a good esthetic result with a low rate of postoperative complications.

  20. Implant failure in osteosynthesis of fractures of long bones ...

    African Journals Online (AJOL)

    Patients who had open operative treatment of fractures of long bones were reviewed retrospectively to identify the incidence of and risk factors for implant failure. One hundred and five patients had open reduction and internal fixation of 117 fractures of long bones, out of which four patients suffered implant failure.

  1. Biomechanical comparison of mono-segment transpedicular fixation with short-segment fixation for treatment of thoracolumbar fractures: a finite element analysis.

    Science.gov (United States)

    Xu, Guijun; Fu, Xin; Du, Changling; Ma, Jianxiong; Li, Zhijun; Tian, Peng; Zhang, Tao; Ma, Xinlong

    2014-10-01

    Mono-segment transpedicular fixation is a method for the treatment of certain types of thoracolumbar spinal fracture. Finite element models were constructed to evaluate the biomechanics of mono-segment transpedicular fixation of thoracolumbar fracture. Spinal motion (T10-L2) was scanned and used to establish the models. The superior half of the cortical bone of T12 was removed and the superior half of the cancellous bone of the T12 body was assigned the material properties of injured bone to mimic vertebral fracture. Transpedicular fixation of T11 and T12 was performed to produce a mono-segment fixation model; T11 and L1 were fixed to produce a short-segment fixation model. Motion differences between functional units and von Mises stress on the spine and implants were measured under axial compression, anterior bending, extensional bending, lateral bending and axial rotation. We found no significant difference between mono- and short-segment fixations in the motion of any functional unit. Stress on the T10/T11 nucleus pulposus and T10/T11 and L1/L2 annulus fibrosus increased significantly by about 75% on anterior bending, extensional bending and lateral bending. In the fracture model, stress was increased by 24% at the inferior endplate of T10 and by 43% at the superior endplate of L2. All increased stresses were reduced after fixation and lower stress was observed with mono-segment fixation. In summary, the biomechanics of mono-segment pedicle screw instrumentation was similar to that of conventional short-segment fixation. As a minimally invasive treatment, mono-segment fixation would be appropriate for the treatment of selected thoracolumbar spinal fractures. © IMechE 2014.

  2. Plasma Treatment Maintains Surface Energy of the Implant Surface and Enhances Osseointegration

    Directory of Open Access Journals (Sweden)

    Fernando P. S. Guastaldi

    2013-01-01

    Full Text Available The surface energy of the implant surface has an impact on osseointegration. In this study, 2 surfaces: nonwashed resorbable blasting media (NWRBM; control and Ar-based nonthermal plasma 30 days (Plasma 30 days; experimental, were investigated with a focus on the surface energy. The surface energy was characterized by the Owens-Wendt-Rabel-Kaelble method and the chemistry by X-ray photoelectron spectroscopy (XPS. Five adult beagle dogs received 8 implants (n=2 per surface, per tibia. After 2 weeks, the animals were euthanized, and half of the implants (n=20 were removal torqued and the other half were histologically processed (n=20. The bone-to-implant contact (BIC and bone area fraction occupancy (BAFO were evaluated on the histologic sections. The XPS analysis showed peaks of C, Ca, O, and P for the control and experimental surfaces. While no significant difference was observed for BIC parameter (P>0.75, a higher level for torque (P<0.02 and BAFO parameter (P<0.01 was observed for the experimental group. The surface elemental chemistry was modified by the plasma and lasted for 30 days after treatment resulting in improved biomechanical fixation and bone formation at 2 weeks compared to the control group.

  3. Biodegradable radioactive implants for glaucoma filtering surgery produced by ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Assmann, W. [Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, 85748 Garching (Germany)]. E-mail: walter.assmann@lmu.de; Schubert, M. [Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, 85748 Garching (Germany); Held, A. [Augenklinik, Technische Universitaet Muenchen, 81675 Munich (Germany); Pichler, A. [Augenklinik, Technische Universitaet Muenchen, 81675 Muenchen (Germany); Chill, A. [Zentralinstitut fuer Medizintechnik, Technische Universitaet Muenchen, 85748 Garching (Germany); Kiermaier, S. [Zentralinstitut fuer Medizintechnik, Technische Universitaet Muenchen, 85748 Garching (Germany); Schloesser, K. [Forschungszentrum Karlsruhe, 76021 Karlsruhe (Germany); Busch, H. [NTTF GmbH, 53619 Rheinbreitbach (Germany); Schenk, K. [NTTF GmbH, 53619 Rheinbreitbach (Germany); Streufert, D. [Acri.Tec GmbH, 16761 Hennigsdorf (Germany); Lanzl, I. [Augenklinik, Technische Universitaet Muenchen, 81675 Munich (Germany)

    2007-04-15

    A biodegradable, {beta}-emitting implant has been developed and successfully tested which prevents fresh intraocular pressure increase after glaucoma filtering surgery. Ion implantation has been used to load the polymeric implants with the {beta}-emitter {sup 32}P. The influence of ion implantation and gamma sterilisation on degradation and {sup 32}P-fixation behavior has been studied by ion beam and chemical analysis. Irradiation effects due to the applied ion fluence (10{sup 15} ions/cm{sup 2}) and gamma dose (25 kGy) are found to be tolerable.

  4. REVISION ANKLE SYNDESMOSIS FIXATION - FUNCTIONAL OUTCOME AFTER TIGHTROPE ® FIXATION

    Directory of Open Access Journals (Sweden)

    Sendhilvelan Rajagopalan

    2016-07-01

    Full Text Available BACKGROUND Syndesmotic disruptions are often seen in ankle fractures. Malreduction of these fractures can result in arthritis and instability. A proportion of these patients with malreduction require revision fixation. This study presents the results of revision fixation in such patients, using the Ankle TightRope ® (Arthrex system. METHODS Between January 2000 to December 2009, 124 patients who underwent ankle fracture fixations with syndesmotic stabilisation were analysed. Out of 124 patients, 8 patients were diagnosed with failure of primary stabilisation (based on radiological and clinical criteria and subjected to revision fixation using the Ankle TightRope ® (Arthrex system. Followup was done at periodic time intervals of 3, 6 and 12 months. Both clinical and radiological assessment was performed. Complications and duration of hospital stay was recorded. Functional evaluation was performed using the American Orthopaedic Foot and Ankle Society (AOFAS scoring system. RESULTS Five patients had good results, one satisfactory and two had poor outcomes. CONCLUSIONS Ankle TightRope ® fixation is an alternative method of stabilisation in patients who require revision syndesmosis fixation. Further studies are required to evaluate this method of revision stabilisation as compared to screws.

  5. Neuronal control of fixation and fixational eye movements

    Science.gov (United States)

    2017-01-01

    Ocular fixation is a dynamic process that is actively controlled by many of the same brain structures involved in the control of eye movements, including the superior colliculus, cerebellum and reticular formation. In this article, we review several aspects of this active control. First, the decision to move the eyes not only depends on target-related signals from the peripheral visual field, but also on signals from the currently fixated target at the fovea, and involves mechanisms that are shared between saccades and smooth pursuit. Second, eye position during fixation is actively controlled and depends on bilateral activity in the superior colliculi and medio-posterior cerebellum; disruption of activity in these circuits causes systematic deviations in eye position during both fixation and smooth pursuit eye movements. Third, the eyes are not completely still during fixation but make continuous miniature movements, including ocular drift and microsaccades, which are controlled by the same neuronal mechanisms that generate larger saccades. Finally, fixational eye movements have large effects on visual perception. Ocular drift transforms the visual input in ways that increase spatial acuity; microsaccades not only improve vision by relocating the fovea but also cause momentary changes in vision analogous to those caused by larger saccades. This article is part of the themed issue ‘Movement suppression: brain mechanisms for stopping and stillness’. PMID:28242738

  6. Neuronal control of fixation and fixational eye movements.

    Science.gov (United States)

    Krauzlis, Richard J; Goffart, Laurent; Hafed, Ziad M

    2017-04-19

    Ocular fixation is a dynamic process that is actively controlled by many of the same brain structures involved in the control of eye movements, including the superior colliculus, cerebellum and reticular formation. In this article, we review several aspects of this active control. First, the decision to move the eyes not only depends on target-related signals from the peripheral visual field, but also on signals from the currently fixated target at the fovea, and involves mechanisms that are shared between saccades and smooth pursuit. Second, eye position during fixation is actively controlled and depends on bilateral activity in the superior colliculi and medio-posterior cerebellum; disruption of activity in these circuits causes systematic deviations in eye position during both fixation and smooth pursuit eye movements. Third, the eyes are not completely still during fixation but make continuous miniature movements, including ocular drift and microsaccades, which are controlled by the same neuronal mechanisms that generate larger saccades. Finally, fixational eye movements have large effects on visual perception. Ocular drift transforms the visual input in ways that increase spatial acuity; microsaccades not only improve vision by relocating the fovea but also cause momentary changes in vision analogous to those caused by larger saccades.This article is part of the themed issue 'Movement suppression: brain mechanisms for stopping and stillness'. © 2017 The Authors.

  7. Novel anterior cruciate ligament graft fixation device reduces slippage

    Directory of Open Access Journals (Sweden)

    Lopez MJ

    2013-05-01

    Full Text Available Mandi J Lopez,1 Allen Borne,2 W Todd Monroe,3 Prakash Bommala,1 Laura Kelly,1 Nan Zhang11Laboratory for Equine and Comparative Orthopedic Research, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, 2Louisiana State University, New Orleans Health Sciences Center, School of Medicine, New Orleans, 3Department of Biological and Agricultural Engineering, Agricultural Center, Louisiana State University, Baton Rouge, LA, USAAbstract: Clinically significant laxity occurs in 10%–30% of knees after anterior cruciate ligament reconstruction. Graft slippage and tension loss at the hamstring graft tibial fixation site during and after reconstruction surgery contribute to postoperative joint laxity and are detrimental to long-term knee stability and graft properties. Limiting graft slippage will reduce associated complications. We sought to compare the in vitro mechanical properties and in vivo joint stabilization, postoperative limb use, and graft incorporation of the novel GraftGrab™ (GG device designed to reduce hamstring graft tibial fixation slippage with the commercially available bioabsorbable Bio-Post™ and spiked washer (BP. Mechanical testing was performed on canine tibia-hamstring graft constructs to quantify initial fixation properties. In vivo joint stabilization, postoperative limb use and graft incorporation of hamstring graft reconstructions were determined in a canine model. Outcomes included tibial translation and ground reaction forces preoperatively and 4 and 8 weeks postoperatively, three-dimensional graft and bone tunnel dimensions at the latter two time points, and graft-bone microstructure, as well as mechanical properties 8 weeks after implantation. Immediately after fixation, all grafts slipped from the BP constructs versus about 30% of GG constructs. In vivo limb use remained low, and tibial translation increased with time in the BP cohort. These results together

  8. Osseodensification for enhancement of spinal surgical hardware fixation.

    Science.gov (United States)

    Lopez, Christopher D; Alifarag, Adham M; Torroni, Andrea; Tovar, Nick; Diaz-Siso, J Rodrigo; Witek, Lukasz; Rodriguez, Eduardo D; Coelho, Paulo G

    2017-05-01

    Integration between implant and bone is an essential concept for osseous healing requiring hardware placement. A novel approach to hardware implantation, termed osseodensification, is described here as an effective alternative. 12 sheep averaging 65kg had fixation devices installed in their C2, C3, and C4 vertebral bodies; each device measured 4mm diameter×10mm length. The left-sided vertebral body devices were implanted using regular surgical drilling (R) while the right-sided devices were implanted using osseodensification drilling (OD). The C2 and C4 vertebra provided the t=0 in vivo time point, while the C3 vertebra provided the t=3 and t=6 week time points, in vivo. Structural competence of hardware was measured using biomechanical testing of pullout strength, while the quality and degree of new bone formation and remodeling was assessed via histomorphometry. Pullout strength demonstrated osseodensification drilling to provide superior anchoring when compared to the control group collapsed over time with statistical significance (phardware implantation encourages assessment of current surgical approaches to hardware implantation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Monitoring the osseointegration process in porous Ti6Al4V implants produced by additive manufacturing: an experimental study in sheep.

    Science.gov (United States)

    Kayacan, Mehmet C; Baykal, Yakup B; Karaaslan, Tamer; Özsoy, Koray; Alaca, İlker; Duman, Burhan; Delikanlı, Yunus E

    2017-11-13

    This study investigated the design and osseointegration process of transitive porous implants that can be used in humans and all trabecular and compact bone structure animals. The aim was to find a way of forming a strong and durable tissue bond on the bone-implant interface. Massive and transitive porous implants were produced on a direct metal laser sintering machine, surgically implanted into the skulls of sheep and kept in place for 12 weeks. At the end of the 12-week period, the Massive and porous implants removed from the sheep were investigated by scanning electron microscopy (SEM) to monitor the osseointegration process. In the literature, each study has selected standard sizes for pore diameter in the structures they use. However, none of these involved transitional porous structures. In this study, as opposed to standard pores, there were spherical or elliptical pores at the micro level, development channels and an inner region. Bone cells developed in the inner region. Transitive pores grown gradually in accordance with the natural structure of the bone were modeled in the inner region for cells to develop. Due to this structure, a strong and durable tissue bond could be formed at the bone-implant interface. Osseointegration processes of Massive vs. porous implants were compared. It was observed that cells were concentrated on the surface of Massive implants. Therefore, osseointegration between implant and bone was less than that of porous implants. In transitive porous implants, as opposed to Massive implants, an outer region was formed in the bone-implant interface that allowed tissue development.

  10. Implante de tubo valvulado bioprótese "stentless" em posição aórtica: estudo experimental em ovinos A juvenile sheep model for the stentless bioprostheses implanted as aortic root replacements

    Directory of Open Access Journals (Sweden)

    Paulo César SANTOS

    2002-03-01

    Full Text Available INTRODUÇÃO: O tratamento das lesões valvares representa um grande desafio dentro da cirurgia cardiovascular, pois, até os dias atuais, não temos um substituto ideal para as valvas do coração. As próteses atualmente disponíveis apresentam vantagens e desvantagens; as mecânicas exigem anticoagulação definitiva e as biológicas apresentam baixa durabilidade. Para se chegar a um substituto ideal, são necessárias várias fases, desde a escolha e o preparo do material até o implante em animal de grande porte. Esta última é muito importante, pois a escolha do animal deve ser criteriosa. Ovinos juvenís são animais dóceis de fácil manipulação e suas características anatômicas e biológicas se assemelham muito ao que ocorre com o ser humano e as próteses "stentless" são substitutos mais próximos dos homoenxertos. MATERIAL E MÉTODO: Foram operados 30 ovinos juvenís com idade variando de 4,4 a 6,3 meses, peso de 25 a 37 kg, sendo 28 machos. Todos os animais foram submetidos a circulação extracorpórea para implante de bioprótese "stentless" montada em tubo de aorta porcina, com reimplante de artérias coronárias. A operação foi realizada com hipotermia moderada e cardioplegia gelada. O período de seguimento foi de 30 dias e, ao final, realizado ecocardiograma. RESULTADOS: Houve 8 (26,6% óbitos no intra-operatório e 6 (27,7% óbitos no seguimento. O tempo médio de CEC foi de 98 min. Foi realizado ecocardiograma em 16 animais e em nenhum caso foram vistos sinais de endocardite ou outras alterações; a fração média de ejeção foi de 74%. CONCLUSÃO: Este modelo experimental utilizando ovinos para o estudo de biopróteses "stentless" em posição aórtica mostrou-se bem reprodutível e a performance do enxerto bastante factível de ser avaliada, pois ovinos são animais dóceis e de fácil manipulação no seguimento tardio.INTRODUCTION: Often, studies on aortic prosthetic valves analyze their performance not at the

  11. Molybdenum and phosphorus interact to constrain asymbiotic nitrogen fixation in tropical forests.

    Directory of Open Access Journals (Sweden)

    Nina Wurzburger

    Full Text Available Biological di-nitrogen fixation (N(2 is the dominant natural source of new nitrogen to land ecosystems. Phosphorus (P is thought to limit N(2 fixation in many tropical soils, yet both molybdenum (Mo and P are crucial for the nitrogenase reaction (which catalyzes N(2 conversion to ammonia and cell growth. We have limited understanding of how and when fixation is constrained by these nutrients in nature. Here we show in tropical forests of lowland Panama that the limiting element on asymbiotic N(2 fixation shifts along a broad landscape gradient in soil P, where Mo limits fixation in P-rich soils while Mo and P co-limit in P-poor soils. In no circumstance did P alone limit fixation. We provide and experimentally test a mechanism that explains how Mo and P can interact to constrain asymbiotic N(2 fixation. Fixation is uniformly favored in surface organic soil horizons--a niche characterized by exceedingly low levels of available Mo relative to P. We show that soil organic matter acts to reduce molybdate over phosphate bioavailability, which, in turn, promotes Mo limitation in sites where P is sufficient. Our findings show that asymbiotic N(2 fixation is constrained by the relative availability and dynamics of Mo and P in soils. This conceptual framework can explain shifts in limitation status across broad landscape gradients in soil fertility and implies that fixation depends on Mo and P in ways that are more complex than previously thought.

  12. Molybdenum and Phosphorus Interact to Constrain Asymbiotic Nitrogen Fixation in Tropical Forests

    Science.gov (United States)

    Wurzburger, Nina; Bellenger, Jean Philippe; Kraepiel, Anne M. L.; Hedin, Lars O.

    2012-01-01

    Biological di-nitrogen fixation (N2) is the dominant natural source of new nitrogen to land ecosystems. Phosphorus (P) is thought to limit N2 fixation in many tropical soils, yet both molybdenum (Mo) and P are crucial for the nitrogenase reaction (which catalyzes N2 conversion to ammonia) and cell growth. We have limited understanding of how and when fixation is constrained by these nutrients in nature. Here we show in tropical forests of lowland Panama that the limiting element on asymbiotic N2 fixation shifts along a broad landscape gradient in soil P, where Mo limits fixation in P-rich soils while Mo and P co-limit in P-poor soils. In no circumstance did P alone limit fixation. We provide and experimentally test a mechanism that explains how Mo and P can interact to constrain asymbiotic N2 fixation. Fixation is uniformly favored in surface organic soil horizons - a niche characterized by exceedingly low levels of available Mo relative to P. We show that soil organic matter acts to reduce molybdate over phosphate bioavailability, which, in turn, promotes Mo limitation in sites where P is sufficient. Our findings show that asymbiotic N2 fixation is constrained by the relative availability and dynamics of Mo and P in soils. This conceptual framework can explain shifts in limitation status across broad landscape gradients in soil fertility and implies that fixation depends on Mo and P in ways that are more complex than previously thought. PMID:22470462

  13. Arthroscopy-assisted fracture fixation.

    Science.gov (United States)

    Atesok, Kivanc; Doral, M Nedim; Whipple, Terry; Mann, Gideon; Mei-Dan, Omer; Atay, O Ahmet; Beer, Yiftah; Lowe, Joseph; Soudry, Michael; Schemitsch, Emil H

    2011-02-01

    the purpose of this article was to systematically analyze the results of published studies in the literature which evaluated the use of arthroscopically assisted techniques in intra-articular fracture fixation. published investigations to date were analyzed by classifying them according to joints that were involved with intra-articular fractures including: knee, ankle, hip, shoulder, elbow, and wrist joints. The results were studied to assess the feasibility, efficiency, and outcomes of arthroscopy-assisted fracture fixation. arthroscopy-assisted techniques have been used successfully for the treatment of fractures of the tibial plateau, tibial eminence, malleoli, pilon, calcaneus, femoral head, glenoid, greater tuberosity, distal clavicle, radial head, coronoid, distal radius, and scaphoid. The major advantages of arthroscopic fracture fixation over open methods are direct visualization of the intra-articular space, decreased invasiveness, and the possibility for multitask interventions through which fixation of the fracture, and repair of the soft tissues and the cartilage can be performed simultaneously. The time-consuming and technically demanding nature of the procedures with a prolonged learning curve and limited fixation alternatives are the main disadvantages of this technique. arthroscopic fixation is increasingly utilized for certain intra-articular fracture types due to the minimally invasive nature of the procedures and high accuracy. Randomized controlled trials are needed to justify wider use of arthroscopy-assisted techniques for treatment of intra-articular fractures.

