Marginal bone levels at single tooth implants with a conical fixture design. The influence of surface macro- and microstructure.

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Norton, M R

1998-04-01

The concept of a conical implant design to accommodate single tooth replacement, has previously been shown to result in excessive bone loss, around the machined titanium conical collar, usually down to the 1st thread. This unusually aggressive loss of bone was shown to occur within a short period of time, post loading, with greater than 3 mm of bone loss occurring within the 1st 6 months to 1 year. The influence of implant design, surface texture and microleakage have all been highlighted as a potential cause. A modification of the surface structure, both at the macroscopic and microscopic level, as well as an altered fixture-abutment interface design has resulted in the maintenance of marginal bone around a single tooth titanium implant with a similar conical design. The radiographic follow-up of 33 implants loaded for up to 4 years, has revealed, by comparison, a most favourable maintenance of marginal bone around the conical collar, with a mean marginal bone loss of 0.32 mm mesially and 0.34 mm distally for the whole group. The cumulative mean marginal bone loss mesially and distally is 0.42 mm and 0.40 mm from 1 to 2 years, 0.54 mm and 0.43 mm from 2 to 3 years, 0.51 mm and 0.24 mm from 3 to 4 years, and 0.62 mm and 0.60 mm for implants past their 4 year recall.

Influence of Different Implant Geometry in Clinical Longevity and Maintenance of Marginal Bone: A Systematic Review.

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Lovatto, Sabrina Telles; Bassani, Rafaela; Sarkis-Onofre, Rafael; Dos Santos, Mateus Bertolini Fernandes

2018-03-26

To assess, through a systematic review, the influence of different implant geometries on clinical longevity and maintenance of marginal bone tissue. An electronic search was conducted in MEDLINE, Scopus, and Web of Science databases, limited to studies written in English from 1996 to 2017 using specific search strategies. Only randomized controlled trials (RCTs) that compared dental implants and their geometries were included. Two reviewers independently selected studies, extracted data, and assessed the risk of bias of included studies. From the 4006 references identified by the search, 24 were considered eligible for full-text analysis, after which 10 studies were included in this review. A similar behavior of marginal bone loss between tapered and cylindrical geometries was observed; however, implants that had micro-threads in the neck presented a slight decrease of marginal bone loss compared to implants with straight or smooth neck. Success and survival rates were high, with cylindrical implants presenting higher success and survival rates than tapered ones. Implant geometry seems to have little influence on marginal bone loss (MBL) and survival and success rates after 1 year of implant placement; however, the evidence in this systematic review was classified as very low due to limitations such as study design, sample size, and publication bias. Thus, more well-designed RCTs should be conducted to provide evidence regarding the influence of implant geometry on MBL and survival and success rates after 1 year of implant placement. © 2018 by the American College of Prosthodontists.

Stress and Alterations in Bones: An Interdisciplinary Perspective

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Pia-Maria Wippert

2017-05-01

Full Text Available Decades of research have demonstrated that physical stress (PS stimulates bone remodeling and affects bone structure and function through complex mechanotransduction mechanisms. Recent research has laid ground to the hypothesis that mental stress (MS also influences bone biology, eventually leading to osteoporosis and increased bone fracture risk. These effects are likely exerted by modulation of hypothalamic–pituitary–adrenal axis activity, resulting in an altered release of growth hormones, glucocorticoids and cytokines, as demonstrated in human and animal studies. Furthermore, molecular cross talk between mental and PS is thought to exist, with either synergistic or preventative effects on bone disease progression depending on the characteristics of the applied stressor. This mini review will explain the emerging concept of MS as an important player in bone adaptation and its potential cross talk with PS by summarizing the current state of knowledge, highlighting newly evolving notions (such as intergenerational transmission of stress and its epigenetic modifications affecting bone and proposing new research directions.

Meta-Analysis of Correlations Between Marginal Bone Resorption and High Insertion Torque of Dental Implants.

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Li, Haoyan; Liang, Yongqiang; Zheng, Qiang

2015-01-01

To evaluate correlations between marginal bone resorption and high insertion torque value (> 50 Ncm) of dental implants and to assess the significance of immediate and early/conventional loading of implants under a certain range torque value. Specific inclusion and exclusion criteria were used to retrieve eligible articles from Ovid, PubMed, and EBSCO up to December 2013. Screening of eligible studies, quality assessment, and data extraction were conducted in duplicate. The results were expressed as random/fixed-effects models using weighted mean differences for continuous outcomes with 95% confidence intervals. Initially, 154 articles were selected (11 from Ovid, 112 from PubMed, and 31 from EBSCO). After exclusion of duplicate articles and articles that did not meet the inclusion criteria, six clinical studies were selected. Assessment of P values revealed that correlations between marginal bone resorption and high insertion torque were not statistically significant and that there was no difference between immediately versus early/conventionally loaded implants under a certain range of torque. None of the meta-analyses revealed any statistically significant differences between high insertion torque and conventional insertion torque in terms of effects on marginal bone resorption.

Bone alterations by stress in athletes

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Doege, H.

1990-01-01

This report describes our experiences with the bone imaging in athletes. We studied 10 athletes and 10 other patients with spondylolisthesis of the lumbar spine and 16 athletes with suspicion of alterations of extremities. An increased uptake of this radiopharmaceutical was detected in six of 10 athletes with spondylolisthesis caused probably by stress fracture. Bone scans were negative in seven of 16 athletes with suspicion of lesion of extremities. In the remaining 9 patients scans were abnormal and showed periosteal injuries, epiphyseal alteration, joint abnormalities, tibial stress fractures and couvert fracture. It was also abnormal in bone injuries not evident in radiography. (orig.) [de

Prospective Analysis of Surgical Bone Margins After Partial Foot Amputation in Diabetic Patients Admitted With Moderate to Severe Foot Infections.

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Schmidt, Brian M; McHugh, Jonathan B; Patel, Rajiv M; Wrobel, James S

2018-04-01

Osteomyelitis is common in diabetic foot infections and medical management can lead to poor outcomes. Surgical management involves sending histopathologic and microbiologic specimens which guides future intervention. We examined the effect of obtainment of surgical margins in patients undergoing forefoot amputations to identify patient characteristics associated with outcomes. Secondary aims included evaluating interobserver reliability of histopathologic data at both the distal-to and proximal-to surgical bone margin. Data were prospectively collected on 72 individuals and was pooled for analysis. Standardized method to retrieve intraoperative bone margins was established. A univariate analysis was performed. Negative outcomes, including major lower extremity amputation, wound dehiscence, reulceration, reamputation, or death were recorded. Viable proximal margins were obtained in 63 out of 72 cases (87.5%). Strong interobserver reliability of histopathology was recorded. Univariate analysis demonstrated preoperative platelets, albumin, probe-to-bone testing, absolute toe pressures, smaller wound surface area were associated with obtaining viable margins. Residual osteomyelitis resulted in readmission 2.6 times more often and more postoperative complications. Certain patients were significantly different in the viable margin group versus dirty margin group. High interobserver reliability was demonstrated. Obtainment of viable margins resulted in reduced rates of readmission and negative outcomes. Prognostic, Level I: Prospective.

Influence of surgical and prosthetic techniques on marginal bone loss around titanium implants. Part I: immediate loading in fresh extraction sockets.

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Berberi, Antoine N; Tehini, Georges E; Noujeim, Ziad F; Khairallah, Alexandre A; Abousehlib, Moustafa N; Salameh, Ziad A

2014-10-01

Delayed placement of implant abutments has been associated with peri-implant marginal bone loss; however, long-term results obtained by modifying surgical and prosthetic techniques after implant placement are still lacking. This study aimed to evaluate the marginal bone loss around titanium implants placed in fresh extraction sockets using two loading protocols after a 5-year follow-up period. A total of 36 patients received 40 titanium implants (Astra Tech) intended for single-tooth replacement. Implants were immediately placed into fresh extraction sockets using either a one-stage (immediate loading by placing an interim prosthesis into functional occlusion) or a two-stage prosthetic loading protocol (insertion of abutments after 8 weeks of healing time). Marginal bone levels relative to the implant reference point were evaluated at four time intervals using intraoral radiographs: at time of implant placement, and 1, 3, and 5 years after implant placement. Measurements were obtained from mesial and distal surfaces of each implant (α = 0.05). One-stage immediate implant placement into fresh extraction sockets resulted in a significant reduction in marginal bone loss (p sockets reduced marginal bone loss and did not compromise the success rate of the restorations. © 2014 by the American College of Prosthodontists.

Effects of Active Mastication on Chronic Stress-Induced Bone Loss in Mice.

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Azuma, Kagaku; Furuzawa, Manabu; Fujiwara, Shu; Yamada, Kumiko; Kubo, Kin-ya

2015-01-01

Chronic psychologic stress increases corticosterone levels, which decreases bone density. Active mastication or chewing attenuates stress-induced increases in corticosterone. We evaluated whether active mastication attenuates chronic stress-induced bone loss in mice. Male C57BL/6 (B6) mice were randomly divided into control, stress, and stress/chewing groups. Stress was induced by placing mice in a ventilated restraint tube (60 min, 2x/day, 4 weeks). The stress/chewing group was given a wooden stick to chew during the experimental period. Quantitative micro-computed tomography, histologic analysis, and biochemical markers were used to evaluate the bone response. The stress/chewing group exhibited significantly attenuated stress-induced increases in serum corticosterone levels, suppressed bone formation, enhanced bone resorption, and decreased trabecular bone mass in the vertebrae and distal femurs, compared with mice in the stress group. Active mastication during exposure to chronic stress alleviated chronic stress-induced bone density loss in B6 mice. Active mastication during chronic psychologic stress may thus be an effective strategy to prevent and/or treat chronic stress-related osteopenia.

Does the Laser-Microtextured Short Implant Collar Design Reduce Marginal Bone Loss in Comparison with a Machined Collar?

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B. Alper Gultekin

2016-01-01

Full Text Available Purpose. To compare marginal bone loss between subgingivally placed short-collar implants with machined collars and those with machined and laser-microtextured collars. Materials and Methods. The investigators used a retrospective study design and included patients who needed missing posterior teeth replaced with implants. Short-collar implants with identical geometries were divided into two groups: an M group, machined collar; and an L group, machined and laser-microtextured collar. Implants were evaluated according to marginal bone loss, implant success, and probing depth (PD at 3 years of follow-up. Results. Sixty-two patients received 103 implants (56 in the M group and 47 in the L group. The cumulative survival rate was 100%. All implants showed clinically acceptable marginal bone loss, although bone resorption was lower in the L group (0.49 mm than in the M group (1.38 mm at 3 years (p<0.01. A significantly shallower PD was found for the implants in the L group during follow-up (p<0.01. Conclusions. Our results suggest predictable outcomes with regard to bone loss for both groups; however, bone resorption was less in the L group than in the M group before and after loading. The laser-microtextured collar implant may provide a shallower PD than the machined collar implant.

Computer stress study of bone with computed tomography

International Nuclear Information System (INIS)

Linden, M.J.; Marom, S.A.; Linden, C.N.

1986-01-01

A computer processing tool has been developed which, together with a finite element program, determines the stress-deformation pattern in a long bone, utilizing Computed Tomography (CT) data files for the geometry and radiographic density information. The geometry, together with mechanical properties and boundary conditions: loads and displacements, comprise the input of the Finite element (FE) computer program. The output of the program is the stresses and deformations in the bone. The processor is capable of developing an accurate three-dimensional finite element model from a scanned human long bone due to the CT high pixel resolution and the local mechanical properties determined from the radiographic densities of the scanned bone. The processor, together with the finite element program, serves first as an analysis tool towards improved understanding of bone function and remodelling. In this first stage, actual long bones may be scanned and analyzed under applied loads and displacements, determined from existing gait analyses. The stress-deformation patterns thus obtained may be used for studying the biomechanical behavior of particular long bones such as bones with implants and with osteoporosis. As a second stage, this processor may serve as a diagnostic tool for analyzing the biomechanical response of a specific patient's long long bone under applied loading by utilizing a CT data file of the specific bone as an input to the processor with the FE program

99mTc-MDP bone scintigraphy in the diagnosis of stress fracture of the metatarsal bones mimicking oligoarthritis

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Jauković Ljiljana

2008-01-01

Full Text Available Background. Stress fractures are the injuries of soft tissues and bones caused by intensive and repeated stress on a bone. Repeated submaximal stress disturbs the balance between the processes of bone production and resorption that results in fracture. Case report. We presented a case of a patient with stress fracture of metatarsal bone. The patient was diagnosed and treated as having reactive oligoarthritis caused by Chlamydia trachomatis and administered antibiotics. Initial plain radiography was negative for bone fracture. Tc-99m bone scintigraphy suggested stress fracture of the second metatarsal. Plain radiography was became positive three weeks later, showing callus formation in the proximal part of the second metatarsal. Conclusion. Bone scintigraphy is a diagnostic test of choice in early diagnosis of stress fracture, and it is important to apply it timely in order to include the entire therapy and prevent complications, as well as to let a patient return to previous daily activites.

Giant cell tumor in long bones: the significance of marginal sclerosis for the differential diagnosis

International Nuclear Information System (INIS)

Kim, Hee Jin; Suh, Jin Suck; Park, Chang Yun

1993-01-01

Plain radiographs of thirty nine patients with giant cell tumor of long bone and CT scans of twenty patients among the thirty patients were reviewed retrospectively to evaluate the frequency and significance of sclerosis of the tumor margin. The sclerosis of the tumor margin was observed on plain radiographs in thirteen patients(33.3%) and they were located either on epiphyseal or on both epiphyseal or metaphyseal portion of the tumor. The authors concluded that the giant cell tumor should not be excluded from the differential entities even though the tumor has the marginal sclerosis

Marginal bone-level alterations of loaded zirconia and titanium dental implants: an experimental study in the dog mandible.

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Thoma, Daniel S; Benic, Goran I; Muñoz, Fernando; Kohal, Ralf; Sanz Martin, Ignacio; Cantalapiedra, Antonio G; Hämmerle, Christoph H F; Jung, Ronald E

2016-04-01

The aim was to test whether or not the marginal bone-level alterations of loaded zirconia implants are similar to the bone-level alterations of a grade 4 titanium one-piece dental implant. In six dogs, all premolars and the first molars were extracted in the mandible. Four months later, three zirconia implants (BPI, VC, ZD) and a control titanium one-piece (STM) implant were randomly placed in each hemimandible and left for transmucosal healing (baseline). Six months later, CAD/CAM crowns were cemented. Sacrifice was scheduled at 6-month postloading. Digital X-rays were taken at implant placement, crowns insertion, and sacrifice. Marginal bone-level alterations were calculated, and intra- and intergroup comparisons performed adjusted by confounding factors. Implants were successfully placed. Until crown insertion, two implants were fractured (one VC, one ZD). At sacrifice, 5 more implants were (partly) fractured (one BPI, four ZD), and one lost osseointegration (VC). No decementation of crowns occurred. All implant systems demonstrated a statistically significant (except VC) loss of marginal bone between baseline and crown insertion ranging from 0.29 mm (VC; P = 0.116) to 0.80 mm (ZD; P = 0.013). The estimated marginal bone loss between baseline and 6 months of loading ranged between 0.19 mm (BPI) and 1.11 mm (VC), being statistically significant for STM and VC only (P implants and control implants (STM vs. BPI P = 0.007; vs. VC P = 0.001; vs. ZD P = 0.011). Zirconia implants were more prone to fracture prior to and after loading with implant-supported crowns compared to titanium implants. Individual differences and variability in the extent of the bone-level changes during the 12-month study period were found between the different implant types and materials. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Clinical evaluation of stress fractures using bone scintigraphy

International Nuclear Information System (INIS)

Furuta, Atsuhiko; Tanohata, Kazunori; Otake, Toru; Hashizume, Toshiyuki; Kobayashi, Yozi; Nakazima, Hiroyuki.

1984-01-01

Clinical evaluation of stress fractures were performed in 58 athletes using bone scintigraphy with sup(99m)Tc-MDP. Stress fractures of the tibia were most often seen in the males with running type sports. They occurred more often in the proximal tibia and on the right side. Stress fractures of the fibula were most often seen in females with jumping type sports, such as volley ball. They occurred more often in the distal fibula and on the right side. Tarsal bone fractures were seen most often rugby players. Metatarsal fractures occurred in the third fourth and fifth metatarsals. No lesion was seen in the first and second metatarsals. We feel that stress fractures of the femur can be differentiated from osteosarcoma by small loculated radionuclide accumulation as well as symptome, course and tomographic and CT finding. Bilateral involvement was seen in two cases in patellae and calcanei. Most of the other fractures were seen on the right side. Negative radiographs were seen in 36% of the patients and occurred most commonly in the tarsal bones excluding calcaneus. Bone scintigrams were positive in all cases and were most useful in fractures of the tarsal bones excluding calcaneus. (author)

Clinical evaluation of stress fractures using bone scintigraphy

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Furuta, Atsuhiko; Tanohata, Kazunori; Otake, Toru; Hashizume, Toshiyuki (Kanto Rosai Hospital, Kawasaki, Kanagawa (Japan)); Kobayashi, Yozi; Nakazima, Hiroyuki

1984-05-01

Clinical evaluation of stress fractures were performed in 58 athletes using bone scintigraphy with sup(99m)Tc-MDP. Stress fractures of the tibia were most often seen in the males with running type sports. They occurred more often in the proximal tibia and on the right side. Stress fractures of the fibula were most often seen in females with jumping type sports, such as volley ball. They occurred more often in the distal fibula and on the right side. Tarsal bone fractures were seen most often rugby players. Metatarsal fractures occurred in the third fourth and fifth metatarsals. No lesion was seen in the first and second metatarsals. We feel that stress fractures of the femur can be differentiated from osteosarcoma by small loculated radionuclide accumulation as well as symptoms, course and tomographic and CT findings. Bilateral involvement was seen in two cases in patellae and calcanei. Most of the other fractures were seen on the right side. Negative radiographs were seen in 36% of the patients and occurred most commonly in the tarsal bones excluding calcaneus. Bone scintigrams were positive in all cases and were most useful in fractures of the tarsal bones excluding calcaneus.

Retrospective analysis of survival rates and marginal bone loss on short implants in the mandible.

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Draenert, Florian G; Sagheb, Keyvan; Baumgardt, Katharina; Kämmerer, Peer W

2012-09-01

Short implants have become an interesting alternative to bone augmentation in dental implantology. Design of shorter implants and longer surveillance times are a current research issue. The goal of this study was to show the survival rates of short implants below 9 mm in the partly edentulous mandibular premolar and molar regions with fixed prosthetics. Marginal vertical and 2D bone loss was evaluated additionally. Different implant designs are orientationally evaluated. A total of 247 dental implants with fixed prosthetics (crowns and bridges) in the premolar and molar region of the mandible were evaluated; 47 implants were 9 mm or shorter. Patient data were evaluated to acquire implant survival rates, implant diameter, gender and age. Panoramic X-rays were analysed for marginal bone loss. Average surveillance time was 1327 days. Cumulative survival rate (CSR) of short implants was 98% (1 implants lost) compared to 94% in the longer implants group without significance. Thirty-five of the short implants were Astratech (0 losses) and 12 were Camlog Screw Line Promote Plus (1 loss). Early vertical and two-dimensional marginal bone loss was not significantly different in short and regular length implant group with an average of 0.6 mm and 0.7 mm(2) in short implants over the observation period. Within the limitations of this study, we conclude that short implants with a length of 9 mm or less have equal survival rates compared with longer implants over the observation period of 1-3 years. © 2011 John Wiley & Sons A/S.

Minority Stress and Stress Proliferation Among Same-Sex and Other Marginalized Couples.

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LeBlanc, Allen J; Frost, David M; Wight, Richard G

2015-02-01

Drawing from 2 largely isolated approaches to the study of social stress-stress proliferation and minority stress-the authors theorize about stress and mental health among same-sex couples. With this integrated stress framework, they hypothesized that couple-level minority stressors may be experienced by individual partners and jointly by couples as a result of the stigmatized status of their same-sex relationship-a novel concept. They also consider dyadic minority stress processes, which result from the relational experience of individual-level minority stressors between partners. Because this framework includes stressors emanating from both status- (e.g., sexual minority) and role-based (e.g., partner) stress domains, it facilitates the study of stress proliferation linking minority stress (e.g., discrimination), more commonly experienced relational stress (e.g., conflict), and mental health. This framework can be applied to the study of stress and health among other marginalized couples, such as interracial/ethnic, interfaith, and age-discrepant couples.

Bone density and anisotropy affect periprosthetic cement and bone stresses after anatomical glenoid replacement: A micro finite element analysis.

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Chevalier, Yan; Santos, Inês; Müller, Peter E; Pietschmann, Matthias F

2016-06-14

Glenoid loosening is still a main complication for shoulder arthroplasty. We hypothesize that cement and bone stresses potentially leading to fixation failure are related not only to glenohumeral conformity, fixation design or eccentric loading, but also to bone volume fraction, cortical thickness and degree of anisotropy in the glenoid. In this study, periprosthetic bone and cement stresses were computed with micro finite element models of the replaced glenoid depicting realistic bone microstructure. These models were used to quantify potential effects of bone microstructural parameters under loading conditions simulating different levels of glenohumeral conformity and eccentric loading simulating glenohumeral instability. Results show that peak cement stresses were achieved near the cement-bone interface in all loading schemes. Higher stresses within trabecular bone tissue and cement mantle were obtained within specimens of lower bone volume fraction and in regions of low anisotropy, increasing with decreasing glenohumeral conformity and reaching their maxima below the keeled design when the load is shifted superiorly. Our analyses confirm the combined influences of eccentric load shifts with reduced bone volume fraction and anisotropy on increasing periprosthetic stresses. They finally suggest that improving fixation of glenoid replacements must reduce internal cement and bone tissue stresses, in particular in glenoids of low bone density and heterogeneity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Minority Stress and Stress Proliferation Among Same-Sex and Other Marginalized Couples

Science.gov (United States)

LeBlanc, Allen J.; Frost, David M.; Wight, Richard G.

2014-01-01

Drawing from 2 largely isolated approaches to the study of social stress—stress proliferation and minority stress—the authors theorize about stress and mental health among same-sex couples. With this integrated stress framework, they hypothesized that couple-level minority stressors may be experienced by individual partners and jointly by couples as a result of the stigmatized status of their same-sex relationship—a novel concept. They also consider dyadic minority stress processes, which result from the relational experience of individual-level minority stressors between partners. Because this framework includes stressors emanating from both status- (e.g., sexual minority) and role-based (e.g., partner) stress domains, it facilitates the study of stress proliferation linking minority stress (e.g., discrimination), more commonly experienced relational stress (e.g., conflict), and mental health. This framework can be applied to the study of stress and health among other marginalized couples, such as interracial/ethnic, interfaith, and age-discrepant couples. PMID:25663713

[Influence of different designs of marginal preparation on stress distribution in the mandibular premolar restored with endocrown].

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Guo, Jing; Wang, Xiao-Yu; Li, Xue-Sheng; Sun, Hai-Yang; Liu, Lin; Li, Hong-Bo

2016-02-01

To evaluate the effect of different designs of marginal preparation on stress distribution in the mandibular premolar restored with endocrown using three-dimensional finite element method. Four models with different designs of marginal preparation, including the flat margin, 90° shoulder, 135° shoulder and chamfer shoulder, were established to imitate mandibular first premolar restored with endocrown. A load of 100 N was applied to the intersection of the long axis and the occlusal surface, either parallel or with an angle of 45° to the long axis of the tooth. The maximum values of Von Mises stress and the stress distribution around the cervical region of the abutment and the endocrown with different designs of marginal preparation were analyzed. The load parallel to the long axis of the tooth caused obvious stress concentration in the lingual portions of both the cervical region of the tooth tissue and the restoration. The stress distribution characteristics on the cervical region of the models with a flat margin and a 90° shoulder were more uniform than those in the models with a 135° shoulder and chamfer shoulder. Loading at 45° to the long axis caused stress concentration mainly on the buccal portion of the cervical region, and the model with a flat margin showed the most favorable stress distribution patterns with a greater maximum Von Mises stress under this circumstance than that with a parallel loading. Irrespective of the loading direction, the stress value was the lowest in the flat margin model, where the stress value in the cervical region of the endocrown was greater than that in the counterpart of the tooth tissue. The stress level on the enamel was higher than that on the dentin nearby in the flat margin model. From the stress distribution point of view, endocrowns with flat margin followed by a 90° shoulder are recommended.