  14. Intraocular lens iris fixation. Clinical and macular OCT outcomes

    Directory of Open Access Journals (Sweden)

    Garcia-Rojas Leonardo

    2012-10-01

    Full Text Available Abstract Background To assess the efficacy, clinical outcomes, visual acuity (VA, incidence of adverse effects, and complications of peripheral iris fixation of 3-piece acrylic IOLs in eyes lacking capsular support. Thirteen patients who underwent implantation and peripheral iris fixation of a 3-piece foldable acrylic PC IOL for aphakia in the absence of capsular support were followed after surgery. Clinical outcomes and macular SD-OCT (Cirrus OCT; Carl Zeiss Meditec, Germany were analyzed. Findings The final CDVA was 20/40 or better in 8 eyes (62%, 20/60 or better in 12 eyes (92%, and one case of 20/80 due to corneal astigmatism and mild persistent edema. No intraoperative complications were reported. There were seven cases of medically controlled ocular hypertension after surgery due to the presence of viscoelastic in the AC. There were no cases of cystoid macular edema, chronic iridocyclitis, IOL subluxation, pigment dispersion, or glaucoma. Macular edema did not develop in any case by means of SD-OCT. Conclusions We think that this technique for iris suture fixation provides safe and effective results. Patients had substantial improvements in UDVA and CDVA. This surgical strategy may be individualized however; age, cornea status, angle structures, iris anatomy, and glaucoma are important considerations in selecting candidates for an appropriate IOL fixation method.

  15. Intraprosthetic fixation techniques in the treatment of periprosthetic fractures-A biomechanical study

    Science.gov (United States)

    Brand, Stephan; Klotz, Johannes; Hassel, Thomas; Petri, Maximilian; Haasper, Carl; Bach, Friedrich-Wilhelm; Krettek, Christian; Goesling, Thomas

    2012-01-01

    AIM: To develop new fixation techniques for the treatment of periprosthetic fractures using intraprosthetic screw fixation with inserted threaded liners. METHODS: A Vancouver B1 periprosthetic fracture was simulated in femur prosthesis constructs using sawbones and cemented regular straight hip stems. Fixation was then performed with either unicortical locked-screw plating using the less invasive stabilization system-plate or with intraprosthetic screw fixation using inserted liners. Two experimental groups were formed using either prostheses made of titanium alloy or prostheses made of cobalt chrome alloy. Fixation stability was compared in an axial load-to-failure model. Drilling was performed using a specially invented prosthesis drill with constantly applied internal cooling. RESULTS: The intraprosthetic fixation model with titanium prostheses was superior to the unicortical locked-screw fixation in all tested devices. The intraprosthetic fixation model required 10 456 N ± 1892 N for failure and the unicortical locked-screw plating required 7649 N ± 653 N (P < 0.05). There was no significant difference between the second experimental group and the control group. CONCLUSION: Intraprosthetic screw anchorage with special threaded liners enhances the primary stability in treating periprosthetic fractures by internal fixation. PMID:23326763

  16. Comparing fixation used for calcaneal displacement osteotomies: a look at removal rates and cost.

    Science.gov (United States)

    Lucas, Douglas E; Simpson, G Alex; Philbin, Terrence M

    2015-02-01

    The calcaneal displacement osteotomy is a procedure frequently used by foot and ankle surgeons for hindfoot angular deformity. Traditional techniques use compression screw fixation that can result in prominent hardware. While the results of the procedure are generally good, a common concern is the development of plantar heel pain related to prominent hardware. The primary purpose of this study is to retrospectively compare clinical outcomes of 2 fixation methods for the osteotomy. Secondarily a cost analysis will compare implant costs to hardware removal costs. Records were reviewed for patients who had undergone a calcaneal displacement osteotomy fixated with either lag screw or a locked lateral compression plate (LLCP). Neuropathy, previous ipsilateral calcaneus surgery, heel pad trauma, or incomplete radiographic follow-up were exclusionary. Thirty-two patients (19.4%) required hardware removal from the screw fixation group compared to 1 (1.6%) of the LLCP group, which is significant (P cost was remarkably different with screw fixation costing on average $247.12, compared to the LLCP costing $1175.59. Although the LLCP cost was significantly higher, cost savings were identified when the cost of removal and removal rates were included. This study demonstrates that this device provides adequate stabilization for healing in equivalent time to screw fixation. The LLCP required decreased rates of hardware removal with fewer postoperative visits over a shorter period of time. Significant savings were demonstrated in the LLCP group despite the higher implant cost. Therapeutic, Level III, Retrospective Comparative Study. © 2014 The Author(s).

  17. Damping Factor as a Diagnostic Parameter for Assessment of Osseointegration during the Dental Implant Healing Process: An Experimental Study in Rabbits.

    Science.gov (United States)

    Feng, Sheng-Wei; Ho, Kuo-Ning; Chan, Ya-Hui; Chang, Kai-Jung; Lai, Wei-Yi; Huang, Haw-Ming

    2016-12-01

    The purpose of this study was to evaluate the possibility of using damping factor (DF) analysis to provide additional information on osseointegration of dental implants during the healing period. A total of 30 dental implants were installed in the bilateral femoral condyles of 15 rabbits. A DF analyzer detected with an impulse-forced vibration method and a commercialized dental implant stability analyzer based on resonance frequency (RF) analysis were used to measure the implant stability immediately after implant placement and 1, 2, 4, and 8 weeks post-surgically. Results of DF and RF analyses at different time points were compared with the corresponding osseointegration performance of dental implants via micro-computed tomography (micro-CT), histological and histomorphometrical analysis. The DF values revealed a decrease with time and reached 0.062 ± 0.007 at 8 weeks after implantation, which is almost 50% lower than the initial value. Moreover, highly significant correlations between DF values and bone volume densities (R (2) = 0.9797) and percentages of bone-to-implant contact measured at trabecular bone area (R (2) = 0.9773) were also observed. These results suggested that DF analysis combined with RF analysis results in a more sensitive assessment of changes in the dental implant/bone complex during the healing period than RF analysis alone.

  18. Finite element analysis of osteosynthesis screw fixation in the bone stock: an appropriate method for automatic screw modelling.

    Science.gov (United States)

    Wieding, Jan; Souffrant, Robert; Fritsche, Andreas; Mittelmeier, Wolfram; Bader, Rainer

    2012-01-01

    The use of finite element analysis (FEA) has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with screws in the adjacent

  19. Finite element analysis of osteosynthesis screw fixation in the bone stock: an appropriate method for automatic screw modelling.

    Directory of Open Access Journals (Sweden)

    Jan Wieding

    Full Text Available The use of finite element analysis (FEA has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with

  20. Intramedullary fixation with screwed, conical stems--unsolicited results from animal experiments

    NARCIS (Netherlands)

    P.J.M. van Loon (Piet); H.H. Weinans (Harrie); R. Huiskes (Rik)

    1992-01-01

    textabstractFor the purpose of studying bone remodeling around prostheses, a segmental replacement for the goat tibia was designed, using a conical, screw-threaded, hydroxyapatite-coated stem for fixation. Eight goats were provided with the implant, seven of which loosened within 10 days

  1. Comparison of routine fixation of tissues with rapid tissue fixation.

    Science.gov (United States)

    Tripathi, Meenakshi; Bansal, Rani; Gupta, Mamta; Bharat, Vinay

    2013-12-01

    Conventional formalin-fixed, paraffin-embedded tissue provides superior cellular morphology and long-term storage. Problems with formalin fixation comprise delay of fixation and variations in the duration of fixation. Microwave assisted tissue fixation removes the use of noxious and potentially toxic formalin that decreases the turnaround time and creates a personnel friendly workflow. The present study was conducted over a period of two years. One hundred and forty paired tissue sections were taken including both neoplastic and non-neoplastic tissues. One of the paired tissues was fixed in formalin and the other was fixed by using microwave irradiation in phosphate buffered saline. Both were then processed by conventional method. Each slide was examined and rated for the adequacy of fixation by two pathologists in a blinded fashion using 7 parameters: Cellular outline, cytoplasmic detail, nuclear detail, erythrocyte integrity, lymphocyte appearance, overall morphology and overall staining. Statistical analysis showed that sections obtained from microwave fixed tissues were comparable to that of routinely fixed tissue. The p-values of all parameters were not significant except for the overall morphology for which p-value was significant owing to loss of tissue in some cases. Microwave irradiation substantially shortened the time from specimen reception to diagnosis (turnaround time) and allowed same-day tissue processing and diagnosis of specimens without compromising the overall quality of the histologic section.

  2. Nitrogen fixation in trees - 1

    Energy Technology Data Exchange (ETDEWEB)

    Dobereiner, J.; Gauthier, D.L.; Diem, H.G.; Dommergues, Y.R.; Bonetti, R.; Oliveira, L.A.; Magalhaes, F.M.M.; Faria, S.M. de; Franco, A.A.; Menandro, M.S.

    1984-01-01

    Six papers are presented from the symposium. Dobereiner, J.; Nodulation and nitrogen fixation in leguminous trees, 83-90, (15 ref.), reviews studies on Brazilian species. Gauthier, D.L., Diem, H.G., Dommergues, Y.R., Tropical and subtropical actinorhizal plants, 119-136, (Refs. 50), reports on studies on Casuarinaceae. Bonetti, R., Oliveira, L.A., Magalhaes, F.M.M.; Rhizobium populations and occurrence of VA mycorrhizae in plantations of forest trees, 137-142, (Refs. 15), studies Amazonia stands of Cedrelinga catenaeformis, Calophyllum brasiliense, Dipteryx odorata, D. potiphylla, Carapa guianensis, Goupia glabra, Tabebuia serratifolia, Clarisia racemosa, Pithecellobium racemosum, Vouacapoua pallidior, Eperua bijuga, and Diplotropis species. Nodulation was observed in Cedrelinga catenaeformis and V. pallidior. Faria, S.M. de, Franco, A.A., Menandro, M.S., Jesus, R.M. de, Baitello, J.B.; Aguiar, O.T. de, Doebereiner, J; survey of nodulation in leguminous tree species native to southeastern Brazil, 143-153, (Refs. 7), reports on 119 species, with first reports of nodulation in the genera Bowdichia, Poecilanthe, Melanoxylon, Moldenhaurea (Moldenhawera), and Pseudosamanea. Gaiad, S., Carpanezzi, A.A.; Occurrence of Rhizobium in Leguminosae of silvicultural interest for south Brazil, 155-158, (Refs. 2). Nodulation is reported in Mimosa scabrella, Acacia mearnsii, A. longifolia various trinervis, Enterolobium contortisiliquum, and Erythrina falcata. Magalhaes, L.M.S., Blum, W.E.H., Nodulation and growth of Cedrelinga catanaeformis in experimental stands in the Manaus region - Amazonas, 159-164, (Refs. 5). Results indicate that C. catenaeformis can be used in degraded areas of very low soil fertility.

  3. Prediction of midterm performance of active-fixation leads using current of injury.

    Science.gov (United States)

    Haghjoo, Majid; Mollazadeh, Reza; Aslani, Amir; Dastmalchi, Jalal; Mashreghi-Moghadam, Hamidreza; Heidari-Mokarar, Hadi; Vakili-Zarch, Anoushiravan; Alizadeh, Abolfath

    2014-02-01

    There are only limited prospective data on the clinical relevance of current of injury (COI) as a predictor of the midterm performance of active-fixation leads. This study sought to investigate whether it is possible to predict the midterm performance of active-fixation leads using COI recorded at the time of implantation. One hundred fifty patients (78 men; mean age, 63 ± 19 years) who received active-fixation pacing (n = 201) and defibrillator (n = 51) leads were studied. COI was measured from the intracardiac bipolar electrogram recorded at the time of lead implantation. The study outcome was good lead performance at 6 months, defined as P wave ≥ 1.5 mV, threshold lead, R-wave ≥ 5 mV, and threshold lead. A total of 102 active-fixation atrial and 150 ventricular leads were implanted. During a 6-month follow-up, invasive intervention was required for seven atrial and seven ventricular leads. In multivariate analysis, COI was the only independent predictor of good outcome for the active-fixation atrial (odds ratio [OR]: 5.67, 95% confidence interval [CI]: 2.18-14.76, P = 0.001) and ventricular leads (OR: 3.99, 95% CI: 1.08-21.26, P = 0.002). Receiver-operating characteristic analysis identified ST-segment elevation ≥2.0 mV for the atrial leads (sensitivity, 75%; specificity, 89%) and ≥10.0 mV for the ventricular leads (sensitivity, 70%; specificity, 87%) as optimal cutoffs for good midterm performance. Midterm performance of active-fixation leads is predictable using COI recorded at the time of lead implantation. A ST-segment elevation ≥2.0 mV in the atrial leads and ≥10.0 mV in the ventricular leads are recommended to improve the lead performance at 6 months. ©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.

  4. Safety and Biocompatibility of a New High-Density Polyethylene-Based Spherical Integrated Porous Orbital Implant: An Experimental Study in Rabbits

    Directory of Open Access Journals (Sweden)

    Ivan Fernandez-Bueno

    2015-01-01

    Full Text Available Purpose. To evaluate clinically and histologically the safety and biocompatibility of a new HDPE-based spherical porous orbital implants in rabbits. Methods. MEDPOR (Porex Surgical, Inc., Fairburn, GA, USA, OCULFIT I, and OCULFIT II (AJL Ophthalmic S.A., Vitoria, Spain implants were implanted in eviscerated rabbis. Animals were randomly divided into 6 groups (n=4 each according to the 3 implant materials tested and 2 follow-up times of 90 or 180 days. Signs of regional pain and presence of eyelid swelling, conjunctival hyperemia, and amount of exudate were semiquantitatively evaluated. After animals sacrifice, the implants and surrounding ocular tissues were processed for histological staining and polarized light evaluation. Statistical study was performed by ANOVA and Kaplan-Meier analysis. Results. No statistically significant differences in regional pain, eyelid swelling, or conjunctival hyperemia were shown between implants and/or time points evaluated. However, amount of exudate differed, with OCULFIT I causing the smallest amount. No remarkable clinical complications were observed. Histological findings were similar in all three types of implants and agree with minor inflammatory response. Conclusions. OCULFIT ophthalmic tolerance and biocompatibility in rabbits were comparable to the clinically used MEDPOR. Clinical studies are needed to determine if OCULFIT is superior to the orbital implants commercially available.

  5. The Synergistic Effect of Leukocyte Platelet-Rich Fibrin and Micrometer/Nanometer Surface Texturing on Bone Healing around Immediately Placed Implants: An Experimental Study in Dogs

    Science.gov (United States)

    Neiva, Rodrigo F.; Gil, Luiz Fernando; Tovar, Nick; Janal, Malvin N.; Marao, Heloisa Fonseca; Pinto, Nelson; Coelho, Paulo G.

    2016-01-01

    Aims. This study evaluated the effects of L-PRF presence and implant surface texture on bone healing around immediately placed implants. Methods. The first mandibular molars of 8 beagle dogs were bilaterally extracted, and implants (Blossom™, Intra-Lock International, Boca Raton, FL) were placed in the mesial or distal extraction sockets in an interpolated fashion per animal. Two implant surfaces were distributed per sockets: (1) dual acid-etched (DAE, micrometer scale textured) and (2) micrometer/nanometer scale textured (Ossean™ surface). L-PRF (Intraspin system, Intra-Lock International) was placed in a split-mouth design to fill the macrogap between implant and socket walls on one side of the mandible. The contralateral side received implants without L-PRF. A mixed-model ANOVA (at α = 0.05) evaluated the effect of implant surface, presence of L-PRF, and socket position (mesial or distal), individually or in combination on bone area fraction occupancy (BAFO). Results. BAFO values were significantly higher for the Ossean relative to the DAE surface on the larger mesial socket. The presence of L-PRF resulted in higher BAFO. The Ossean surface and L-PRF presence resulted in significantly higher BAFO. Conclusion. L-PRF and the micro-/nanometer scale textured surface resulted in increased bone formation around immediately placed implants. PMID:28042577

  6. The Synergistic Effect of Leukocyte Platelet-Rich Fibrin and Micrometer/Nanometer Surface Texturing on Bone Healing around Immediately Placed Implants: An Experimental Study in Dogs

    Directory of Open Access Journals (Sweden)

    Rodrigo F. Neiva

    2016-01-01

    Full Text Available Aims. This study evaluated the effects of L-PRF presence and implant surface texture on bone healing around immediately placed implants. Methods. The first mandibular molars of 8 beagle dogs were bilaterally extracted, and implants (Blossom™, Intra-Lock International, Boca Raton, FL were placed in the mesial or distal extraction sockets in an interpolated fashion per animal. Two implant surfaces were distributed per sockets: (1 dual acid-etched (DAE, micrometer scale textured and (2 micrometer/nanometer scale textured (Ossean™ surface. L-PRF (Intraspin system, Intra-Lock International was placed in a split-mouth design to fill the macrogap between implant and socket walls on one side of the mandible. The contralateral side received implants without L-PRF. A mixed-model ANOVA (at α=0.05 evaluated the effect of implant surface, presence of L-PRF, and socket position (mesial or distal, individually or in combination on bone area fraction occupancy (BAFO. Results. BAFO values were significantly higher for the Ossean relative to the DAE surface on the larger mesial socket. The presence of L-PRF resulted in higher BAFO. The Ossean surface and L-PRF presence resulted in significantly higher BAFO. Conclusion. L-PRF and the micro-/nanometer scale textured surface resulted in increased bone formation around immediately placed implants.

  7. The Synergistic Effect of Leukocyte Platelet-Rich Fibrin and Micrometer/Nanometer Surface Texturing on Bone Healing around Immediately Placed Implants: An Experimental Study in Dogs.

    Science.gov (United States)

    Neiva, Rodrigo F; Gil, Luiz Fernando; Tovar, Nick; Janal, Malvin N; Marao, Heloisa Fonseca; Bonfante, Estevam Augusto; Pinto, Nelson; Coelho, Paulo G

    2016-01-01

    Aims. This study evaluated the effects of L-PRF presence and implant surface texture on bone healing around immediately placed implants. Methods. The first mandibular molars of 8 beagle dogs were bilaterally extracted, and implants (Blossom™, Intra-Lock International, Boca Raton, FL) were placed in the mesial or distal extraction sockets in an interpolated fashion per animal. Two implant surfaces were distributed per sockets: (1) dual acid-etched (DAE, micrometer scale textured) and (2) micrometer/nanometer scale textured (Ossean™ surface). L-PRF (Intraspin system, Intra-Lock International) was placed in a split-mouth design to fill the macrogap between implant and socket walls on one side of the mandible. The contralateral side received implants without L-PRF. A mixed-model ANOVA (at α = 0.05) evaluated the effect of implant surface, presence of L-PRF, and socket position (mesial or distal), individually or in combination on bone area fraction occupancy (BAFO). Results. BAFO values were significantly higher for the Ossean relative to the DAE surface on the larger mesial socket. The presence of L-PRF resulted in higher BAFO. The Ossean surface and L-PRF presence resulted in significantly higher BAFO. Conclusion. L-PRF and the micro-/nanometer scale textured surface resulted in increased bone formation around immediately placed implants.

  8. Safety and Biocompatibility of a New High-Density Polyethylene-Based Spherical Integrated Porous Orbital Implant: An Experimental Study in Rabbits

    Science.gov (United States)

    Fernandez-Bueno, Ivan; Di Lauro, Salvatore; Alvarez, Ivan; Lopez, Jose Carlos; Garcia-Gutierrez, Maria Teresa; Fernandez, Itziar; Larra, Eva; Pastor, Jose Carlos

    2015-01-01

    Purpose. To evaluate clinically and histologically the safety and biocompatibility of a new HDPE-based spherical porous orbital implants in rabbits. Methods. MEDPOR (Porex Surgical, Inc., Fairburn, GA, USA), OCULFIT I, and OCULFIT II (AJL Ophthalmic S.A., Vitoria, Spain) implants were implanted in eviscerated rabbis. Animals were randomly divided into 6 groups (n = 4 each) according to the 3 implant materials tested and 2 follow-up times of 90 or 180 days. Signs of regional pain and presence of eyelid swelling, conjunctival hyperemia, and amount of exudate were semiquantitatively evaluated. After animals sacrifice, the implants and surrounding ocular tissues were processed for histological staining and polarized light evaluation. Statistical study was performed by ANOVA and Kaplan-Meier analysis. Results. No statistically significant differences in regional pain, eyelid swelling, or conjunctival hyperemia were shown between implants and/or time points evaluated. However, amount of exudate differed, with OCULFIT I causing the smallest amount. No remarkable clinical complications were observed. Histological findings were similar in all three types of implants and agree with minor inflammatory response. Conclusions. OCULFIT ophthalmic tolerance and biocompatibility in rabbits were comparable to the clinically used MEDPOR. Clinical studies are needed to determine if OCULFIT is superior to the orbital implants commercially available. PMID:26689343

  9. Posterior atlantoaxial transpedicle screw fixation for traumatic atlatoaxial instability

    Directory of Open Access Journals (Sweden)

    Zheng-lei WANG

    2015-10-01

    Full Text Available Objective To explore the clinical efficacy of posterior atlantoaxial pedicle screw fixation for traumatic atlantoaxial instability. Methods From September 2009 to March 2013, 17 patients with atlantoaxial instability received posterior atlantoaxial pedicle screw fixation. There were 12 males and 5 females, with a mean age of 42 years old (ranged from 19 to 63 years old. Transpedicle screw fixation was employed in 8 patients with atlantoaxial fracture and dislocation, in 2 with traumatic disruption of transverse atlantal ligament, and in 7 with odontoid fracture. The Japanese Orthopaedic Association (JOA score before operation was from 5 to 14, with a mean of 11.2. Preoperative CT, MRI and radiographs, as well as intraoperative screw placement and bone graft were administered in all the patients. Results In all the patients, complete reduction was achieved without injury to the vertebral artery, spinal cord or never root, and they started to be ambulatory on the first day after the operation. The patients were followed up for 6-36 months (mean 21 months, and clinical symptoms were seen to be improved significantly. Imaging reexamination 6 months after the surgery showed satisfactory healing of implanted bone and position of all the screws without loosening of the implant. The mean JOA scores was 15.5(11.0-17.0 twelve months after the operation. Conclusion Atlantoaxial pedicle screw fixation for traumatic atlantoaxial instability is safe and reliable with a favorable clinical result. DOI: 10.11855/j.issn.0577-7402.2015.09.14

  10. Biomechanical effect of interspinous process distraction height after lumbar fixation surgery: An in vitro model.

    Science.gov (United States)

    Fu, Lin; Ma, Jianxiong; Lu, Bin; Jia, Haobo; Zhao, Jie; Kuang, Mingjie; Feng, Rui; Xu, Liyan; Bai, Haohao; Sun, Lei; Wang, Ying; Ma, Xinlong

    2017-07-01

    Pedicle screw fixation may induce abnormal activity at adjacent segment and accelerate the degeneration of lumbar vertebrae. Dynamic stabilizers could provide an intermediate solution between conservative treatment and fusion surgery. Lumbar vertebral segment cephalad to instrumented fixation was the most common localization of adjacent segment degeneration. The aim of this study is to explore the use of interspinous process devices in the lumbar vertebral segment cephalad to fixation segment in changing the mechanical distribution and limiting abnormal activity of the spine. Eight specimens were tested in the following groups: intact group, instability group (bilateral facetectomy at L3-L4), fixation group (bilateral facetectomy and pedicle screw fixation at L3-L4), and hybrid fixation group (fixation at L3-L4 and simulating interspinous device implantation of 6, 8, 10, 12, 14, 16, and 18 mm at L2-L3). Range of motion, motion of vertebral body, and strain distribution change were recorded. The range of motion in extension with 16- and 18-mm hybrid constructs was significantly lower than intact, instability, and fixation groups. In flexion and lateral bending, the strain values of L4 inferior articular process with 18-mm hybrid construct have a significant difference compared with other groups. In axial rotation, under the condition of a contralateral state, the strain values of L2 superior articular process with 18-mm hybrid construct have a significant difference compared with intact and fixation groups. The strain value of the L4 inferior articular process had negative correlation with height distraction in three dimensions, except extension. A negative correlation between the strain value of the L2 superior articular process and distraction height was found in contralateral bending and contralateral axial rotation. Interspinous process devices above the fixation segment can change the mechanical distribution of the spine and limit activity in some of the

  11. In Vitro Measurement Of Insertion Torque, Removal Torque And Resonance Frequency Analysis Of Implants Placed Into Simulated Bony Defects

    Science.gov (United States)

    2014-05-14

    post-operative infection. The blade and pin form implants were the first endosseous type implants placed. These blade and pin type endosseous implants...implantation- related injury and key histological events as related to the host response after insertion and mechanical fixation of cementless dental...implants. The histological events include hematoma formation, and mesenchymal tissue development, woven bone formation 7     through the

  12. Intracranial biodegradable silica-based nimodipine drug release implant for treating vasospasm in subarachnoid hemorrhage in an experimental healthy pig and dog model.

    Science.gov (United States)

    Koskimäki, Janne; Tarkia, Miikka; Ahtola-Sätilä, Tuula; Saloranta, Lasse; Simola, Outi; Forsback, Ari-Pekka; Laakso, Aki; Frantzén, Janek

    2015-01-01

    Nimodipine is a widely used medication for treating delayed cerebral ischemia (DCI) after subarachnoid hemorrhage. When administrated orally or intravenously, systemic hypotension is an undesirable side effect. Intracranial subarachnoid delivery of nimodipine during aneurysm clipping may be more efficient way of preventing vasospasm and DCI due to higher concentration of nimodipine in cerebrospinal fluid (CSF). The risk of systemic hypotension may also be decreased with intracranial delivery. We used animal models to evaluate the feasibility of surgically implanting a silica-based nimodipine releasing implant into the subarachnoid space through a frontotemporal craniotomy. Concentrations of released nimodipine were measured from plasma samples and CSF samples. Implant degradation was followed using CT imaging. After completing the recovery period, full histological examination was performed on the brain and meninges. The in vitro characteristics of the implant were determined. Our results show that the biodegradable silica-based implant can be used for an intracranial drug delivery system and no major histopathological foreign body reactions were observed. CT imaging is a feasible method for determining the degradation of silica implants in vivo. The sustained release profiles of nimodipine in CSF were achieved. Compared to a traditional treatment, higher nimodipine CSF/plasma ratios can be obtained with the implant.

  13. Intracranial Biodegradable Silica-Based Nimodipine Drug Release Implant for Treating Vasospasm in Subarachnoid Hemorrhage in an Experimental Healthy Pig and Dog Model

    Directory of Open Access Journals (Sweden)

    Janne Koskimäki

    2015-01-01

    Full Text Available Nimodipine is a widely used medication for treating delayed cerebral ischemia (DCI after subarachnoid hemorrhage. When administrated orally or intravenously, systemic hypotension is an undesirable side effect. Intracranial subarachnoid delivery of nimodipine during aneurysm clipping may be more efficient way of preventing vasospasm and DCI due to higher concentration of nimodipine in cerebrospinal fluid (CSF. The risk of systemic hypotension may also be decreased with intracranial delivery. We used animal models to evaluate the feasibility of surgically implanting a silica-based nimodipine releasing implant into the subarachnoid space through a frontotemporal craniotomy. Concentrations of released nimodipine were measured from plasma samples and CSF samples. Implant degradation was followed using CT imaging. After completing the recovery period, full histological examination was performed on the brain and meninges. The in vitro characteristics of the implant were determined. Our results show that the biodegradable silica-based implant can be used for an intracranial drug delivery system and no major histopathological foreign body reactions were observed. CT imaging is a feasible method for determining the degradation of silica implants in vivo. The sustained release profiles of nimodipine in CSF were achieved. Compared to a traditional treatment, higher nimodipine CSF/plasma ratios can be obtained with the implant.

  14. Impact of immediate loading on early bone healing at two-piece implants placed in fresh extraction sockets: an experimental study in the beagle dog.

    Science.gov (United States)

    Blanco, Juan; Mareque, Santiaqo; Liñares, Antonio; Pérez, Javier; Muñoz, Fernando; Ramos, Isabel

    2013-04-01

    To study early bone healing of immediately loaded implants placed in fresh extraction sockets versus immediate implants without occlusal loading in the dog. A total of 48 implants were placed in the distal sockets of Pm3 and Pm4 in the lower jaw of 12 Beagle dogs immediately after tooth extraction. In the control group, no loading was applied. In the test group, an immediate loading restoration with occlusal contacts was performed. Dogs were sacrificed at 2, 4 and 8 weeks for histological analysis. At the end of the study, there was a 100% implant and prosthesis survival. Similar results for test and control groups were observed for bone-to-implant contact (%) and peri-implant bone area. Inter-thread bone area tended to decrease in the control and increase in the test. With respect to ridge alterations, bone resorption was more pronounced on the buccal aspect and was observed in both groups. Immediate loading did not impair early stages of bone healing and crestal bone modelling at two-piece implants in fresh extraction sockets in the beagle dog; however, bone resorption occurred in all specimens in both groups. © 2013 John Wiley & Sons A/S.

  15. Bone grafting of cleft lip and palate patients for placement of endosseous implants

    NARCIS (Netherlands)

    Jansma, J; Raghoebar, GM; Batenburg, RHK; Stellingsma, C; van Oort, RP

    Objective: Fixation of a prosthesis or single tooth replacement using osseointegrated implants has the potential to overcome functional and psychological inconveniences that many patients experience from such appliances. However, the dimensions of the recipient site are relatively often inadequate

  16. Single-staged implant placement using bone ring technique with and without membrane placement: An experimental study in the Beagle dog.

    Science.gov (United States)

    Haga-Tsujimura, Maiko; Nakahara, Ken; Kobayashi, Eizaburo; Igarashi, Kensuke; Schaller, Benoit; Saulacic, Nikola

    2017-12-12

    To evaluate the impact of a collagen membrane on bone remodeling and osseointegration of implants placed simultaneously with a bone ring technique. Standardized, vertical alveolar bone defects in the mandibles of six dogs were created. Tapered dental implants designed for two-stage subcrestal placement were inserted simultaneously with a bone ring technique. On one side of the mandible, the augmented sites were covered with a collagenous membrane. Implants with (M Group) and without membranes (NM Group) were left for an osseointegration period of 3 and 6 months, respectively. Block biopsies of the implants with surrounding bone were harvested and analyzed histologically. Implant exposure was a common finding (2/3) concomitantly with loss of healing caps. It appeared to be related to advanced bone loss around the implants. Exposure of implants was more frequent in M Group, however, without significant differences when compared to NM Group. The total bone area within the region of the bone ring was greater in the NM Group compared to the M Group. Moreover, in the region of the pristine bone of the M Group, the total bone was greater than at the corresponding NM Group sites at both observation periods. A nonparametric analysis of variance (ANOVA) revealed no significant effects of membrane placement or healing period on the total area of the bone. The total bone-to-implant contact (BIC) for the two groups was similar at each observation time point. However, BIC increased significantly at 6-month compared with 3-month observation period (p = .0088) in both groups. In vertical bone augmentation applying the bone ring technique, the disruption of soft tissue was a frequent complication. Membrane placement yielded no significant advantage on the osseointegration (BIC) of implants or bone characteristics. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Biologic and biomechanic evaluation of posterior lumbar fusion in the rabbit. The effect of fixation rigidity.

    Science.gov (United States)

    Feighan, J E; Stevenson, S; Emery, S E

    1995-07-15

    The histologic and biomechanic characteristics of posterior lumbar fusion with varying rigidity of a novel internal fixation construct in the rabbit were analyzed. To evaluate this rabbit model for future studies of fusion augmentation. Previous studies in goats and dogs showed internal fixation enhances spinal arthrodesis. Twenty eight New Zealand white rabbits underwent a posterior midline fusion from L4 to L6. Some animals received autogenous iliac crest bone graft, stabilized by wiring the superior facets bilaterally, and supplementation with polymethylmethacrylate. The experimental groups were iliac crest bone graft with either no fixation, wire fixation, or wire and polymethylmethacrylate fixation; and no graft and either no fixation, wire fixation, or wire and polymethylmethacrylate fixation. Animals were killed 2 months after surgery, and the specimens were nondestructively tested biomechanically for stiffness in six modes (flexion, extension, left and right bending, compression, and torsion) and histologically for evidence of fusion, revascularization, and new bone formation. Fusions with either wire or wire and polymethylmethacrylate fixation were significantly stiffer than those without fixation (P < 0.05). There was no statistical difference between the iliac crest bone graft and wire group and the iliac crest bone graft, wire, and polymethylmethacrylate group in the modes tested. Nine of 14 motion segments receiving the stiffest construct (iliac crest bone graft, wire, and polymethylmethacrylate) had evidence of solid bony fusion. None of the 12 motion segments receiving iliac crest bone graft and wire had evidence of bony fusion, but five had a fibrocartilage union with some ossification present. Eight of 12 motion segments receiving iliac crest bone graft and no fixation had predominantly fibrous unions with some fibrocartilage, and only one motion segment of 12 showed bony fusion. This study suggests that more rigid fixation produces more successful

  18. The effects of fixation target size and luminance on microsaccades and square-wave jerks

    Directory of Open Access Journals (Sweden)

    Michael B. McCamy

    2013-02-01

    Full Text Available A large amount of classic and contemporary vision studies require subjects to fixate a target. Target fixation serves as a normalizing factor across studies, promoting the field’s ability to compare and contrast experiments. Yet, fixation target parameters, including luminance, contrast, size, shape and color, vary across studies, potentially affecting the interpretation of results. Previous research on the effects of fixation target size and luminance on the control of fixation position rendered conflicting results, and no study has examined the effects of fixation target characteristics on square-wave jerks, the most common type of saccadic intrusion. Here we set out to determine the effects of fixation target size and luminance on the characteristics of microsaccades and square-wave jerks, over a large range of stimulus parameters. Human subjects fixated a circular target with varying luminance and size while we recorded their eye movements with an infrared video tracker (EyeLink 1000, SR Research. We detected microsaccades and SWJs automatically with objective algorithms developed previously. Microsaccade rates decreased linearly and microsaccade magnitudes increased linearly with target size. The percent of microsaccades forming part of SWJs decreased, and the time from the end of the initial SWJ saccade to the beginning of the second SWJ saccade (SWJ inter-saccadic interval; ISI increased with target size. The microsaccadic preference for horizontal direction also decreased moderately with target size . Target luminance did not affect significantly microsaccades or SWJs, however. In the absence of a fixation target, microsaccades became scarcer and larger, while SWJ prevalence decreased and SWJ ISIs increased. Thus, the choice of fixation target can affect experimental outcomes, especially in human factors and in visual and oculomotor studies. These results have implications for previous and future research conducted under fixation

  19. The effects of fixation target size and luminance on microsaccades and square-wave jerks.

    Science.gov (United States)

    McCamy, Michael B; Najafian Jazi, Ali; Otero-Millan, Jorge; Macknik, Stephen L; Martinez-Conde, Susana

    2013-01-01

    A large amount of classic and contemporary vision studies require subjects to fixate a target. Target fixation serves as a normalizing factor across studies, promoting the field's ability to compare and contrast experiments. Yet, fixation target parameters, including luminance, contrast, size, shape and color, vary across studies, potentially affecting the interpretation of results. Previous research on the effects of fixation target size and luminance on the control of fixation position rendered conflicting results, and no study has examined the effects of fixation target characteristics on square-wave jerks, the most common type of saccadic intrusion. Here we set out to determine the effects of fixation target size and luminance on the characteristics of microsaccades and square-wave jerks, over a large range of stimulus parameters. Human subjects fixated a circular target with varying luminance and size while we recorded their eye movements with an infrared video tracker (EyeLink 1000, SR Research). We detected microsaccades and SWJs automatically with objective algorithms developed previously. Microsaccade rates decreased linearly and microsaccade magnitudes increased linearly with target size. The percent of microsaccades forming part of SWJs decreased, and the time from the end of the initial SWJ saccade to the beginning of the second SWJ saccade (SWJ inter-saccadic interval; ISI) increased with target size. The microsaccadic preference for horizontal direction also decreased moderately with target size . Target luminance did not affect significantly microsaccades or SWJs, however. In the absence of a fixation target, microsaccades became scarcer and larger, while SWJ prevalence decreased and SWJ ISIs increased. Thus, the choice of fixation target can affect experimental outcomes, especially in human factors and in visual and oculomotor studies. These results have implications for previous and future research conducted under fixation conditions, and should

  20. Elevated CO2 concentration around alfalfa nodules increases N2 fixation

    Science.gov (United States)

    Fischinger, Stephanie A.; Hristozkova, Marieta; Mainassara, Zaman-Allah; Schulze, Joachim

    2010-01-01

    Nodule CO2 fixation via PEPC provides malate for bacteroids and oxaloacetate for N assimilation. The process is therefore of central importance for efficient nitrogen fixation. Nodule CO2 fixation is known to depend on external CO2 concentration. The hypothesis of the present paper was that nitrogen fixation in alfalfa plants is enhanced when the nodules are exposed to elevated CO2 concentrations. Therefore nodulated plants of alfalfa were grown in a hydroponic system that allowed separate aeration of the root/nodule compartment that avoided any gas leakage to the shoots. The root/nodule compartments were aerated either with a 2500 μl l−1 (+CO2) or zero μl l−1 (–CO2) CO2-containing N2/O2 gas flow (80/20, v/v). Nodule CO2 fixation, nitrogen fixation, and growth were strongly increased in the +CO2 treatment in a 3-week experimental period. More intensive CO2 and nitrogen fixation coincided with higher per plant amounts of amino acids and organic acids in the nodules. Moreover, the concentration of asparagine was increased in both the nodules and the xylem sap. Plants in the +CO2 treatment tended to develop nodules with higher %N concentration and individual activity. In a parallel experiment on plants with inefficient nodules (fix–) the +CO2 treatment remained without effect. Our data support the thesis that nodule CO2 fixation is pivotal for efficient nitrogen fixation. It is concluded that strategies which enhance nodule CO2 fixation will improve nitrogen fixation and nodule formation. Moreover, sufficient CO2 application to roots and nodules is necessary for growth and efficient nitrogen fixation in hydroponic and aeroponic growth systems. PMID:19815686

  1. Comparison of Outcomes of Operatively Treated Bicondylar Tibial Plateau Fractures by External Fixation and Internal Fixation

    Directory of Open Access Journals (Sweden)

    CC Chan

    2012-03-01

    Full Text Available The outcome of bicondylar tibial plateau fractures treated with either external fixation (35 patients or internal fixation (24 patients was reviewed. Outcome measures included the Rasmussen score, clinical complications, development of osteoarthritis and the requirement for total knee replacement (TKR. Twenty-two (92% anatomical reductions were achieved in the internal fixation group compared to 27 (77% in the external fixation group. Infective complications were more common in the external fixation group (9 patients, 26% due to pin tract infection. There were no deep infections in the internal fixation group. The mean Rasmussen score was not significantly different (mean score 32 in external fixation and 29 in internal fixation between the two groups and the incidence of osteoarthritis was the same in both groups. Four patients in the external fixation group underwent a TKR compared to 5 patients in the internal fixation group. Bicondylar tibial plateau fractures have similar outcomes following external or internal fixation.

  2. Phase-Contrast Hounsfield Units of Fixated and Non-Fixated Soft-Tissue Samples.

    Directory of Open Access Journals (Sweden)

    Marian Willner

    Full Text Available X-ray phase-contrast imaging is a novel technology that achieves high soft-tissue contrast. Although its clinical impact is still under investigation, the technique may potentially improve clinical diagnostics. In conventional attenuation-based X-ray computed tomography, radiological diagnostics are quantified by Hounsfield units. Corresponding Hounsfield units for phase-contrast imaging have been recently introduced, enabling a setup-independent comparison and standardized interpretation of imaging results. Thus far, the experimental values of few tissue types have been reported; these values have been determined from fixated tissue samples. This study presents phase-contrast Hounsfield units for various types of non-fixated human soft tissues. A large variety of tissue specimens ranging from adipose, muscle and connective tissues to liver, kidney and pancreas tissues were imaged by a grating interferometer with a rotating-anode X-ray tube and a photon-counting detector. Furthermore, we investigated the effects of formalin fixation on the quantitative phase-contrast imaging results.

  3. Bioreactor activated graft material for early implant fixation in bone

    DEFF Research Database (Denmark)

    Snoek Henriksen, Susan; Ding, Ming; Overgaard, Søren

    2011-01-01

    Technological Institute, Denmark). The granules were coated with poly-lactic acid (PLA) 12%, in order to increase the mechanical strength of the material (Phusis, France). Scaffold granules (Ø~900-1400 µm, 80% porosity) in group 2 consisted of pure HA/β-TCP (FinCeramica, Italy). For both groups, cells were...

  4. Comparative Evaluation of Osseointegration of Dental Endodontic Implants with and without Plasma- Sprayed Hydroxy apatite Coating

    OpenAIRE

    Moosavi SB.; Fathi MH. BS; MSC; Feizi Gh; Mortazavi V

    2001-01-01

    Bone osseointegration around dental implant can cause earlier stabilization and fixation of implant and reduce healing time. Hydroxyapatite coating can affect bone osseointegration and enhance its rates. The aim of this study was comparison of osseointegration between plasma sprayed hydroxyapatite coated and uncoated dental implants in cats. Four endodontic implants including, vitallium and two stainless steel with and without hydroxyapatite coating were prepared and placed in mandibular cani...