Evaluation of marginal bone loss of dental implants with internal or external connections and its association with other variables: A systematic review.

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de Medeiros, Rodrigo Antonio; Pellizzer, Eduardo Piza; Vechiato Filho, Aljomar José; Dos Santos, Daniela Micheline; da Silva, Emily Vivianne Freitas; Goiato, Marcelo Coelho

2016-10-01

Different factors can influence marginal bone loss around dental implants, including the type of internal and external connection between the implant and the abutment. The evidence needed to evaluate these factors is unclear. The purpose of this systematic review was to evaluate marginal bone loss by radiographic analysis around dental implants with internal or external connections. A systematic review was conducted following the criteria defined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Initially, a population, intervention, comparison, and outcome(s) (PICO) question was defined: does the connection type (internal or external) influence marginal bone loss in patients undergoing implantation? An electronic search of PubMed/MEDLINE and Scopus databases was performed for studies in English language published between January 2000 and December 2014 by 2 independent reviewers, who analyzed the marginal bone loss of dental implants with an internal and/or external connection. From an initial screening yield of 595 references and after considering inclusion and exclusion criteria, 17 articles were selected for this review. Among them, 10 studies compared groups of implants with internal and external connections; 1 study evaluated external connections; and 6 studies analyzed internal connections. A total of 2708 implants were placed in 864 patients. Regarding the connection type, 2347 implants had internal connections, and 361 implants had external connections. Most studies showed lower marginal bone loss values for internal connection implants than for external connection implants. Osseointegrated dental implants with internal connections exhibited lower marginal bone loss than implants with external connections. This finding is mainly the result of the platform switching concept, which is more frequently found in implants with internal connections. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry

Oxidative stress in bone remodeling: role of antioxidants.

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Domazetovic, Vladana; Marcucci, Gemma; Iantomasi, Teresa; Brandi, Maria Luisa; Vincenzini, Maria Teresa

2017-01-01

ROS are highly reactive molecules which consist of a number of diverse chemical species, including radical and non-radical oxygen species. Oxidative stress occurs as a result of an overproduction of ROS not balanced by an adequate level of antioxidants. The natural antioxidants are: thiol compounds among which GSH is the most representative, and non-thiol compounds such as polyphenols, vitamins and also various enzymes. Many diseases have been linked to oxidative stress including bone diseases among which one of the most important is the osteoporosis. The redox state changes are also related to the bone remodeling process which allows the continuous bone regeneration through the coordinated action of bone cells: osteoclasts, osteoblasts and osteocytes. Changes in ROS and/or antioxidant systems seem to be involved in the pathogenesis of bone loss. ROS induce the apoptosis of osteoblasts and osteocytes, and this favours osteoclastogenesis and inhibits the mineralization and osteogenesis. Excessive osteocyte apoptosis correlates with oxidative stress causing an imbalance in favor of osteoclastogenesis which leads to increased turnover of bone remodeling and bone loss. Antioxidants either directly or by counteracting the action of oxidants contribute to activate the differentiation of osteoblasts, mineralization process and the reduction of osteoclast activity. In fact, a marked decrease in plasma antioxidants was found in aged or osteoporotic women. Some evidence shows a link among nutrients, antioxidant intake and bone health. Recent data demonstrate the antioxidant properties of various nutrients and their influence on bone metabolism. Polyphenols and anthocyanins are the most abundant antioxidants in the diet, and nutritional approaches to antioxidant strategies, in animals or selected groups of patients with osteoporosis or inflammatory bone diseases, suggest the antioxidant use in anti-resorptive therapies for the treatment and prevention of bone loss.

Impact of platform switching on marginal peri-implant bone-level changes. A systematic review and meta-analysis

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Strietzel, Frank Peter; Neumann, Konrad; Hertel, Moritz

2015-01-01

Objective To address the focused question, is there an impact of platform switching (PS) on marginal bone level (MBL) changes around endosseous implants compared to implants with platform matching (PM) implant-abutment configurations? Material and methods A systematic literature search was conducted using electronic databases PubMed, Web of Science, Journals@Ovid Full Text and Embase, manual search for human randomized clinical trials (RCTs) and prospective clinical controlled cohort studies (PCCS) reporting on MBL changes at implants with PS-, compared with PM-implant-abutment connections, published between 2005 and June 2013. Results Twenty-two publications were eligible for the systematic review. The qualitative analysis of 15 RCTs and seven PCCS revealed more studies (13 RCTs and three PCCS) showing a significantly less mean marginal bone loss around implants with PS- compared to PM-implant-abutment connections, indicating a clear tendency favoring the PS technique. A meta-analysis including 13 RCTs revealed a significantly less mean MBL change (0.49 mm [CI95% 0.38; 0.60]) at PS implants, compared with PM implants (1.01 mm [CI95% 0.62; 1.40] (P marginal bone loss compared with PM technique. Due to heterogeneity of the included studies, their results require cautious interpretation. PMID:24438506

Peri-implant soft tissue and marginal bone adaptation on implant with non-matching healing abutments: micro-CT analysis.

Science.gov (United States)

Finelle, Gary; Papadimitriou, Dimitrios E V; Souza, André B; Katebi, Negin; Gallucci, German O; Araújo, Mauricio G

2015-04-01

To assess (i) the outcome of changing the horizontal-offset dimension on the peri-implant soft tissues and the crestal bone and (ii) the effect of different healing abutments (flared vs. straight) on the marginal peri-implant soft tissues and crestal bone. Two-piece dental implants diameters of 3.5 and 4.5 mm were placed at least 1 mm subcrestal in five beagle dogs. Three different investigational groups: (i) 3.5-mm-diameter implant with narrow healing abutment (3.5N), (ii) 4.5-mm-diameter implant with narrow healing abutment (4.5N), and (iii) 3.5-mm-diameter implant with wide healing abutment (3.5W), were assessed. After 4 months of healing, the vertical distance from the marginal crestal bone (MB) to the implant shoulder (IS); the vertical distance from the IS to the first bone-to-implant contact; and the horizontal distance of bone ingrowth on the implant platform were measured with a high-resolution micro-CT (Xradia MicroXCT-200 system). Implants with a narrow healing caps showed an interproximal MB located between 0 and 1 mm above the implant shoulder, while the 3.5W group exhibits a mean value -0.50 mm. As all implants in group 3.5N presented a fBIC located at the level of the IS. For the 4.5N group, the mean fBIC-IS distance was -0.52 mm apically to the IS. For the 3.5WC group, the mean fBIC-IS distance was -1.42 mm. Horizontal bone apposition was only observed for the 3.5N group and the 4.5N group. The dimension of the horizontal offset would play a minimal role in reducing bone remodeling, whereas the configuration of the transmucosal component would directly influence marginal bone remodeling. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Comparison of marginal bone loss and implant success between axial and tilted implants in maxillary All-on-4 treatment concept rehabilitations after 5 years of follow-up.

Science.gov (United States)

Hopp, Milena; de Araújo Nobre, Miguel; Maló, Paulo

2017-10-01

There is need for more scientific and clinical information on longer-term outcomes of tilted implants compared to implants inserted in an axial position. Comparison of marginal bone loss and implant success after a 5-year follow-up between axial and tilted implants inserted for full-arch maxillary rehabilitation. The retrospective clinical study included 891 patients with 3564 maxillary implants rehabilitated according to the All-on-4 treatment concept. The follow-up time was 5 years. Linear mixed-effect models were performed to analyze the influence of implant orientation (axial/tilted) on marginal bone loss and binary logistic regression to assess the effect of patient characteristics on occurrence of marginal bone loss >2.8 mm. Only those patients with measurements of at least one axial and one tilted implant available were analyzed. This resulted in a data set of 2379 implants (1201 axial, 1178 tilted) in 626 patients (=reduced data set). Axial and tilted implants showed comparable mean marginal bone losses of 1.14 ± 0.71 and 1.19 ± 0.82 mm, respectively. Mixed model analysis indicated that marginal bone loss levels at 5 years follow up was not significantly affected by the orientation (axial/tilted) of the implants in the maxillary bone. Smoking and female gender were associated with marginal bone loss >2.8 mm in a logistic regression analysis. Five-year implant success rates were 96%. The occurrence of implant failure showed to be statistically independent from orientation. Within the limitations of this study and considering a follow-up time of 5 years, it can be concluded that tilted implants behave similarly with regards to marginal bone loss and implant success in comparison to axial implants in full-arch rehabilitation of the maxilla. Longer-term outcomes (10 years +) are needed to verify this result. © 2017 Wiley Periodicals, Inc.

Pilot study of intraoperative digital imaging with the use of a mammograph for assessment of bone surgical margins in the head and neck region

International Nuclear Information System (INIS)

Ntomouchtsis, A.; Xinou, K.; Patrikidou, A.; Paraskevopoulos, K.; Kechagias, N.; Tsekos, A.; Balis, G.C.; Gerasimidou, D.; Thuau, H.; Mangoudi, D.; Vahtsevanos, K.

2013-01-01

Aim: To investigate alternative possibilities for the intraoperative evaluation of surgical margins after bone resection utilizing more conventional hospital infrastructure technologies. Materials and methods: A small pilot study was performed using digital mammograph imaging intraoperatively on 16 surgical specimens of bone tumours or malignancies with bone infiltration of the head and neck area, with the aim of evaluating the resection margins. Results: In thirteen cases the intraoperative specimen images indicated clinically complete excision. In two cases incomplete resection or close proximity of margins was detected, which required additional resection. Conclusions: The results indicated that intraoperative specimen radiography can prove useful in evaluating completeness of excision. The significance of intraoperative assessment of surgical margin is of paramount importance when immediate reconstruction is performed. This proposed method is cheap, easy to perform and fast. Its cost–benefit ratio is superior than that of any other available technique. Intraoperative analysis of specimens with digital mammography imaging can potentially become a useful tool for immediate evaluation of osseous margins after resection

Abutment-to-fixture load transfer and peri-implant bone stress

NARCIS (Netherlands)

van Oers, R.F.; Feilzer, A.J.

2015-01-01

Purpose: To uncover design principles for the abutment-fixture complex that reduce the stress concentration on the bone. Methods: A 3-dimensional finite element model was used to vary shape, elasticity, and connectivity of the abutment-fixture complex. We compared peri-implant bone stress of these

Comparison of Marginal Bone Loss Between Implants with Internal and External Connections: A Systematic Review.

Science.gov (United States)

Palacios-Garzón, Natalia; Mauri-Obradors, Elisabeth; Roselló-LLabrés, Xavier; Estrugo-Devesa, Albert; Jané-Salas, Enric; López-López, José

The objective of this systematic review was to compare the loss of marginal bone between implants with internal and external connections by analyzing results reported in studies published after 2010. A literature search in MEDLINE with the keywords "dental implant connections, external internal implant connection, bone loss implant designs, internal and external connection implant studies in humans" was conducted. Clinical trials on human beings, comparing both connections and published in English, from 2010 to 2016 were selected. Their methodologic quality was assessed using the Jadad scale. From the initial search, 415 articles were obtained; 32 were chosen as potentially relevant based on their titles and abstracts. Among them, only 10 finally met the inclusion criteria. A total of 1,523 patients with 3,965 implants were analyzed. Six out of 10 studies observed that internal connections showed significantly less bone loss compared with external connections. The remaining four articles did not find statistically significant differences between the two connections. According to this systematic review and considering its limitation due to the degree of heterogeneity between the included studies, both internal and external connections present high survival rates. To assess whether marginal bone loss differs significantly between the two connections, more homogenous clinical studies are needed with identical implant characteristics, larger samples, and longer follow-up periods. Studies included in this review and characterized by long-term follow-ups showed that the external connection is a reliable connection on a long-term basis.

Is bone marrow biopsy always indicated in patients with primary cutaneous marginal zone B-cell lymphoma?

Science.gov (United States)

Muniesa, C; Hernández-Machín, B

2013-10-01

Bone marrow involvement at the time of diagnosis is uncommon in patients with primary cutaneous marginal zone B-cell lymphoma (PCMZL). Moreover, in these patients such involvement is rarely found in isolation on diagnosis. Typically the few patients with PCMZL who have early bone marrow involvement also present secondary nodal or visceral involvement, which is detected by other staging studies (usually computed tomography). In recent years, this has given rise to some debate about whether a bone marrow biopsy should be routinely performed in patients diagnosed with PCMZL in view of the good prognosis and low incidence of bone marrow infiltration and/or extracutaneous involvement in this type of lymphoma. Copyright © 2012 Elsevier España, S.L. and AEDV. All rights reserved.

Hypericum perforatum L. treatment restored bone mass changes in swimming stressed rats.

Science.gov (United States)

Seferos, Nikos; Petrokokkinos, Loukas; Kotsiou, Antonia; Rallis, George; Tesseromatis, Christine

2016-01-01

Stress, via corticosteroids release, influences bone mass density. Hypericum perforatum (Hp) a traditional remedy possess antidepressive activity (serotonin reuptake inhibitor) and wound healing properties. Hp preparation contains mainly hypericin, hyperforin, hyperoside and flavonoids exerting oestrogen-mimetic effect. Cold swimming represents an experimental model of stress associating mental strain and corporal exhaustion. This study investigates the Hp effect on femur and mandible bone mass changes in rats under cold forced swimming procedure. 30 male Wistar rats were randomized into three groups. Group A was treated with Methanolic extract of Hp (Jarsin®) via gastroesophageal catheter, and was submitted to cold swimming stress for 10 min/daily. Group B was submitted to cold stress, since group C served as control. Experiment duration was 10 days. Haematocrite and serum free fatty acids (FFA) were estimated. Furthermore volume and specific weight of each bone as well as bone mass density via dual energy X-Ray absorptiometry (DEXA) were measured. Statistic analysis by t-test. Hp treatment restores the stress injuries. Adrenals and bone mass density regain their normal values. Injuries occurring by forced swimming stress in the rats are significantly improved by Hp treatment. Estrogen-like effects of Hp flavonoids eventually may act favorable in bone remodeling.

Maintenance of marginal bone support and soft tissue esthetics at immediately provisionalized OsseoSpeed implants placed into extraction sites: 2-year results.

Science.gov (United States)

Noelken, Robert; Neffe, Bettina Anna; Kunkel, Martin; Wagner, Wilfried

2014-02-01

Placement of implants into extraction sockets targets the maintenance of peri-implant hard and soft tissue structures and the support of a natural and esthetic contour. The main advantages of immediate implant insertion in comparison with delayed implant placement protocols are as follows: a reduced treatment time, less number of sessions, and, thus, the less invasive procedure. This study examines the clinical performance (survival rate, marginal bone levels and Pink Esthetic Score [PES]) of OsseoSpeed implants placed into extraction sockets with immediate provisionalization in the anterior maxilla after a follow-up of at least 12 months. Twenty patients received a total number of 37 OsseoSpeed implants which were immediately inserted into extraction sockets with or without facial bone deficiencies of various dimensions. A flapless procedure was applied, and the implants were immediately provisionalized with temporary crowns without occlusal contacts. Facial gaps between implant surface and facial bone or the previous contour of the alveolar process were grafted with autogenous bone chips. Implants in diameters 3.5, 4.0, 4.5, and 5.0 with lengths of 11-17 mm were used in the study. During the course of the study, interproximal marginal bone levels, the thickness of the facial bony wall, implant success rate according to the criteria established by Buser, and the PES were assessed per implant. One patient with three implants did not continue the study after prosthesis delivery, the remaining 34 implants were still in function at the final follow-up (survival rate: 100%). The mean follow-up period was 27 months (range, 12-40 months). Marginal bone height at the level of the implant shoulder averaged -0.1 ± 0.55 mm (range, -1.25 to 1.47 mm) at the final follow-up. The mean PES ratings were 11.3 ± 1.8 (range, 6-14) at the final follow-up. In 78% of the patients, the PES was preserved or even improved. Success rates, marginal bone levels, and esthetic results suggest

Cement stress predictions after anatomic total shoulder arthroplasty are correlated with preoperative glenoid bone quality.

Science.gov (United States)

Terrier, Alexandre; Obrist, Raphaël; Becce, Fabio; Farron, Alain

2017-09-01

We hypothesized that biomechanical parameters typically associated with glenoid implant failure after anatomic total shoulder arthroplasty (aTSA) would be correlated with preoperative glenoid bone quality. We developed an objective automated method to quantify preoperative glenoid bone quality in different volumes of interest (VOIs): cortical bone, subchondral cortical plate, subchondral bone after reaming, subchondral trabecular bone, and successive layers of trabecular bone. Average computed tomography (CT) numbers (in Hounsfield units [HU]) were measured in each VOI from preoperative CT scans. In parallel, we built patient-specific finite element models of simulated aTSAs to predict cement stress, bone-cement interfacial stress, and bone strain around the glenoid implant. CT measurements and finite element predictions were obtained for 20 patients undergoing aTSA for primary glenohumeral osteoarthritis. We tested all linear correlations between preoperative patient characteristics (age, sex, height, weight, glenoid bone quality) and biomechanical predictions (cement stress, bone-cement interfacial stress, bone strain). Average CT numbers gradually decreased from cortical (717 HU) to subchondral and trabecular (362 HU) bone. Peak cement stress (4-10 MPa) was located within the keel hole, above the keel, or behind the glenoid implant backside. Cement stress, bone-cement interfacial stress, and bone strain were strongly negatively correlated with preoperative glenoid bone quality, particularly in VOIs behind the implant backside (subchondral trabecular bone) but also in deeper trabecular VOIs. Our numerical study suggests that preoperative glenoid bone quality is an important parameter to consider in aTSA, which may be associated with aseptic loosening of the glenoid implant. These initial results should now be confronted with clinical and radiologic outcomes. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc

Splenic marginal zone lymphoma.

Science.gov (United States)

Piris, Miguel A; Onaindía, Arantza; Mollejo, Manuela

Splenic marginal zone lymphoma (SMZL) is an indolent small B-cell lymphoma involving the spleen and bone marrow characterized by a micronodular tumoral infiltration that replaces the preexisting lymphoid follicles and shows marginal zone differentiation as a distinctive finding. SMZL cases are characterized by prominent splenomegaly and bone marrow and peripheral blood infiltration. Cells in peripheral blood show a villous cytology. Bone marrow and peripheral blood characteristic features usually allow a diagnosis of SMZL to be performed. Mutational spectrum of SMZL identifies specific findings, such as 7q loss and NOTCH2 and KLF2 mutations, both genes related with marginal zone differentiation. There is a striking clinical variability in SMZL cases, dependent of the tumoral load and performance status. Specific molecular markers such as 7q loss, p53 loss/mutation, NOTCH2 and KLF2 mutations have been found to be associated with the clinical variability. Distinction from Monoclonal B-cell lymphocytosis with marginal zone phenotype is still an open issue that requires identification of precise and specific thresholds with clinical meaning. Copyright © 2016 Elsevier Ltd. All rights reserved.

Regular and platform switching: bone stress analysis varying implant type.

Science.gov (United States)

Gurgel-Juarez, Nália Cecília; de Almeida, Erika Oliveira; Rocha, Eduardo Passos; Freitas, Amílcar Chagas; Anchieta, Rodolfo Bruniera; de Vargas, Luis Carlos Merçon; Kina, Sidney; França, Fabiana Mantovani Gomes

2012-04-01

This study aimed to evaluate stress distribution on peri-implant bone simulating the influence of platform switching in external and internal hexagon implants using three-dimensional finite element analysis. Four mathematical models of a central incisor supported by an implant were created: External Regular model (ER) with 5.0 mm × 11.5 mm external hexagon implant and 5.0 mm abutment (0% abutment shifting), Internal Regular model (IR) with 4.5 mm × 11.5 mm internal hexagon implant and 4.5 mm abutment (0% abutment shifting), External Switching model (ES) with 5.0 mm × 11.5 mm external hexagon implant and 4.1 mm abutment (18% abutment shifting), and Internal Switching model (IS) with 4.5 mm × 11.5 mm internal hexagon implant and 3.8 mm abutment (15% abutment shifting). The models were created by SolidWorks software. The numerical analysis was performed using ANSYS Workbench. Oblique forces (100 N) were applied to the palatal surface of the central incisor. The maximum (σ(max)) and minimum (σ(min)) principal stress, equivalent von Mises stress (σ(vM)), and maximum principal elastic strain (ε(max)) values were evaluated for the cortical and trabecular bone. For cortical bone, the highest stress values (σ(max) and σ(vm) ) (MPa) were observed in IR (87.4 and 82.3), followed by IS (83.3 and 72.4), ER (82 and 65.1), and ES (56.7 and 51.6). For ε(max), IR showed the highest stress (5.46e-003), followed by IS (5.23e-003), ER (5.22e-003), and ES (3.67e-003). For the trabecular bone, the highest stress values (σ(max)) (MPa) were observed in ER (12.5), followed by IS (12), ES (11.9), and IR (4.95). For σ(vM), the highest stress values (MPa) were observed in IS (9.65), followed by ER (9.3), ES (8.61), and IR (5.62). For ε(max) , ER showed the highest stress (5.5e-003), followed by ES (5.43e-003), IS (3.75e-003), and IR (3.15e-003). The influence of platform switching was more evident for cortical bone than for trabecular bone, mainly for the external hexagon

Marginal bone loss evaluation around immediate non-occlusal microthreaded implants placed in fresh extraction sockets in the maxilla: a 3-year study.

Science.gov (United States)

Calvo-Guirado, José L; Gómez-Moreno, Gerardo; Aguilar-Salvatierra, Antonio; Guardia, Javier; Delgado-Ruiz, Rafael A; Romanos, Georgios E

2015-07-01

To evaluate marginal bone loss over 3 years around immediate microthreaded implants placed in the maxillary anterior/esthetic zone and immediately restored with single crowns. Seventy-one implants (with microthreads up to the platform--rough surface body and neck, internal connection and platform switching) were placed in fresh extraction sockets in the maxillary arches of 30 men and 23 women (mean age 37.85 ± 7.09 years, range 27-60). All subjects had at least 3 mm of soft tissue to allow the establishment of adequate biologic width and to reduce bone resorption. Each patient received a provisional restoration immediately after implant placement with slight occlusal contact. Mesial and distal bone height was evaluated using digital radiography on the day following implant placement (baseline) and after 1, 2, and 3 years. Primary stability was measured with resonance frequency analysis. No implants failed, resulting in a cumulative survival rate of 100% after 3 years. Marginal bone loss from implant collar to bone crest measured at baseline (peri-implant bone defect at the fresh extraction socket) and after 3 years was 0.86 mm ± 0.29 mm. Mesial and distal site crestal bone loss ranged from 3.42 mm ± 1.2 mm at baseline to 3.51 mm ± 1.5 mm after 3 years (P = 0.063) and from 3.38 mm ± 0.9 mm at baseline to 3.49 mm ± 0.9 mm after 3 years, respectively (P = 0.086). This prospective study found minimal marginal bone loss and a 100% implant survival rate over the 3-year follow-up for microthreaded immediate implants subjected to immediate non-occlusal loading. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Marginal bone and soft tissue behavior following platform switching abutment connection/disconnection--a dog model study.

Science.gov (United States)

Alves, Célia C; Muñoz, Fernando; Cantalapiedra, António; Ramos, Isabel; Neves, Manuel; Blanco, Juan

2015-09-01

The effect on the marginal peri-implant tissues following repeated platform switching abutment removal and subsequent reconnection was studied. Six adult female Beagle dogs were selected, and Pm3 and Pm4 teeth, both left and right sides, were extracted and the sites healed for 3 months. At this time, 24 bone level (BL) (Straumann, Basel, Switzerland) Ø 3.3/8 mm implants were placed, 2 in each side on Pm3 and Pm4 regions. In one side (control group), 12 bone level conical Ø 3.6 mm healing abutments and, on the other side (test group), 12 Narrow CrossFit (NC) multibase abutments (Straumann) , Basel, Switzerland) were connected at time of implant surgery. On test group, all prosthetic procedures were carried out direct to multibase abutment without disconnecting it, where in the control group, the multibase abutment was connected/disconnected five times (at 6/8/10/12/14 weeks) during prosthetic procedures. Twelve fixed metal bridges were delivered 14 weeks after implant placement. A cleaning/control appointment was scheduled 6 months after implant placement. The animals were sacrificed at 9 months of the study. Clinical parameters and peri-apical x-rays were registered in every visit. Histomorphometric analysis was carried out for the 24 implants. The distance from multibase abutment shoulder to the first bone implant contact (S-BIC) was defined as the primary histomorphometric parameter. Wilcoxon comparison paired test (n = 6) found no statistically significant differences (buccal P = 0.917; Lingual P = 0.463) between test and control groups both lingually and buccally for S-BIC distance. Only Pm3 buccal aBE-BC (distance from the apical end of the barrier epithelium to the first bone implant contact) (P = 0.046) parameter presented statistically significant differences between test and control groups. Control group presented 0.57 mm more recession than test group, being this difference statistically significant between the two groups (P < 0.001). It can be conclude

Ground reaction forces and bone parameters in females with tibial stress fracture.

Science.gov (United States)

Bennell, Kim; Crossley, Kay; Jayarajan, Jyotsna; Walton, Elizabeth; Warden, Stuart; Kiss, Z Stephen; Wrigley, Tim

2004-03-01

Tibial stress fracture is a common overuse running injury that results from the interplay of repetitive mechanical loading and bone strength. This research project aimed to determine whether female runners with a history of tibial stress fracture (TSF) differ in ground reaction force (GRF) parameters during running, regional bone density, and tibial bone geometry from those who have never sustained a stress fracture (NSF). Thirty-six female running athletes (13 TSF; 23 NSF) ranging in age from 18 to 44 yr were recruited for this cross-sectional study. The groups were well matched for demographic, training, and menstrual parameters. A force platform measured selected GRF parameters (peak and time to peak for vertical impact and active forces, and horizontal braking and propulsive forces) during overground running at 4.0 m.s.(-1). Lumbar spine, proximal femur, and distal tibial bone mineral density were assessed by dual energy x-ray absorptiometry. Tibial bone geometry (cross-sectional dimensions and areas, and second moments of area) was calculated from a computerized tomography scan at the junction of the middle and distal thirds. There were no significant differences between the groups for any of the GRF, bone density, or tibial bone geometric parameters (P > 0.05). Both TSF and NSF subjects had bone density levels that were average or above average compared with a young adult reference range. Factor analysis followed by discriminant function analysis did not find any combinations of variables that differentiated between TSF and NSF groups. These findings do not support a role for GRF, bone density, or tibial bone geometry in the development of tibial stress fractures, suggesting that other risk factors were more important in this cohort of female runners.

Finite element analysis of maxillary bone stress caused by Aramany Class IV obturator prostheses.

Science.gov (United States)

Miyashita, Elcio Ricardo; Mattos, Beatriz Silva Câmara; Noritomi, Pedro Yoshito; Navarro, Hamilton

2012-05-01

The retention of an Aramany Class IV removable partial dental prosthesis can be compromised by a lack of support. The biomechanics of this obturator prosthesis result in an unusual stress distribution on the residual maxillary bone. This study evaluated the biomechanics of an Aramany Class IV obturator prosthesis with finite element analysis and a digital 3-dimensional (3-D) model developed from a computed tomography scan; bone stress was evaluated according to the load placed on the prosthesis. A 3-D model of an Aramany Class IV maxillary resection and prosthesis was constructed. This model was used to develop a finite element mesh. A 120 N load was applied to the occlusal and incisal platforms corresponding to the prosthetic teeth. Qualitative analysis was based on the scale of maximum principal stress; values obtained through quantitative analysis were expressed in MPa. Under posterior load, tensile and compressive stresses were observed; the tensile stress was greater than the compressive stress, regardless of the bone region, and the greatest compressive stress was observed on the anterior palate near the midline. Under an anterior load, tensile stress was observed in all of the evaluated bone regions; the tensile stress was greater than the compressive stress, regardless of the bone region. The Aramany Class IV obturator prosthesis tended to rotate toward the surgical resection when subjected to posterior or anterior loads. The amount of tensile and compressive stress caused by the Aramany Class IV obturator prosthesis did not exceed the physiological limits of the maxillary bone tissue. (J Prosthet Dent 2012;107:336-342). Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Exercise-induced rib stress fractures: influence of reduced bone mineral density

DEFF Research Database (Denmark)

Vinther, Anders; Kanstrup, Inge-Lis; Christiansen, Erik

2005-01-01

study investigated BMD in seven Danish national team rowers with previous rib stress fracture (RSF) and 7 controls (C) matched for gender, age, height, weight and training experience. Total body scan and specific scans of the lumbar spine (L2-L4), femoral neck and distal radius were performed using......Exercise-induced rib stress fractures have been reported frequently in elite rowers during the past decade. The etiology of rib stress fractures is unclear, but low bone mineral density (BMD) has been suggested to be a potential risk factor for stress fractures in weight-bearing bones. The present...... density may be a potential risk factor for the development of exercise-induced rib stress fractures in elite rowers....

Design of a multi-axis implantable MEMS sensor for intraosseous bone stress monitoring

International Nuclear Information System (INIS)

Alfaro, Fernando; Weiss, Lee; Campbell, Phil; Fedder, Gary K; Miller, Mark

2009-01-01

The capability to assess the biomechanical properties of living bone is important for basic research as well as the clinical management of skeletal trauma and disease. Even though radiodensitometric imaging is commonly used to infer bone quality, bone strength does not necessarily correlate well with these non-invasive measurements. This paper reports on the design, fabrication and initial testing of an implantable ultra-miniature multi-axis sensor for directly measuring bone stresses at a micro-scale. The device, which is fabricated with CMOS-MEMS processes, is intended to be permanently implanted within open fractures, or embedded in bone grafts, or placed on implants at the interfaces between bone and prosthetics. The stress sensor comprises an array of piezoresistive pixels to detect a stress tensor at the interfacial area between the MEMS chip and bone, with a resolution to 100 Pa, in 1 s averaging. The sensor system design and manufacture is also compatible with the integration of wireless RF telemetry, for power and data retrieval, all within a 3 mm × 3 mm × 0.3 mm footprint. The piezoresistive elements are integrated within a textured surface to enhance sensor integration with bone. Finite element analysis led to a sensor design for normal and shear stress detection. A wired sensor was fabricated in the Jazz 0.35 µm BiCMOS process and then embedded in mock bone material to characterize its response to tensile and bending loads up to 250 kPa

A 5-year comparison of marginal bone level following immediate loading of single-tooth implants placed in healed alveolar ridges and extraction sockets in the maxilla.

Science.gov (United States)

Berberi, Antoine N; Sabbagh, Joseph M; Aboushelib, Moustafa N; Noujeim, Ziad F; Salameh, Ziad A

2014-01-01

The aim of present investigation was to evaluate marginal bone level after 5-year follow-up of implants placed in healed ridges and fresh extraction sockets in maxilla with immediate loading protocol. Thirty-six patients in need of a single-tooth replacement in the anterior maxilla received 42 Astra Tech implants (Astra Tech Implant system™, Dentsply Implants, Mölndal, Sweden). Implants were placed either in healed ridges (group I) or immediately into fresh extraction sockets (group II). Implants were restored and placed into functional loading immediately by using a prefabricated abutment. Marginal bone level relative to the implant reference point was recorded at implant placement, crown cementation, 12, 36, and 60 months following loading using intra-oral radiographs. Measurements were made on the mesial and distal sides of each implant. Overall, two implants were lost from the group II, before final crown cementation: they were excluded from the study. The mean change in marginal bone loss (MBL) after implant placement was 0.26 ± 0.161 mm for 1 year, and 0.26 ± 0.171 mm for 3 years, and 0.21 ± 0.185 mm for 5 years in extraction sockets and was 0.26 ± 0.176 mm for 1 year and 0.21 ± 0.175 mm for 3 years, and 0.19 ± 0.172 mm for 5 years in healed ridges group. Significant reduction of marginal bone was more pronounced in implants inserted in healed ridges (P sockets (P sockets or healed ridges were similar. Functional loading technique by using prefabricated abutment placed during the surgery time seems to maintain marginal bone around implant in both healed and fresh extraction sites.

A 5-year comparison of marginal bone level following immediate loading of single-tooth implants placed in healed alveolar ridges and extraction sockets in the maxilla

Science.gov (United States)

Berberi, Antoine N.; Sabbagh, Joseph M.; Aboushelib, Moustafa N.; Noujeim, Ziad F.; Salameh, Ziad A.

2014-01-01

Purpose: The aim of present investigation was to evaluate marginal bone level after 5-year follow-up of implants placed in healed ridges and fresh extraction sockets in maxilla with immediate loading protocol. Materials and Methods: Thirty-six patients in need of a single-tooth replacement in the anterior maxilla received 42 Astra Tech implants (Astra Tech Implant system™, Dentsply Implants, Mölndal, Sweden). Implants were placed either in healed ridges (group I) or immediately into fresh extraction sockets (group II). Implants were restored and placed into functional loading immediately by using a prefabricated abutment. Marginal bone level relative to the implant reference point was recorded at implant placement, crown cementation, 12, 36, and 60 months following loading using intra-oral radiographs. Measurements were made on the mesial and distal sides of each implant. Results: Overall, two implants were lost from the group II, before final crown cementation: they were excluded from the study. The mean change in marginal bone loss (MBL) after implant placement was 0.26 ± 0.161 mm for 1 year, and 0.26 ± 0.171 mm for 3 years, and 0.21 ± 0.185 mm for 5 years in extraction sockets and was 0.26 ± 0.176 mm for 1 year and 0.21 ± 0.175 mm for 3 years, and 0.19 ± 0.172 mm for 5 years in healed ridges group. Significant reduction of marginal bone was more pronounced in implants inserted in healed ridges (P prefabricated abutment placed during the surgery time seems to maintain marginal bone around implant in both healed and fresh extraction sites. PMID:24550840

An expression relating breaking stress and density of trabecular bone

DEFF Research Database (Denmark)

Rajapakse, C.S.; Thomsen, J.S.; Ortiz, J.S.E.

2004-01-01

Bone mineral density (BMD) is the principal diagnostic tool used in clinical settings to diagnose and monitor osteoporosis. Experimental studies on ex vivo bone samples from multiple skeletal locations have been used to propose that their breaking stress bears a power-law relationship to volumetric...

Immediately loaded mini dental implants as overdenture retainers: 1-Year cohort study of implant stability and peri-implant marginal bone level.

Science.gov (United States)

Šćepanović, Miodrag; Todorović, Aleksandar; Marković, Aleksa; Patrnogić, Vesna; Miličić, Biljana; Moufti, Adel M; Mišić, Tijana

2015-05-01

This 1-year cohort study investigated stability and peri-implant marginal bone level of immediately loaded mini dental implants used to retain overdentures. Each of 30 edentulous patients received 4 mini dental implants (1.8 mm × 13 mm) in the interforaminal mandibular region. The implants were immediately loaded with pre-made overdentures. Outcome measures included implant stability and bone resorption. Implant stability was measured using the Periotest Classic(®) device immediately after placement and on the 3rd and 6th weeks and the 4th, 6th and 12th months postoperatively. The peri-implant marginal bone level (PIBL) was evaluated at the implant's mesial and distal sides from the polished platform to the marginal crest. Radiographs were taken using a tailored film holder to reproducibly position the X-ray tube at the 6th week, 4th and 12th months postoperatively. The primary stability (Periotest value, PTV) measured -0.27 ± 3.41 on a scale of -8 to + 50 (lower PTV reflects higher stability). The secondary stability decreased significantly until week 6 (mean PTV = 7.61 ± 7.05) then increased significantly reaching (PTV = 6.17 ± 6.15) at 12 months. The mean PIBL measured -0.40 mm after 1 year of functional loading, with no statistically significant differences at the various follow-ups (p = 0.218). Mini dental implants placed into the interforaminal region could achieve a favorable primary stability for immediate loading. The follow-up Periotest values fluctuated, apparently reflecting the dynamics of bone remodeling, with the implants remaining clinically stable (98.3%) after 1 year of function. The 1-year bone resorption around immediately loaded MDIs is within the clinically acceptable range for standard implants. Copyright © 2014 Elsevier GmbH. All rights reserved.

Abutment height influences the effect of platform switching on peri-implant marginal bone loss.

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Galindo-Moreno, Pablo; León-Cano, Ana; Monje, Alberto; Ortega-Oller, Inmaculada; O'Valle, Francisco; Catena, Andrés

2016-02-01

The purpose was to radiographically analyze and compare the marginal bone loss (MBL) between implants with different mismatching distance and to study the influence of the prosthetic abutment height on the MBL in association with the related mismatching distances. This retrospective study included 108 patients in whom 228 implants were placed, 180 with diameter of 4.5 mm and 48 with diameter of 5 mm. All patients received OsseoSpeed™ implants with internal tapered conical connection (Denstply Implants). Different mismatching distances were obtained, given that all implants were loaded with the same uni-abutment type (Lilac; Denstply Implants). Data were gathered on age, gender, bone substratum, smoking habits, previous history of periodontitis, and prosthetic features. MBL was analyzed radiographically at 6 and 18 months post-loading. Mixed linear analysis of mesial and distal MBL values yielded significant effects of abutment, implant diameter, follow-up period, bone substratum, smoking, and abutment × time interaction. MBL was greater at 18 vs. 6 months, for short vs. long abutments, for grafted vs. pristine bone, for a heavier smoking habit, and for implants with a diameter of 5.0 vs. 4.5 mm. Greater mismatching does not minimize the MBL; abutment height, smoking habit, and bone substratum may play a role in the MBL over the short- and medium term. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Stress fracture as a complication of autogenous bone graft harvest from the distal tibia.

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Chou, Loretta B; Mann, Roger A; Coughlin, Michael J; McPeake, William T; Mizel, Mark S

2007-02-01

Autogenous bone graft from the distal tibia provides cancellous bone graft for foot and ankle operations, and it has osteogenic and osteoconductive properties. The site is in close proximity to the foot and ankle, and published retrospective studies show low morbidity from the procedure. One-hundred autografts were obtained from the distal tibia between 2000 and 2003. In four cases the distal tibial bone graft harvest resulted in a stress fracture. There were three women and one man. The average time of diagnosis of the stress fracture from the operation was 1.8 months. All stress fractures healed with a short course (average 2.4 months) of cast immobilization. This study demonstrated that a stress fracture from the donor site of autogenous bone graft of the distal tibia occurs and can be successfully treated nonoperatively.

Marginal Bone Remodeling around healing Abutment vs Final Abutment Placement at Second Stage Implant Surgery: A 12-month Randomized Clinical Trial.

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Nader, Nabih; Aboulhosn, Maissa; Berberi, Antoine; Manal, Cordahi; Younes, Ronald

2016-01-01

The periimplant bone level has been used as one of the criteria to assess the success of dental implants. It has been documented that the bone supporting two-piece implants undergoes resorption first following the second-stage surgery and later on further to abutment connection and delivery of the final prosthesis. The aim of this multicentric randomized clinical trial was to evaluate the crestal bone resorption around internal connection dental implants using a new surgical protocol that aims to respect the biological distance, relying on the benefit of a friction fit connection abutment (test group) compared with implants receiving conventional healing abutments at second-stage surgery (control group). A total of partially edentulous patients were consecutively treated at two private clinics, with two adjacent two-stage implants. Three months after the first surgery, one of the implants was randomly allocated to the control group and was uncovered using a healing abutment, while the other implant received a standard final abutment and was seated and tightened to 30 Ncm. At each step of the prosthetic try-in, the abutment in the test group was removed and then retightened to 30 Ncm. Horizontal bone changes were assessed using periapical radiographs immediately after implant placement and at 3 (second-stage surgery), 6, 9 and 12 months follow-up examinations. At 12 months follow-up, no implant failure was reported in both groups. In the control group, the mean periimplant bone resorption was 0.249 ± 0.362 at M3, 0.773 ± 0.413 at M6, 0.904 ± 0.36 at M9 and 1.047 ± 0.395 at M12. The test group revealed a statistically significant lower marginal bone loss of 20.88% at M3 (0.197 ± 0.262), 22.25% at M6 (0.601 ± 0.386), 24.23% at M9 (0.685 ± 0.341) and 19.2% at M9 (0.846 ± 0.454). The results revealed that bone loss increased over time, with the greatest change in bone loss occurring between 3 and 6 months. Alveolar bone loss was significantly greater in the

Chronic psychosocial stress disturbs long-bone growth in adolescent mice

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Sandra Foertsch

2017-12-01

Full Text Available Although a strong association between psychiatric and somatic disorders is generally accepted, little is known regarding the interrelationship between mental and skeletal health. Although depressive disorders have been shown to be strongly associated with osteoporosis and increased fracture risk, evidence from post-traumatic stress disorder (PTSD patients is less consistent. Therefore, the present study investigated the influence of chronic psychosocial stress on bone using a well-established murine model for PTSD. C57BL/6N mice (7 weeks old were subjected to chronic subordinate colony housing (CSC for 19 days, whereas control mice were singly housed. Anxiety-related behavior was assessed in the open-field/novel-object test, after which the mice were euthanized to assess endocrine and bone parameters. CSC mice exhibited increased anxiety-related behavior in the open-field/novel-object test, increased adrenal and decreased thymus weights, and unaffected plasma morning corticosterone. Microcomputed tomography and histomorphometrical analyses revealed significantly reduced tibia and femur lengths, increased growth-plate thickness and reduced mineral deposition at the growth plate, suggesting disturbed endochondral ossification during long-bone growth. This was associated with reduced Runx2 expression in hypertrophic chondrocytes in the growth plate. Trabecular thicknesses and bone mineral density were significantly increased in CSC compared to singly housed mice. Tyrosine hydroxylase expression was increased in bone marrow cells located at the growth plates of CSC mice, implying that local adrenergic signaling might be involved in the effects of CSC on the skeletal phenotype. In conclusion, chronic psychosocial stress negatively impacts endochondral ossification in the growth plate, affecting both longitudinal and appositional bone growth in adolescent mice.

Bone geometry, strength, and muscle size in runners with a history of stress fracture.

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Popp, Kristin L; Hughes, Julie M; Smock, Amanda J; Novotny, Susan A; Stovitz, Steven D; Koehler, Scott M; Petit, Moira A

2009-12-01

Our primary aim was to explore differences in estimates of tibial bone strength, in female runners with and without a history of stress fractures. Our secondary aim was to explore differences in bone geometry, volumetric density, and muscle size that may explain bone strength outcomes. A total of 39 competitive distance runners aged 18-35 yr, with (SFX, n = 19) or without (NSFX, n = 20) a history of stress fracture were recruited for this cross-sectional study. Peripheral quantitative computed tomography (XCT 3000; Orthometrix, White Plains, NY) was used to assess volumetric bone mineral density (vBMD, mg x mm(-3)), bone area (ToA, mm(2)), and estimated compressive bone strength (bone strength index (BSI) = ToA x total volumetric density (ToD(2))) at the distal tibia (4%). Total (ToA, mm(2)) and cortical (CoA, mm(2)) bone area, cortical vBMD, and estimated bending strength (strength-strain index (SSIp), mm(3)) were measured at the 15%, 25%, 33%, 45%, 50%, and 66% sites. Muscle cross-sectional area (MCSA) was measured at the 50% and 66% sites. Participants in the SFX group had significantly smaller (7%-8%) CoA at the 45%, 50%, and 66% sites (P stress fracture. However, the lower strength was appropriate for the smaller muscle size, suggesting that interventions to reduce stress fracture risk might be aimed at improving muscle size and strength.

Discordant lymphoma consisting of splenic mantle cell lymphoma and marginal zone lymphoma involving the bone marrow and peripheral blood: a case report

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Caracciolo Francesco

2011-09-01

Full Text Available Abstract Introduction Discordant lymphomas are rare entities characterized by the simultaneous presence of two distinct types of lymphomas in different anatomic sites. We describe a very rare case of simultaneous occurrence of splenic mantle cell lymphoma and marginal zone lymphoma involving the bone marrow and peripheral blood. Case presentation We report the case of a 60-year-old asymptomatic Caucasian woman in whom discordant lymphomas were discovered when a slight lymphocytosis and a conspicuous splenomegaly were observed. The different morphological, immunophenotypical and immunohistochemical features found in the different pathologic samples obtained from peripheral blood, bone marrow and spleen sections made it possible to differentiate two types of non-Hodgkin B-cell lymphomas: a mantle cell lymphoma infiltrating the spleen and a marginal zone lymphoma involving both the bone marrow and peripheral blood. Since a similar IgH gene rearrangement was found both in the bone marrow and in the spleen, the hypothesis of a common origin, followed by a different clonal selection of the neoplastic lymphocytes may be taken into consideration. Conclusion Our case emphasizes the usefulness of investigating simultaneous specimens from different anatomic sites from the same patient and the relevant diagnostic role of splenectomy.

Bone turnover and oxidative stress markers in estrogen- deficient ...

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Bone turnover and oxidative stress markers in estrogen- ... reproduction in any medium, provided the original work is properly credited. ..... Institute for Laboratory Animal Research: Guide for the ... American Veterinary Medical Association.

Bone stress injury of the ankle in professional ballet dancers seen on MRI

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Besser Marcus P

2008-03-01

Full Text Available Abstract Background Ballet Dancers have been shown to have a relatively high incidence of stress fractures of the foot and ankle. It was our objective to examine MR imaging patterns of bone marrow edema (BME in the ankles of high performance professional ballet dancers, to evaluate clinical relevance. Methods MR Imaging was performed on 12 ankles of 11 active professional ballet dancers (6 female, 5 male; mean age 24 years, range 19 to 32. Individuals were imaged on a 0.2 T or 1.5 T MRI units. Images were evaluated by two musculoskeletal radiologists and one orthopaedic surgeon in consensus for location and pattern of bone marrow edema. In order to control for recognized sources of bone marrow edema, images were also reviewed for presence of osseous, ligamentous, tendinous and cartilage injuries. Statistical analysis was performed to assess the strength of the correlation between bone marrow edema and ankle pain. Results Bone marrow edema was seen only in the talus, and was a common finding, observed in nine of the twelve ankles imaged (75% and was associated with pain in all cases. On fluid-sensitive sequences, bone marrow edema was ill-defined and centered in the talar neck or body, although in three cases it extended to the talar dome. No apparent gender predilection was noted. No occult stress fracture could be diagnosed. A moderately strong correlation (phi = 0.77, p= 0.0054 was found between edema and pain in the study population. Conclusion Bone marrow edema seems to be a specific MRI finding in the talus of professional ballet dancers, likely related to biomechanical stress reactions, due to their frequently performed unique maneuvers. Clinically, this condition may indicate a sign of a bone stress injury of the ankle.

Bone stress injury of the ankle in professional ballet dancers seen on MRI

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Elias, Ilan; Zoga, Adam C; Raikin, Steven M; Peterson, Judith R; Besser, Marcus P; Morrison, William B; Schweitzer, Mark E

2008-01-01

Background Ballet Dancers have been shown to have a relatively high incidence of stress fractures of the foot and ankle. It was our objective to examine MR imaging patterns of bone marrow edema (BME) in the ankles of high performance professional ballet dancers, to evaluate clinical relevance. Methods MR Imaging was performed on 12 ankles of 11 active professional ballet dancers (6 female, 5 male; mean age 24 years, range 19 to 32). Individuals were imaged on a 0.2 T or 1.5 T MRI units. Images were evaluated by two musculoskeletal radiologists and one orthopaedic surgeon in consensus for location and pattern of bone marrow edema. In order to control for recognized sources of bone marrow edema, images were also reviewed for presence of osseous, ligamentous, tendinous and cartilage injuries. Statistical analysis was performed to assess the strength of the correlation between bone marrow edema and ankle pain. Results Bone marrow edema was seen only in the talus, and was a common finding, observed in nine of the twelve ankles imaged (75%) and was associated with pain in all cases. On fluid-sensitive sequences, bone marrow edema was ill-defined and centered in the talar neck or body, although in three cases it extended to the talar dome. No apparent gender predilection was noted. No occult stress fracture could be diagnosed. A moderately strong correlation (phi = 0.77, p= 0.0054) was found between edema and pain in the study population. Conclusion Bone marrow edema seems to be a specific MRI finding in the talus of professional ballet dancers, likely related to biomechanical stress reactions, due to their frequently performed unique maneuvers. Clinically, this condition may indicate a sign of a bone stress injury of the ankle. PMID:18371230

Dealing with extreme environmental degradation: stress and marginalization of Sahel dwellers.