  5. Analysis and an overview of fixators in medicine and the methods of processing materials for producing fixators

    Directory of Open Access Journals (Sweden)

    Dalibor Milojko Đenadić

    2013-06-01

    Full Text Available The fixator is a medical device that provides support to fractured biological structures. Metal biomaterials are mainly used for replacing broken or damaged hard tissues such as bones because of their high strenght, toughness and corrosion resistance. Materials such as stainless steel, titanium and aluminium alloys (Ti-6Al-4V, cobalt and chromium alloys, composite materials and other biocompatible materials are used in orthopedy for the stabilization of connective tissue injuries or as a substitute for the bone tissues. Fixators are classified according to the place of installation to external and internal fixators. Widely used medical fixators are pins, rods plates, screws, pipes, wires, nails and external fixators. Conventional and non-conventional methods of processing are used in the production process for all types of fixators. Introduction Fixators are medical devices manufactured to support damaged biological structures. In the field of orthopedic surgery that deals with skeletal disorders such as bone, spine, joints, muscles and tendons injuries and diseases, various metals, titanium and cobalt alloys etc. are used to stabilize the supporting tissue injuries or as a substitute for bone tissues. Metallic implants are frequently used in orthopedic surgery as joint prosthesis (hip, knee and elbow fracture fixation devices (plates, screws, external fixators and devices for the fixation of the spine. In principle, fixators are devided into external and internal ones, depending on the place of installation (outside or inside the body. The most common types of medical fixators are pins, rods and plates. This paper presents some of the most common materials used for the production of fixators, their processing and possibilties of use in medicine for various purposes. Types of fixators and materials used for their production Nowadays, biocompatible materials are usually used for the production of fixators and implants. These materials show good

  6. Implantable contraception.

    Science.gov (United States)

    Meckstroth, K R; Darney, P D

    2000-12-01

    Although levonorgestrel contraceptive implants have been available for over 15 years, innovations have only recently led to a wider choice. These new implants offer easier insertion and removal and other advantages depending on the type of progestin. Implants prevent pregnancy by several mechanisms, including inhibition of ovulation and luteal function and alteration of cervical mucus and the endometrium. The high efficacy and ease of maintenance make implants an ideal contraceptive for many women, including adolescents, a population that uses implants infrequently but reports high satisfaction. Implants are appropriate for women who are breastfeeding, who have contraindications to estrogen, or who have diseases such as diabetes, hypertension, sickle cell anemia, or an HIV infection because implants have few metabolic or hematologic effects. Long-term use has not been associated with a decrease in BMD and generally leads to increased blood levels and iron stores. Women who wish to space their pregnancies appreciate the nearly immediate onset of action with insertion and the rapid termination of all effects with removal. All types of implants lead to menstrual changes and other side effects in some women. Adverse effects that occur in implant users more than the general population include headaches and acne. Women must be thoroughly counseled regarding the potential for menstrual alteration, side effects, and sexually transmitted infections if they do not use condoms. Despite their initial high cost, implants are a cost-effective method over several years, even when discontinued before the life of the implant.

  7. Enhancement of Apoptosis by Titanium Alloy Internal Fixations during Microwave Treatments for Fractures: An Animal Study.

    Directory of Open Access Journals (Sweden)

    Gang Wang

    Full Text Available Microwaves are used in one method of physical therapy and can increase muscle tissue temperature which is useful for improving muscle, tendon and bone injuries. In the study, we sought to determine whether titanium alloy internal fixations influence apoptosis in tissues subjected to microwave treatments at 2,450 MHz and 40 W during the healing of fractures because this issue is not yet fully understood.In this study, titanium alloy internal fixations were used to treat 3.0-mm transverse osteotomies in the middle of New Zealand rabbits' femurs. After the operation, 30-day microwave treatments were applied to the 3.0 mm transverse osteotomies 3 days after the operation. The changes in the temperatures of the muscle tissues in front of the implants or the 3.0 mm transverse osteotomies were measured during the microwave treatments. To characterize the effects of titanium alloy internal fixations on apoptosis in the muscles after microwave treatment, we performed TUNEL assays, fluorescent real-time (quantitative PCR, western blotting analyses, reactive oxygen species (ROS detection and transmission electron microscopy examinations.The temperatures were markedly increased in the animals with the titanium alloy implants. Apoptosis in the muscle cells of the implanted group was significantly more extensive than that in the non-implanted control group at different time points. Transmission electron microscopy examinations of the skeletal muscles of the implanted groups revealed muscular mitochondrial swelling, vacuolization. ROS, Bax and Hsp70 were up-regulated, and Bcl-2 was down-regulated in the implanted group.Our results suggest that titanium alloy internal fixations caused greater muscular tissue cell apoptosis following 2,450 MHz, 40 W microwave treatments in this rabbit femur fracture models.

  8. Dental Implant Surgery

    Science.gov (United States)

    ... to find out more. Dental Implant Surgery Dental Implant Surgery Dental implant surgery is, of course, surgery, and is ... to find out more. Dental Implant Surgery Dental Implant Surgery Dental implant surgery is, of course, surgery, and is ...

  9. Short-term outcomes of arthroscopic TightRope® fixation are better than hook plate fixation in acute unstable acromioclavicular joint dislocations.

    Science.gov (United States)

    Bin Abd Razak, Hamid Rahmatullah; Yeo, Eng-Meng Nicholas; Yeo, William; Lie, Tijauw-Tjoen Denny

    2017-12-09

    The aim of this study was to compare the short-term outcomes of arthroscopic TightRope® fixation with that of hook plate fixation in patients with acute unstable acromioclavicular joint dislocations. We conducted a prospective case-control study of twenty-six patients with an acute ACJ dislocation who underwent surgical repair with either an arthroscopic TightRope® fixation or a hook plate from 2013 to 2016. Clinical and radiological data were collected prospectively. Clinical outcomes were evaluated using the Constant Score, the University of California at Los Angeles (UCLA) Shoulder Score, Oxford Shoulder Score as well as the visual analogue scale. Radiological outcomes were assessed with the coracoclavicular distance (CCD). Sixteen patients underwent arthroscopic TightRope® fixation, while 10 patients underwent hook plate fixation. There were no significant differences in the preoperative variables except for the mean UCLA 4b infraspinatus score (TightRope® 2.8 vs. hook plate 3.8; p = 0.030). Duration of surgery was significantly longer in the TightRope® group. At 1 year post-operatively, the TightRope® group had a significantly better Constant Score and CCD with no complications. All patients with hook plate fixation had to undergo a second procedure for removal of implant, and 3 patients had complications. Arthroscopic TightRope® fixation is a good option for the treatment of acute unstable ACJ dislocations. It has better short-term clinical and radiological outcomes as well as lesser complications when compared to hook plate fixation. Therapeutic, Level III.

  10. Influence of prosthesis design and implantation technique on implant stresses after cementless revision THR

    Directory of Open Access Journals (Sweden)

    Duda Georg N

    2011-05-01

    Full Text Available Abstract Background Femoral offset influences the forces at the hip and the implant stresses after revision THR. For extended bone defects, these forces may cause considerable bending moments within the implant, possibly leading to implant failure. This study investigates the influences of femoral anteversion and offset on stresses in the Wagner SL revision stem implant under varying extents of bone defect conditions. Methods Wagner SL revision stems with standard (34 mm and increased offset (44 mm were virtually implanted in a model femur with bone defects of variable extent (Paprosky I to IIIb. Variations in surgical technique were simulated by implanting the stems each at 4° or 14° of anteversion. Muscle and joint contact forces were applied to the reconstruction and implant stresses were determined using finite element analyses. Results Whilst increasing the implant's offset by 10 mm led to increased implant stresses (16.7% in peak tensile stresses, altering anteversion played a lesser role (5%. Generally, larger stresses were observed with reduced bone support: implant stresses increased by as much as 59% for a type IIIb defect. With increased offset, the maximum tensile stress was 225 MPa. Conclusion Although increased stresses were observed within the stem with larger offset and increased anteversion, these findings indicate that restoration of offset, key to restoring joint function, is unlikely to result in excessive implant stresses under routine activities if appropriate fixation can be achieved.

  11. Hard and soft tissue changes around implants installed in regular-sized and reduced alveolar bony ridges. An experimental study in dogs.

    Science.gov (United States)

    Baffone, Gabriele; Lang, Niklaus P; Pantani, Fabio; Favero, Giovanni; Ferri, Mauro; Botticelli, Daniele

    2015-01-01

    To study bony and soft tissue changes at implants installed in alveolar bony ridges of different widths. In 6 Labrador dogs, the mandibular premolars and first molars were extracted, and a buccal defect was created in the left side at the third and fourth premolars by removing the buccal bone and the inter-radicular and interdental septa. Three months after tooth extraction, full-thickness mucoperiosteal flaps were elevated, and implants were installed, two at the reduced (test) and two at the regular-sized ridges (control). Narrow or wide abutments were affixed to the implants. After 3 months, biopsies were harvested, and ground sections prepared for histological evaluation. A higher vertical buccal bony crest resorption was found at the test (1.5 ± 0.7 mm and 1.0 ± 0.7 mm) compared to the control implants (1.0 ± 0.5 mm and 0.7 ± 0.4 mm), for both wide and narrow abutment sites. A higher horizontal alveolar resorption was identified at the control compared to the test implants. The difference was significant for narrow abutment sites. The peri-implant mucosa was more coronally positioned at the narrow abutment, in the test sites, while for the control sites, the mucosal adaptation was more coronal at the wide abutment sites. These differences, however, did not reach statistical significance. Implants installed in regular-sized alveolar ridges had a higher horizontal, but a lower vertical buccal bony crest resorption compared to implants installed in reduced alveolar ridges. Narrow abutments in reduced ridges as well as wide abutments in regular-sized ridges yielded less soft tissue recession compared to their counterparts. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. Impact of immediate loading on early soft tissue healing at two-piece implants placed in fresh extraction sockets: an experimental study in the beagle dog.

    Science.gov (United States)

    Mareque, S; Liñares, A; Pérez, J; Muñoz, F; Ramos, I; Blanco, J

    2014-08-01

    To study early soft tissue healing of immediately placed implants with or without immediate loading in the dog. Forty-eight implants were placed in the distal sockets of Pm3 and Pm4 in the lower jaw of 12 beagle dogs immediately after tooth extraction. In the control group, no loading was applied. In the test group, an immediate loading restoration with occlusal contacts was performed. Dogs were sacrificed at 2, 4, and 8 weeks for histological analysis. At the end of the study, there was a 100% implant and prosthesis survival. The biological width dimension was similar in both groups at all the studied healing periods. This dimension tended to decrease from week 2 to 8 in both groups, on both the buccal and lingual side. The barrier epithelium tended to stop at the implant-abutment interface in both groups and also decreased in length from week 2 to 8, on the buccal and the lingual side. Soft tissue recession remained low and occurred mainly in the test group. The characteristics, dimension, and healing pattern of the peri-implant soft tissues were similar around immediate implants with or without immediate loading. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Understanding Nitrogen Fixation

    Energy Technology Data Exchange (ETDEWEB)

    Paul J. Chirik

    2012-05-25

    synthesis of ammonia, NH{sub 3}, from its elements, H{sub 2} and N{sub 2}, via the venerable Haber-Bosch process is one of the most significant technological achievements of the past century. Our research program seeks to discover new transition metal reagents and catalysts to disrupt the strong N {triple_bond} N bond in N{sub 2} and create new, fundamental chemical linkages for the construction of molecules with application as fuels, fertilizers and fine chemicals. With DOE support, our group has discovered a mild method for ammonia synthesis in solution as well as new methods for the construction of nitrogen-carbon bonds directly from N{sub 2}. Ideally these achievements will evolve into more efficient nitrogen fixation schemes that circumvent the high energy demands of industrial ammonia synthesis. Industrially, atmospheric nitrogen enters the synthetic cycle by the well-established Haber-Bosch process whereby N{sub 2} is hydrogenated to ammonia at high temperature and pressure. The commercialization of this reaction represents one of the greatest technological achievements of the 20th century as Haber-Bosch ammonia is responsible for supporting approximately 50% of the world's population and serves as the source of half of the nitrogen in the human body. The extreme reaction conditions required for an economical process have significant energy consequences, consuming 1% of the world's energy supply mostly in the form of pollution-intensive coal. Moreover, industrial H{sub 2} synthesis via the water gas shift reaction and the steam reforming of methane is fossil fuel intensive and produces CO{sub 2} as a byproduct. New synthetic methods that promote this thermodynamically favored transformation ({Delta}G{sup o} = -4.1 kcal/mol) under milder conditions or completely obviate it are therefore desirable. Most nitrogen-containing organic molecules are derived from ammonia (and hence rely on the Haber-Bosch and H{sub 2} synthesis processes) and direct synthesis from

  14. Biomechanical considerations in slipped capital femoral epiphysis and insights into prophylactic fixation.

    Science.gov (United States)

    Leblanc, E; Bellemore, J M; Cheng, T; Little, D G; Birke, O

    2017-04-01

    Slipped capital femoral epiphysis (SCFE) is a deformity of the proximal femur secondary to widened and unstable physis. In stabilising the slip, gold standard treatments stop growth and involve premature physeal closure, which prevents the remodelling of the acquired deformity and creates a leg length discrepancy that may be significant in younger patients. We measured the impact of placing threaded screws across the proximal femoral physis by measuring the centre-trochanteric distance (CTD) and articulo-trochanteric distance (ATD) in participants with or without prophylactic fixation. We then compared the mechanical performance of static (stainless and titanium cannulated Synthes screws) and potentially growing implants (Synthes SCFE screw and Pega Medical Free Gliding screw) in a validated synthetic bone model. In the review of 30 non-fixed and 60 fixated hips over a mean follow-up of 1.9 years, we have noted a significant difference in pre/post CTD and ATD, as well as the change in CTD and ATD over time. In the biomechanical study, the newer implants allowing growth (Synthes SCFE screw and Pega Medical Free Gliding screw) were both shown to be at least non-inferior. The primary deformity of a SCFE in itself alters hip mechanics. Also, as confirmed in this study, there is a secondary deformity that is created by static fixation and relative trochanteric overgrowth. To help remodel mild deformities and prevent secondary trochanteric overgrowth, growing implants seem to be non-inferior to the more standard means of fixation in static testing.

  15. A long-term, prospective, cohort study on the performance of right ventricular pacing leads: comparison of active-fixation with passive-fixation leads.

    Science.gov (United States)

    Liu, Lie; Tang, Jiaojiao; Peng, Hu; Wu, Shulin; Lin, Chunying; Chen, Dongli; Zhang, Qianhuan; Liang, Yuanhong; Chen, Silin; Chen, Yan; Wei, Huiqiang

    2015-01-07

    Active-fixation pacing leads allow the use of selective pacing sites. We evaluated their long-term performance versus passive-fixation leads in 199 newly implanted patients (n = 100 active and n = 99 passive). Postoperative pacing thresholds in the active group were higher than in the passive group (0.85 ± 0.31 V vs. 0.53 ± 0.21 V at baseline, P leads returned to below 1 V. One active left ventricular lead dislodged. One passive left subclavian lead insulation fracture occurred. Thus Active fixation pacing leads are stable in a five-year long-term follow up. There was no difference between active and passive leads in terms of electrical performance.

  16. Primary fixation of mini slings: a comparative biomechanical study in vivo

    Directory of Open Access Journals (Sweden)

    Paulo Palma

    2012-04-01

    Full Text Available INTRODUCTION AND OBJECTIVES: The mini sling concept for stress urinary incontinence is an anatomical approach that involves placing a midurethral low-tension tape anchored to the obturator internus muscles bilaterally. They overcome the blind passage of long needles and all the related complications. There are many different devices available and because these are outpatient procedures, primary fixation plays an important role in the outcome. The objective is to evaluate the primary fixation of the various devices of attachment of the commercially available mini-slings through biomechanical tests. MATERIALS AND METHODS: A total of 45 Wistar rats were divided in 3 groups of 15 rats each. They underwent 5 subcutaneous implantation of different mini slings and one polipropilene mesh (control, as follows: TVT-Secur® (Gynecare, USA, Type 1 polypropylene mesh (control; Ophira Mini Sling System® (Promedon, Argentina, Tissue Fixation System® (TFS PTY, Australia, Zipper Sling® and "T device" (Prosurg, USA. The abdominal wall was removed on bloc at different times after implant for biomechanical evaluation, which consisted in application of unidirectional force to the extremity of the fixation system or mesh, until it was completely removed from the tissue using a tension meter (Nexygen 3.0 Universal Testing Machine - LLOYD Instruments. The force was measured in Newtons (N. RESULTS: There was significant difference in the resistance to extraction among the different fixation systems. At 7 days the Ophira Mini Sling System® presented the best fixation and "T dispositive" the worst. CONCLUSION: Ophira mini sling System® presented the best primary fixation at 7º, 14º and 30º days. The impact of this feature in the clinical setting needs to be verified.

  17. Postoperative complications associated with external skeletal fixators in cats.

    Science.gov (United States)

    Beever, Lee; Giles, Kirsty; Meeson, Richard

    2017-07-01

    The objective of this study was to quantify complications associated with external skeletal fixators (ESFs) in cats and to identify potential risk factors. A retrospective review of medical records and radiographs following ESF placement was performed. Case records of 140 cats were reviewed; fixator-associated complications (FACs) occurred in 19% of cats. The region of ESF placement was significantly associated with complication development. Complications developed most frequently in the femur (50%), tarsus (35%) and radius/ulna (33%). Superficial pin tract infection (SPTI) and implant failure accounted for 45% and 41% of all FACs, respectively. SPTI occurred more frequently in the femur, humerus and tibia, with implant failure more frequent in the tarsus. No association between breed, age, sex, weight, fracture type (open vs closed), ESF classification, number of pins per bone segment, degree of fracture load sharing, and the incidence or type of FAC was identified. No association between region of placement, breed, age, sex, weight, fracture type (open vs closed), ESF classification, number of pins per bone segment, fracture load sharing and the time to complication development was identified. Complication development is not uncommon in cats following ESF placement. The higher complication rate in the femur, tarsus and radius/ulna should be considered when reviewing options for fracture management. However, cats appear to have a lower rate of pin tract infections than dogs.

  18. Keratoprosthesis. Implantation of artificial corneas.

    Science.gov (United States)

    Berta, A

    1997-01-01

    Keratoprosthesis (implantation of artificial, plastic cornea) is indicated in severe cases with corneal leucoma (non-transparent, cicatrized cornea) in which keratoplasty (corneal transplantation) is not possible or has repeatedly failed. In the past 40 years we implanted 37 artificial corneas (7 Cardona type, 29 Konstantinov type, 1 Fjodorov type). The visual acuity increase was temporary (lasting from a few weeks to a few months) in 25 patients. The visual acuity was at least 0.2 three years following the implantation of keratoprosthesis in 12 patients. One patient had 1.0 vision 10 years after surgery. Our results indicate that the implantation of artificial corneal is still an "ultimum refugium", an operation that can be justified only in monocular patients, in eyes that cannot be and/or had unsuccessfully been operated on with repeated keratoplasties. The visual improvement is temporary, but in some cases may last for several years. Still this is the only procedure by which useful vision can be provided, for shorter or longer time intervals, for patients suffering from corneal blindness (nontransparent cornea in otherwise functioning eye) whose only eye cannot be treated with corneal transplantation. Keratoprosthesis with better biocompatibility, better fixation techniques, and wider visual fields have to be developed before the implantation of artificial cornea can be looked upon as a surgical procedure with which full optical rehabilitation can be achieved.

  19. miR-451 deficiency is associated with altered endometrial fibrinogen alpha chain expression and reduced endometriotic implant establishment in an experimental mouse model.

    Directory of Open Access Journals (Sweden)

    Warren B Nothnick

    Full Text Available Endometriosis is defined as the growth of endometrial glandular and stromal components in ectopic locations and affects as many as 10% of all women of reproductive age. Despite its high prevalence, the pathogenesis of endometriosis remains poorly understood. MicroRNAs, small non-coding RNAs that post-transcriptionally regulate gene expression, are mis-expressed in endometriosis but a functional role in the disease pathogenesis remains uncertain. To examine the role of microRNA-451 (miR-451 in the initial development of endometriosis, we utilized a novel mouse model in which eutopic endometrial fragments used to induce endometriosis were deficient for miR-451. After induction of the disease, we evaluated the impact of this deficiency on implant development and survival. Loss of miR-451 expression resulted in a lower number of ectopic lesions established in vivo. Analysis of differential protein profiles between miR-451 deficient and wild-type endometrial fragments revealed that fibrinogen alpha polypeptide isoform 2 precursor was approximately 2-fold higher in the miR-451 null donor endometrial tissue and this elevated expression of the protein was associated with altered expression of the parent fibrinogen alpha chain mRNA and protein. As this polypeptide contains RGD amino acid "cell adhesion" motifs which could impact early establishment of lesion development, we examined and confirmed using a cyclic RGD peptide antagonist, that endometrial cell adhesion and endometriosis establishment could be respectively inhibited both in vitro and in vivo. Collectively, these results suggest that the reduced miR-451 eutopic endometrial expression does not enhance initial establishment of these fragments when displaced into the peritoneal cavity, that loss of eutopic endometrial miR-451 expression is associated with altered expression of fibrinogen alpha chain mRNA and protein, and that RGD cyclic peptide antagonists inhibit establishment of endometriosis

  20. Minimally invasive treatment of unstable pelvic ring injuries with modified pedicle screw-rod fixator.

    Science.gov (United States)

    Wu, Xiao-Tian; Liu, Zuo-Qing; Fu, Wen-Qin; Zhao, Shan

    2018-01-01

    Objective To evaluate the clinical application of the minimally invasive modified pedicle screw-rod fixator for unstable pelvic ring injuries, including its feasibility, merits, and limitations. Methods Twenty-three patients (13 males, 10 females; average age, 36.3 years) with unstable pelvic ring injuries underwent anterior fixation using a modified pedicle screw-rod fixator with or without posterior fixation using a transiliac internal fixator. The clinical findings were assessed using Majeed scores. The quality of reduction was evaluated using the Matta criteria. Results Clinical results at 1 year postoperatively were excellent in 14 patients, good in 7, and fair in 2. The two patients with fair results had intermittent pain at the sacroiliac joint because of the posterior implant. One woman complained of persistent pain at the pubic tubercle during sexual intercourse. Iatrogenic neuropraxia of the unilateral lateral femoral cutaneous nerve occurred in three patients. Unilateral femoral nerve palsy occurred in one patient. The quality of fracture reduction was excellent in 12 patients, good in 8, and fair in 3. Heterotopic ossification occurred in eight patients; all were asymptomatic. Conclusions Minimally invasive modified pedicle screw-rod fixation is an effective alternative treatment for pelvic ring injuries.

  1. Prosthetic strap system for simplified ventral hernia repair: results of a porcine experimental model.

    Science.gov (United States)

    Amato, G; Romano, G; Agrusa, A; Cassata, G; Salamone, G; Gulotta, G

    2010-08-01

    Aiming to achieve a simplified ventral hernia repair, a proprietary oval-shaped mesh was experimentally tested in a porcine model. The mesh is structured with a large central body and radiating straps. The friction of the straps passing through the tissues are hypothesized to be adequate to maintain the position of the mesh during tissue ingrowth, avoiding classic point fixation while ensuring a wide coverage of the abdomen. The mesh, having six radial straps, was placed using a sublay preperitoneal technique in four pigs. All straps were passed laterally through the abdominal wall and exteriorized from the skin. The straps were trimmed at the level of the skin, allowing the stumps to recoil into the subcutaneous space. The animals were euthanized at 1 and 4 months to determine the integration of the straps. Macroscopically, all 24 straps were firmly incorporated within the abdominal wall. The tension-free placement of the mesh by using the straps was effective. The friction of the straps passing through the tissues was adequate to keep the mesh well orientated. No dislocation of the implants was observed. The strap system also allowed a broader coverage of the abdominal wall, far beyond the wound opening. The described arm system of the aforementioned implant seems to be effective in eliminating point fixation of the mesh. The fixation arms seemed to have ensured that the mesh stayed orientated in all of the animals. A very wide lateral mesh placement was accomplished, assuring sufficient defect overlap when shrinkage occurs.

  2. Kangaroo vs. porcine aortic valves: calcification potential after glutaraldehyde fixation.

    Science.gov (United States)

    Narine, K; Chéry, Cyrille C; Goetghebeur, Els; Forsyth, R; Claeys, E; Cornelissen, Maria; Moens, L; Van Nooten, G

    2005-01-01

    The aim of this study was to evaluate and compare the calcification potential of kangaroo and porcine aortic valves after glutaraldehyde fixation at both low (0.6%) and high (2.0%) concentrations of glutaraldehyde in the rat subcutaneous model. To our knowledge this is the first report comparing the time-related, progressive calcification of these two species in the rat subcutaneous model. Twenty-two Sprague-Dawley rats were each implanted with two aortic valve leaflets (porcine and kangaroo) after fixation in 0.6% glutaraldehyde and two aortic valve leaflets (porcine and kangaroo) after fixation in 2% glutaraldehyde respectively. Animals were sacrificed after 24 h and thereafter weekly for up to 10 weeks after implantation. Calcium content was determined using inductively coupled plasma-mass spectrometry and confirmed histologically. Mean calcium content per milligram of tissue (dry weight) treated with 0.6 and 2% glutaraldehyde was 116.2 and 110.4 microg/mg tissue for kangaroo and 95.0 and 106.8 microg/mg tissue for porcine valves. Calcium content increased significantly over time (8.8 microg/mg tissue per week) and was not significantly different between groups. Regression analysis of calcification over time showed no significant difference in calcification of valves treated with 0.6 or 2% glutaraldehyde within and between the two species. Using the subcutaneous model, we did not detect a difference in calcification potential between kangaroo and porcine aortic valves treated with either high or low concentrations of glutaraldehyde. Copyright 2005 S. Karger AG, Basel.

  3. Sulfur Fixation by Chemically Modified Red Mud Samples Containing Inorganic Additives: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-01-01

    Full Text Available Sulfur retention ability of Bayer red mud from alumina plant was investigated. Bayer red mud modified by fusel salt and waste mother liquor of sodium ferrocyanide as the main sulfur fixation agent and the calcium based natural mineral materials as servicing additives; the experimental results showed the following: (1 Through 10 wt% waste mother liquor of sodium ferrocyanide modifying Bayer red mud, sulfur fixation rate can increase by 13 wt%. (2 Magnesium oxide can obviously improve the sulfur fixation performance of Bayer red mud and up to a maximum sulfur fixation rate of 47 wt% at adding 1 wt% magnesium oxide. (3 Dolomite enhanced the sulfur fixation performances with the sulfur fixation rate of 68 wt% in optimized condition. (4 Vermiculite dust reduced sulfur dioxide during the fixed-sulfur process of modified Bayer red mud, and the desulphurization ration could reach up to a maximum 76 wt% at 950°C. (5 An advanced three-component sulfur fixation agent was investigated, in which the optimized mass ratio of modified Bayer red mud, dolomite, and vermiculite dust was 70 : 28 : 2 in order, and its sulfur fixation efficiency has reached to a maximum 87 wt% under its 20 wt% dosage in the coal.

  4. Efectos de diferentes tratamientos antiosteoporóticos sobre la osteointegración de implantes dentales en un modelo experimental en conejos

    OpenAIRE

    Almagro Fernández, María Isabel

    2011-01-01

    Los ensayos clínicos sugieren que la pérdida de masa ósea con el deterioro de la microarquitectura que caracteriza a la osteoporosis se considera un factor de riesgo para la osteointegración de los implantes dentales. Sin embargo, existen pocos estudios comparativos que proporcionen información sobre los efectos que el tratamiento antiosteoporótico provoca en la osteointegración de implantes dentales en estos pacientes. La hipótesis de esta tesis es que el tratamiento antiosteo...

  5. Robot Motion Vision by Fixation

    Science.gov (United States)

    1992-09-01

    These are 8 - bit images but the last two digits are usually too noisy to be reliable. The true motion between these frames is a combination of...Brightness Gradients 2nd ImageN Ist Image yk t k+) Sti+ l Figure B-i: The first brightness derivatives required in the direct methods can be estimated...individual time varying frames, the above algorithms compensate for part of the tessellation errors involved in discrete digitized images. Depth at Fixation

  6. Implant contraception.

    Science.gov (United States)

    Meckstroth, K R; Darney, P D

    2001-12-01

    The experience of 6 million Norplant users has led to several more advanced implants. Implanon is a single-rod implant system containing a low androgenic progestin and requires 1 to 2 minutes for insertion and removal. Like other implants, Implanon prevents pregnancy by changing the character of the cervical mucus and interfering with luteal function. Unlike Norplant, though, Implanon is designed to prevent ovulation for the full duration of use. Implant contraception has several advantages over other types of contraception including high efficacy, minimal required maintenance, absence of estrogen, and rapid return of fertility after discontinuation. Implants can be a good choice for adolescents; women with hypertension, diabetes, anemia, endometriosis, or other medical problems; and women who are breast-feeding. Irregular bleeding is the most common adverse effect of implants and can be treated with several medication regimens. Preinsertion counseling, however, is the most important factor in ensuring satisfaction with implants. Unfortunately, no implant system is currently available in the United States since August 2000, but Implanon is expected to reach the U.S. market within the next 2 years.

  7. Smaller Fixation Target Size Is Associated with More Stable Fixation and Less Variance in Threshold Sensitivity.

    Directory of Open Access Journals (Sweden)

    Kazunori Hirasawa

    Full Text Available The aims of this randomized observational case control study were to quantify fixation behavior during standard automated perimetry (SAP with different fixation targets and to evaluate the relationship between fixation behavior and threshold variability at each test point in healthy young participants experienced with perimetry. SAP was performed on the right eyes of 29 participants using the Octopus 900 perimeter, program 32, dynamic strategy. The fixation targets of Point, Cross, and Ring were used for SAP. Fixation behavior was recorded using a wearable eye-tracking glass. All participants underwent SAP twice with each fixation target in a random fashion. Fixation behavior was quantified by calculating the bivariate contour ellipse area (BCEA and the frequency of deviation from the fixation target. The BCEAs (deg2 of Point, Cross, and Ring targets were 1.11, 1.46, and 2.02, respectively. In all cases, BCEA increased significantly with increasing fixation target size (p < 0.05. The logarithmic value of BCEA demonstrated the same tendency (p < 0.05. A positive correlation was identified between fixation behavior and threshold variability for the Point and Cross targets (ρ = 0.413-0.534, p < 0.05. Fixation behavior increased with increasing fixation target size. Moreover, a larger fixation behavior tended to be associated with a higher threshold variability. A small fixation target is recommended during the visual field test.

  8. Mechanical evaluation of adjunctive fixation for prevention of periprosthetic femur fracture with the Zurich cementless total hip prosthesis.

    Science.gov (United States)

    Pozzi, Antonio; Peck, Jeffrey N; Chao, Peini; Choate, Christina J; Barousse, Dan; Conrad, Bryan

    2013-06-01

    To evaluate whether cerclage wire or a lateral plate increases the peak-torque load to failure, compared to femora without adjunctive fixation, in femora implanted with Zurich Cementless stems. In vitro biomechanical study. Paired femora from adult dogs (n = 24) weighing 28-35 kg. Pairs of femora were implanted with a stem and randomly assigned to 2 treatment groups: cerclage or plate. Within each pair, either 3 loop cerclage wires or a laterally applied 12-hole Advanced Locking Plate System 10-mm plate (ALPS 10) were implanted in a femur, whereas the contralateral femur acted as control with no adjunctive fixation. After application of a static axial load each specimen was loaded to failure in torsion. Peak torque load at failure was compared between femora with each adjunctive fixation and the control using a paired t-test; P plated group (P plates and with cerclage were 13.9% and 7.2% stronger in torsion than the femora without fixation, respectively. Adjunctive fixation with a laterally applied ALPS 10 may aid in the prevention of peri-prosthetic fractures associated with Zurich Cementless medium stems. © Copyright 2013 by The American College of Veterinary Surgeons.

  9. Particle migration and gap healing around trabecular metal implants

    DEFF Research Database (Denmark)

    Rahbek, O; Kold, S; Zippor, B

    2005-01-01

    Bone on-growth and peri-implant migration of polyethylene particles were studied in an experimental setting using trabecular metal and solid metal implants. Cylindrical implants of trabecular tantalum metal and solid titanium alloy implants with a glass bead blasted surface were inserted either...

  10. Different methods of mesh fixation in open retromuscular incisional hernia repair: a comparative study in pigs.

    Science.gov (United States)

    Grommes, J; Binnebösel, M; Klink, C D; von Trotha, K T; Junge, K; Conze, J

    2010-12-01

    Reinforcement of the abdominal wall with alloplastic mesh material in incisional hernia repair is well established. To avoid dislocation and migration of the prostheses, mesh fixation is recommended. However, there seems to be a correlation between postoperative pain and mesh fixation. Furthermore, it remains unclear whether mesh fixation is necessary at all. A retromuscular mesh implantation was performed in 36 pigs using a polypropylene-polyglecaprone 25 composite mesh (Ultrapro(®), 12 × 18 cm). In group 1, the mesh was fixed to the posterior rectus sheet with non absorbable single sutures (Prolene(®) 2-0), in group 2 fixation was with absorbable sutures (Vicryl(®) 2-0), in group 3 mesh fixation was with 5 ml fibrin sealant (Quixil(®)), and, as a control, there was no fixation in group 4. The abdominal wall was explanted on postoperative day 7, 14 and 56. Mesh size and position was measured, and pull-out force of the mesh was analysed mechanically by tensiometry. The ratio of collagen type I/III was analysed to determine the quality of mesh integration. Neither mesh dislocation nor mesh migration was detected. Mesh size showed no significant differences, whether comparing time points or groups. No significant differences in the tensile strength of mesh integration were found when comparing the groups (group 1: 155 ± 17 mmHg; group 2: 175 ± 9 mmHg; group 3: 166 ± 24 mmHg; group 4: 172 ± 28 mmHg). Though the type I/III collagen ratio increased over time, no significant differences according to the type of fixation used were detected. Mesh fixation in open incisional hernia repair with retromuscular mesh augmentation to avoid mesh dislocation or migration in the early postoperative period appears to be unnecessary.

  11. Estudo histológico comparativo de implantes (ímãs em órbitas de coelhas Comparative histologic study of implants (magnets in orbits of female rabbits

    Directory of Open Access Journals (Sweden)

    Elcio Roque Kleinpaul

    2005-10-01

    Full Text Available OBJETIVOS: Avaliação microscópica dos sinais da reação inflamatória causada pela fixação de implante orbitário (ímã, recoberto por ouro. MÉTODOS: Estudo experimental em 54 coelhas adultas, divididas em três grupos de 18, com 3 subgrupos de 6, avaliação com uma, três e seis semanas de pós-operatório. Fixação, no rebordo inferior da órbita, de implante (ímã e ouro por meio de cola, parafuso ou fio inabsorvível (Mersilene 5.0®. As órbitas contralaterais (sem implante compuseram o grupo-controle. RESULTADOS: Sinais histológicos de reação inflamatória à fixação orbitária do implante foram observados, com cianoacrilato, parafuso, ou sutura inabsorvível (Mersilene 5.0®, até a sexta semana pós-operatória, com predomínio do processo inflamatório crônico e fibrótico cicatricial, sem demonstrar diferenças estatisticamente significativas na maior parte dos casos. CONCLUSÃO: O exame histopatológico demonstrou, na maior parte das órbitas com e sem implante, presença de reação inflamatória aguda e crônica até a sexta semana pós-operatória, com predomínio de processo inflamatório crônico e fibrótico cicatricial, sem demonstrar, na maior parte dos casos, diferenças estatisticamente significante entre os grupos experimental e controle.PURPOSE: To evaluate microscopically the signs of inflammatory reaction due to the fixation of an orbitary implant (magnet, covered by gold. METHODS: An experimental study was performed in 54 adult female rabbits, divided into 3 groups of eighteen with 3 subgroups of 6; an evaluation at 1, 3 and 6 postoperative weeks was performed. An implant (magnet, covered by gold was fixed in the inferior orbital rim using biologic glue, screw or unabsorbable suture (Mersilene 5.0®. The opposite orbits (without implants represented the control group. RESULTS: Microscopic signs of inflammatory reaction due to orbitary fixation of the implant were observed with the use of the three

  12. About Implantable Contraception

    Science.gov (United States)

    ... Helping Your Child Deal With Death About Implantable Contraception KidsHealth > For Parents > About Implantable Contraception Print A ... How Much Does It Cost? What Is Implantable Contraception? Implantable contraception (often called the birth control implant) ...

  13. On the possibility of intermittence during fixations: a conceptual assessment.

    Science.gov (United States)

    Talasli, U

    1993-08-01

    A prevalent tacit assumption of the continuity of visual representation during fixations is challenged and shown to be logically tenuous. Relying upon three lines of suggestive evidence, it is then argued that representation must be in the form of static snapshots which alternate with very short dark periods wherein the image is omitted from vision. In view of the difficulties of a direct experimental verification of such a high-frequency intermittence, a conceptual approach to the question is defended.

  14. Abnormal Fixational Eye Movements in Amblyopia.

    Science.gov (United States)

    Shaikh, Aasef G; Otero-Millan, Jorge; Kumar, Priyanka; Ghasia, Fatema F

    2016-01-01

    Fixational saccades shift the foveal image to counteract visual fading related to neural adaptation. Drifts are slow eye movements between two adjacent fixational saccades. We quantified fixational saccades and asked whether their changes could be attributed to pathologic drifts seen in amblyopia, one of the most common causes of blindness in childhood. Thirty-six pediatric subjects with varying severity of amblyopia and eleven healthy age-matched controls held their gaze on a visual target. Eye movements were measured with high-resolution video-oculography during fellow eye-viewing and amblyopic eye-viewing conditions. Fixational saccades and drifts were analyzed in the amblyopic and fellow eye and compared with controls. We found an increase in the amplitude with decreased frequency of fixational saccades in children with amblyopia. These alterations in fixational eye movements correlated with the severity of their amblyopia. There was also an increase in eye position variance during drifts in amblyopes. There was no correlation between the eye position variance or the eye velocity during ocular drifts and the amplitude of subsequent fixational saccade. Our findings suggest that abnormalities in fixational saccades in amblyopia are independent of the ocular drift. This investigation of amblyopia in pediatric age group quantitatively characterizes the fixation instability. Impaired properties of fixational saccades could be the consequence of abnormal processing and reorganization of the visual system in amblyopia. Paucity in the visual feedback during amblyopic eye-viewing condition can attribute to the increased eye position variance and drift velocity.

  15. No effect of platelet-rich plasma with frozen or processed bone allograft around noncemented implants

    DEFF Research Database (Denmark)

    Jensen, T B; Rahbek, O; Overgaard, S

    2005-01-01

    We compared processed morselized bone allograft with fresh-frozen bone graft around noncemented titanium implants. Also, the influence of platelet-rich plasma (PRP) in combination with bone allograft was evaluated. Analysis was based on implant fixation and histomorphometry. PRP was prepared...

  16. Tophaceous Gout simulating infected Ankle Implants

    Directory of Open Access Journals (Sweden)

    Ioannis K

    2016-11-01

    Full Text Available Gout is a well known metabolic disorder characterized by the formation of urate crystals in joints resulting in recurrent attacks of acute inflammatory arthritis following which tophi can occur in joints or subcutaneous tissues. We report a rare localization of gouty tophi in a 52 years old male. The tophi had formed over the stainless steel implant used for the fixation of a lateral malleolus fracture 20 years ago.

  17. Start Position Strongly Influences Fixation Patterns during Face Processing: Difficulties with Eye Movements as a Measure of Information Use

    Science.gov (United States)

    Arizpe, Joseph; Kravitz, Dwight J.; Yovel, Galit; Baker, Chris I.