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Van Haaften, E H; Van de Vijver, F J

1999-07-01

Psychological aspects of environmental degradation are hardly investigated. In the present study these aspects were examined among Sahel dwellers, who live in environments with different states of degradation. The degradation was assessed in terms of vegetation cover, erosion, and loss of organic matter. Subjects came from three cultural groups: Dogon (agriculturalists, n = 225), Mossi (agriculturalists, n = 914), and Fulani (pastoralists, n = 844). Questionnaires addressing marginalization, locus of control, and coping were administered. Environmental degradation was associated with higher levels of stress, marginalization, passive coping (avoidance), a more external locus of control, and lower levels of active coping (problem solving and support seeking). Compared to agriculturalists, pastoralists showed a stronger variation in all psychological variables across all regions, from the least to the most environmentally degraded. Women showed higher scores of stress, (external) locus of control, problem solving, and support seeking than men. The interaction of gender and region was significant for several variables. It was concluded that environmental degradation has various psychological correlates: people are likely to display an active approach to environmental degradation as long as the level of degradation is not beyond their control.

Full-Thickness Skin Grafting with De-Epithelization of the Wound Margin for Finger Defects with Bone or Tendon Exposure

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Jun Hee Lee

2015-05-01

Full Text Available BackgroundFull-thickness skin grafts (FTSGs are generally considered unreliable for coverage of full-thickness finger defects with bone or tendon exposure, and there are few clinical reports of its use in this context. However, animal studies have shown that an FTSG can survive over an avascular area ranging up to 12 mm in diameter. In our experience, the width of the exposed bones or tendons in full-thickness finger defects is <7 mm. Therefore, we covered the bone- or tendon-exposed defects of 16 fingers of 10 patients with FTSGs.MethodsThe surgical objectives were healthy granulation tissue formation in the wound bed, marginal de-epithelization of the normal skin surrounding the defect, preservation of the subdermal plexus of the central graft, and partial excision of the dermis along the graft margin. The donor site was the mastoid for small defects and the groin for large defects.ResultsMost of the grafts (15 of 16 fingers survived without significant surgical complications and achieved satisfactory functional and aesthetic results. Minor complications included partial graft loss in one patient, a minimal extension deformity in two patients, a depression deformity in one patient, and mild hyperpigmentation in four patients.ConclusionsWe observed excellent graft survival with this method with no additional surgical injury of the normal finger, satisfactory functional and aesthetic outcomes, and no need for secondary debulking procedures. Potential disadvantages include an insufficient volume of soft tissue and graft hyperpigmentation. Therefore, FTSGs may be an option for treatment of full-thickness finger defects with bone or tendon exposure.

A 5- Year Comparison of Marginal Bone Level Following Immediate Loading of Single-Tooth Implants Placed in Healed Alveolar Ridges and Extraction Sockets in the Maxilla.

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Antoine Nicolas Berberi

2014-01-01

Full Text Available AbstractPurpose: The aim of present investigation was to evaluate marginal bone level after 5-year follow-up of implants placed in healed ridges and fresh extraction sockets in maxilla with immediate loading protocol.Materials and Methods: Thirty-six patients in need of a single tooth replacement in the anterior maxilla received 42 Astra Tech implants (Astra Tech Implant system™, Dentsply Implants, Mölndal, Sweden. Implants were placed in healed ridges (group I or immediately into extraction sockets (group II. Implants were restored and placed into functional loading immediately by using a prefabricated abutment. Marginal bone level relative to the implant reference point was recorded at implant placement, crown cementation, 12, 36 and 60 months following loading using intra-oral radiographs. Measurements were made on the mesial and distal sides of each implantResults: Overall, two implants were lost from the group II, before final crown cementation: they were excluded from the study and all remaining implants osseointegrated successfully after 5 years of functional loading. The mean change in marginal bone loss after implant placement was 0.267±0.161 for one year, and 0.265±0.171 for three years and 0.213±0.185 for five years in extraction sockets and was 0.266±0.176 for one year and 0.219±0.175 for three years and 0.194±0.172 for five years in healed ridges group. Significant reduction of marginal bone loss was more pronounced in implants inserted in healed ridges (P

Implant angulation: 2-year retrospective analysis on the influence of dental implant angle insertion on marginal bone resorption in maxillary and mandibular osseous onlay grafts.

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Ramaglia, Luca; Toti, Paolo; Sbordone, Carolina; Guidetti, Franco; Martuscelli, Ranieri; Sbordone, Ludovico

2015-05-01

The purpose of this study was to determine the existence of correlations between marginal peri-implant linear bone loss and the angulation of implants in maxillary and mandibular augmented areas over the course of a 2-year survey. Dependent variables described the sample of the present retrospective chart review. By using three-dimensional radiographs, input variables, describing the implant angulation (buccal-lingual angle [φ] and mesial-distal angle [θ]) were measured; outcome variables described survival rate and marginal bone resorption (MBR) around dental implants in autogenous grafts (10 maxillae and 14 mandibles). Pairwise comparisons and linear correlation coefficient were computed. The peri-implant MBR in maxillary buccal and palatal areas appeared less intensive in the presence of an increased angulation of an implant towards the palatal side. Minor MBR was recorded around mandibular dental implants positioned at a right angle and slightly angulated towards the mesial. Resorption in buccal areas may be less intensive as the angulation of placed implants increases towards the palatal area in the maxilla, whereas for the mandible, a greater inclination towards the lingual area could be negative. In the mandibular group, when the implant was slightly angulated in the direction of the distal area, bone resorption seemed to be more marked in the buccal area. In the planning of dental implant placement in reconstructed alveolar bone with autograft, the extremely unfavourable resorption at the buccal aspect should be considered; this marginal bone loss seemed to be very sensitive to the angulation of the dental implant.

Bone alterations by stress in athletes. Schaedigung des Knochens durch Ueberlastung bei Leistungssportlern

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Doege, H. (Bezirkskrankenhaus ' Friedrich Wolf' , Abt. fuer Nuklearmedizin, Chemnitz (Germany))

1990-01-01

This report describes our experiences with the bone imaging in athletes. We studied 10 athletes and 10 other patients with spondylolisthesis of the lumbar spine and 16 athletes with suspicion of alterations of extremities. An increased uptake of this radiopharmaceutical was detected in six of 10 athletes with spondylolisthesis caused probably by stress fracture. Bone scans were negative in seven of 16 athletes with suspicion of lesion of extremities. In the remaining 9 patients scans were abnormal and showed periosteal injuries, epiphyseal alteration, joint abnormalities, tibial stress fractures and couvert fracture. It was also abnormal in bone injuries not evident in radiography. (orig.).

Sacral Stress Fracture following the Bone Union of Lumbar Spondylolysis

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Tatsuro Sasaji

2016-01-01

Full Text Available While 22 articles have reported on sacral stress fractures, it is a rare injury and its etiology is not well known. We present the case of a 16-year-old male who presented with low back pain in 2015. He was a high school soccer player with a previous history of a bilateral L5 lumbar spondylolysis in 2014. The patient refrained from soccer and wore a brace for six months. Two months after restarting soccer, he again complained of low back pain. After 1 year, a lumbar spine computed tomography revealed the bone union of the spondylolysis. At his first visit to our hospital, his general and neurological conditions were normal and laboratory data were within the normal range. Sacral coronal magnetic resonance imaging (MRI of the left sacral ala revealed an oblique lineal signal void surrounding bone marrow edema. Based on his symptoms, sports history, and MRI, he was diagnosed with a sacral stress fracture. He again refrained from soccer; his low back pain soon improved, and, after 1 year, the abnormal signal change had disappeared on sacral MRI. Recurrent low back pain case caused by a sacral stress fracture occurring after the bone union of lumbar spondylolysis is uncommon.

A 5-year prospective radiographic evaluation of marginal bone levels adjacent to parallel-screw cylinder machined-neck implants and rough-surfaced microthreaded implants using digitized panoramic radiographs.

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Nickenig, Hans-Joachim; Wichmann, Manfred; Happe, Arndt; Zöller, Joachim E; Eitner, Stephan

2013-10-01

The purpose of this split-mouth study was to compare macro- and microstructure implant surfaces at the marginal bone level over five years of functional loading. From January to February 2006, 133 implants (70 rough-surfaced microthreaded implants and 63 machined-neck implants) were inserted in the mandible of 34 patients with Kennedy Class I residual dentitions and followed until December 2011. Marginal bone level was radiographically determined at six time points: implant placement (baseline), after the healing period, after six months, and at two years, three years, and five years follow-up. Median follow-up time was 5.2 years (range: 5.1-5.4). The machined-neck group had a mean crestal bone loss of 0.5 mm (0.0-2.3) after the healing period, 1.1 mm (0.0-3.0) at two years follow-up, and 1.4 mm (0.0-2.9) at five years follow-up. The rough-surfaced microthreaded implant group had a mean bone loss of 0.1 mm (-0.4 to 2.0) after the healing period, 0.5 mm (0.0-2.1) at two years follow-up, and 0.7 mm (0.0-2.3) at five years follow-up. The two implant types showed significant differences in marginal bone levels. Rough-surfaced microthreaded design caused significantly less loss of crestal bone levels under long-term functional loading in the mandible when compared to machined-neck implants. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Adaptation of BAp crystal orientation to stress distribution in rat mandible during bone growth

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Nakano, T; Fujitani, W; Ishimoto, T [Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan); Umakoshi, Y [National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaragi, 305-0471 (Japan)], E-mail: nakano@mat.eng.osaka-u.ac.jp

2009-05-01

Biological apatite (BAp) c-axis orientation strongly depends on stress distribution in vivo and tends to align along the principal stress direction in bones. Dentulous mandible is subjected to a complicated stress condition in vivo during chewing but few studies have been carried out on the BAp c-axis orientation; so the adaptation of BAp crystal orientation to stress distribution was examined in rat dentulous mandible during bone growth and mastication. Female SD rats 4 to 14 weeks old were prepared, and the bone mineral density (BMD) and BAp crystal orientation were analyzed in a cross-section of mandible across the first molar focusing on two positions: separated from and just under the tooth root on the same cross-section perpendicular to the mesiodistal axis. The degree of BAp orientation was analyzed by a microbeam X-ray diffractometer using Cu-K{alpha} radiation equipped with a detector of curved one-dimensional PSPC and two-dimensional PSPC in the reflection and transmission optics, respectively. BMD quickly increased during bone growth up to 14 weeks, although it was independent of the position from the tooth root. In contrast, BAp crystal orientation strongly depended on the age and the position from the tooth root, even in the same cross-section and direction, especially along the mesiodistal and the biting axes. With increased biting stress during bone growth, the degree of BAp orientation increased along the mesiodistal axis in a position separated from the tooth root more than that near the tooth root. In contrast, BAp preferential alignment clearly appeared along the biting axis near the tooth root. We conclude that BAp orientation rather than BMD sensitively adapts to local stress distribution, especially from the chewing stress in vivo in the mandible.

[Stress reactions in bones of the foot in sport: diagnosis, assessment and therapy].

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Miltner, O

2013-06-01

Stress reactions and stress fractures are defined as structural damage to bone caused by repetitive stress or stereotypical loading. The balance between loading and unloading of bone is disrupted in stress reactions and stress fractures through the sport-specific demands and by the exogenous or endogenous risk factors present. In sports orthopedics the localization of stress reactions and stress fractures are subdivided into high risk fractures and low risk fractures. Conventional diagnostic radiology can initially be inconclusive. With symptoms persisting over 2 weeks further diagnostics using magnetic resonance imaging (MRI) should be performed. In the area of the foot stress reactions and stress fractures can often occur bilaterally or multifocally and most commonly affect the second metatarsals followed by the third metatarsals. Fractures of the fifth metatarsal, second metatarsal base, medial malleolus as well as navicular and sesamoid fractures are high risk fractures requiring special clinical and radiological monitoring. Basically, conservative treatment using the 2-phase model is the treatment of choice. In delayed union or severe pain surgical treatment is indicated.

Bone strength estimates relative to vertical ground reaction force discriminates women runners with stress fracture history.

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Popp, Kristin L; McDermott, William; Hughes, Julie M; Baxter, Stephanie A; Stovitz, Steven D; Petit, Moira A

2017-01-01

To determine differences in bone geometry, estimates of bone strength, muscle size and bone strength relative to load, in women runners with and without a history of stress fracture. We recruited 32 competitive distance runners aged 18-35, with (SFX, n=16) or without (NSFX, n=16) a history of stress fracture for this case-control study. Peripheral quantitative computed tomography (pQCT) was used to assess volumetric bone mineral density (vBMD, mg/mm 3 ), total (ToA) and cortical (CtA) bone areas (mm 2 ), and estimated compressive bone strength (bone strength index; BSI, mg/mm 4 ) at the distal tibia. ToA, CtA, cortical vBMD, and estimated strength (section modulus; Zp, mm 3 and strength strain index; SSIp, mm 3 ) were measured at six cortical sites along the tibia. Mean active peak vertical (pkZ) ground reaction forces (GRFs), assessed from a fatigue run on an instrumented treadmill, were used in conjunction with pQCT measurements to estimate bone strength relative to load (mm 2 /N∗kg -1 ) at all cortical sites. SSIp and Zp were 9-11% lower in the SFX group at mid-shaft of the tibia, while ToA and vBMD did not differ between groups at any measurement site. The SFX group had 11-17% lower bone strength relative to mean pkZ GRFs (phistory of stress fracture. Bone strength relative to load is also lower in this same region suggesting that strength deficits in the middle 1/3 of the tibia and altered gait biomechanics may predispose an individual to stress fracture. Copyright © 2016. Published by Elsevier Inc.

Bone Stress Injuries in Runners.

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Tenforde, Adam S; Kraus, Emily; Fredericson, Michael

2016-02-01

Bone stress injuries (BSIs) are common running injuries and may occur at a rate of 20% annually. Both biological and biomechanical risk factors contribute to BSI. Evaluation of a runner with suspected BSI includes completing an appropriate history and physical examination. MRI grading classification for BSI has been proposed and may guide return to play. Management includes activity modification, optimizing nutrition, and addressing risk factors, including the female athlete triad. BSI prevention strategies include screening for risk factors during preparticipation evaluations, optimizing nutrition (including adequate caloric intake, calcium, and vitamin D), and promoting ball sports during childhood and adolescence. Copyright © 2016 Elsevier Inc. All rights reserved.

Peri-implant stress correlates with bone and cement morphology: Micro-FE modeling of implanted cadaveric glenoids.

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Wee, Hwabok; Armstrong, April D; Flint, Wesley W; Kunselman, Allen R; Lewis, Gregory S

2015-11-01

Aseptic loosening of cemented joint replacements is a complex biological and mechanical process, and remains a clinical concern especially in patients with poor bone quality. Utilizing high resolution finite element analysis of a series of implanted cadaver glenoids, the objective of this study was to quantify relationships between construct morphology and resulting mechanical stresses in cement and trabeculae. Eight glenoid cadavers were implanted with a cemented central peg implant. Specimens were imaged by micro-CT, and subject-specific finite element models were developed. Bone volume fraction, glenoid width, implant-cortex distance, cement volume, cement-cortex contact, and cement-bone interface area were measured. Axial loading was applied to the implant of each model and stress distributions were characterized. Correlation analysis was completed across all specimens for pairs of morphological and mechanical variables. The amount of trabecular bone with high stress was strongly negatively correlated with both cement volume and contact between the cement and cortex (r = -0.85 and -0.84, p implant-cortex distance. Contact between the cement and underlying cortex may dramatically reduce trabecular bone stresses surrounding the cement, and this contact depends on bone shape, cement amount, and implant positioning. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Changes in In Situ Stress Across the Nankai and Cascadia Convergent Margins From Borehole Breakout Measurements During Ocean Drilling

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McNeill, L.; Moore, J. C.; Yamada, Y.; Chang, C.; Tobin, H.; Kinoshita, M.; Gulick, S.; Moore, G.; Iodp Exp. 314/315/316 Science Party, &

2008-12-01

Borehole breakouts are commonly observed in borehole images shortly after drilling of continental margin sites. This study aims to compile and compare these results to determine what in situ shallow stress measurements can tell us about the larger scale tectonic regime. Recent Logging While Drilling resistivity images across the Kumano transect of the Nankai subduction zone, during Expedition 314, Stage 1 of the IODP NanTroSEIZE project, add to this dataset. Expedition 314 site data within the prism (C0001, C0004, C0006, including the megasplay fault system which may overlie the seismogenic updip limit) suggest maximum compressive stress (SHmax) is perpendicular to the margin (not parallel to the convergence vector) but is rotated through 90° at the forearc basin site (C0002). These results may point to changes in stress state of the shallow forearc from east to west: compression in the aseismic active prism (with evidence of strain partitioning of oblique convergence); and extension above the updip seismogenic zone suggesting focus of plate coupling at the plate boundary and not in the shallow forearc. Further south, ODP Leg 196 drilled the prism toe (808) with breakouts indicating SHmax parallel to the convergence vector, in contrast to Exp. 314 results. The stress state in the shallow prism at Site 808 may be affected by nearby seamount subduction or may represent differences in strain partitioning. On the Cascadia margin, two drilling legs have collected LWD borehole images (Leg 204 and Exp. 311). Leg 204 drilled 3 sites at hydrate ridge in the C Cascadia outer prism with breakout orientations variable between closely spaced sites. Prism fold axes are parallel to the margin so we might expect SHmax perpendicular to the margin as in Exp. 314. Deviations from this orientation may reflect local and surface effects (Goldberg and Janik, 2006). Exp. 311, N Cascadia, drilled 5 sites across the prism with breakouts in LWD images. Subduction is not oblique here, in

Oxidative stress and antioxidant status in primary bone and soft tissue sarcoma

International Nuclear Information System (INIS)

Nathan, Fatima M; Singh, Vivek A; Dhanoa, Amreeta; Palanisamy, Uma D

2011-01-01

Oxidative stress is characterised by an increased level of reactive oxygen species (ROS) that disrupts the intracellular reduction-oxidation (redox) balance and has been implicated in various diseases including cancer. Malignant tumors of connective tissue or sarcomas account for approximately 1% of all cancer diagnoses in adults and around 15% of paediatric malignancies per annum. There exists no information on the alterations of oxidant/antioxidant status of sarcoma patients in literature. This study was aimed to determine the levels of oxidative stress and antioxidant defence in patients with primary bone and soft tissue sarcoma and to investigate if there exists any significant differences in these levels between both the sarcomas. The study cohort consisted of 94 subjects; 20 soft tissue sarcoma, 27 primary bone sarcoma and 47 healthy controls. Malondialdehyde (MDA) and protein carbonyls were determined to assess their oxidative stress levels while antioxidant status was evaluated using catalase (CAT), superoxide dismutase (SOD), thiols and trolox equivalent antioxidant capacity (TEAC). Sarcoma patients showed significant increase in plasma and urinary MDA and serum protein carbonyl levels (p < 0.05) while significant decreases were noted in TEAC, thiols, CAT and SOD levels (p < 0.05). No significant difference in oxidative damage was noted between both the sarcomas (p > 0.05). In conclusion, an increase in oxidative stress and decrease in antioxidant status is observed in both primary bone and soft tissue sarcomas with a similar extent of damage. This study offers the basis for further work on whether the manipulation of redox balance in patients with sarcoma represents a useful approach in the design of future therapies for bone disease

Influence of Trabecular Bone on Peri-Implant Stress and Strain Based on Micro-CT Finite Element Modeling of Beagle Dog.

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Liao, Sheng-Hui; Zhu, Xing-Hao; Xie, Jing; Sohodeb, Vikesh Kumar; Ding, Xi

2016-01-01

The objective of this investigation is to analyze the influence of trabecular microstructure modeling on the biomechanical distribution of the implant-bone interface. Two three-dimensional finite element mandible models, one with trabecular microstructure (a refined model) and one with macrostructure (a simplified model), were built. The values of equivalent stress at the implant-bone interface in the refined model increased compared with those of the simplified model and strain on the contrary. The distributions of stress and strain were more uniform in the refined model of trabecular microstructure, in which stress and strain were mainly concentrated in trabecular bone. It was concluded that simulation of trabecular bone microstructure had a significant effect on the distribution of stress and strain at the implant-bone interface. These results suggest that trabecular structures could disperse stress and strain and serve as load buffers.

Stress fracture of the second metacarpal bone in a badminton player.

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Fukuda, Koji; Fujioka, Hiroyuki; Fujita, Ikuo; Uemoto, Harunobu; Hiranaka, Takafumi; Tsuji, Mitsuo; Kurosaka, Masahiro

2008-07-18

We present a rare case of stress fracture of the second metacarpal bone. A 14-year-old girl felt pain on the dorsal aspect of the right wrist without any history of major trauma, when she played a smash during a game of badminton. On the radiographs, periosteal reaction was detected on the ulnar aspect of the base of the second metacarpal bone. She was treated conservatively and she returned to the original activity level.

Stress fracture development classified by bone scintigraphy

International Nuclear Information System (INIS)

Zwas, S.T.; Elkanovich, R.; Frank, G.; Aharonson, Z.

1985-01-01

There is no consensus on classifying stress fractures (SF) appearing on bone scans. The authors present a system of classification based on grading the severity and development of bone lesions by visual inspection, according to three main scintigraphic criteria: focality and size, intensity of uptake compare to adjacent bone, and local medular extension. Four grades of development (I-IV) were ranked, ranging from ill defined slightly increased cortical uptake to well defined regions with markedly increased uptake extending transversely bicortically. 310 male subjects aged 19-2, suffering several weeks from leg pains occurring during intensive physical training underwent bone scans of the pelvis and lower extremities using Tc-99-m-MDP. 76% of the scans were positive with 354 lesions, of which 88% were in th4e mild (I-II) grades and 12% in the moderate (III) and severe (IV) grades. Post-treatment scans were obtained in 65 cases having 78 lesions during 1- to 6-month intervals. Complete resolution was found after 1-2 months in 36% of the mild lesions but in only 12% of the moderate and severe ones, and after 3-6 months in 55% of the mild lesions and 15% of the severe ones. 75% of the moderate and severe lesions showed residual uptake in various stages throughout the follow-up period. Early recognition and treatment of mild SF lesions in this study prevented protracted disability and progression of the lesions and facilitated complete healing

Stress distribution in dental prosthesis under an occlusal combined dynamic loading

International Nuclear Information System (INIS)

Merdji, A.; Bachir Bouiadjra, B.; Ould Chikh, B.; Mootanah, R.; Aminallah, L.; Serier, B.; Muslih, I.M.

2012-01-01

Highlights: ► The mechanical stress reaches the highest in areas of cortical bones. ► The mechanical stress in the cancellous bone reaches greatest in the bottom of the dental implant. ► Implant with low-volume bone might cause increased stress concentration in the cortical bone. -- Abstract: The biomechanical behavior of osseointegrated dental prostheses systems plays an important role in its functional longevity inside the bone. Simulation of these systems requires an accurate modeling of the prosthesis components, the jaw bone, the implant–bone interface, and the response of the system to different types of applied forces. The purpose of this study was to develop a new three-dimensional model of an osseointegrated molar dental prosthesis and to carry out finite element analysis to evaluate stress distributions in the bone and the dental prosthesis compounds under an occlusal combined dynamic load was applied to the top of the occlusale face of the prosthesis crown. The jaw bone model containing cortical bone and cancellous bone was constructed by using computer tomography scan pictures and Computer Aided Design tools. The dental prosthesis compounds were constructed, simulating the commercially available cylindrical implant of 4.8 mm diameter and 10 mm length. Both finite element models were created in Abaqus finite element software. All materials used in the models were considered to be isotropic, homogeneous and linearly elastic. The elastic properties, loads and constraints used in the model were taken from published data. Results of our finite element analyses, indicated that the maximum stresses were located around the mesial neck of the implant, in the marginal bone. Thus, this area should be preserved clinically in order to maintain the bone–implant interface structurally and functionally.

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

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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.

Fundamental differences in axial and appendicular bone density in stress fractured and uninjured Royal Marine recruits--a matched case-control study.

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Davey, Trish; Lanham-New, Susan A; Shaw, Anneliese M; Cobley, Rosalyn; Allsopp, Adrian J; Hajjawi, Mark O R; Arnett, Timothy R; Taylor, Pat; Cooper, Cyrus; Fallowfield, Joanne L

2015-04-01

Stress fracture is a common overuse injury within military training, resulting in significant economic losses to the military worldwide. Studies to date have failed to fully identify the bone density and bone structural differences between stress fractured personnel and controls due to inadequate adjustment for key confounding factors; namely age, body size and physical fitness; and poor sample size. The aim of this study was to investigate bone differences between male Royal Marine recruits who suffered a stress fracture during the 32 weeks of training and uninjured control recruits, matched for age, body weight, height and aerobic fitness. A total of 1090 recruits were followed through training and 78 recruits suffered at least one stress fracture. Bone mineral density (BMD) was measured at the lumbar spine (LS), femoral neck (FN) and whole body (WB) using Dual X-ray Absorptiometry in 62 matched pairs; tibial bone parameters were measured using peripheral Quantitative Computer Tomography in 51 matched pairs. Serum C-terminal peptide concentration was measured as a marker of bone resorption at baseline, week-15 and week-32. ANCOVA was used to determine differences between stress fractured recruits and controls. BMD at the LS, WB and FN sites was consistently lower in the stress fracture group (Pstress fracture recruits and controls were evident in all slices of the tibia, with the most prominent differences seen at the 38% tibial slice. There was a negative correlation between the bone cross-sectional area and BMD at the 38% tibial slice. There was no difference in serum CTx concentration between stress fracture recruits and matched controls at any stage of training. These results show evidence of fundamental differences in bone mass and structure in stress fracture recruits, and provide useful data on bone risk factor profiles for stress fracture within a healthy military population. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

Real-time synchronous measurement of curing characteristics and polymerization stress in bone cements with a cantilever-beam based instrument

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Palagummi, Sri Vikram; Landis, Forrest A.; Chiang, Martin Y. M.

2018-03-01

An instrumentation capable of simultaneously determining degree of conversion (DC), polymerization stress (PS), and polymerization exotherm (PE) in real time was introduced to self-curing bone cements. This comprises the combination of an in situ high-speed near-infrared spectrometer, a cantilever-beam instrument with compliance-variable feature, and a microprobe thermocouple. Two polymethylmethacrylate-based commercial bone cements, containing essentially the same raw materials but differ in their viscosity for orthopedic applications, were used to demonstrate the applicability of the instrumentation. The results show that for both the cements studied the final DC was marginally different, the final PS was different at the low compliance, the peak of the PE was similar, and their polymerization rates were significantly different. Systematic variation of instrumental compliance for testing reveals differences in the characteristics of PS profiles of both the cements. This emphasizes the importance of instrumental compliance in obtaining an accurate understanding of PS evaluation. Finally, the key advantage for the simultaneous measurements is that these polymerization properties can be correlated directly, thus providing higher measurement confidence and enables a more in-depth understanding of the network formation process.

Identification of predisposing factors for osteonecrosis of the jaw after marginal mandibulectomy in the surgical management of oral squamous cell carcinoma.

Science.gov (United States)

Ito, Ran; Huang, Jung-Ju; Hsieh, Wei-Chuan; Kao, Huang-Kai; Lao, William Wei-Kai; Fang, Ku-Hao; Huang, Yenlin; Chang, Yu-Liang; Cheng, Ming-Huei; Chang, Kai-Ping

2018-03-01

The aim of this study is to evaluate osteonecrosis of the jaw (ONJ) with the extent of marginal mandibulectomy. Between January 2006 and December 2012, 3087 patients undergoing ablative resection were consecutively enrolled. Among them, 345 cases undergoing marginal mandibulectomy were retrospectively reviewed. The occurrence of ONJ was 5.51% and associated with body mass index, overall stage, diabetes, concomitant mandibulotomy, and radiotherapy (P = 0.023, 0.033, 0.009, 0.016, and 0.006, respectively). As for bone parameters based on radiological measurements after marginal mandibulectomy, resected bone height, remaining bone height to original bone height ratio, and resected bone height to original bone height ratio were associated with ONJ. In multivariate logistic analyses, concomitant mandibulotomy, radiotherapy, diabetes, resected bone height of >14.5 mm, resected bone height to original bone height ratio of >49.5%, and remaining bone height to original bone height ratio of marginal mandibulectomy; more caution is necessitated in performing marginal mandibulectomy in patients with multiple risks to prevent ONJ. © 2017 Wiley Periodicals, Inc.

Increased activity of osteocyte autophagy in ovariectomized rats and its correlation with oxidative stress status and bone loss

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Yang, Yuehua, E-mail: yuesjtu@126.com; Zheng, Xinfeng, E-mail: zxf272@126.com; Li, Bo, E-mail: libo@126.com; Jiang, Shengdan, E-mail: jiangsd@126.com; Jiang, Leisheng, E-mail: leisheng_jiang@126.com

2014-08-15

Highlights: • Examine autophagy level in the proximal tibia of ovariectomized rats. • Investigate whether autophagy level is associated with bone loss. • Investigate whether autophagy level is associated with oxidative stress status. - Abstract: Objectives: The objectives of the present study were to investigate ovariectomy on autophagy level in the bone and to examine whether autophagy level is associated with bone loss and oxidative stress status. Methods: 36 female Sprague–Dawley rats were randomly divided into sham-operated (Sham), and ovariectomized (OVX) rats treated either with vehicle or 17-β-estradiol. At the end of the six-week treatment, bone mineral density (BMD) and bone micro-architecture in proximal tibias were assessed by micro-CT. Serum 17β-estradiol (E2) level were measured. Total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, catalase (CAT) activity in proximal tibia was also determined. The osteocyte autophagy in proximal tibias was detected respectively by Transmission Electron Microscopy (TEM), immunofluorescent histochemistry (IH), realtime-PCR and Western blot. In addition, the spearman correlation between bone mass, oxidative stress status, serum E2 and autophagy were analyzed. Results: Ovariectomy increased Atg5, LC3, and Beclin1 mRNA and proteins expressions while decreased p62 expression. Ovariectomy also declined the activities of T-AOC, CAT, and SOD. Treatment with E2 prevented the reduction in bone mass as well as restored the autophagy level. Furthermore, LC3-II expression was inversely correlated with T-AOC, CAT, and SOD activities. A significant inverse correlation between LC3-II expression and BV/TV, Tb.N, BMD in proximal tibias was found. Conclusions: Ovariectomy induced oxidative stress, autophagy and bone loss. Autophagy of osteocyte was inversely correlated with oxidative stress status and bone loss.

Rap system of stress stimulation can promote bone union after lower tibial bone fracture: a clinical research.

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Yao, Jian-fei; Shen, Jia-zuo; Li, Da-kun; Lin, Da-sheng; Li, Lin; Li, Qiang; Qi, Peng; Lian, Ke-jian; Ding, Zhen-qi

2012-01-01

Lower tibial bone fracture may easily cause bone delayed union or nonunion because of lacking of dynamic mechanical load. Research Group would design a new instrument as Rap System of Stress Stimulation (RSSS) to provide dynamic mechanical load which would promote lower tibial bone union postoperatively. This clinical research was conducted from January 2008 to December 2010, 92 patients(male 61/female 31, age 16-70 years, mean 36.3 years) who suffered lower tibial bone closed fracture were given intramedullary nail fixation and randomly averagely separated into experimental group and control group(according to the successively order when patients went for the admission procedure). Then researchers analysed the clinical healing time, full weight bearing time, VAS (Visual Analogue Scales) score and callus growth score of Lane-Sandhu in 3,6,12 months postoperatively. The delayed union and nonunion rates were compared at 6 and 12 months separately. All the 92 patients had been followed up (mean 14 months). Clinical bone healing time in experimental group was 88.78±8.80 days but control group was 107.91±9.03 days. Full weight bearing time in experimental group was 94.07±9.81 days but control group was 113.24±13.37 days respectively (Ptibial bone union, reduce bone delayed union or nonunion rate. It is an adjuvant therapy for promoting bone union after lower tibial bone fracture.

Nutritional factors that influence change in bone density and stress fracture risk among young female cross-country runners.

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Nieves, Jeri W; Melsop, Kathryn; Curtis, Meredith; Kelsey, Jennifer L; Bachrach, Laura K; Greendale, Gail; Sowers, Mary Fran; Sainani, Kristin L

2010-08-01

To identify nutrients, foods, and dietary patterns associated with stress fracture risk and changes in bone density among young female distance runners. Two-year, prospective cohort study. Observational data were collected in the course of a multicenter randomized trial of the effect of oral contraceptives on bone health. One hundred and twenty-five female competitive distance runners ages 18-26 years. Dietary variables were assessed with a food frequency questionnaire. Bone mineral density and content (BMD/BMC) of the spine, hip, and total body were measured annually by dual x-ray absorptiometry (DEXA). Stress fractures were recorded on monthly calendars, and had to be confirmed by radiograph, bone scan, or magnetic resonance imaging. Seventeen participants had at least one stress fracture during follow-up. Higher intakes of calcium, skim milk, and dairy products were associated with lower rates of stress fracture. Each additional cup of skim milk consumed per day was associated with a 62% reduction in stress fracture incidence (P stress fracture rate. Potassium intake was also associated with greater gains in hip and whole-body BMD. Copyright © 2010 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Bone Geometry as a Predictor of Tissue Fragility and Stress Fracture Risk

Science.gov (United States)

2004-10-01

eferences ........................................................................ 11 A ppendices ...School of Medicine, New York NY Stress fractures occur among persons with normal bones, no acute injury, and are most common among elite runners and

Case of femoral diaphyseal stress fracture after long-term risedronate administration diagnosed by iliac bone biopsy

Directory of Open Access Journals (Sweden)

Nagai T

2013-04-01

Full Text Available Takashi Nagai, Keizo Sakamoto, Koji Ishikawa, Emi Saito, Takuma Kuroda, Katsunori Inagaki Department of Orthopaedic Surgery, Showa University School of Medicine, Shinagwa-ku, Tokyo, Japan Abstract: Bisphosphonate excessively inhibits bone resorption and results in pathological fracture of the femur or ilium. The subject of this study was administered risedronate for 7 years; we suspected an easy fracture of the femoral diaphysis. In this study, we report the results of this patient's bone biopsy and bone morphometric analysis. A 76-year-old female patient presented with right femoral pain. Bone mineral density of the anteroposterior surface of the 2nd to 4th lumbar vertebrae (L2-L4 was decreased and levels of bone turnover markers were high. Therefore, we initiated treatment with risedronate. As she continued the medication, urinary levels of cross-linked N-terminal telopeptides of type I collagen and alkaline phosphatase (bone-type isozyme were found to be within the normal ranges. After 7 years of administration, the patient experienced pain when she put weight on the right femur and right femoral pain while walking. Plain radiographic examination revealed polypoid stress fracture-like lesions on the right femoral diaphysis and on the slightly distal-lateral cortical bone. Similar lesions were observed on magnetic resonance imaging and bone scintigraphy. We suspected severely suppressed bone turnover. Bone biopsy was obtained after labeling with tetracycline, and bone morphometric analysis was performed. On microscopic examination, slight double tetracycline labeling was observed. The trabeculae were narrow, and the numbers of osteoblasts and osteoclasts were decreased. Further, rates of bone calcification and bone formation were slow. Hence, we diagnosed fracture as a result of low turnover osteopathy. Risedronate was withdrawn, and Vitamin D3 was administered to improve the bone turnover. At 6 months, abnormal signals on magnetic resonance

[Effect of zirconia abutment angulation on stress distribution in the abutment and the bone around implant: a finite element study].

Science.gov (United States)

Yang, Yan-zhong; Tian, Xiao-hua; Zhou, Yan-min

2015-08-01

To investigate the effect of three different zirconia angular abutments on the stress distribution in bone and abutment using three-dimensional finite element analysis, and provide instruction for clinical application. Finite element analysis (FEA) was applied to analyze the stress distribution of three different zirconia/titanium angular abutments and bone around implant. The maximum Von Minses stress that existed in abutment, bolt and bone of the angular abutment model was significantly higher than that existed in the straight abutment model. The maximum Von Minses stress that existed in abutment, bolt and bone of the 20 ° angular abutment model was significantly higher than that existed in 15 ° angular abutment model. There was no significant difference between zirconia abutment model and titanium abutment model. The abutment angulation has a significant influence on the stress distribution in the abutment, bolt and bone, and exacerbates as the angulation increases, which suggest that we should take more attention to the implant orientation and use straight abutment or little angular abutment. The zirconia abutment can be used safely, and there is no noticeable difference between zirconia abutment and titanium abutment on stress distribution.

Clonidine reduces norepinephrine and improves bone marrow function in a rodent model of lung contusion, hemorrhagic shock, and chronic stress.

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Alamo, Ines G; Kannan, Kolenkode B; Ramos, Harry; Loftus, Tyler J; Efron, Philip A; Mohr, Alicia M

2017-03-01

Propranolol has been shown previously to restore bone marrow function and improve anemia after lung contusion/hemorrhagic shock. We hypothesized that daily clonidine administration would inhibit central sympathetic outflow and restore bone marrow function in our rodent model of lung contusion/hemorrhagic shock with chronic stress. Male Sprague-Dawley rats underwent 6 days of restraint stress after lung contusion/hemorrhagic shock during which the animals received clonidine (75 μg/kg) after the restraint stress. On postinjury day 7, we assessed urine norepinephrine, blood hemoglobin, plasma granulocyte colony stimulating factor, and peripheral blood mobilization of hematopoietic progenitor cells, as well as bone marrow cellularity and erythroid progenitor cell growth. The addition of clonidine to lung contusion/hemorrhagic shock with chronic restraint stress significantly decreased urine norepinephrine levels, improved bone marrow cellularity, restored erythroid progenitor colony growth, and improved hemoglobin (14.1 ± 0.6 vs 10.8 ± 0.6 g/dL). The addition of clonidine to lung contusion/hemorrhagic shock with chronic restraint stress significantly decreased hematopoietic progenitor cells mobilization and restored granulocyte colony stimulating factor levels. After lung contusion/hemorrhagic shock with chronic restraint stress, daily administration of clonidine restored bone marrow function and improved anemia. Alleviating chronic stress and decreasing norepinephrine is a key therapeutic target to improve bone marrow function after severe injury. Copyright © 2016 Elsevier Inc. All rights reserved.

To reduce the maximum stress and the stress shielding effect around a dental implant-bone interface using radial functionally graded biomaterials.

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Asgharzadeh Shirazi, H; Ayatollahi, M R; Asnafi, A

2017-05-01

In a dental implant system, the value of stress and its distribution plays a pivotal role on the strength, durability and life of the implant-bone system. A typical implant consists of a Titanium core and a thin layer of biocompatible material such as the hydroxyapatite. This coating has a wide range of clinical applications in orthopedics and dentistry due to its biocompatibility and bioactivity characteristics. Low bonding strength and sudden variation of mechanical properties between the coating and the metallic layers are the main disadvantages of such common implants. To overcome these problems, a radial distributed functionally graded biomaterial (FGBM) was proposed in this paper and the effect of material property on the stress distribution around the dental implant-bone interface was studied. A three-dimensional finite element simulation was used to illustrate how the use of radial FGBM dental implant can reduce the maximum von Mises stress and, also the stress shielding effect in both the cortical and cancellous bones. The results, of course, give anybody an idea about optimized behaviors that can be achieved using such materials. The finite element solver was validated by familiar methods and the results were compared to previous works in the literature.

Microgap and Micromotion at the Implant Abutment Interface Cause Marginal Bone Loss Around Dental Implant but More Evidence is Needed.

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Alqutaibi, Ahmed Yaseen; Aboalrejal, Afaf Noman

2018-06-01

Influences of micro-gap and micromotion of the implant-abutment interface on marginal bone loss around implant neck. Liu Y, Wang J. Arch Oral Biol 2017;83:153-60. This study was financially supported by grants from the National Natural Science Foundation of China (81570956) and the Bureau of Science and Technology of Wuhan ([2014]160, 2015060101010051) TYPE OF STUDY/DESIGN: Comprehensive literature review. Copyright © 2018 Elsevier Inc. All rights reserved.

Preventive Effects of Drinking Hydrogen-Rich Water on Gingival Oxidative Stress and Alveolar Bone Resorption in Rats Fed a High-Fat Diet.

Science.gov (United States)

Yoneda, Toshiki; Tomofuji, Takaaki; Kunitomo, Muneyoshi; Ekuni, Daisuke; Irie, Koichiro; Azuma, Tetsuji; Machida, Tatsuya; Miyai, Hisataka; Fujimori, Kouhei; Morita, Manabu

2017-01-13

Obesity induces gingival oxidative stress, which is involved in the progression of alveolar bone resorption. The antioxidant effect of hydrogen-rich water may attenuate gingival oxidative stress and prevent alveolar bone resorption in cases of obesity. We examined whether hydrogen-rich water could suppress gingival oxidative stress and alveolar bone resorption in obese rats fed a high-fat diet. Male Fischer 344 rats ( n = 18) were divided into three groups of six rats each: a control group (fed a regular diet and drinking distilled water) and two experimental groups (fed a high-fat diet and drinking distilled water or hydrogen-rich water). The level of 8-hydroxydeoxyguanosine was determined to evaluate oxidative stress. The bone mineral density of the alveolar bone was analyzed by micro-computerized tomography. Obese rats, induced by a high-fat diet, showed a higher gingival level of 8-hydroxydeoxyguanosine and a lower level of alveolar bone density compared to the control group. Drinking hydrogen-rich water suppressed body weight gain, lowered gingival level of 8-hydroxydeoxyguanosine, and reduced alveolar bone resorption in rats on a high-fat diet. The results indicate that hydrogen-rich water could suppress gingival oxidative stress and alveolar bone resorption by limiting obesity.

[Bone Cell Biology Assessed by Microscopic Approach. Response to mechanical stress by osteocyte network].

Science.gov (United States)

Komori, Toshihisa

2015-10-01

Osteocytes were considered to be involved in the response to mechanical stress from their network structure. However, it was difficult to prove the function because of the lack of animal models for a long time. Recently, the function of osteocytes was clarified using various knockout and transgenic mice. Osteocyte death causes bone remodeling, which is a repair process induced by osteocyte necrosis but not by the loss of the function of live osteocytes. The osteocyte network mildly inhibits bone formation and mildly stimulates bone resorption in physiological condition. In unloaded condition, it strongly inhibits bone formation and strongly stimulates bone resorption, at least in part, through the induction of Sost in osteocytes and Rankl in osteoblasts.

Effects of the implant design on peri-implant bone stress and abutment micromovement: three-dimensional finite element analysis of original computer-aided design models.

Science.gov (United States)

Yamanishi, Yasufumi; Yamaguchi, Satoshi; Imazato, Satoshi; Nakano, Tamaki; Yatani, Hirofumi

2014-09-01

Occlusal overloading causes peri-implant bone resorption. Previous studies examined stress distribution in alveolar bone around commercial implants using three-dimensional (3D) finite element analysis. However, the commercial implants contained some different designs. The purpose of this study is to reveal the effect of the target design on peri-implant bone stress and abutment micromovement. Six 3D implant models were created for different implant-abutment joints: 1) internal joint model (IM); 2) external joint model (EM); 3) straight abutment (SA) shape; 4) tapered abutment (TA) shapes; 5) platform switching (PS) in the IM; and 6) modified TA neck design (reverse conical neck [RN]). A static load of 100 N was applied to the basal ridge surface of the abutment at a 45-degree oblique angle to the long axis of the implant. Both stress distribution in peri-implant bone and abutment micromovement in the SA and TA models were analyzed. Compressive stress concentrated on labial cortical bone and tensile stress on the palatal side in the EM and on the labial side in the IM. There was no difference in maximum principal stress distribution for SA and TA models. Tensile stress concentration was not apparent on labial cortical bone in the PS model (versus IM). Maximum principal stress concentrated more on peri-implant bone in the RN than in the TA model. The TA model exhibited less abutment micromovement than the SA model. This study reveals the effects of the design of specific components on peri-implant bone stress and abutment displacement after implant-supported single restoration in the anterior maxilla.

Association of stressful life events with accelerated bone loss in older men: the Osteoporotic Fractures in Men (MrOS) Study

Science.gov (United States)

Fink, Howard A.; Kuskowski, Michael A.; Cauley, Jane A.; Taylor, Brent C.; Schousboe, John T.; Cawthon, Peggy M.; Ensrud, Kristine E.

2015-01-01

Purpose/Introduction Prior studies suggest that stressful life events may increase adverse health outcomes, including falls and possibly fractures. The current study builds on these findings and examines whether stressful life events are associated with increased bone loss. Methods 4388 men aged ≥65 years in the Osteoporotic Fractures in Men study completed total hip bone mineral density (BMD) measures at baseline and visit 2, approximately 4.6 years later, and self-reported stressful life events data mid-way between baseline and visit 2, and at visit 2. We used linear regression to model the association of stressful life events with concurrent annualized total hip BMD loss, and log binomial regression or Poisson regression to model risk of concurrent accelerated BMD loss (>1 SD more than mean annualized change). Results 75.3% of men reported ≥1 type of stressful life event, including 43.3% with ≥2 types of stressful life events. Mean annualized BMD loss was −0.36% (SD 0.88) and 13.9% of men were categorized with accelerated BMD loss (about 5.7% or more total loss). Rate of annualized BMD loss increased with the number of types of stressful life events after adjustment for age (pstressful life events (RR, 1.10 [95% CI, 1.04–1.16]) per increase of 1 type of stressful life event). Fracture risk was not significantly different between stressful life event-accelerated bone loss subgroups (p=0.08). Conclusions In these older men, stressful life events were associated with a small, dose-related increase in risk of concurrent accelerated hip bone loss. Low frequency of fractures limited assessment of whether rapid bone loss mediates any association of stressful life events with incident fractures. Future studies are needed to confirm these findings and to investigate the mechanism that may underlie this association. PMID:25169421

Stress states in the Zagros fold-and-thrust belt from passive margin to collisional tectonic setting

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Navabpour, Payman; Barrier, Eric

2012-12-01

The present-day Zagros fold-and-thrust belt of SW-Iran corresponds to the former Arabian passive continental margin of the southern Neo-Tethyan basin since the Permian-Triassic rifting, undergoing later collisional deformation in mid-late Cenozoic times. In this paper an overview of brittle tectonics and palaeostress reconstructions of the Zagros fold-and-thrust belt is presented, based on direct stress tensor inversion of fault slip data. The results indicate that, during the Neo-Tethyan oceanic opening, an extensional tectonic regime affectedthe sedimentary cover in Triassic-Jurassic times with an approximately N-S trend of the σ3 axis, oblique to the margin, which was followed by some local changes to a NE-SW trend during Jurassic-Cretaceous times. The stress state significantly changed to thrust setting, with a NE-SW trend of the σ1 axis, and a compressional tectonic regime prevailed during the continental collision and folding of the sedimentary cover in Oligocene-Miocene times. This compression was then followed by a strike-slip stress state with an approximately N-S trend of the σ1 axis, oblique to the belt, during inversion of the inherited extensional basement structures in Pliocene-Recent times. The brittle tectonic reconstructions, therefore, highlighted major changes of the stress state in conjunction with transitions between thin- and thick-skinned structures during different extensional and compressional stages of continental deformation within the oblique divergent and convergent settings, respectively.

Marginal zone in femoral head avascular necrosis: scintigraphic characteristics and clinical prognostic value

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Milcinski, M.; Sedonja, I.; Dolinar, D.; Jevtic, V.

2002-01-01

Aim: Marginal zone, seen on magnetic resonance imaging (MRI) in femoral head avascular necrosis, consists of granulation tissue and sclerosis at the junction of necrotic and normal bone. Prognostic value of this finding is not clear. Aim of our study was to evaluate osteoblastic activity of marginal zone with bone scintigraphy and to assess prognostic importance of marginal zone for further evolution of femoral head necrosis. Material and methods: MRI was performed in 37 hips in 26 patients (17 m, 9 f, 20-64 y, mean 42,9 y) with Ficat 0-II avascular necrosis (SE T1W, STIR and SE T1W FAT.SAT after Gd DTPA in the coronal plane and GE FLASH in the sagittal plane). In 26 hips of 17 patients planar and pinhole scintigraphy with 99mTc-DPD was performed. Results: On MRI, marginal zone divided necrotic and normal bone in 26/37 (70,3%) hips, in 14/26 it was thin (2% of femoral head diameter or less), but in 12/26 it was wide (more than 2% of femoral head diameter). In 11/37 (29,7%) hips marginal zone was not seen. Pinhole scintigraphy was performed in 26 hips; in all 10/10 (100%) hips with wide marginal zone, seen on MRI, increased osteoblastic activity was detected, while only in 1/9 (11,1%) hips with thin marginal zone on MRI osteoblastic activity was increased. Patients were followed 1 to 5 years (mean 2,2 y). In hips without marginal zone no collapse of femoral head was seen until now, in 2/11 (18,2%) femoral heads MRI and clinical regression was observed. Ten of 12 lesions with wide marginal zone (83,3 %) collapsed 0,25 to 2,5 (mean 1) years after onset of pain. Two of 12 lesions with wide marginal zone (16,7%) have not collapsed until now. From lesions with thin marginal zone, 4/14 (28,6 %) collapsed 0,7 to 3 (mean 1,9) years after onset of pain, 10/14 (71,4%) did not collapse until now. Conclusion: Increased osteoblastic activity in wide marginal zone between necrotic and vital bone in hip avascular necrosis is bad prognostic factor for femoral head collapse

Minimum Abutment Height to Eliminate Bone Loss: Influence of Implant Neck Design and Platform Switching.