    2012-01-01

    Fixation patterns are thought to reflect cognitive processing and, thus, index the most informative stimulus features for task performance. During face recognition, initial fixations to the center of the nose have been taken to indicate this location is optimal for information extraction. However, the use of fixations as a marker for information use rests on the assumption that fixation patterns are predominantly determined by stimulus and task, despite the fact that fixations are also influenced by visuo-motor factors. Here, we tested the effect of starting position on fixation patterns during a face recognition task with upright and inverted faces. While we observed differences in fixations between upright and inverted faces, likely reflecting differences in cognitive processing, there was also a strong effect of start position. Over the first five saccades, fixation patterns across start positions were only coarsely similar, with most fixations around the eyes. Importantly, however, the precise fixation pattern was highly dependent on start position with a strong tendency toward facial features furthest from the start position. For example, the often-reported tendency toward the left over right eye was reversed for the left starting position. Further, delayed initial saccades for central versus peripheral start positions suggest greater information processing prior to the initial saccade, highlighting the experimental bias introduced by the commonly used center start position. Finally, the precise effect of face inversion on fixation patterns was also dependent on start position. These results demonstrate the importance of a non-stimulus, non-task factor in determining fixation patterns. The patterns observed likely reflect a complex combination of visuo-motor effects and simple sampling strategies as well as cognitive factors. These different factors are very difficult to tease apart and therefore great caution must be applied when interpreting absolute

  18. Cephalomedullary fixation for femoral neck/intertrochanteric and ipsilateral shaft fractures: surgical tips and pitfalls

    Directory of Open Access Journals (Sweden)

    Bali Kamal

    2013-02-01

    Full Text Available 【Abstract】Objective: Surgical management op-tions for femoral shaft fracture and ipsilateral proximal fe-mur fracture vary from single-implant to double-implant fixation. Cephalomedullary fixation in such fractures has rela-tive advantages over other techniques especially because of less soft tissue dissection and immediate postoperative weight bearing with accelerated rehabilitation. However, the surgery is technically demanding and there is a paucity of literature describing the surgical techniques for this fixation. The aim of the study was to describe the surgical technique of cephalomedullary fixation for femoral shaft fracture and ipsilateral proximal femur fracture. Methods: Sixteen cases (10 males and 6 females with a mean age of 41.8 years of ipsilateral proximal femur and shaft fractures were treated by single-stage cephalomedullary fixa-tion at tertiary level trauma center in northern India. The fractures were classified according to AO classification. An intraoperative record of duration of surgery as well as tech-nical challenges unique to each fracture pattern was kept for all the patients. Results: The most common proximal femoral pattern was AO B2.1 observed in 9 of our patients. The AO B2.3 fractures were seen in 4 patients while the AO A1.2 fractures in 3 patients. Four of the AO B2.1 and 2 of the AO B2.3 frac-tures required open reduction with Watson-Jones approach. The mean operative time was around 78 minutes, which tended to decrease as the surgical experience increased. There was only one case of malreduction, which required revision surgery. Conclusion: Combination of ipsilateral femoral shaft fracture and neck/intertrochanteric fracture is a difficult frac-ture pattern for trauma surgeons. Cephalomedullary nail is an excellent implant for such fractures but it requires careful insertion to avoid complications. Surgery is technically de-manding with a definite learning curve. Nevertheless, a ma-jority of these

  19. Does surgically fixation of pubic fracture increase the stability of the operated posterior pelvis?

    Science.gov (United States)

    Bodzay, Tamás; Sztrinkai, Gergely; Pajor, Sándor; Gál, Tamás; Jónás, Zoltán; Erdös, Péter; Váradi, Károly

    2014-01-01

    This study aims to investigate whether surgical treatment of pubic rami fractures increases the stability of the posterior pelvis. A finite element pelvic model with improved geometric and material characteristics was analyzed. By imitating a standing position, a type I Denis sacrum fracture and a unilateral pubis fracture, we measured the differences in tension and displacement. The posterior injury was treated with a direct plate synthesis or transsacral plate synthesis, while the pubis fracture was left without fixation or fixed with either a retrograde pubic screw or plate synthesis. The operative fixation of pubic rami fractures decreased the movement in the fracture gap not only at the site of the pubis fracture, but also at the site of the fixed sacrum fracture. The plate synthesis provided greater stability of the anterior fracture than the retrograde screw. The tensions in the implants were below the allowed values. We concluded that surgically fixation of pubic fracture increases the stability of the operated posterior pelvis.

  20. Comparative analysis of international standards for the fatigue testing of posterior spinal fixation systems: the importance of preload in ISO 12189.

    Science.gov (United States)

    La Barbera, Luigi; Ottardi, Claudia; Villa, Tomaso

    2015-10-01

    Preclinical evaluation of the mechanical reliability of fixation devices is a mandatory activity before their introduction into market. There are two standardized protocols for preclinical testing of spinal implants. The American Society for Testing Materials (ASTM) recommends the F1717 standard, which describes a vertebrectomy condition that is relatively simple to implement, whereas the International Organization for Standardization (ISO) suggests the 12189 standard, which describes a more complex physiological anterior support-based setup. Moreover, ASTM F1717 is nowadays well established, whereas ISO 12189 has received little attention: A few studies tried to accurately describe the ISO experimental procedure through numeric models, but these studies totally neglect the recommended precompression step. This study aimed to build up a reliable, validated numeric model capable of describing the stress on the rods of a spinal fixator assembled according to ISO 12189 standard procedure. Such a model would more adequately represent the in vitro testing condition. This study used finite element (FE) simulations and experimental validation testing. An FE model of the ISO setup was built to calculate the stress on the rods. Simulation was validated by comparison with experimental strain gauges measurements. The same fixator has been previously virtually mounted in an L2-L4 FE model of the lumbar spine, and stresses in the rods were calculated when the spine was subjected to physiological forces and moments. The comparison between the FE predictions and experimental measurements is in good agreement, thus confirming the suitability of the FE method to evaluate the stresses in the device. The initial precompression induces a significant extension of the assembled construct. As the applied load increases, the initial extension is gradually compensated, so that at peak load the rods are bent in flexion: The final stress value predicted is thus reduced to about 50%, if

  1. Computational modelling of long bone fractures fixed with locking plates - How can the risk of implant failure be reduced?

    LENUS (Irish Health Repository)

    Nassiri, M

    2013-03-01

    The Locking Compression Plate (LCP) is part of a new plate generation requiring an adapted surgical technique and new thinking about commonly used concepts of internal fixation using plates. Knowledge of the fixation stability provided by these new plates is very limited and clarification is still necessary to determine how the mechanical stability and the risk of implant failure can best be controlled.

  2. Fixation using alternative implants for the treatment of hip fractures (FAITH): design and rationale for a multi-centre randomized trial comparing sliding hip screws and cancellous screws on revision surgery rates and quality of life in the treatment of femoral neck fractures

    NARCIS (Netherlands)

    McCormack, Robert; Apostle, Kelly; Boyer, Dory; Moola, Farhad; Perey, Bertrand; Stone, Trevor; Viskontas, Darius; Lemke, H. Michael; Zomar, Mauri; Moon, Karyn; Moon, Raely; Oatt, Amber; Buckley, Richard E.; Duffy, Paul; Korley, Robert; Puloski, Shannon; Johnston, Kelly; Powell, James; Carcary, Kimberly; Sanders, David; Lawendy, Abdel; Tieszer, Christina; Stephen, David; Kreder, Hans; Jenkinson, Richard; Nousiainen, Markku; Axelrod, Terry; Murnaghan, John; Nam, Diane; Wadey, Veronica; Yee, Albert; Milner, Katrine; Kunz, Monica; Schemitsch, Emil H.; Ahn, Henry; Hall, Jeremy A.; McKee, Michael D.; Whelan, Daniel B.; Nauth, Aaron; Vicente, Milena R.; Wild, Lisa M.; Khan, Ryan M.; Hidy, Jennifer T.; Coles, Chad; Leighton, Ross; Biddulph, Michael; Johnston, David; Glazebrook, Mark; Alexander, David; Coady, Cathy; Dunbar, Michael; Amirault, David; Gross, Michael; Oxner, William; Reardon, Gerald; Richardson, Glen; Trenholm, Andrew; Wong, Ivan; Trask, Kelly; MacDonald, Shelley; Dobbin, Gwen; Bicknell, Ryan; Yach, Jeff; Bardana, Davide; Wood, Gavin; Harrison, Mark; Yen, David; Lambert, Sue; Howells, Fiona; Ward, Angela; Zalzal, Paul; Brien, Heather; Naumetz, V.; Weening, Brad; Simunovic, Nicole; Wai, Eugene K.; Papp, Steve; Gofton, Wade T.; Liew, Allen; Kingwell, Stephen P.; Johnson, Garth; O'Neil, Joseph; Roffey, Darren M.; Borsella, Vivian; Avram, Victoria; Oliver, Todd M.; Jones, Vicki; Jones, Clifford B.; Ringler, James R.; Endres, Terrence J.; Sietsema, Debra L.; Jeray, Kyle J.; Broderick, J. Scott; Goetz, David R.; Pace, Thomas B.; Schaller, Thomas M.; Porter, Scott E.; Tanner, Stephanie L.; Snider, Rebecca G.; Nastoff, Lauren A.; Bielby, Shea A.; Switzer, Julie A.; Cole, Peter A.; Anderson, Sarah A.; Lafferty, Paul M.; Li, Mengnai; Ly, Thuan V.; Marston, Scott B.; Foley, Amy L.; Vang, Sandy; Wright, David M.; Marcantonio, Andrew J.; Kain, Michael S. H.; Iorio, Richard; Specht, Lawrence M.; Tilzey, John F.; Lobo, Margaret J.; Garfi, John S.; Vallier, Heather A.; Dolenc, Andrea; Robinson, Chalitha; Prayson, Michael J.; Laughlin, Richard; Rubino, L. Joseph; May, Jedediah; Rieser, Geoffrey R.; Dulaney-Cripe, Liz; Gayton, Chris; Shaer, James; Schrickel, Tyson; Hileman, Barbara; Gorczyca, John T.; Gross, Jonathan M.; Humphrey, Catherine A.; Kates, Stephen; Noble, Krista; McIntyre, Allison W.; Pecorella, Kaili; Davis, Craig A.; Weinerman, Stewart; Weingarten, Peter; Stull, Philip; Lindenbaum, Stephen; Hewitt, Michael; Schwappach, John; Baker, Janell K.; Rutherford, Tori; Newman, Heike; Lieberman, Shane; Finn, Erin; Robbins, Kristin; Hurley, Meghan; Lyle, Lindsey; Mitchell, Khalis; Browner, Kieran; Whatley, Erica; Payton, Krystal; Reeves, Christina; Cannada, Lisa K.; Karges, David; Hill, Leslie; Mehta, Samir; Esterhai, John; Ahn, Jaimo; Horan, Annamarie D.; McGinnis, Kelly; Kaminski, Christine A.; Kowalski, Brynn N.; Keeve, Jonathan P.; Anderson, Christopher G.; McDonald, Michael D.; Hoffman, Jodi M.; Tarkin, Ivan; Siska, Peter; Gruen, Gary; Evans, Andrew; Farrell, Dana J.; Irrgang, James; Luther, Arlene; Cross, William W.; Cass, Joseph R.; Sems, Stephen A.; Torchia, Michael E.; Scrabeck, Tyson; Jenkins, Mark; Dumais, Jules; Romero, Amanda W.; Sagebien, Carlos A.; Butler, Mark S.; Monica, James T.; Seuffert, Patricia; Hsu, Joseph R.; Ficke, James; Charlton, Michael; Napierala, Michael; Fan, Mary; Tornetta, Paul; Tannoury, Chadi; Carlisle, Hope; Silva, Heather; Archdeacon, Michael; Finnan, Ryan; Le, Toan; Wyrick, John; Hess, Shelley; Brennan, Michael L.; Probe, Robert; Kile, Evelyn; Mills, Kelli; Clipper, Lydia; Yu, Michelle; Erwin, Katie; Horwitz, Daniel; Strohecker, Kent; Swenson, Teresa K.; Schmidt, Andrew H.; Westberg, Jerald R.; Aurang, Kamran; Zohman, Gary; Peterson, Brett; Huff, Roger B.; Baele, Joseph; Weber, Timothy; Edison, Matt; McBeth, Jessica; Shively, Karl; Ertl, Janos P.; Mullis, Brian; Parr, J. Andrew; Worman, Ripley; Frizzell, Valda; Moore, Molly M.; Tobias, Erin; Thomas, Emily; DePaolo, Charles J.; Alosky, Rachel; Shell, Leslie E.; Hampton, Lynne; Shepard, Stephanie; Nanney, Tracy; Cuento, Claudine; Cantu, Robert V.; Henderson, Eric R.; Eickhoff, Linda S.; Hammerberg, E. Mark; Stahel, Philip; Hak, David; Mauffrey, Cyril; Gibula, Douglas; Gissel, Hannah; Henderson, Corey; Zamorano, David P.; Tynan, Martin C.; Pourmand, Deeba; Lawson, Deanna; Della Rocca, Gregory J.; Crist, Brett D.; Murtha, Yvonne M.; Anderson, Linda K.; Linehan, Colleen; Pilling, Lindsey; Lewis, Courtland G.; Caminiti, Stephanie; Sullivan, Raymond J.; Roper, Elizabeth; Obremskey, William; Kregor, Philip; Richards, Justin E.; Stringfellow, Kenya; Dohm, Michael P.; Zellar, Abby; Segers, Michiel J. M.; Zijl, Jacco A. C.; Verhoeven, Bart; Smits, Anke B.; de Vries, Jean Paul; Fioole, Bram; van der Hoeven, Henk; Theunissen, Evert B.; de Vries Reilingh, Tammo S.; Govaert, Lonneke; Wittich, Philippe; de Brauw, Maurits; Wille, Jan; Go, Peter M.; Ritchie, Ewan D.; Wessel, Ronald N.; Hammacher, Eric R.; Heetveld, Martin J.; Visser, Gijs A.; Stockmann, Heyn; Silvis, Rob; Snellen, Jaap P.; Rijbroek, Bram; Scheepers, Joris J. G.; Vermeulen, Erik G. J.; Siroen, Michiel P. C.; Vuylsteke, Ronald; Brom, Hans L. F.; Rijna, Herman; de Rijcke, Piet A. R.; Koppert, Cees L.; Buijk, Steven E.; Groenendijk, Richard P. R.; Dawson, Imro; Tetteroo, Geert W. M.; Bruijninckx, Milko M. M.; Doornebosch, Pascal G.; de Graaf, Eelco J. R.; van der Elst, Maarten; van der Pol, Carmen C.; van 't Riet, Martijne; Karsten, Tom M.; de Vries, Mark R.; Stassen, Laurents P. S.; Schep, Niels W. L.; Schmidt, G. Ben; Hoffman, W. H.; Poolman, Rudolf W.; Simons, Maarten P.; van der Heijden, Frank H. W. M.; Willems, W. Jaap; de Meulemeester, Frank R. A. J.; van der Hart, Cor P.; Turckan, Kahn; Festen, Sebastiaan; de Nies, Frank; Haverlag, Robert; Out, Nico J. M.; Bosma, Jan; van Kampen, Albert; Biert, Jan; van Vugt, Arie B.; Edwards, Michael J. R.; Blokhuis, Taco J.; Frolke, Jan Paul M.; Geeraedts, Leo M. G.; Gardeniers, Jean W. M.; Tan, Edward T. C. H.; Poelhekke, Lodewijk M. S. J.; de Waal Malefijt, Maarten C.; Schreurs, Bart; Roukema, Gert R.; Josaputra, Hong A.; Keller, Paul; de Rooij, Peter D.; Kuiken, Hans; Boxma, Han; Cleffken, Berry I.; Liem, Ronald; Rhemrev, Steven J.; Bosman, Coks H. R.; de Mol van Otterloo, Alexander; Hoogendoorn, Jochem; de Vries, Alexander C.; Meylaerts, Sven A. G.; Verhofstad, Michiel H. J.; Meijer, Joost; van Egmond, Teun; van der Brand, Igor; Patka, Peter; Eversdijk, Martin G.; Peters, Rolf; den Hartog, Dennis; van Waes, Oscar J. F.; Oprel, Pim; van der Vis, Harm M.; Campo, Martin; Verhagen, Ronald; Albers, G. H. Robert; Zurcher, Arthur W.; Simmermacher, Rogier K. J.; van Mulken, Jeroen; van Wessem, Karlijn; van Gaalen, Steven M.; Leenen, Luke P. H.; Bronkhorst, Maarten W. G. A.; Guicherit, Onno R.; Goslings, J. Carel; Ponsen, Kees Jan; Bhatia, Mahesh; Arora, Vinod; Tyagi, Vivek; Liew, Susan; Bedi, Harvinder; Carr, Ashley; Curry, Hamish; Chia, Andrew; Csongvay, Steve; Donohue, Craig; Doig, Stephen; Edwards, Elton; Etherington, Greg; Esser, Max; Gong, Andrew; Jain, Arvind; Li, Doug; Miller, Russell; Moaveni, Ash; Russ, Matthias; Ton, Lu; Wang, Otis; Dowrick, Adam; Murdoch, Zoe; Sage, Claire; Frihagen, Frede; Clarke-Jenssen, John; Hjorthaug, Geir; Ianssen, Torben; Amundsen, Asgeir; Brattgjerd, Jan Egil; Borch, Tor; Boe, Berthe; Flatoy, Bernhard; Hasselund, Sondre; Haug, Knut Jorgen; Hemlock, Kim; Hoseth, Tor Magne; Jomaas, Geir; Kibsgard, Thomas; Lona, Tarjei; Moatshe, Gilbert; Muller, Oliver; Molund, Marius; Nicolaisen, Tor; Nilsen, Fredrik; Rydinge, Jonas; Smedsrud, Morten; Stodle, Are; Trommer, Axel; Ugland, Stein; Karlsten, Anders; Ekas, Guri; Vesterhus, Elise Berg; Brekke, Anne Christine; Gupta, Ajay; Jain, Neeraj; Khan, Farah; Sharma, Ateet; Sanghavi, Amir; Trivedi, Mittal; Rai, Anil; Subash, N. N.; Rai, Kamal; Yadav, Vineet; Singh, Sanjay; Tetsworth, Kevin; Donald, Geoff; Weinrauch, Patrick; Pincus, Paul; yang, Steven; Halliday, Brett; Gervais, Trevor; Holt, Michael; Flynn, Annette; Prasad, Amal Shankar; Mishra, Vimlesh; Sundaresh, D. C.; Khanna, Angshuman; Cherian, Joe Joseph; Olakkengil, Davy J.; Sharma, Gaurav; Pirpiris, Marinis; Love, David; Bucknill, Andrew; Farrugia, Richard J.; Pape, Hans-Christoph; Knobe, Matthias; Pfeifer, Roman; Hull, Peter; Lewis, Sophie; Evans, Simone; Nanda, Rajesh; Logishetty, Rajanikanth; Anand, Sanjeev; Bowler, Carol; Dadi, Akhil; Palla, Naveen; Ganguly, Utsav; Rai, B. Sachidananda; Rajakumar, Janakiraman; Jennings, Andrew; Chuter, Graham; Rose, Glynis; Horner, Gillian; Clark, Callum; Eke, Kate; Reed, Mike; Herriott, Chris; Dobb, Christine; Bhandari, Mohit; Swiontkowski, Marc; Devereaux, P. J.; Jeray, Kyle; Thabane, Lehana; Walter, Stephen; Sprague, Sheila; Scott, Taryn; Guyatt, Gordon; Viveiros, Helena; McKay, Paula; Swinton, Marilyn; Truong, Victoria; Koo, Kaitlin; Heels-Ansdell, Diane; Zhou, Qi; Buckingham, Lisa; Duraikannan, Aravin; Maddock, Deborah; Agel, Julie; van Lieshout, Esther M. M.; Zielinski, Stephanie M.; Rangan, Amar; Hanusch, Birgit C.; Kottam, Lucksy; Clarkson, Rachel; Slobogean, Gerard; Katz, Jeffrey; Gillespie, Brenda; Greendale, Gail A.; Guy, Pierre; Hartman, Curtis; Rubin, Craig; Waddell, James

    2014-01-01

    Hip fractures are a common type of fragility fracture that afflict 293,000 Americans (over 5,000 per week) and 35,000 Canadians (over 670 per week) annually. Despite the large population impact the optimal fixation technique for low energy femoral neck fractures remains controversial. The primary

  3. Fixation using alternative implants for the treatment of hip fractures (FAITH): Design and rationale for a multi-centre randomized trial comparing sliding hip screws and cancellous screws on revision surgery rates and quality of life in the treatment of femoral neck fractures

    NARCIS (Netherlands)

    2014-01-01

    textabstractBackground: Hip fractures are a common type of fragility fracture that afflict 293,000 Americans (over 5,000 per week) and 35,000 Canadians (over 670 per week) annually. Despite the large population impact the optimal fixation technique for low energy femoral neck fractures remains

  4. A novel method of head fixation for the study of rodent facial function.

    Science.gov (United States)

    Hadlock, Tessa; Kowaleski, Jeffrey; Mackinnon, Susan; Heaton, James T

    2007-05-01

    The rodent vibrissial system offers an excellent model for the study of both sensory and motor function. It has been widely employed to gather data pertaining to sensory and motor function involving the 5th and 7th cranial nerves and the central nervous system. Existing methods of head fixation for precise measurements of ocular and vibrissial function involve exposing the cranium and applying dental cement from which two or more threaded rods emerge. This common approach is suboptimal, requiring a relatively complicated implantation procedure, and results in a large, chronic interface between the scalp and environmentally exposed implant material attached to the skull. Here we describe a head fixation device that is inexpensive, easy to build, less prone to infection, preserves access to the cranial midline, and permits repeated measurements over many months.