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Spinato, Sergio; Galindo-Moreno, Pablo; Bernardello, Fabio; Zaffe, Davide

This retrospective study quantitatively analyzed the minimum prosthetic abutment height to eliminate bone loss after 4.7-mm-diameter implant placement in maxillary bone and how grafting techniques can affect the marginal bone loss in implants placed in maxillary areas. Two different implant types with a similar neck design were singularly placed in two groups of patients: the test group, with platform-switched implants, and the control group, with conventional (non-platform-switched) implants. Patients requiring bone augmentation underwent unilateral sinus augmentation using a transcrestal technique with mineralized xenograft. Radiographs were taken immediately after implant placement, after delivery of the prosthetic restoration, and after 12 months of loading. The average mesial and distal marginal bone loss of the control group (25 patients) was significantly more than twice that of the test group (26 patients), while their average abutment height was similar. Linear regression analysis highlighted a statistically significant inverse relationship between marginal bone loss and abutment height in both groups; however, the intercept of the regression line, both mesially and distally, was 50% lower for the test group than for the control group. The marginal bone loss was annulled with an abutment height of 2.5 mm for the test group and 3.0 mm for the control group. No statistically significant differences were found regarding marginal bone loss of implants placed in native maxillary bone compared with those placed in the grafted areas. The results suggest that the shorter the abutment height, the greater the marginal bone loss in cement-retained prostheses. Abutment height showed a greater influence in platform-switched than in non-platform-switched implants on the limitation of marginal bone loss.

Effects of chronic mild stress on parameters of bone assessment in adult male and female rats

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Fabrício L. Valente

Full Text Available Abstract: Osteoporosis is a multifactorial disease of high prevalence and has great impact on quality of life, because the effects on bone structure increase the risk of fractures, what may be very debilitating. Based on the observation that patients with depression have lower bone mineral density than healthy individuals, many studies have indicated that stress could be an aggravating factor for bone loss. This study evaluates the effect of a protocol of chronic mild stress (CMS on parameters of bone assessment in male and female rats. Five 5-monh-old rats of each sex underwent a schedule of stressor application for 28 days. Stressors included cold, heat, restraint, cage tilt, isolation, overnight illumination, and water and food deprivation. Five rats of each sex were kept under minimum intervention as control group. The animals were weighed at beginning and end of the period, and after euthanasia had their bones harvested. Femur, tibia and lumbar vertebrae were analyzed by bone densitometry. Biomechanical tests were performed in femoral head and diaphysis. Trabecular bone volume was obtained from histomorphometric analysis of femoral head and vertebral body, as well as of femoral midshaft cross-sectional measures. Not all parameters analyzed showed effect of CMS. However, tibial and L4 vertebral bone mineral density and cross-sectional cortical/medullar ratio of femoral shaft were lower in female rats submitted to the CMS protocol. Among male rats, the differences were significant for femoral trabecular bone volume and maximum load obtained by biomechanical test. Thus, it could be confirmed that CMS can affect the balance of bone homeostasis in rats, what may contribute to the establishment of osteopenia or osteoporosis.

Increased sclerostin associated with stress fracture of the third metacarpal bone in the Thoroughbred racehorse

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Singer, E.; Henson, F.

2018-01-01

Objectives The exact aetiology and pathogenesis of microdamage-induced long bone fractures remain unknown. These fractures are likely to be the result of inadequate bone remodelling in response to damage. This study aims to identify an association of osteocyte apoptosis, the presence of osteocytic osteolysis, and any alterations in sclerostin expression with a fracture of the third metacarpal (Mc-III) bone of Thoroughbred racehorses. Methods A total of 30 Mc-III bones were obtained; ten bones were fractured during racing, ten were from the contralateral limb, and ten were from control horses. Each Mc-III bone was divided into a fracture site, condyle, condylar groove, and sagittal ridge. Microcracks and diffuse microdamage were quantified. Apoptotic osteocytes were measured using TUNEL staining. Cathepsin K, matrix metalloproteinase-13 (MMP-13), HtrA1, and sclerostin expression were analyzed. Results In the fracture group, microdamage was elevated 38.9% (sd 2.6) compared with controls. There was no difference in the osteocyte number and the percentage of apoptotic cells between contralateral limb and unraced control; however, there were significantly fewer apoptotic cells in fractured samples (p fractured samples, sclerostin expression was significantly higher (p fractured during racing. In this study, this is not associated with osteocyte apoptosis or osteocytic osteolysis. The finding of increased sclerostin in the region of the fracture suggests that this protein may be playing a key role in the regulation of bone microdamage during stress adaptation. Cite this article: N. Hopper, E. Singer, F. Henson. Increased sclerostin associated with stress fracture of the third metacarpal bone in the Thoroughbred racehorse. Bone Joint Res 2018;7:94–102. DOI: 10.1302/2046-3758.71.BJR-2016-0202.R4. PMID:29363519

A three-dimensional finite element study on the effect of hydroxyapatite coating thickness on the stress distribution of the surrounding dental implant-bone interface

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Hadi Asgharzadeh Shirazi

2014-06-01

Full Text Available   Background and Aims: Hydroxyapatite coating has allocated a special place in dentistry due to its biocompatibility and bioactivity. The purpose of this study was to evaluate the relation between the hydroxyapatite thickness and stress distribution by using finite element method.   Materials and Methods: In this paper, the effect of hydroxyapatite coating thickness on dental implants was studied using finite element method in the range between 0 to 200 microns. A 3D model including one section of mandible bone was modeled by a thick layer of cortical surrounding dense cancellous and a Nobel Biocare commercial brand dental implant was simulated and analyzed under static load in the Abaqus software.   Results The diagram of maximum von Mises stress versus coating thickness was plotted for the cancellous and cortical bones in the range between 0 to 200 microns. The obtained results showed that the magnitude of maximum von Mises stress of bone decreased as the hydroxyapatite coating thickness increased. Also, the thickness of coating exhibited smoother stress distribution and milder variations of maximum von Mises stress in a range between 60 to 120 microns.   Conclusion: In present study, the stress was decreased in the mandible bone where hydroxyapatite coating was used. This stress reduction leads to a faster stabilization and fixation of implant in the mandible bone. Using hydroxyapatite coating as a biocompatible and bioactive material could play an important role in bone formation of implant- bone interface.

Doxorubicin-mediated bone loss in breast cancer bone metastases is driven by an interplay between oxidative stress and induction of TGFβ.

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Tapasi Rana

Full Text Available Breast cancer patients, who are already at increased risk of developing bone metastases and osteolytic bone damage, are often treated with doxorubicin. Unfortunately, doxorubicin has been reported to induce damage to bone. Moreover, we have previously reported that doxorubicin treatment increases circulating levels of TGFβ in murine pre-clinical models. TGFβ has been implicated in promoting osteolytic bone damage, a consequence of increased osteoclast-mediated resorption and suppression of osteoblast differentiation. Therefore, we hypothesized that in a preclinical breast cancer bone metastasis model, administration of doxorubicin would accelerate bone loss in a TGFβ-mediated manner. Administration of doxorubicin to 4T1 tumor-bearing mice produced an eightfold increase in osteolytic lesion areas compared untreated tumor-bearing mice (P = 0.002 and an almost 50% decrease in trabecular bone volume expressed in BV/TV (P = 0.0005, both of which were rescued by anti-TGFβ antibody (1D11. Doxorubicin, which is a known inducer of oxidative stress, decreased osteoblast survival and differentiation, which was rescued by N-acetyl cysteine (NAC. Furthermore, doxorubicin treatment decreased Cu-ZnSOD (SOD1 expression and enzyme activity in vitro, and treatment with anti-TGFβ antibody was able to rescue both. In conclusion, a combination therapy using doxorubicin and anti-TGFβ antibody might be beneficial for preventing therapy-related bone loss in cancer patients.

Human dental pulp cells exhibit bone cell-like responsiveness to fluid shear stress.

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Kraft, David Christian Evar; Bindslev, Dorth Arenholt; Melsen, Birte; Klein-Nulend, Jenneke

2011-02-01

For engineering bone tissue to restore, for example, maxillofacial defects, mechanosensitive cells are needed that are able to conduct bone cell-specific functions, such as bone remodelling. Mechanical loading affects local bone mass and architecture in vivo by initiating a cellular response via loading-induced flow of interstitial fluid. After surgical removal of ectopically impacted third molars, human dental pulp tissue is an easily accessible and interesting source of cells for mineralized tissue engineering. The aim of this study was to determine whether human dental pulp-derived cells (DPC) are responsive to mechanical loading by pulsating fluid flow (PFF) upon stimulation of mineralization in vitro. Human DPC were incubated with or without mineralization medium containing differentiation factors for 3 weeks. Cells were subjected to 1-h PFF (0.7 ± 0.3 Pa, 5 Hz) and the response was quantified by measuring nitric oxide (NO) and prostaglandin E₂ (PGE₂) production, and gene expression of cyclooxygenase (COX)-1 and COX-2. We found that DPC are intrinsically mechanosensitive and, like osteogenic cells, respond to PFF-induced fluid shear stress. PFF stimulated NO and PGE₂ production, and up-regulated COX-2 but not COX-1 gene expression. In DPC cultured under mineralizing conditions, the PFF-induced NO, but not PGE₂, production was significantly enhanced. These data suggest that human DPC, like osteogenic cells, acquire responsiveness to pulsating fluid shear stress in mineralizing conditions. Thus DPC might be able to perform bone-like functions during mineralized tissue remodeling in vivo, and therefore provide a promising new tool for mineralized tissue engineering to restore, for example, maxillofacial defects.

Regional bone geometry of the tibia in triathletes and stress reactions--an observational study.

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Newsham-West, Richard J; Lyons, Brett; Milburn, Peter D

2014-03-01

The association between tibial morphology and tibial stress fractures or tibial stress syndrome was examined in triathletes with an unusually high incidence of these injuries. A cross-sectional study design examined associations between tibial geometry from MRI images and training and injury data between male and female triathletes and between stress fracture (SF) and non-stress fracture (NSF) groups. Fifteen athletes (7 females, 8 males) aged 17-23 years who were currently able to train and race were recruited from the New Zealand Triathlete Elite Development Squad. Geometric measurements were taken at 5 zones along the tibia using MRI and compared between symptomatic and asymptomatic tibiae subjects. SF tibiae displayed either oedema within the cancellous bone and/or stress fracture on MRI. When collapsed across levels, symptomatic tibiae had thicker medial cortices (F1,140=9.285, p=0.003), thicker lateral cortices (F1,140=10.129, p=0.002) and thinner anterior cortices (F1,140=14.517, p=0.000) than NSF tibiae. Only medial cortex thickness in SF tibia was significantly different (F4,140=3.358, p=0.012) at different levels. Follow-up analysis showed that athletes showing oedema within the cancellous bone and/or stress fracture on MRI had, within 2 years of analysis, subsequently taken time off training and racing due a tibial stress fracture. The thinner anterior cortex in SF tibiae is associated with a stress reaction in these triathletes. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Comparison of different hip prosthesis shapes considering micro-level bone remodeling and stress-shielding criteria using three-dimensional design space topology optimization.

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Boyle, Christopher; Kim, Il Yong

2011-06-03

Since the late 1980s, computational analysis of total hip arthroplasty (THA) prosthesis components has been completed using macro-level bone remodeling algorithms. The utilization of macro-sized elements requires apparent bone densities to predict cancellous bone strength, thereby, preventing visualization and analysis of realistic trabecular architecture. In this study, we utilized a recently developed structural optimization algorithm, design space optimization (DSO), to perform a micro-level three-dimensional finite element bone remodeling simulation on the human proximal femur pre- and post-THA. The computational simulation facilitated direct performance comparison between two commercially available prosthetic implant stems from Zimmer Inc.: the Alloclassic and the Mayo conservative. The novel micro-level approach allowed the unique ability to visualize the trabecular bone adaption post-operation and to quantify the changes in bone mineral content by region. Stress-shielding and strain energy distribution were also quantified for the immediate post-operation and the stably fixated, post-remodeling conditions. Stress-shielding was highest in the proximal region and remained unchanged post-remodeling; conversely, the mid and distal portions show large increases in stress, suggesting a distal shift in the loadpath. The Mayo design conserves bone mass, while simultaneously reducing the incidence of stress-shielding compared to the Alloclassic, revealing a key benefit of the distinctive geometry. Several important factors for stable fixation, determined in clinical evaluations from the literature, were evident in both designs: high levels of proximal bone loss and distal bone densification. The results suggest this novel computational framework can be utilized for comparative hip prosthesis shape, uniquely considering the post-operation bone remodeling as a design criterion. Copyright © 2011 Elsevier Ltd. All rights reserved.

Influence of Implant Positions and Occlusal Forces on Peri-Implant Bone Stress in Mandibular Two-Implant Overdentures: A 3-Dimensional Finite Element Analysis.

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Alvarez-Arenal, Angel; Gonzalez-Gonzalez, Ignacio; deLlanos-Lanchares, Hector; Brizuela-Velasco, Aritza; Dds, Elena Martin-Fernandez; Ellacuria-Echebarria, Joseba

2017-12-01

The aim of this study was to evaluate and compare the bone stress around implants in mandibular 2-implant overdentures depending on the implant location and different loading conditions. Four 3-dimensional finite element models simulating a mandibular 2-implant overdenture and a Locator attachment system were designed. The implants were located at the lateral incisor, canine, second premolar, and crossed-implant levels. A 150 N unilateral and bilateral vertical load of different location was applied, as was 40 N when combined with midline load. Data for von Mises stress were produced numerically, color coded, and compared between the models for peri-implant bone and loading conditions. With unilateral loading, in all 4 models much higher peri-implant bone stress values were recorded on the load side compared with the no-load side, while with bilateral occlusal loading, the stress distribution was similar on both sides. In all models, the posterior unilateral load showed the highest stress, which decreased as the load was applied more mesially. In general, the best biomechanical environment in the peri-implant bone was found in the model with implants at premolar level. In the crossed-implant model, the load side greatly altered the biomechanical environment. Overall, the overdenture with implants at second premolar level should be the chosen design, regardless of where the load is applied. The occlusal loading application site influences the bone stress around the implant. Bilateral occlusal loading distributes the peri-implant bone stress symmetrically, while unilateral loading increases it greatly on the load side, no matter where the implants are located.

Bone growth, limb proportions and non-specific stress in archaeological populations from Croatia.

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Pinhasi, R; Timpson, A; Thomas, M; Slaus, M

2014-01-01

The effect of environmental factors and, in particular, non-specific stress on the growth patterns of limbs and other body dimensions of children from past populations is not well understood. This study assesses whether growth of mediaeval and post-mediaeval children aged between 0-11.5 years from Adriatic (coastal) and continental Croatia varies by region and by the prevalence and type of non-specific stress. Dental ages were estimated using the Moorrees, Fanning and Hunt (MFH) scoring method. Growth of long bone diaphyses (femur, tibia, humerus, radius and ulna) was assessed by using a composite Z-score statistic (CZS). Clavicular length was measured as a proxy for upper trunk width, distal metaphyseal width of the femur was measured as a proxy for body mass and upper and lower intra-limb indices were calculated. Differences between sub-sets sampled by (a) region and (b) active vs healed non-specific stress indicators and (c) intra-limb indices were tested by Mann--Whitney U-tests and Analysis of Covariance (ANCOVA). Adriatic children attained larger dimensions-per-age than continental children. Children with healed stress lesions had larger dimensions-per-age than those with active lesions. No inter-regional difference was found in intra-limb indices. These findings highlight the complexity of growth patterns in past populations and indicate that variation in environmental conditions such as diet and differences in the nature of non-specific stress lesions both exert a significant effect on long bone growth.

Vitamin E improved bone strength and bone minerals in male rats given alcohol

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Syuhada Zakaria

2017-12-01

Full Text Available Objective(s: Alcohol consumption induces oxidative stress on bone, which in turn increases the risk of osteoporosis. This study determined the effects of vitamin E on bone strength and bone mineral content in alcohol-induced osteoporotic rats. Materials and Methods: Three months old Sprague Dawley male rats were randomly divided into 5 groups: (I control group; (II alcohol (3 g/kg + normal saline; (III alcohol (3 g/kg + olive oil; (IV alcohol (3 g/kg + alpha-tocopherol (60 mg/kg and (V alcohol (3 g/kg + palm vitamin E (60 mg/kg. The treatment lasted for three months. Following sacrifice, the right tibia was subjected to bone biomechanical test while the lumbar (fourth and fifth lumbar and left tibia bones were harvested for bone mineral measurement. Results: Alcohol caused reduction in bone biomechanical parameters (maximum force, ultimate stress, yield stress and Young’s modulus and bone minerals (bone calcium and magnesium compared to control group (P

Protective effect of zinc supplementation against cadmium-induced oxidative stress and the RANK/RANKL/OPG system imbalance in the bone tissue of rats

International Nuclear Information System (INIS)

Brzóska, Malgorzata M.; Rogalska, Joanna

2013-01-01

It was investigated whether protective influence of zinc (Zn) against cadmium (Cd)-induced disorders in bone metabolism may be related to its antioxidative properties and impact on the receptor activator of nuclear factor (NF)-κΒ (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system. Numerous indices of oxidative/antioxidative status, and Cd and Zn were determined in the distal femur of the rats administered Zn (30 and 60 mg/l) or/and Cd (5 and 50 mg/l) for 6 months. Soluble RANKL (sRANKL) and OPG were measured in the bone and serum. Zn supplementation importantly protected from Cd-induced oxidative stress preventing protein, DNA, and lipid oxidation in the bone. Moreover, Zn protected from the Cd-induced increase in sRANKL concentration and the sRANKL/OPG ratio, and decrease in OPG concentration in the bone and serum. Numerous correlations were noted between indices of the oxidative/antioxidative bone status, concentrations of sRANKL and OPG in the bone and serum, as well as the bone concentrations of Zn and Cd, and previously reported by us in these animals (Brzóska et al., 2007) indices of bone turnover and bone mineral density. The results allow us to conclude that the ability of Zn to prevent from oxidative stress and the RANK/RANKL/OPG system imbalance may be implicated in the mechanisms of its protective impact against Cd-induced bone damage. This paper is the first report from an in vivo study providing evidence that beneficial Zn impact on the skeleton under exposure to Cd is related to the improvement of the bone tissue oxidative/antioxidative status and mediating the RANK/RANKL/OPG system. - Highlights: • Cd induces oxidative stress in the bone tissue. • Cd disturbs bone metabolism via disorder of the RANK/RANKL/OPG system balance. • Zn supplementation protects from Cd-induced oxidative stress in the bone tissue. • Zn protects from the RANK/RANKL/OPG system imbalance caused by Cd in the bone tissue. • Enhanced Zn intake protects from Cd

Protective effect of zinc supplementation against cadmium-induced oxidative stress and the RANK/RANKL/OPG system imbalance in the bone tissue of rats

Energy Technology Data Exchange (ETDEWEB)

Brzóska, Malgorzata M., E-mail: Malgorzata.Brzoska@umb.edu.pl; Rogalska, Joanna

2013-10-01

It was investigated whether protective influence of zinc (Zn) against cadmium (Cd)-induced disorders in bone metabolism may be related to its antioxidative properties and impact on the receptor activator of nuclear factor (NF)-κΒ (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system. Numerous indices of oxidative/antioxidative status, and Cd and Zn were determined in the distal femur of the rats administered Zn (30 and 60 mg/l) or/and Cd (5 and 50 mg/l) for 6 months. Soluble RANKL (sRANKL) and OPG were measured in the bone and serum. Zn supplementation importantly protected from Cd-induced oxidative stress preventing protein, DNA, and lipid oxidation in the bone. Moreover, Zn protected from the Cd-induced increase in sRANKL concentration and the sRANKL/OPG ratio, and decrease in OPG concentration in the bone and serum. Numerous correlations were noted between indices of the oxidative/antioxidative bone status, concentrations of sRANKL and OPG in the bone and serum, as well as the bone concentrations of Zn and Cd, and previously reported by us in these animals (Brzóska et al., 2007) indices of bone turnover and bone mineral density. The results allow us to conclude that the ability of Zn to prevent from oxidative stress and the RANK/RANKL/OPG system imbalance may be implicated in the mechanisms of its protective impact against Cd-induced bone damage. This paper is the first report from an in vivo study providing evidence that beneficial Zn impact on the skeleton under exposure to Cd is related to the improvement of the bone tissue oxidative/antioxidative status and mediating the RANK/RANKL/OPG system. - Highlights: • Cd induces oxidative stress in the bone tissue. • Cd disturbs bone metabolism via disorder of the RANK/RANKL/OPG system balance. • Zn supplementation protects from Cd-induced oxidative stress in the bone tissue. • Zn protects from the RANK/RANKL/OPG system imbalance caused by Cd in the bone tissue. • Enhanced Zn intake protects from Cd

The inclusion of weld residual stress in fracture margin assessments of embrittled nuclear reactor pressure vessels

International Nuclear Information System (INIS)

Dickson, T.L.; Bass, B.R.; McAfee, W.J.

1998-01-01

Analyses were performed to determine the impact of weld residual stresses in a reactor pressure vessel (RPV) on (1) the generation of pressure temperature (P-T) curves required for maintaining specified fracture prevention margins during nuclear plant startup and shutdown, and (2) the conditional probability of vessel failure due to pressurized thermal shock (PTS) loading. The through wall residual stress distribution in an axially oriented weld was derived using measurements taken from a shell segment of a canceled RPV and finite element thermal stress analyses. The P-T curve derived from the best estimate load analysis and a t / 8 deep flaw, based on K Ic , was less limiting than the one derived from the current methodology prescribed in the ASME Boiler and Pressure Vessel Code. The inclusion of the weld residual stresses increased the conditional probability of cleavage fracture due to PTS loading by a factor ranging from 2 to 4

The Effects of Subcrestal Implant Placement on Crestal Bone Levels and Bone-to-Abutment Contact: A Microcomputed Tomographic and Histologic Study in Dogs.

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Fetner, Michael; Fetner, Alan; Koutouzis, Theofilos; Clozza, Emanuele; Tovar, Nick; Sarendranath, Alvin; Coelho, Paulo G; Neiva, Kathleen; Janal, Malvin N; Neiva, Rodrigo

2015-01-01

Implant design and the implant-abutment interface have been regarded as key influences on crestal bone maintenance over time. The aim of the present study was to determine crestal bone changes around implants placed at different depths in a dog model. Thirty-six two-piece dental implants with a medialized implant-abutment interface and Morse taper connection (Ankylos, Dentsply) were placed in edentulous areas bilaterally in six mongrel dogs. On each side of the mandible, three implants were placed randomly at the bone crest, 1.5 mm subcrestally, or 3.0 mm subcrestally. After 3 months, the final abutments were torqued into place. At 6 months, the animals were sacrificed and samples taken for microcomputed tomographic (micro-CT) and histologic evaluations. Micro-CT analysis revealed similar crestal or marginal bone loss among groups. Both subcrestal implant groups lost significantly less crestal and marginal bone than the equicrestal implants. Bone loss was greatest on the buccal of the implants, regardless of implant placement depth. Histologically, implants placed subcrestally were found to have bone in contact with the final abutment and on the implant platform. Implants with a centralized implant-abutment interface and Morse taper connection can be placed subcrestally without significant loss of crestal or marginal bone. Subcrestal placement of this implant system appears to be advantageous in maintaining bone height coronal to the implant platform.