  5. Fixational eye movements and binocular vision.

    Science.gov (United States)

    Otero-Millan, Jorge; Macknik, Stephen L; Martinez-Conde, Susana

    2014-01-01

    During attempted visual fixation, small involuntary eye movements-called fixational eye movements-continuously change of our gaze's position. Disagreement between the left and right eye positions during such motions can produce diplopia (double vision). Thus, the ability to properly coordinate the two eyes during gaze fixation is critical for stable perception. For the last 50 years, researchers have studied the binocular characteristics of fixational eye movements. Here we review classical and recent studies on the binocular coordination (i.e., degree of conjugacy) of each fixational eye movement type: microsaccades, drift and tremor, and its perceptual contribution to increasing or reducing binocular disparity. We also discuss how amblyopia and other visual pathologies affect the binocular coordination of fixational eye movements.

  6. Tibial component fixation with a peri-apatite coating: evaluation by radiostereometric analysis in a canine total knee arthroplasty model.

    Science.gov (United States)

    Allen, Matthew J; Leone, Kendall A; Dunbar, Michael J; Race, Amos; Rosenbaum, Paula F; Sacks, Jonathan M

    2012-06-01

    Cementless fixation for the tibial component in total knee arthroplasty (TKA) remains problematic. Peri-Apatite (PA), a solution-deposited hydroxyapatite, is under investigation as an option for improving the fixation of cementless tibial components. In this study, radiostereometric analysis was used to document implant migration in 48 dogs that underwent TKA with cementless, PA-coated, or cemented tibial components. Migration at 12 weeks was similar in the 2 groups. At 12 months, there was greater migration in the PA-coated group, but the difference between the 2 groups was below the threshold considered clinically significant. In this canine TKA model, cementless fixation with PA performed less well than did cemented fixation, but not to a degree that would make a clinical difference in the short term. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Comparison of fixation disparity curve parameters obtained with the Wesson and Saladin fixation disparity cards

    National Research Council Canada - National Science Library

    Ngan, Janice; Goss, David A; Despirito, Joseph

    2005-01-01

    This study compared fixation curve parameters with two commercially available fixation disparity cards, one that has been available for several years, the Wesson card, and a new one, the Saladin card...

  8. Functional improvement following implantation of a microstructured, type-I collagen scaffold into experimental injuries of the adult rat spinal cord.

    Science.gov (United States)

    Altinova, Haktan; Möllers, Sven; Führmann, Tobias; Deumens, Ronald; Bozkurt, Ahmet; Heschel, Ingo; Damink, Leon H H Olde; Schügner, Frank; Weis, Joachim; Brook, Gary A

    2014-10-17

    The formation of cystic cavitation following severe spinal cord injury (SCI) constitutes one of the major barriers to successful axonal regeneration and tissue repair. The development of bioengineered scaffolds that assist in the bridging of such lesion-induced gaps may contribute to the formulation of combination strategies aimed at promoting functional tissue repair. Our previous in vitro investigations have demonstrated the directed axon regeneration and glial migration supporting properties of microstructured collagen scaffold that had been engineered to possess mechanical properties similar to those of spinal cord tissues. Here, the effect of implanting the longitudinally orientated scaffold into unilateral resection injuries (2mm long) of the mid-cervical lateral funiculus of adult rats has been investigated using behavioural and correlative morphological techniques. The resection injuries caused an immediate and long lasting (up to 12 weeks post injury) deficit of food pellet retrieval by the ipsilateral forepaw. Implantation of the orientated collagen scaffold promoted a significant improvement in pellet retrieval by the ipsilateral forepaw at 6 weeks which continued to improve up to 12 weeks post injury. In contrast, implantation of a non-orientated gelatine scaffold did not result in significant functional improvement. Surprisingly, the improved motor performance was not correlated with the regeneration of lesioned axons through the implanted scaffold. This observation supports the notion that biomaterials may support functional recovery by mechanisms other than simple bridging of the lesion site, such as the local sprouting of injured, or even non-injured fibres. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Reconstituição experimental da parede torácica de gatos com implante heterógeno de cartilagem auricular conservada em glicerina a 98% Experimental reconstitution of the cat's thoracic wall with dog conchal cartilage implant preserved in 98% glycerin

    Directory of Open Access Journals (Sweden)

    Josaine Cristina da Silva Rappeti

    2003-12-01

    Full Text Available Com o objetivo de testar o implante de cartilagem auricular heteróloga conservada em glicerina a 98% como alternativa para reparar defeitos na parede torácica em felinos, foram estudados doze animais adultos, sendo distribuídos em dois grupos GI e GII, e avaliados após 60 dias de pós-operatório. Todos os animais foram submetidos à ressecção costal na porção média do tórax abrangendo a 7ª, 8ª e 9ª costelas e posterior implante de cartilagem conchal heteróloga conservada em glicerina a 98%. No GI, foi preservada a musculatura adjacente, já no GII, a musculatura foi retirada. Os animais foram avaliados clinicamente no pós-operatório e, ao final do período, submetidos à eutanásia e necropsia para avaliação macroscópica e microscópica da região do implante. Observou-se proliferação de tecido fibrovascular neovascularizado sobre o implante, com aderência pulmonar e diafragmática em algumas das unidades experimentais. O implante de cartilagem heteróloga conservado em glicerina a 98% pode ser utilizado para reconstrução de parede costal cujo defeito abranja o espaço de parte de três costelas. O implante em 60 dias é substituído por tecido cicatricial, sem apresentar sinais clínicos de rejeição.Twelve adult cats were divided in groups GI and GII with the objective of testing a dog auricular cartilage implant conserved in 98% glycerin as an alternative to repair thoracic wall defects. All animals were submitted to a resection of the medial portion of the thorax by removal of the 7th, 8th and 9th ribs and posterior cartilage implantation. GI had the adjacent musculature preserved and in GII cat's had it removed. The animals were clinically evaluated in the post operative period and after sixty days submitted to euthanasia for microscopic evaluation of the implanted local. Proliferation of granulation tissue and neomorph over the implant was observed in all animals and some had lung and diaphragm adherence. The

  10. Clinical trial of modified ankylos implants for extraoral use in cranio- and maxillofacial surgery.

    Science.gov (United States)

    Schlegel, Karl Andreas; Schultze-Mosgau, Stefan; Eitner, Stefan; Wiltfang, Joerg; Rupprecht, Stephan

    2004-01-01

    Epithetic solutions in the maxillofacial region are indicated if plastic surgery reconstruction is not a valid option for an extensive defect. The purpose of this study was to examine whether the extraoral implants used provided sufficient retention to be used as anchoring aids. Between November 1999 and September 2002, 33 identical modified Ankylos implants for extraoral anchorage were placed in 10 patients for the fixation of various epitheses in the midfacial (eye, nose) and ear regions in the course of a clinical trial. Over a follow-up period of 2 to 34 months, all implants remained osseointegrated (as confirmed radiographically), and the implants and epithetic restorations were clinically stable. The results demonstrated that the lasting retention of maxillofacial epitheses provided by implants assures patients that their epitheses are securely fixed. The demonstrated extraoral implant system not only achieved sufficient osseointegration but also showed good clinical handling and easy fixation possibilities for epithetic anchorage.

  11. An experimental test of stroke recovery by implanting a hyaluronic acid hydrogel carrying a Nogo receptor antibody in a rat model

    Energy Technology Data Exchange (ETDEWEB)

    Ma Jun [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Tian Weiming [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Hou Shaoping [Beijing Institute of Neuroscience, Capital University of Medical Sciences, Beijing 100054 (China); Xu Qunyuan [Beijing Institute of Neuroscience, Capital University of Medical Sciences, Beijing 100054 (China); Spector, Myron [Tissue Engineering, VA Boston Healthcare System, Harvard Medical School, Boston, MA (United States); Cui Fuzhai [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2007-12-15

    The objective of the study was to determine the effects of a hyaluronic-acid-based (HA-based) hydrogel implant, carrying a polyclonal antibody to the Nogo-66 receptor (NgR), on adult rats that underwent middle cerebral artery occlusion (MCAO). Behavioral tests of a forelimb-reaching task suggested that the disabled function of the impaired forelimb in this stroke model was ameliorated by the implant to a certain extent. These behavioral findings were correlated with immunohistochemical results of investigating the distribution of NgR antibody, neurofilaments (NF) and neuron-specific class III {beta}-tubulin (TuJ1) in the brain sections. The porous hydrogel functioned as a scaffold to deliver the NgR antibody, support cell migration and development. In addition, it was found NF-positive and TuJ1-positive expressions were distributed in the implanted hydrogel. Collectively, the results demonstrate the promise of the HA hydrogel as a scaffold material and the delivery vehicle of the NgR antibody for the repair of defects and the support of neural regeneration in the brain.

  12. Percutaneous Fixation of Displaced Calcaneal Fracture

    Directory of Open Access Journals (Sweden)

    Yeung Yip-Kan

    2011-06-01

    Conclusion: Percutaneous fixation of displaced tongue-type calcaneal fractures is an effective treatment with acceptable clinical outcome, short hospital stay, minimal skin complications, and quick recovery.

  13. Suppressive interactions underlying visually evoked fixational saccades.

    Science.gov (United States)

    Wang, Helena X; Yuval-Greenberg, Shlomit; Heeger, David J

    2016-01-01

    Small saccades occur frequently during fixation, and are coupled to changes in visual stimulation and cognitive state. Neurophysiologically, fixational saccades reflect neural activity near the foveal region of a continuous visuomotor map. It is well known that competitive interactions between neurons within visuomotor maps contribute to target selection for large saccades. Here we asked how such interactions in visuomotor maps shape the rate and direction of small fixational saccades. We measured fixational saccades during periods of prolonged fixation while presenting pairs of visual stimuli (parafoveal: 0.8° eccentricity; peripheral: 5° eccentricity) of various contrasts. Fixational saccade direction was biased toward locations of parafoveal stimuli but not peripheral stimuli, ∼100-250ms following stimulus onset. The rate of fixational saccades toward parafoveal stimuli (congruent saccades) increased systematically with parafoveal stimulus contrast, and was suppressed by the simultaneous presentation of a peripheral stimulus. The suppression was best characterized as a combination of two processes: a subtractive suppression of the overall fixational saccade rate and a divisive suppression of the direction bias. These results reveal the nature of suppressive interactions within visuomotor maps and constrain models of the population code for fixational saccades. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Penile Implants

    Science.gov (United States)

    ... men with erectile dysfunction (ED) to get an erection. Penile implants are typically recommended after other treatments for ... the scrotum, and two inflatable cylinders inside the penis. To achieve an erection, you pump the fluid from the reservoir into ...

  15. Cochlear Implants

    Science.gov (United States)

    ... the skin. An implant does not restore normal hearing. It can help a person understand speech. Children and adults can benefit from them. National Institute on Deafness and Other Communication Disorders

  16. Current concepts of regenerative biomaterials in implant dentistry

    Directory of Open Access Journals (Sweden)

    Annapurna Ahuja

    2015-01-01

    Full Text Available The primary objective of any implant system is to achieve firm fixation to the bone and this could be influenced by biomechanical as well as biomaterial selection. An array of materials is used in the replacement of missing teeth through implantation. The appropriate selection of biomaterials directly influences the clinical success and longevity of implants. Thus the clinician needs to have adequate knowledge of the various biomaterials and their properties for their judicious selection and application in his/her clinical practice. The recent materials such as bioceramics and composite biomaterials that are under consideration and investigation have a promising future. For optimal performance, implant biomaterials should have suitable mechanical strength, biocompatibility, and structural biostability in the physiological environment. This article reviews the various implant biomaterials and their ease of use in implant dentistry.

  17. Temporomandibular joint ankylosis fixation technique with ultra thin silicon sheet

    Directory of Open Access Journals (Sweden)

    G S Kalra

    2011-01-01

    Full Text Available Background: Temporomandibular joint ankylosis is a highly distressing condition in which the joint space is obliterated by scar tissue and the patient has an inability to open the mouth. Different autogenous and alloplastic interposition materials have been used after the resection of the ankylotic bone to achieve desirable and long lasting results. The recurrence of disease is most distressing for both patients and surgeon. We have been using ultra thin silicon sheet as our preferred material for providing proper fixation and cover to the joint. We have been encouraged by good patient compliance, no implant extrusion and favourable outcome. Materials and Methods: The clinical study included 80 patients with temporomandibular joint ankylosis, treated between April 2001 and March 2009. In all patients, temporomandibular joint ankylosis had resulted following trauma. Diagnosis was based on clinical assessment supplemented by radiographic examination consisting of a panoramic radiograph, axial and coronal computer tomography. The technique of using ultra thin silicon sheet covering whole of the joint space fixed with non-absorbable nylon 3-0 suture both medially to medial pterygoid muscle and laterally to periosteum of zygomatic arch was employed in all patients. Results: A total of 80 patients were in this study (59 males and 21 females. The aetiology of temporomandibular joint ankylosis was post-traumatic in all cases. The patients′ age ranged from 5 to 45 years. The disease was unilateral in 61 cases and bilateral in 19 cases. Twelve patients, who had previous surgery done in the form of gap arthroplasty in 6 cases, costochondral graft in 4 cases and temporalis muscle in 2 cases, presented with recurrence on the same side. The pre-op inter-incisal mouth opening ranged from 4 to 12 mm. The intraoperative inter-incisal mouth opening ranged from 28 to 46 mm. An additional procedure was done in 13 patients, including placement of costochondral

  18. Microbiology of post-operative wound infection in implant surgery ...

    African Journals Online (AJOL)

    Background: Open reduction and internal fixation (ORIF) of fractures with implants and prosthesis has become the first line in the management of fractures in most trauma centres. Incidentally, this is associated with post-operative wound infection which is accompanied by significant morbidity, cost and mortality.

  19. Orthopaedic Implants And Prosthesis: Economic Costs Of Post ...

    African Journals Online (AJOL)

    OBJECTIVE: To assess the economic impact of post-operative wound infection in trauma patients who had open reduction and internal fixation with implants and prostheses following fractures of the femur. METHOD: This is a 2-year case controlled prospective study carried out at the National Orthopaedic Hospital, Lagos.

  20. Intertrochanteric fracture non-unions with implant failure of the ...

    African Journals Online (AJOL)

    Failure of internal fixation of intertrochanteric fracture is associated with delayed union or malunion resulting in persistent pain and diminished function. We report a rare case of implant failure of the gamma nail with intertrochanteric fracture non union treated by DCS plate screw and bone graft. Pan African Medical Journal ...

  1. Fractures around a previous fixation of proximal femur. A simple solution to a complex problem.

    Directory of Open Access Journals (Sweden)

    Fernando Manuel Bidolegui

    2016-05-01

    Full Text Available The number of hip fractures in the elderly growth with the increase in life expectancy. Therefore meet with a femur fractured, distal to a previously  implant fixation used in intertrochanteric femur fractures as dynamic hip screw or fixed angle plate, is not an uncommon scenario despite year mortality of hip fracture of 30 to 50%. Given this situation, we used a retrograde intramedullary nail associated with extracting screws percutaneously prior implant. We present 8 cases in patients with an average age of 85.6 years, 5 female and 3 male with a time from the proximal femur fixation to the  new fracture average 3.5 years. Will we track 36 months and we evaluated postoperative mobility and pain getting a consolidation of the fracture in all cases. We found this technique effective; capable of achieving stable fixation without adding morbidity due to the possibility of overlapping two implants decreasing the possibility of potential new interimplantes fracture.

  2. Osteogenesis and Morphology of the Peri-Implant Bone Facing Dental Implants

    Directory of Open Access Journals (Sweden)

    Marco Franchi

    2004-01-01

    tissue showed different results. Around the SS screws, the compact bone with areas of different mineralisation rate appeared very smooth, while around the rougher TPS screws, the bone still showed an irregular surface corresponding to the implant macro/microroughness. Around the Zr-SLA screws, a more regular implant-bone surface and sparse, calcified marrow spaces were detectable.Results from this research suggest that 2 weeks after implantation, trabecular bone represents the calcified healing tissue, which supports the early biological fixation of the implants. The peri-implant marrow spaces, rich in undifferentiated cells and blood vasculature, observed both 2 weeks and 3 months after surgery, favour the biological turnover of both early and mature peri-implant bone. The implant surface morphology strongly influences the rate and the modality of peri-implant osteogenesis, as do the morphology and arrangement of the implant face in peri-implant bone both during early healing (after 2 weeks and when the implant is just osseointegrated; rough surfaces, and in particular Zr-SLA, seem to better favour bone deposition on the metal surface.

  3. Biomechanical analysis of trochanteric fracture fixations using a Y-shaped locking plate.

    Science.gov (United States)

    Cloutier, Luc P; Laflamme, G Yves; Petit, Yvan

    2013-12-01

    Clinical evidence suggests that the use of Y-shaped locking plates with anterior and lateral locking screws provide improved primary fixation stability over the use of straight locking plates in the treatment of greater trochanter (GT) fractures. However, it remains unclear how the use of cable cerclages, in replacement or addition to the locking screws, would impact the primary fixation stability. Nine surgical fixations were tested on a dynamic test bench through 27 sawbones experiments. These fixations on the GT and bone shaft (BS) included locking screws alone, cable cerclages alone, or 7 combinations of both. Migrations, defined as the remaining movements of the unloaded GT fragment, were measured for all 9 fixations submitted to dynamic stair climbing cycling after an experimental plan. Under dynamic stair climbing conditions: (1) Y-shaped locking plates fixed by locking screws alone (vs cable cerclages alone) significantly reduced GT migrations, (2) adding cable cerclages to screws provided no significant reduction of migrations, and (3) cable cerclages alone can be used on the BS but is not recommended on the GT. Y-shaped locking plates with anterior and lateral locking screws improved primary stability of GT fractures over fixation with cable cerclages. Cable cerclages provided acceptable primary stability when screw fixations were unachievable but on the BS only.

  4. Cochlear implant by adult

    OpenAIRE

    Kratochvílová, Tereza

    2011-01-01

    Bachelor thesis "The cochlear implant in an adult deaf" deals primarily with the cochlear implant. The most extensive part of the thesis talks about this topic, which also talks about the development and design of cochlear implants, explains the difference between cochlear implantation and tribal implantation and describes operation of implant and the subsequent setting of the implant. This section is also dedicated to binaural cochlear implantation, myths of cochlear implants and problems wh...

  5. Osteogenic protein 1 device increases bone formation and bone graft resorption around cementless implants

    DEFF Research Database (Denmark)

    Jensen, Thomas B; Overgaard, Søren; Lind, Martin

    2002-01-01

    In each femoral condyle of 8 Labrador dogs, a non weight-bearing hydroxyapatite-coated implant was inserted surrounded by a 3 mm gap. Each gap was filled with bone allograft or ProOsteon with or without OP-1 delivered in a bovine collagen type I carrier (OP-1 device). 300 microg OP-1 was used...... in the 0.75 cc gap surrounding the implant. After 3 weeks, the OP-1 device enhanced implant fixation by 800% (p...

  6. Hip-inspired implant for revision of failed reverse shoulder arthroplasty with severe glenoid bone loss

    OpenAIRE

    Uri, Ofir; Bayley, Ian; Lambert, Simon

    2014-01-01

    Background and purpose Glenoid reconstruction and inverted glenoid re-implantation is strongly advocated in revisions of failed reverse shoulder arthroplasty (RSA). Nevertheless, severe glenoid deficiency may preclude glenoid reconstruction and may dictate less favorable solutions, such as conversion to hemiarthropasty or resection arthropasty. The CAD/CAM shoulder (Stanmore Implants, Elstree, UK), a hip arthroplasty-inspired implant, may facilitate glenoid component fixation in these challen...