The Role of Musculoskeletal Dynamics and Neuromuscular Control in Stress Development in Bone

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DeWoody, Yssa

1996-01-01

The role of forces produced by the musculotendon units in the stress development of the long bones during gait has not been fully analyzed. It is well known that the musculotendons act as actuators producing the joint torques which drive the body. Although the joint torques required to perform certain motor tasks can be recovered through a kinematic analysis, it remains a difficult problem to determine the actual forces produced by each muscle that resulted in these torques. As a consequence, few studies have focused on the role of individual muscles in the development of stress in the bone. This study takes a control theoretic approach to the problem. A seven-link, eight degrees of freedom model of the body is controlled by various muscle groups on each leg to simulate gait. The simulations incorporate Hill-type models of muscles with activation and contraction dynamics controlled through neural inputs. This direct approach allows one to know the exact muscle forces exerted by each musculotendon throughout the gait cycle as well the joint torques and reaction forces at the ankle and knee. Stress and strain computed by finite element analysis on skeletal members will be related to these derived loading conditions. Thus the role of musculoskeletal dynamics and neuromuscular control in the stress development of the tibia during gait can be analyzed.

Stress fractures of the base of the metatarsal bones in young trainee ballet dancers

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Albisetti, Walter; De Bartolomeo, Omar; Tagliabue, Lorenzo; Camerucci, Emanuela; Calori, Giorgio Maria

2009-01-01

Classical ballet is an art form requiring extraordinary physical activity, characterised by rigorous training. These can lead to many overuse injuries arising from repetitive minor trauma. The purpose of this paper is to report our experience in the diagnosis and treatment of stress fractures at the base of the second and third metatarsal bones in young ballet dancers. We considered 150 trainee ballet dancers from the Ballet Schools of "Teatro Alla Scala" of Milan from 2005 to 2007. Nineteen of them presented with stress fractures of the base of the metatarsal bones. We treated 18 dancers with external shockwave therapy (ESWT) and one with pulsed electromagnetic fields (EMF) and low-intensity ultrasound (US); all patients were recommended rest. In all cases good results were obtained. The best approach to metatarsal stress fractures is to diagnose them early through clinical examination and then through X-ray and MRI. ESWT gave good results, with a relatively short time of rest from the patients’ activities and a return to dancing without pain. PMID:19415273

A numerical study on stress distribution across the ankle joint: Effects of material distribution of bone, muscle force and ligaments.

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Mondal, Subrata; Ghosh, Rajesh

2017-09-01

The goal of this study is to develop a realistic three dimensional FE model of intact ankle joint. Three dimensional FE model of the intact ankle joint was developed using computed tomography data sets. The effect of muscle force, ligaments and proper material property distribution of bone on stress distribution across the intact ankle joint was studied separately. Present study indicates bone material property, ligaments and muscle force have influence on stress distribution across the ankle joint. Proper bone material, ligaments and muscle must be considered in the computational model for pre-clinical analysis of ankle prosthesis.

Participation in ball sports may represent a prehabilitation strategy to prevent future stress fractures and promote bone health in young athletes.

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Tenforde, Adam Sebastian; Sainani, Kristin Lynn; Carter Sayres, Lauren; Milgrom, Charles; Fredericson, Michael

2015-02-01

Sports participation has many benefits for the young athlete, including improved bone health. However, a subset of athletes may attain suboptimal bone health and be at increased risk for stress fractures. This risk is greater for female than for male athletes. In healthy children, high-impact physical activity has been shown to improve bone health during growth and development. We offer our perspective on the importance of promoting high-impact, multidirectional loading activities, including ball sports, as a method of enhancing bone quality and fracture prevention based on collective research. Ball sports have been associated with greater bone mineral density and enhanced bone geometric properties compared with participation in repetitive, low-impact sports such as distance running or nonimpact sports such as swimming. Runners and infantry who participated in ball sports during childhood were at decreased risk of future stress fractures. Gender-specific differences, including the coexistence of female athlete triad, may negate the benefits of previous ball sports on fracture prevention. Ball sports involve multidirectional loading with high ground reaction forces that may result in stiffer and more fracture-resistant bones. Encouraging young athletes to participate in ball sports may optimize bone health in the setting of adequate nutrition and in female athletes, eumenorrhea. Future research to determine timing, frequency, and type of loading activity could result in a primary prevention program for stress fracture injuries and improved life-long bone health. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Bone scanning in the evaluation of exercise-related stress injuries

International Nuclear Information System (INIS)

Wilcox, J.R. Jr.; Moniot, A.L.; Green, J.P.

1977-01-01

Bone scintigraphy was used to evaluate 34 patients with the physical findings and history of stress fracture of the lower extremity. Of the 34, 21 had abnormal studies, 11 involving the femoral neck, 9 the tibia, and 1 the femur. All of these had abnormal scintiscans prior to or at the time of the appearance of radiographic changes. Of the 9 with abnormal tibial studies, radiographic changes never evolved in 3. No false negatives were found among the 13 with normal scintiscans

An Evaluation of the Marginal Sharpness of the Porcelain Labial Margin Metal Ceramic Restoration

Science.gov (United States)

1991-05-01

these subgingival margins are open, significant bone resorption can result (Bjorn et al., 1969). Larato (1969a) examined 546 cast gold crowns and found...platinum foil was welded to the casting at three locations approximately 1.5 to 2 mm apart using an orthodontic spotwelder (Rocky Mountain Associates...individual stone dies with an autopolymerizing unfilled resin (Concise Orthodontic Bonding System, Dental Products/3M, St. Paul, MN). This Bis-GMA resin

Finite Element Analysis of Stress Distribution in Three Commonly Used Implant Systems in D2 and D4 Bone Densities

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C Radha

2016-01-01

Materials and Methods : Pro-engineer 3-0 software was used to create the geometric models of the three implant systems (Nobel biocare, Biohorizon, Adin and two bone densities D2 and D4. Six 3D models were created to simulate each one of the three implant systems supporting a metal ceramic crown placed in two different densities of bone D2 and D4. The Poisson′s ratio(΅ and Youngs modulus(E of elasticity were assigned to different materials used for the models. Vertical and oblique loads of 450N each were applied on all six models. Von Mises stress analysis was done with ANSYS software. Results : Von Mises stresses were more within D4 type bone than D2 type, for all the three systems of implants and less stresses were seen in Biohorizon implant followed by Nobel Biocare and Adin implant particularly in D4 bone. Conclusion: The study concluded that the selection of a particular implant system should be based on the scientific research rather than on popularity.

Ferritin associates with marginal band microtubules

International Nuclear Information System (INIS)

Infante, Anthony A.; Infante, Dzintra; Chan, M.-C.; How, P.-C.; Kutschera, Waltraud; Linhartova, Irena; Muellner, Ernst W.; Wiche, Gerhard; Propst, Friedrich

2007-01-01

We characterized chicken erythrocyte and human platelet ferritin by biochemical studies and immunofluorescence. Erythrocyte ferritin was found to be a homopolymer of H-ferritin subunits, resistant to proteinase K digestion, heat stable, and contained iron. In mature chicken erythrocytes and human platelets, ferritin was localized at the marginal band, a ring-shaped peripheral microtubule bundle, and displayed properties of bona fide microtubule-associated proteins such as tau. Red blood cell ferritin association with the marginal band was confirmed by temperature-induced disassembly-reassembly of microtubules. During erythrocyte differentiation, ferritin co-localized with coalescing microtubules during marginal band formation. In addition, ferritin was found in the nuclei of mature erythrocytes, but was not detectable in those of bone marrow erythrocyte precursors. These results suggest that ferritin has a function in marginal band formation and possibly in protection of the marginal band from damaging effects of reactive oxygen species by sequestering iron in the mature erythrocyte. Moreover, our data suggest that ferritin and syncolin, a previously identified erythrocyte microtubule-associated protein, are identical. Nuclear ferritin might contribute to transcriptional silencing or, alternatively, constitute a ferritin reservoir

Influence of Crack Morphology on Leak Before Break Margins

International Nuclear Information System (INIS)

Weilin Zang

2007-11-01

The purpose of the project is to evaluate the deterministic LBB-margins for different pipe systems in a Swedish PWR-plant and using different crack morphology parameters. Results: - The influence of crack morphology on Leak Before Break (LBB) margins is studied. The subject of the report is a number of LBB-submittals to SKI where deterministic LBB-margins are reported. These submittals typically uses a surface roughness of 0.0762 mm (300 microinch) and number of turns equal to zero and an in-house code for the leak rate evaluations. The present report has shown that these conditions give the largest LBB-margins both in terms of the quotient between the critical crack length and the leakage crack size and for the leak rate margin. - Crack morphology parameters have a strong influence on the leak rate evaluations. Using the SQUIRT code and more recent recommendations for crack morphology parameters, it is shown that in many cases the evaluated margins, using 1 gpm as the reference leak rate detection limit, are below the safety factor of 2 on crack size and 10 on leak rate, which is generally required for LBB approval. - The effect of including weld residual stresses on the LBB margins is also investigated. It is shown that for the two examples studied, weld residual stresses were important for the small diameter thin wall pipe whereas it was negligible for the large diameter thick wall pipe which had a self-balanced weld residual stress distribution

[Mechanical behavior of the subchondral bone in the experimentally induced osteoarthritis].

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Miyanaga, Y

1979-06-01

In order to evaluate the role of the subchondral bone (cancellous bone) in the development and progression of the joint degeneration, osteoarthritis of the knee joint was produced experimentally in the rabbits and viscoelasticity and strength of the subchondral bone from the femoral medial condyle have been investigated along with the pathological, histological study of the joint. The viscoelastic spectrometer and the Instron type testing machine were used. As the first change after operation, osteophyte formation around the joint margin has been observed before the initiation of the degeneration of articular cartilage and there is a possibility that mechanical properties of subchondral bone such as high deformability and low elasticity to the mechanism of osteophyte formation. Subchondral bone softening with marked increase of ultimate strain and phase lag, marked decrease of compressive elastic modulus and ultimate stress precedes or occurs concurrently with the degeneration of the articular cartilage. These facts indicate the relationship between the mechanical properties of the subchondral bone and joint degeneration. Once the joint degeneration starts, degeneration continues progressively while the subchondral bone tends to become brittle. These changes may be considered as a kind of functional adaptation to the damage or denudation of articular cartilage. It is postulated that some architectural changes of the subchondral bone may provide alterations of the mechanical properties. Biomechanical roles of the subchondral bone is suggested as one of the factors in the joint degeneration.

Finite element analysis of the stress distributions in peri-implant bone in modified and standard-threaded dental implants

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Serkan Dundar

2016-01-01

Full Text Available The aim of this study was to examine the stress distributions with three different loads in two different geometric and threaded types of dental implants by finite element analysis. For this purpose, two different implant models, Nobel Replace and Nobel Active (Nobel Biocare, Zurich, Switzerland, which are currently used in clinical cases, were constructed by using ANSYS Workbench 12.1. The stress distributions on components of the implant system under three different static loadings were analysed for the two models. The maximum stress values that occurred in all components were observed in FIII (300 N. The maximum stress values occurred in FIII (300 N when the Nobel Replace implant is used, whereas the lowest ones, in the case of FI (150 N loading in the Nobel Active implant. In all models, the maximum tensions were observed to be in the neck region of the implants. Increasing the connection between the implant and the bone surface may allow more uniform distribution of the forces of the dental implant and may protect the bone around the implant. Thus, the implant could remain in the mouth for longer periods. Variable-thread tapered implants can increase the implant and bone contact.

Comparisons of maximum deformation and failure forces at the implant–abutment interface of titanium implants between titanium-alloy and zirconia abutments with two levels of marginal bone loss

Science.gov (United States)

2013-01-01

Background Zirconia materials are known for their optimal aesthetics, but they are brittle, and concerns remain about whether their mechanical properties are sufficient for withstanding the forces exerted in the oral cavity. Therefore, this study compared the maximum deformation and failure forces of titanium implants between titanium-alloy and zirconia abutments under oblique compressive forces in the presence of two levels of marginal bone loss. Methods Twenty implants were divided into Groups A and B, with simulated bone losses of 3.0 and 1.5 mm, respectively. Groups A and B were also each divided into two subgroups with five implants each: (1) titanium implants connected to titanium-alloy abutments and (2) titanium implants connected to zirconia abutments. The maximum deformation and failure forces of each sample was determined using a universal testing machine. The data were analyzed using the nonparametric Mann–Whitney test. Results The mean maximum deformation and failure forces obtained the subgroups were as follows: A1 (simulated bone loss of 3.0 mm, titanium-alloy abutment) = 540.6 N and 656.9 N, respectively; A2 (simulated bone loss of 3.0 mm, zirconia abutment) = 531.8 N and 852.7 N; B1 (simulated bone loss of 1.5 mm, titanium-alloy abutment) = 1070.9 N and 1260.2 N; and B2 (simulated bone loss of 1.5 mm, zirconia abutment) = 907.3 N and 1182.8 N. The maximum deformation force differed significantly between Groups B1 and B2 but not between Groups A1 and A2. The failure force did not differ between Groups A1 and A2 or between Groups B1 and B2. The maximum deformation and failure forces differed significantly between Groups A1 and B1 and between Groups A2 and B2. Conclusions Based on this experimental study, the maximum deformation and failure forces are lower for implants with a marginal bone loss of 3.0 mm than of 1.5 mm. Zirconia abutments can withstand physiological occlusal forces applied in the anterior region. PMID

Effect of different periods of chronic heat stress with or without vitamin C supplementation on bone and selected serum parameters of broiler chickens.

Science.gov (United States)

Mosleh, Najmeh; Shomali, Tahoora; Nematollahi, Fahimeh; Ghahramani, Zahra; Ahrari Khafi, Mohammad Saeid; Namazi, Fatemeh

2018-04-01

This study evaluates the effect of different periods of chronic heat stress (CHS) on selected bone and serum parameters of broiler chickens with or without vitamin C administration. Ninety 23-day-old chickens were randomly allocated into seven groups: (1) control, (2) short-term CHS (5 days), (3) short-term CHS + vitamin C (12 g/100 l drinking water of a 50% product), (4) medium-term CHS (10 days), (5) medium-term CHS + vitamin C, (6) long-term CHS (20 days) and (7) long-term CHS + vitamin C. In heat-stressed groups the temperature was increased to 39 ± 1°C for 8 h/day. At the end of the experiment, blood samples were collected and shank, keel and tibia bones were removed. CHS was not associated with a drastic change in serum Ca and corticosterone, or bone characteristics (both cortical and trabecular bones in radiographical and histological evaluation), or birds' performance. Oxidative stress was present especially with short-term CHS. CHS, especially for short or medium periods, showed a tendency to increase serum vitamin C and administration of this vitamin did not make a significant change in its serum levels although it ameliorated oxidative stress. In conclusion, it seems that CHS is not associated with an appreciable change in broiler performance, bone characteristics, or selected serum parameters; and simultaneous vitamin C administration at the dosage of 12 g/100 l in drinking water has no beneficial effect apart from reducing oxidative stress especially in short-term chronically heat-stressed birds.

Chronological Age as Factor Influencing the Dental Implant Osseointegration in the Jaw Bone

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Jan Papež

2018-04-01

Full Text Available The objectives of this study were to evaluate osseointegration of dental implant in the jaw bone in the young and elderly population and comparing the results to assess indicators and risk factors as age for the success or failure of dental implants. A retrospective study of 107 implants (Impladent, LASAK, Czech Republic was prepared. The patients at implants surgery were divided in three groups. The patients were followed-up for a 7-year period. We evaluated osseointegration from long term point of view as a change of marginal bone levels close to dental implant. Marginal bone levels were recorded and analysed with regard to different patient- and implant-related factors. An influence of chronological age on change of marginal bone levels during 6-year retrospective study vas evaluated. The study examined 47 patient charts and 107 implants from the Second Faculty of Medicine, Charles University and University Hospital Motol. We proved that young healthy patients with long bridges or Branemarks have the same progression of marginal bone levels changes. The chronological age hasn’t therefore direct influence on the osseointegration from long term point of view. But we found that the length of dental suprastrucure-prosthetic construction negatively influences marginal bone changes, though these results weren’t statistically significant. More extensive dental implant suprastrucure undergoes smaller osseointegration. On the other hand the length of dental suprastrucure (prosthetic construction negatively influences dental osseointegration in both groups of patient.

Stress analysis of implant-bone fixation at different fracture angle

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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.

Interstitial ultrasound ablation of tumors within or adjacent to bone: Contributions of preferential heating at the bone surface

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Scott, Serena J.; Prakash, Punit; Salgaonkar, Vasant; Jones, Peter D.; Cam, Richard N.; Han, Misung; Rieke, Viola; Burdette, E. Clif; Diederich, Chris J.

2013-02-01

Preferential heating of bone due to high ultrasound attenuation may enhance thermal ablation performed with cathetercooled interstitial ultrasound applicators in or near bone. At the same time, thermally and acoustically insulating cortical bone may protect sensitive structures nearby. 3D acoustic and biothermal transient finite element models were developed to simulate temperature and thermal dose distributions during catheter-cooled interstitial ultrasound ablation near bone. Experiments in ex vivo tissues and tissue-mimicking phantoms were performed to validate the models and to quantify the temperature profiles and ablated volumes for various distances between the interstitial applicator and the bone surface. 3D patient-specific models selected to bracket the range of clinical usage were developed to investigate what types of tumors could be treated, applicator configurations, insertion paths, safety margins, and other parameters. Experiments show that preferential heating at the bone surface decreases treatment times compared to when bone is absent and that all tissue between an applicator and bone can be ablated when they are up to 2 cm apart. Simulations indicate that a 5-7 mm safety margin of normal bone is needed to protect (thermal dose tumors 1.0-3.8 cm (L) and 1.3-3.0 cm (D) near or within bone were ablated (thermal dose > 240 CEM43°C) within 10 min without damaging the nearby spinal cord, lungs, esophagus, trachea, or major vasculature. Preferential absorption of ultrasound by bone may provide improved localization, faster treatment times, and larger treatment zones in tumors in and near bone compared to other heating modalities.

A Patient Specific Biomechanical Analysis of Custom Root Analogue Implant Designs on Alveolar Bone Stress: A Finite Element Study

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David Anssari Moin

2016-01-01

Full Text Available Objectives. The aim of this study was to analyse by means of FEA the influence of 5 custom RAI designs on stress distribution of peri-implant bone and to evaluate the impact on microdisplacement for a specific patient case. Materials and Methods. A 3D surface model of a RAI for the upper right canine was constructed from the cone beam computed tomography data of one patient. Subsequently, five (targeted press-fit design modification FE models with five congruent bone models were designed: “Standard,” “Prism,” “Fins,” “Plug,” and “Bulbs,” respectively. Preprocessor software was applied to mesh the models. Two loads were applied: an oblique force (300 N and a vertical force (150 N. Analysis was performed to evaluate stress distributions and deformed contact separation at the peri-implant region. Results. The lowest von Mises stress levels were numerically observed for the Plug design. The lowest levels of contact separation were measured in the Fins model followed by the Bulbs design. Conclusions. Within the limitations of the applied methodology, adding targeted press-fit geometry to the RAI standard design will have a positive effect on stress distribution, lower concentration of bone stress, and will provide a better primary stability for this patient specific case.

The role of the margins in ice stream dynamics

Science.gov (United States)

Echelmeyer, Keith; Harrison, William

1993-07-01

At first glance, it would appear that the bed of the active ice stream plays a much more important role in the overall force balance than do the margins, especially because the ratio of the half-width to depth for a typical ice stream is large (15:1 to 50:1). On the other hand, recent observations indicate that at least part of the ice stream is underlain by a layer of very weak till (shear strength about 2 kPa), and this weak basal layer would then imply that some or all of the resistive drag is transferred to the margins. In order to address this question, a detailed velocity profile near Upstream B Camp, which extends from the center of the ice stream, across the chaotic shear margin, and onto the Unicorn, which is part of the slow-moving ice sheet was measured. Comparison of this observed velocity profile with finite-element models of flow shows several interesting features. First, the shear stress at the margin is on the order of 130 kPa, while the mean value along the bed is about 15 kPa. Integration of these stresses along the boundaries indicates that the margins provide 40 to 50 percent, and the bed, 60 to 40 percent of the total resistive drag needed to balance the gravitational driving stress in this region. (The range of values represents calculations for different values of surface slope.) Second, the mean basal stress predicted by the models shows that the entire bed cannot be blanketed by the weak till observed beneath upstream B - instead there must be a distribution of weak till and 'sticky spots' (e.g., 85 percent till and 15 percent sticky spots of resistive stress equal to 100 kPa). If more of the bed were composed of weak till, then the modeled velocity would not match that observed. Third, the ice must exhibit an increasing enhancement factor as the margins are approached (E equals 10 in the chaotic zone), in keeping with laboratory measurements on ice under prolonged shear strain. Also, there is either a narrow zone of somewhat stiffer ice (E

Biomechanical Influence of Implant Neck Designs on Stress Distribution over Adjacent Bone: A Three-Dimensional Non-Linear Finite Element Analysis

Science.gov (United States)

Ikman Ishak, Muhammad; Shafi, Aisyah Ahmad; Mohamad, Su Natasha; Jizat, Noorlindawaty Md

2018-03-01

The design of dental implant body has a major influence on the stress dissipation over adjacent bone as numbers of implant failure cases reported in past clinical studies. Besides, the inappropriate implant features may cause excessive high or low stresses which could possibly contribute to pathologic bone resorption or atrophy. The aim of this study is to evaluate the effect of different configurations of implant neck on stress dispersion within the adjacent bone via three-dimensional (3-D) finite element analysis (FEA). A set of computed tomography (CT) images of craniofacial was used to reconstruct a 3-D model of mandible using an image-processing software. The selected region of interest was the left side covering the second premolar, first molar and second molar regions. The bone model consisted of both compact (cortical) and porous (cancellous) structures. Three dental implant sets (crown, implant body, and abutment) with different designs of implant neck – straight, tapered with 15°, and tapered with 30° were modelled using a computer-aided design (CAD) software and all models were then analysed via 3-D FEA software. Top surface of first molar crown was subjected to occlusal forces of 114.6 N, 17.2 N, and 23.4 N in the axial, lingual, and mesio-distal directions, respectively. All planes of the mandible model were rigidly constrained in all directions. The result has demonstrated that the straight implant body neck is superior in attributing to high stress generation over adjacent bone as compared to others. This may associate with lower frictional resistance produced than those of tapered designs to withstand the applied loads.

Instrumental and laboratory assessment of stressful remodelling processes in bone tissue at total hip replacement

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E.V. Karjakina

2010-06-01

Full Text Available Research objective is to estimate stressful remodelling features of bone tissue according to the densitometry data and to the level of biochemical markers of bone resorption and formation in total hip replacement (THR. Bone tissue mineral density (BTMD, condition of calcium-phosphoric metabolism and biochemical markers of bone formation (osteocalcin and bone isoenzyme of alkaline phosphatase and resorption (С-terminal bodypeptide of the I type collagen have been determined in 52 patients with coxarthrosis of ll-lll stages with marked joint dysfunction before and after THR. The control group included 24 donors. The data were considered to be reliable when the probability index was р<0,05. The reliable (р<0,05 change of BTMD was determined only in 3-6 months after the operation, whereas the change of biochemical markers of remodeling had already been done after 1,5-3 months, allowing to define the group of patients with obvious negative bone balance: strong predominance of resorption processes without compensation of the subsequent adequate osteogenesis, that subsequently could lead to significant bone tissue deficiency in the area adjacent to the endoprosthesis. Changes of indices of calcium-phosphoric metabolism were not certain during the investigation term. ln conclusion it is to state that biochemical markers of remodeling in comparison with BTMD allow to estimate objectively features of adaptive bone tissue remodeling after THR in earlier periods and to define group of patients with sharp intensification of metabolism and obvious negative bone balance

Cancer patients undertaking bone scans in a department of Nuclear Medicine have significant stress related to the examination

International Nuclear Information System (INIS)

Sioka, C.; Manetou, M.; Dimakopoulos, N.; Christidi, S.; Kouraklis, G.