  7. Posterior fixation keratoprostheses and mechanical biocompatibility: determination of critical intraocular pressure causing aqueous humor leak and/or keratoprosthesis extrusion

    Science.gov (United States)

    Tahi, Hassan; Duchesne, Bernard; Parel, Jean-Marie A.; Nose, Izuru; Denham, David B.; Villain, Franck L.; Lacombe, Emmanuel

    1997-05-01

    The effect of increased intraocular pressure (IOP) in human cadaver eyes implanted with posterior fixation keratoprosthesis was evaluated. Experiments were carried out with six fresh pairs of human cadaver eyes. One eye of each pair was implanted with a PCL-5 keratoprosthesis (8.60 mm diameter with an optic of 5.60 nm diameter) and the contralateral eye was used as a control. The keratoprosthesis was inserted through a 6 mm diameter opening trephined in the cornea. The resistance of the implanted eye to pressure on `aqueous humor' leak and/or keratoprosthesis extrusion was tested by infusing water at a constant flow of 60 mmHg/second into the anterior chamber. IOP variations were recorded with a transducer connected to a computer. IOP could be increased up to 1520 to 2324 mmHg before aqueous humor leaks occurred. Leaks were always located at the keratoprosthesis-cornea interface. No prosthesis extrusion was observed. Implanted eyes that did not leak aqueous and control eyes tore at the sclera. All posterior fixation keratoprostheses implanted eyes resisted more than 100 times the normal physiological intraocular pressure and on this standpoint is safe. Additional experiments were needed to assess the influence of suture fixation and wound healing in an animal model.

  8. Short-term strength of non-penetrating mesh fixation: LifeMesh™, Tisseel™, and ProGrip™.

    Science.gov (United States)

    Shahan, Charles P; Stoikes, Nathaniel N; Roan, Esra; Tatum, James; Webb, David L; Voeller, Guy R

    2017-03-01

    Non-penetrating mesh fixation is becoming widely accepted even though little is known about the short-term fixation strength of these techniques. Although clinical outcomes are the ultimate measure of effectiveness, ex vivo biomechanical evaluation provides insights about the load-carrying capacity of the mesh-tissue complex in vivo. As such, the purpose of this study was to compare the short-term fixation strength of three unique non-penetrating methods of fixation: LifeMesh™, ProGrip™, and Tisseel™. Among these, LifeMesh™ is a novel technology where large-pore, mid-weight polypropylene mesh is embedded in a dry matrix of porcine gelatin and microbial transglutaminase enzyme, providing self-fixation without the need for a separate adhesive application. Seven mongrel swine underwent implantation of two 4 × 7 cm pieces of either LifeMesh™, ProGrip™, or polypropylene mesh fixated with 2 mL of Tisseel™; 10 min after application, the samples were excised with the abdominal wall and stored for immediate biomechanical testing. The samples underwent lap shear testing to determine the short-term fixation strength of these three technologies. ProGrip™ demonstrated mean fixation strength of 1.3 N/cm (±STE 0.2). Mean fixation for mesh fixated with Tisseel™ was 2.6 N/cm (±STE 0.5). LifeMesh™ samples had mean fixation strength of 8.0 N/cm (±STE 2.1). Analysis of variance testing showed that interfacial strength of LifeMesh™ was significantly greater than that of either ProGrip™ or Tisseel™. ProGrip™ and Tisseel™ were not significantly different from each other (p = 0.06). Short-term strength of mesh fixation is an undescribed factor in hernia repair, but could have significant implications for early recurrence and mesh contraction. While further investigation is needed to define adequate interfacial strength, this comparison of non-penetrating mesh fixation methods shows that the novel LifeMesh™ technology exhibits greater strength

  9. Models of Fixation and Tissue Processing

    Science.gov (United States)

    Grizzle, William E.

    2009-01-01

    Fixation and processing of tissue to paraffin blocks are used to permit tissues to be cut thinly (4 to 5 µm); cutting thin sections of tissue and staining them histochemically or immunohistochemically are necessary to permit tissues to be viewed adequately as to their structures (e.g., subcellular components and surrounding stroma) using a bright field microscope. Over the last century, anatomists and pathologists have used fixation in 10% neutral buffered formalin (10% NBF) as the fixative of choice. Also, both human and veterinary pathologists have trained using fixation in 10% NBF so these professionals have been and are reluctant to change the microscopic appearance of diagnostic tissues by using a different type of fixation; in addition, the effects of tissue processing on the microscopic appearance of tissue has essentially been ignored in most studies. Because of the use of 10% NBF by pathologists, archives of paraffin blocks contain essentially paraffin blocks only fixed in 10% NBF. Thus, if retrospective studies use archival paraffin blocks to correlate the molecular features of diseases with the outcomes of diseases, the studies must be based upon using tissue fixed in 10% NBF. Studies of how fixation in 10% NBF interacts with histochemical and immunohistochemical staining are very limited in number and most are based upon relatively long times of fixation in 10% NBF (≥ 36 hours). Current times of fixation in 10% NBF have been reduced to fixation in 10% NBF and its interaction with tissue processing at any time of fixation, especially short times of fixation. Even less is known about how fixation of tissues in 10% NBF interact with more modern assays using immunohistochemistry, real time quantitative PCR, and techniques which depend upon the analysis of proteins extracted from paraffin blocks such as analysis by multiplex immunoassays or by mass spectrometry. In general, multiple antibody-antigen combinations are reported not to work in tissues fixed

  10. Fixational eye movements during viewing of dynamic natural scenes

    Directory of Open Access Journals (Sweden)

    James A. Roberts

    2013-10-01

    Full Text Available Even during periods of fixation our eyes undergo small amplitude movements. These movements are thought to be essential to the visual system because neural responses rapidly fade when images are stabilized on the retina. The considerable recent interest in fixational eye movements (FEMs has thus far concentrated on idealized experimental conditions with artificial stimuli and restrained head movements, which are not necessarily a suitable model for natural vision. Natural dynamic stimuli, such as movies, offer the potential to move beyond restrictive experimental settings to probe the visual system with greater ecological validity. Here, we study FEMs recorded in humans during the unconstrained viewing of a dynamic and realistic visual environment, revealing that drift trajectories exhibit the properties of a random walk with memory. Drifts are correlated at short time scales such that the gaze position diverges from the initial fixation more quickly than would be expected for an uncorrelated random walk. We propose a simple model based on the premise that the eye tends to avoid retracing its recent steps to prevent photoreceptor adaptation. The model reproduces key features of the observed dynamics and enables estimation of parameters from data. Our findings show that FEM correlations thought to prevent perceptual fading exist even in highly dynamic real-world conditions.

  11. Fixational saccades alter the gap effect.

    Science.gov (United States)

    Watanabe, Masayuki; Matsuo, Yuka; Zha, Ling; MacAskill, Michael R; Kobayashi, Yasushi

    2014-06-01

    The reaction times of saccadic eye movements have been studied extensively as a probe for cognitive behavior controlled by large-scale cortical and subcortical neural networks. Recent studies have shown that the reaction times of targeting saccades toward peripheral visual stimuli are prolonged by fixational saccades, the largest miniature eye movements including microsaccades. We have shown previously that the frequency of fixational saccades is decreased by volitional action preparation controlled internally during the antisaccade paradigm (look away from a stimulus). Instead, here we examined whether fixational saccade modulation induced externally by sensory events could also account for targeting saccade facilitation by the same sensory events. When targeting saccades were facilitated by prior fixation stimulus disappearance (gap effect), fixational saccade occurrence was reduced, which could theoretically facilitate targeting saccades. However, such reduction was followed immediately by the rebound of fixational saccade occurrence in some subjects, which could eliminate potential benefits from the previous fixational saccade reduction. These results do not mean that fixational saccades were unrelated to the gap effect because they indeed altered that effect by delaying targeting saccade initiation on trials without the fixation gap more strongly than trials with it. Such changes might be attributed to the disruption of volitional saccade preparation because the frequency of fixational saccades observed in this study was associated with the ability of volitional control over antisaccade behavior. These results suggest that fixational saccades alter the gap effect on targeting saccade reaction times, presumably by disrupting volitional saccade commands. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  12. Treatment of acute proximal humeral fractures in children with modular exter nal fixator

    Directory of Open Access Journals (Sweden)

    Michele Bisaccia

    2016-11-01

    Full Text Available Objective: To evaluate the follow-up of the fractures treated by external fixator. Methods: A total of 31 children aged 6–15 years with proximal humeral fractures Grade IV according to Neer–Horowitz classification were treated. The medium follow-up was 24 months. Results: In all cases, a good stability of the fracture and a quick healing process were obtained. The mean time of follow-up was 24 months. The external fixation was removed after 6 weeks (5–8 weeks on average. Constant shoulder score was proposed to all patients and the average result was 97.5 (84–100. Conclusions: Advantages of the external fixation are rapid mobilization of the joint, low invasiveness, a single surgery and the possibility to correct any secondary displacement. It is important to underline that the positioning of external fixator should be implanted by expert surgeons and that the patients must cooperate during the entire process up to the time of the removal of the fixator.

  13. Beaming in Charcot Arthropathy-Intramedullary Fixation for Complicated Reconstructions: A Cadaveric Study.

    Science.gov (United States)

    Fidler, Corey M; Watson, Benjamin C; Reb, Christopher W; Hyer, Christopher F

    In the modern treatment of Charcot neuroarthropathy, beam screw fixation is an alternative to plate and screw fixation. Exposure is minimized for implantation, and this technique supports the longitudinal columns of the foot as a rigid load-sharing construct. A published data review identified a paucity of data regarding metatarsal intramedullary canal morphology relevant to beam screw fixation. The purpose of the present study was to describe metatarsal diaphyseal morphology qualitatively and quantitatively in an effort to provide data that can be used by surgeons when selecting axially based intramedullary fixation. Twenty fresh-frozen cadaveric below-the-knee specimens were obtained. The metatarsals were exposed, cleaned of soft tissue, and axially transected at the point of the narrowest external diameter. Next, a digital caliper was used to measure the size and shape of the diaphysis of the first through fourth metatarsals. The diaphyseal canal shape was categorized as round, oval, triangular, or pear. The widest distance between the endosteal cortical surfaces was measured. Triangular endosteal canals were only found in the first metatarsal, and the remainder of the metatarsal canals were largely round or oval. These data help to approximate the size of fixation needed to achieve maximal screw-endosteal purchase. Copyright © 2017 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  14. Host tissue reactions of non-demineralized autogenic and xenogenic dentin blocks implanted in a non-osteogenic environment. An experimental study in rabbits.

    Science.gov (United States)

    Al-Asfour, Adel; Farzad, Payam; Andersson, Lars; Joseph, Bobby; Dahlin, Christer

    2014-06-01

    Dentoalveolar ankylosis with osseous replacement is often seen after replantation of avulsed teeth, and this process may be used for preservation of alveolar crests after trauma. Its exact mechanisms with regard to osteoinductive properties are not yet fully understood and need to be systematically investigated. Dentin can possibly act as a slow-releasing carrier of bone morphogenic proteins (BMP), and this property of dentin has been proposed to be used as an alternative or supplement to bone grafting in the maxillofacial region. We aimed to initially asses host tissue reactions to dentin by implanting dentin blocks of autogenic and xenogenic human origin in rabbit connective tissue of the abdominal wall and femoral muscle. Animals were sacrificed after a period of 3 months, and histological processing, sectioning and examinations were carried out. Bone formation, cell counts and thickness of capsule surrounding the grafts were evaluated. Only minor signs of heterotopic bone formation were seen. There were no significant differences between autografts and xenografts or grafts implanted in connective tissue or muscle with regards to tissue reactions except for a significant difference (P = 0.018) in findings of more local inflammatory cells in relation to grafts placed in connective tissue in the autograft group. We conclude that during the time frame of this study, non-demineralized dentin, whether autogenous or xenogenic did not have the potential to induce bone formation when implanted in non-osteogenic areas such as the abdominal wall and abdominal muscle of rabbits. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Deproteinized Bovine Bone Mineral or Autologous Bone at Dehiscence Type Defects at Implants Installed Immediately into Extraction Sockets: An Experimental Study in Dogs.

    Science.gov (United States)

    Pereira, Flavia Priscila; De Santis, Enzo; Hochuli-Vieira, Eduardo; de Souza Faco, Eduardo F; Pantani, Fabio; Salata, Luiz A; Botticelli, Daniele

    2016-06-01

    The aim of this study was to evaluate bone regeneration at surgically created dehiscence buccal defects at implants placed immediately into extraction sockets (IPIES) of small dimensions filled with autogenous bone or deproteinized bovine bone mineral (DBBM) associated with a collagen membrane. Eight Labrador dogs were used and implants were placed immediately into the extraction sockets of the second premolar. The buccal wall was subsequently removed to create a standardized defect, 4 mm wide coronally, 2 mm wide apically, and 6 mm high. Autogenous bone particles (AB) or DBBM granules were used to fill the defects. All surgical sites were subsequently covered by a resorbable collagen membrane and a non-submerged healing was allowed. After 4 months, the animals were euthanized and bone blocks harvested and processed for histomorphometric analysis. The bony crest at the buccal aspect (C) was located 2.3 ± 0.8 mm and 1.7 ± 0.7 mm apically to the implant shoulder (IS) at the AB and DBBM sites, respectively. The coronal levels of osseointegration at the buccal aspect (B) were located 2.7 ± 0.7 mm and 2.2 ± 1.0 mm apically to IS at the AB and DBBM sites, respectively. At the AB sites, the peri-implant mucosa was located 4.3 ± 0.9 mm, 4.7 ± 0.9 mm, and 2.0 ± 1.6 mm coronally to C, B, and IS, respectively. The corresponding values at the DBBM sites were 4.3 ± 0.6 mm, 4.8 ± 0.6 mm, and 2.5 ± 0.8 mm, respectively. No statistically significant differences were found. The treatment of surgically created buccal defects at IPIES sites using Bio-Oss® (Geistlich Biomaterials, Wolhusen, LU, Switzerland) or autogenous bone, concomitantly with a collagen membrane, engenders bone regeneration to a similar extent after 4 months of healing. © 2015 Wiley Periodicals, Inc.

  16. Tips and Tricks in Mallet Fracture Fixation.

    Science.gov (United States)

    Chin, Yuin Cheng; Foo, Tun-Lin

    2016-10-01

    We describe three steps to aid fracture assessment and fixation in the extensor block pin technique for mallet fractures. The first step is the use of fluoroscopy in the initial assessment to determine indication for fixation. Next is the use of supplementary extension block pin to control larger dorsal fragments. The third technique described details the steps of open reduction of nascently malunited fractures.

  17. Outcome of rail fixator system in reconstructing bone gap

    Directory of Open Access Journals (Sweden)

    Amit Lakhani

    2014-01-01

    Conclusion: All patients well tolerated rail fixator with good functional results and gap reconstruction. Easy application of rail fixator and comfortable distraction procedure suggest rail fixator a good alternative for gap reconstruction of limbs.

  18. Ligature-induced peri-implantitis in mice.

    Science.gov (United States)

    Pirih, F Q; Hiyari, S; Barroso, A D V; Jorge, A C A; Perussolo, J; Atti, E; Tetradis, S; Camargo, P M

    2015-08-01

    Peri-implantitis has a prevalence of 11-47%, involves destruction of peri-implant bone and may lead to implant loss. A detailed understanding of the pathogenesis of peri-implantitis is lacking. The objective of this study was to develop a murine model of experimental peri-implantitis. Machined, smooth-surface, screw-shaped titanium implants were placed in the healed alveolar bone of the left maxillary molars of C57BL/6J male mice, 8 wk after tooth extraction. Peri-implantitis was induced by securing silk ligatures around the head of the implant fixtures. Implant survival and peri-implant bone levels were analyzed by micro-computed tomography (micro-CT) scans and histology, 12 wk after ligature placement. Implant survival was 60% (six of 10) for implants with ligatures and 100% (eight of eight) for controls. Micro-CT revealed significantly greater bone loss around the implants that received ligatures and that survived, compared with controls. The radiographic findings were confirmed via histology and toluidine blue staining. This study describes a murine model of experimental peri-implantitis around screw-shaped titanium implants placed in the edentulous alveolar bone. This model should be a useful tool to dissect pathogenic mechanisms of peri-implantitis and evaluate potential treatment interventions. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Absolute Versus Relative Fracture Fixation: Impact on Fracture Healing.

    Science.gov (United States)

    Norris, Brent L; Lang, Gerald; Russell, Thomas A Toney; Rothberg, David L; Ricci, William M; Borrelli, Joseph

    2018-03-01

    The goals of all orthopaedic surgeons treating fractures are, and will remain, obtaining union of the fracture with a well-aligned and functional limb while minimizing the risk of complications. This requires us to understand how the biomechanical environment of the fracture affects healing and to be able to discern which mechanical environment is preferred over another. Understanding the spectrum of stability imparted by our current surgical devices is paramount to giving our patients the best opportunity to heal and recover from their injury. Gone are the simplistic views of plates and screws being applied for absolute stability and nails and external fixators being applied for relative stability. This review sheds new light on how the use of different implants provides the appropriate stability to encourage fracture healing and limit the risk of complication and loss of function.

  20. Intraoperative Periprosthetic Femur Fracture: A Biomechanical Analysis of Cerclage Fixation.

    Science.gov (United States)

    Frisch, Nicholas B; Charters, Michael A; Sikora-Klak, Jakub; Banglmaier, Richard F; Oravec, Daniel J; Silverton, Craig D

    2015-08-01

    Intraoperative periprosthetic femur fracture is a known complication of total hip arthroplasty (THA) and a variety of cerclage systems are available to manage these fractures. The purpose of this study was to examine the in situ biomechanical response of cerclage systems for fixation of periprosthetic femur fractures that occur during cementless THA. We compared cobalt chrome (CoCr) cables, synthetic cables, monofilament wires and hose clamps under axial compressive and torsional loading. Metallic constructs with a positive locking system performed the best, supporting the highest loads with minimal implant subsidence (both axial and angular) after loading. Overall, the CoCr cable and hose clamp had the highest construct stiffness and least reduction in stiffness with increased loading. They were not demonstrably different from each other. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Rapid eye-fixation training without eyetracking.

    Science.gov (United States)

    Guzman-Martinez, Emmanuel; Leung, Parkson; Franconeri, Steve; Grabowecky, Marcia; Suzuki, Satoru

    2009-06-01

    Maintenance of stable central eye fixation is crucial for a variety of behavioral, electrophysiological, and neuroimaging experiments. Naive observers in these experiments are not typically accustomed to fixating, either requiring the use of cumbersome and costly eyetracking or producing confounds in results. We devised a flicker display that produced an easily detectable visual phenomenon whenever the eyes moved. A few minutes of training using this display dramatically improved the accuracy of eye fixation while observers performed a demanding spatial attention cuing task. The same amount of training using control displays did not produce significant fixation improvements, and some observers consistently made eye movements to the peripheral attention cue, contaminating the cuing effect. Our results indicate that (1) eye fixation can be rapidly improved in naive observers by providing real-time feedback about eye movements, and (2) our simple flicker technique provides an easy and effective method for providing this feedback.

  2. Safe corridor for the implantation of thoracolumbar pedicle screws in growing pigs: A morphometric study.

    Directory of Open Access Journals (Sweden)

    Thibaut Cachon

    Full Text Available The pig spine is widely used as a large animal model for preclinical research in human medicine to test new spinal implants and surgical procedures. Among them, pedicle screw is one of the most common method of fixation of those implants. However, the pedicle of the porcine vertebra is not as well defined and not as large as the pedicle of the human vertebra. Therefore, the position of the screw should be adapted to the pig and not merely transposed based on the literature on humans. The purpose of this study is to determine the characteristics of the optimum implantation corridors for pedicle screws in the thoracolumbar spine of piglets of different ages using computed tomography (CT and to determine the size and length of these corridors in pigs of different ages. CT scans from five groups of age: 6, 10, 14, 18, and 26 weeks were reviewed. For each thoracolumbar vertebrae, the pedicle width, pedicle axis length, and the pedicle angle was measured for the left and right pedicle. A total of 326 thoracic vertebrae and 126 lumbar vertebrae were included in the study. Pedicles are statistically larger but not longer for the lumbar vertebrae. An important variation of the pedicle angle is observed along the spine. In all pigs, an abrupt modification of the pedicle angle between T10 and T11 was observed, which corresponds to the level of the anticlinal vertebra which is the vertebra for which the spinous process is nearly perpendicular to the vertebral body. In conclusion, this study provides a quantitative database of pedicle screw implantation corridors in pigs of different ages. When using pedicle screws in experimental studies in pigs, these results should be considered for selecting the most suitable implants for the study but also to ensure a correct and safer screw position. Improving study procedures may limit postoperative complications and pain, thereby limiting the use of live animals.

  3. Safe corridor for the implantation of thoracolumbar pedicle screws in growing pigs: A morphometric study.

    Science.gov (United States)

    Cachon, Thibaut; Pillard, Paul; Odent, Thierry; Carozzo, Claude; Viguier, Eric

    2017-01-01

    The pig spine is widely used as a large animal model for preclinical research in human medicine to test new spinal implants and surgical procedures. Among them, pedicle screw is one of the most comm