2005-01-01

Bone scanning is a standard screening procedure for evaluation of metastases in cancer patient. In addition to the staging procedures, bone scan is a valuable test for deciding palliative therapeutic options in selected patients. The aim of this study was to investigate if patients with cancer who were undertaking routine bone scans had any stress related to the test. We asked 83 consecutive patients with various types of cancer if they had anxiety just prior to undergoing the test. Overall, we found that 53 (64%) patients had increased anxiety related to the examination and 30 (36%) patients did not. Among the 53 patients who were anxious about the bone scan, 32 were concerned about the results of the examination, 13 worried about the effects of the radiation, 4 were anxious for both results/radiation, and 4 patients had stress but could not specify the reason. Among the 32 patients who were concerned about the results of the examination, 15 were having their first bone scans, while 17 had already undergone the procedure before. Among the 13 patients who were mainly concerned about the risks of the radiation exposure during the test, 9 were having bone scans for the first time. Out of the 4 patients who feared both the results and radiation, 3 were having bone scans for the first time and 1 had it for several times. Finally, out of the 4 patients who had anxiety about the test but could not identify the reason, 3 were having bone scans for the first time and one had the test before but was claustrophobic. Our findings indicate that most patients (64%) with cancer who underwent a routine bone scan to check for metastatic disease had intense stress related either to the results or the side effects of the examination. However, there were more patients who were concerned about the results of the test rather than the effects of radiation. Among the patients who feared the effects of radioactivity most were having the test for the first time. A previous study in a

Radionuclide bone scanning of medullary chondrosarcoma

International Nuclear Information System (INIS)

Hudson, T.M.; Chew, F.S.; Manaster, B.J.

1982-01-01

Technetium-99m methylene diphosphonate bone scans of 18 medullary chondrosarcomas of bone were correlated with pathologic macrosections of the resected tumors. There was increased scan intake by all 18 tumors, and the uptake in 15 scans corresponded accurately to the anatomic extent of the tumors. Only three scans displayed increased uptake beyond the true tumor margins; thus, the ''extended pattern of uptake'' beyond the true tumor extent is much less common in medullary chondrosarcomas than in many other primary bone tumors. Therefore, increased uptake beyond the apparent radiographic margin of the tumor suggests possible occult tumor spread. Pathologically, there was intense reactive new bone formation and hyperemia around the periphery of all 18 tumors, and there were foci of enchondral ossification, hyperemia, or calcification within the tumor itself in nearly every tumor. Three scans displayed less uptake in the center of the tumors than around their peripheries. One of these tumors was necrotic in the center, but the other two were pathologically no different from tumors that displayed homogenous uptake on the scan

Radionuclide bone scanning of medullary chondrosarcoma

International Nuclear Information System (INIS)

Hudson, T.M.; Chew, F.S.; Manaster, B.J.

1982-01-01

/sup 99m/Tc methylene diphosphonate bone scans of 18 medullary chondrosarcomas of bone were correlated with pathologic macrosections of the resected tumors. There was increased scan uptake by all 18 tumors, and the uptake in 15 scans corresponded accurately to the anatomic extent of the tumors. Only three scans displayed increased uptake beyond the true tumor margins; thus, the extended pattern of uptake beyond the true tumor extent is much less common in medullary chondrosarcomas than in many other primary bone tumors. Therefore, increased uptake beyond the apparent radiographic margin of the tumor suggests possible occult tumor spread. Pathologically, there was intense reactive new bone formation and hyperemia around the periphery of all 18 tumors, and there were foci of enchondral ossification, hyperemia, or calcification within the tumor itself in nearly every tumor. Three scans displayed less uptake in the center of the tumors than around their peripheries. One of these tumors was necrotic in the center, but the other two were pathologically no different from tumors that displayed homogeneous uptake on the scan

Transdermal drug delivery: feasibility for treatment of superficial bone stress fractures.

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Aghazadeh-Habashi, Ali; Yang, Yang; Tang, Kathy; Lőbenberg, Raimar; Doschak, Michael R

2015-12-01

Transdermal drug delivery offers the promise of effective drug therapy at selective sites of pathology whilst reducing systemic exposure to the pharmaceutical agents in off-target organs and tissues. However, that strategy is often limited to cells comprising superficial tissues of the body (rarely to deeper bony structures) and mostly indicated with small hydrophobic pharmacological agents, such as steroid hormones and anti-inflammatory gels to skin, muscle, and joints. Nonetheless, advances in transdermal liposomal formulation have rendered the ability to readily incorporate pharmacologically active hydrophilic drug molecules and small peptide biologics into transdermal dosage forms to impart the effective delivery of those bioactive agents across the skin barrier to underlying superficial tissue structures including bone, often enhanced by some form of electrical, chemical, and mechanical facilitation. In the following review, we evaluate transdermal drug delivery systems, with a particular focus on delivering therapeutic agents to treat superficial bone pain, notably stress fractures. We further introduce and discuss several small peptide hormones active in bone (such as calcitonins and parathyroid hormone) that have shown potential for transdermal delivery, often under the added augmentation of transdermal drug delivery systems that employ lipo/hydrophilicity, electric charge, and/or microprojection facilitation across the skin barrier.

Effectiveness of various isometric exercises at improving bone strength in cortical regions prone to distal tibial stress fractures.

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Florio, C S

2018-06-01

A computational model was used to compare the local bone strengthening effectiveness of various isometric exercises that may reduce the likelihood of distal tibial stress fractures. The developed model predicts local endosteal and periosteal cortical accretion and resorption based on relative local and global measures of the tibial stress state and its surface variation. Using a multisegment 3-dimensional leg model, tibia shape adaptations due to 33 combinations of hip, knee, and ankle joint angles and the direction of a single or sequential series of generated isometric resultant forces were predicted. The maximum stress at a common fracture-prone region in each optimized geometry was compared under likely stress fracture-inducing midstance jogging conditions. No direct correlations were found between stress reductions over an initially uniform circular hollow cylindrical geometry under these critical design conditions and the exercise-based sets of active muscles, joint angles, or individual muscle force and local stress magnitudes. Additionally, typically favorable increases in cross-sectional geometric measures did not guarantee stress decreases at these locations. Instead, tibial stress distributions under the exercise conditions best predicted strengthening ability. Exercises producing larger anterior distal stresses created optimized tibia shapes that better resisted the high midstance jogging bending stresses. Bent leg configurations generating anteriorly directed or inferiorly directed resultant forces created favorable adaptations. None of the studied loads produced by a straight leg was significantly advantageous. These predictions and the insight gained can provide preliminary guidance in the screening and development of targeted bone strengthening techniques for those susceptible to distal tibial stress fractures. Copyright © 2018 John Wiley & Sons, Ltd.

The Seismicity of Two Hyperextended Margins

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Redfield, Tim; Terje Osmundsen, Per

2013-04-01

A seismic belt marks the outermost edge of Scandinavia's proximal margin, inboard of and roughly parallel to the Taper Break. A similar near- to onshore seismic belt runs along its inner edge, roughly parallel to and outboard of the asymmetric, seaward-facing escarpment. The belts converge at both the northern and southern ends of Scandinavia, where crustal taper is sharp and the proximal margin is narrow. Very few seismic events have been recorded on the intervening, gently-tapering Trøndelag Platform. Norway's distribution of seismicity is systematically ordered with respect to 1) the structural templates of high-beta extension that shaped the thinning gradient during Late Jurassic or Early Cretaceous time, and 2) the topographically resurgent Cretaceous-Cenozoic "accommodation phase" family of escarpments that approximate the innermost limit of crustal thinning [See Redfield and Osmundsen (2012) for diagrams, definitions, discussion, and supporting citations.] Landwards from the belt of earthquake epicenters that mark the Taper Break the crust consistently thickens, and large fault arrays tend to sole out at mid crustal levels. Towards the sea the crystalline continental crust is hyperextended, pervasively faulted, and generally very thin. Also, faulting and serpentinization may have affected the uppermost parts of the distal margin's lithospheric mantle. Such contrasting structural conditions may generate a contrasting stiffness: for a given stress, more strain can be accommodated in the distal margin than in the less faulted proximal margin. By way of comparison, inboard of the Taper Break on the gently-tapered Trøndelag Platform, faulting was not penetrative. There, similar structural conditions prevail and proximal margin seismicity is negligible. Because stress concentration can occur where material properties undergo significant contrast, the necking zone may constitute a natural localization point for post-thinning phase earthquakes. In Scandinavia

Bone marrow-derived microglia infiltrate into the paraventricular nucleus of chronic psychological stress-loaded mice.

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Koji Ataka

Full Text Available BACKGROUND: Microglia of the central nervous system act as sentinels and rapidly react to infection or inflammation. The pathophysiological role of bone marrow-derived microglia is of particular interest because they affect neurodegenerative disorders and neuropathic pain. The hypothesis of the current study is that chronic psychological stress (chronic PS induces the infiltration of bone marrow-derived microglia into hypothalamus by means of chemokine axes in brain and bone marrow. METHODS AND FINDINGS: Here we show that bone marrow-derived microglia specifically infiltrate the paraventricular nucleus (PVN of mice that received chronic PS. Bone marrow derived-microglia are CX3CR1(lowCCR2(+CXCR4(high, as distinct from CX3CR1(highCCR2(-CXCR4(low resident microglia, and express higher levels of interleukin-1β (IL-1β but lower levels of tumor necrosis factor-α (TNF-α. Chronic PS stimulates the expression of monocyte chemotactic protein-1 (MCP-1 in PVN neurons, reduces stromal cell-derived factor-1 (SDF-1 in the bone marrow and increases the frequency of CXCR4(+ monocytes in peripheral circulation. And then a chemokine (C-C motif receptor 2 (CCR2 or a β3-adrenoceptor blockade prevents infiltration of bone marrow-derived microglia in the PVN. CONCLUSION: Chronic PS induces the infiltration of bone marrow-derived microglia into PVN, and it is conceivable that the MCP-1/CCR2 axis in PVN and the SDF-1/CXCR4 axis in bone marrow are involved in this mechanism.

Increased sclerostin associated with stress fracture of the third metacarpal bone in the Thoroughbred racehorse.

Science.gov (United States)

Hopper, N; Singer, E; Henson, F

2018-01-01

The exact aetiology and pathogenesis of microdamage-induced long bone fractures remain unknown. These fractures are likely to be the result of inadequate bone remodelling in response to damage. This study aims to identify an association of osteocyte apoptosis, the presence of osteocytic osteolysis, and any alterations in sclerostin expression with a fracture of the third metacarpal (Mc-III) bone of Thoroughbred racehorses. A total of 30 Mc-III bones were obtained; ten bones were fractured during racing, ten were from the contralateral limb, and ten were from control horses. Each Mc-III bone was divided into a fracture site, condyle, condylar groove, and sagittal ridge. Microcracks and diffuse microdamage were quantified. Apoptotic osteocytes were measured using TUNEL staining. Cathepsin K, matrix metalloproteinase-13 (MMP-13), HtrA1, and sclerostin expression were analyzed. In the fracture group, microdamage was elevated 38.9% (sd 2.6) compared with controls. There was no difference in the osteocyte number and the percentage of apoptotic cells between contralateral limb and unraced control; however, there were significantly fewer apoptotic cells in fractured samples (p fractured samples, sclerostin expression was significantly higher (p bones that have fractured during racing. In this study, this is not associated with osteocyte apoptosis or osteocytic osteolysis. The finding of increased sclerostin in the region of the fracture suggests that this protein may be playing a key role in the regulation of bone microdamage during stress adaptation. Cite this article: Bone Joint Res 2018;7:94-102. © 2018 Hopper et al.

Implant-tooth-supported fixed partial prostheses: correlations between in vivo occlusal bite forces and marginal bone reactions.

Science.gov (United States)

Akça, Kivanç; Uysal, Serdar; Cehreli, Murat Cavit

2006-06-01

To evaluate maximal occlusal bite forces (MOF) and marginal bone level (MBL) changes in patients with implant-tooth-supported fixed partial prostheses (FPP). Twenty nine partially edentulous patients consecutively who received 34 three-occlusal unit FPP with terminal implant and tooth support were subjected to quantification of MOFs using a sub-miniature load cell connected to a data acquisition system and measurement of the MBL changes around implants in digitalized periapical radiographs obtained at prostheses delivery and 24-month follow-up. MOFs for implant support (mean: 353.61 N) significantly differed from tooth support (mean: 275.48 N) (P 0.05). MBL changes at mesial and distal sites of the implants at 24 months of functional loading were 0.28 and 0.097 mm respectively. Although MOFs under functional loading might indicate an increase in load participation for supporting implant, the rigid connection between implant and natural tooth via three-occlusal unit FPP does not jeopardize the time-dependent MBL stability of the implant under functional loads.

Scintigraphic appearance of stress-induced trauma of the dorsal cortex of the third metacarpal bone in racing Thoroughbred horses: 121 cases (1978-1986)

International Nuclear Information System (INIS)

Koblik, P.D.; Hornof, W.J.; Seeherman, H.J.

1988-01-01

Review of 121 bone scintigrams obtained on racing Thoroughbred horses with clinical histories indicative of forelimb lameness revealed 3 scintigraphic patterns of stress-induced trauma to the dorsal cortex of the third metacarpal bone: (1) focal, intense uptake associated with recent stress fracture; (2) regional uptake of varying intensity or a mixed pattern of uptake associated with chronic stress fracture; and (3) diffuse, mild to moderate uptake associated with periostitis (bucked shins). The latter scintigraphic pattern appeared to be an exaggerated manifestation of the normal remodeling process evident in immature horses (2 to 3 years old). Scintigraphy was most helpful in identifying radiographically occult stress fractures, determining the extent of cortical involvement before surgical intervention in cases of chronic stress fractures, and monitoring the fracture healing process

2D FEA of evaluation of micromovements and stresses at bone-implant interface in immediately loaded tapered implants in the posterior maxilla

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Shrikar R Desai

2013-01-01

Full Text Available Aim: The aim of the study is to evaluate the influence implant length on stress distribution at bone implant interface in single immediately loaded implants when placed in D4 bone quality. Materials and Methods: A 2-dimensional finite element models were developed to simulate two types of implant designs, standard 3.75 mm-diameter tapered body implants of 6 and 10 mm lengths. The implants were placed in D4 bone quality with a cortical bone thickness of 0.5 mm. The implant design incorporated microthreads at the crestal part and the rest of the implant body incorporated Acme threads. The Acme thread form has a 29° thread angle with a thread height half of the pitch; the apex and valley are flat. A 100 N of force was applied vertically and in the oblique direction (at an angle of 45° to the long axis of the implants. The respective material properties were assigned. Micro-movements and stresses at the bone implant interface were evaluated. Results: The results of total deformation (micro-movement and Von mises stress were found to be lower for tapered long implant (10 mm than short implant (6 mm while using both vertical as well as oblique loading. Conclusion: Short implants can be successfully placed in poor bone quality under immediate loading protocol. The novel approach of the combination of microthreads at the crestal portion and acme threads for body portion of implant fixture gave promising results.

2D FEA of evaluation of micromovements and stresses at bone-implant interface in immediately loaded tapered implants in the posterior maxilla.

Science.gov (United States)

Desai, Shrikar R; Singh, Rika; Karthikeyan, I

2013-09-01

The aim of the study is to evaluate the influence implant length on stress distribution at bone implant interface in single immediately loaded implants when placed in D4 bone quality. A 2-dimensional finite element models were developed to simulate two types of implant designs, standard 3.75 mm-diameter tapered body implants of 6 and 10 mm lengths. The implants were placed in D4 bone quality with a cortical bone thickness of 0.5 mm. The implant design incorporated microthreads at the crestal part and the rest of the implant body incorporated Acme threads. The Acme thread form has a 29° thread angle with a thread height half of the pitch; the apex and valley are flat. A 100 N of force was applied vertically and in the oblique direction (at an angle of 45°) to the long axis of the implants. The respective material properties were assigned. Micro-movements and stresses at the bone implant interface were evaluated. The results of total deformation (micro-movement) and Von mises stress were found to be lower for tapered long implant (10 mm) than short implant (6 mm) while using both vertical as well as oblique loading. Short implants can be successfully placed in poor bone quality under immediate loading protocol. The novel approach of the combination of microthreads at the crestal portion and acme threads for body portion of implant fixture gave promising results.

Bone development

DEFF Research Database (Denmark)

Tatara, M.R.; Tygesen, Malin Plumhoff; Sawa-Wojtanowicz, B.

2007-01-01

The objective of this study was to determine the long-term effect of alpha-ketoglutarate (AKG) administration during early neonatal life on skeletal development and function, with emphasis on bone exposed to regular stress and used to serve for systemic changes monitoring, the rib. Shropshire ram.......01). Furthermore, AKG administration induced significantly higher bone mineral density of the cortical bone by 7.1% (P

The involvement of oxidative stress in the mechanisms of damaging cadmium action in bone tissue: A study in a rat model of moderate and relatively high human exposure

International Nuclear Information System (INIS)

Brzoska, Malgorzata M.; Rogalska, Joanna; Kupraszewicz, Elzbieta

2011-01-01

It was investigated whether cadmium (Cd) may induce oxidative stress in the bone tissue in vivo and in this way contribute to skeleton damage. Total antioxidative status (TAS), antioxidative enzymes (glutathione peroxidase, superoxide dismutase, catalase), total oxidative status (TOS), hydrogen peroxide (H 2 O 2 ), lipid peroxides (LPO), total thiol groups (TSH) and protein carbonyl groups (PC) as well as Cd in the bone tissue at the distal femoral epiphysis and femoral diaphysis of the male rats that received drinking water containing 0, 5, or 50 mg Cd/l for 6 months were measured. Cd, depending on the level of exposure and bone location, decreased the bone antioxidative capacity and enhanced its oxidative status resulting in oxidative stress and oxidative protein and/or lipid modification. The treatment with 5 and 50 mg Cd/l decreased TAS and activities of antioxidative enzymes as well as increased TOS and concentrations of H 2 O 2 and PC at the distal femur. Moreover, at the higher exposure, the concentration of LPO increased and that of TSH decreased. The Cd-induced changes in the oxidative/antioxidative balance of the femoral diaphysis, abundant in cortical bone, were less advanced than at the distal femur, where trabecular bone predominates. The results provide evidence that, even moderate, exposure to Cd induces oxidative stress and oxidative modifications in the bone tissue. Numerous correlations noted between the indices of oxidative/antioxidative bone status, and Cd accumulation in the bone tissue as well as indices of bone turnover and bone mineral status, recently reported by us (Toxicology 2007, 237, 89-103) in these rats, allow for the hypothesis that oxidative stress is involved in the mechanisms of damaging Cd action in the skeleton. The paper is the first report from an in vivo study indicating that Cd may affect bone tissue through disorders in its oxidative/antioxidative balance resulting in oxidative stress.

Influence of implantoplasty on stress distribution of exposed implants at different bone insertion levels

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João Paulo Mendes TRIBST

2017-12-01

Full Text Available Abstract This study evaluated the effect of implantoplasty on different bone insertion levels of exposed implants. A model of the Bone Level Tapered implant (Straumann Institute, Waldenburg, Switzerland was created through the Rhinoceros software (version 5.0 SR8, McNeel North America, Seattle, WA, USA. The abutment was fixed to the implant through a retention screw and a monolithic crown was modeled over a cementation line. Six models were created with increasing portions of the implant threads exposed: C1 (1 mm, C2 (2 mm, C3 (3 mm, C4 (4 mm, C5 (5 mm and C6 (6 mm. The models were made in duplicates and one of each pair was used to simulate implantoplasty, by removing the threads (I1, I2, I3, I4, I5 and I6. The final geometry was exported in STEP format to ANSYS (ANSYS 15.0, ANSYS Inc., Houston, USA and all materials were considered homogeneous, isotropic and linearly elastic. To assess distribution of stress forces, an axial load (300 N was applied on the cusp. For the periodontal insert, the strains increased in the peri-implant region according to the size of the exposed portion and independent of the threads’ presence. The difference between groups with and without implantoplasty was less than 10%. Critical values were found when the inserted portion was smaller than the exposed portion. In the exposed implants, the stress generated on the implant and retention screw was higher in the models that received implantoplasty. For the bone tissue, exposure of the implant’s thread was a damaging factor, independent of implantoplasty. Implantoplasty treatment can be safely used to control peri-implantitis if at least half of the implant is still inserted in bone.

Tibial stress reaction presenting as bilateral shin pain in a man taking denosumab for giant cell tumor of the bone.

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Lim, Sian Yik; Rastalsky, Naina; Choy, Edwin; Bolster, Marcy B

2015-12-01

Prolonged bisphosphonate use has been associated with increased risk of atypical femoral fractures. Very few cases of atypical femoral fractures have been reported with denosumab. We report a case of bilateral tibial stress reactions in a 60-year-old man with no history of osteoporosis who was on prolonged high-dose denosumab for the treatment of giant cell tumor of bone. He presented with a 3-month history of pain in his bilateral shins worsening with activity and improving with rest. Although initial radiographs were unremarkable, he was found to have changes consistent with a stress reaction on magnetic resonance imaging of the distal tibia. To our knowledge, bilateral tibial stress reactions have not been previously reported with anti-resorptive therapies (neither bisphosphonates nor denosumab). Our case is intriguing in terms of the development of stress reactions as a precursor to stress fractures which may also relate to atypical fractures. Our case suggests a possible association between denosumab use and stress reactions. Of note the indication for denosumab in our case was for the treatment of giant cell tumor of bone where the Food and Drug Administration (FDA) approved dose is substantially higher than the FDA approved dose for osteoporosis treatment. Although rare, clinicians should consider the possibility of stress fractures in patients on anti-resorptive medications such as denosumab, especially when a patient presents with new onset thigh pain, hip pain or pain over an area affecting the long bones. Evaluation by imaging of affected areas should be pursued to enable early detection and intervention, as well as prevention of morbidity and associated ongoing risk to the patient. Copyright © 2015 Elsevier Inc. All rights reserved.

Analysis of bone mineral density of human bones for strength ...

Indian Academy of Sciences (India)

Different types of bone strength are required for various ... To statically analyse various methods to find BMD and related material ... bone study for research purpose. ..... and Dagoberto Vela Arvizo 2007 A qualitative stress analysis of a cross ...

Short-term effects of teriparatide versus placebo on bone biomarkers, structure, and fracture healing in women with lower-extremity stress fractures: A pilot study.

Science.gov (United States)

Almirol, Ellen A; Chi, Lisa Y; Khurana, Bharti; Hurwitz, Shelley; Bluman, Eric M; Chiodo, Christopher; Matzkin, Elizabeth; Baima, Jennifer; LeBoff, Meryl S

2016-09-01

In this pilot, placebo-controlled study, we evaluated whether brief administration of teriparatide (TPTD) in premenopausal women with lower-extremity stress fractures would increase markers of bone formation in advance of bone resorption, improve bone structure, and hasten fracture healing according to magnetic resonance imaging (MRI). Premenopausal women with acute lower-extremity stress fractures were randomized to injection of TPTD 20-µg subcutaneous (s.c.) (n = 6) or placebo s.c. (n = 7) for 8 weeks. Biomarkers for bone formation N-terminal propeptide of type I procollagen (P1NP) and osteocalcin (OC) and resorption collagen type-1 cross-linked C-telopeptide (CTX) and collagen type 1 cross-linked N-telopeptide (NTX) were measured at baseline, 4 and 8 weeks. The area between the percent change of P1NP and CTX over study duration is defined as the anabolic window. To assess structural changes, peripheral quantitative computed topography (pQCT) was measured at baseline, 8 and 12 weeks at the unaffected tibia and distal radius. The MRI of the affected bone assessed stress fracture healing at baseline and 8 weeks. After 8 weeks of treatment, bone biomarkers P1NP and OC increased more in the TPTD- versus placebo-treated group (both p ≤ 0.01), resulting in a marked anabolic window (p ≤ 0.05). Results from pQCT demonstrated that TPTD-treated women showed a larger cortical area and thickness compared to placebo at the weight bearing tibial site, while placebo-treated women had a greater total tibia and cortical density. No changes at the radial sites were observed between groups. According to MRI, 83.3% of the TPTD- and 57.1% of the placebo-treated group had improved or healed stress fractures (p = 0.18). In this randomized, pilot study, brief administration of TPTD showed anabolic effects that TPTD may help hasten fracture healing in premenopausal women with lower-extremity stress fractures. Larger prospective studies are warranted to determine

Comparative limb bone loading in the humerus and femur of the tiger salamander: testing the 'mixed-chain' hypothesis for skeletal safety factors.

Science.gov (United States)

Kawano, Sandy M; Economy, D Ross; Kennedy, Marian S; Dean, Delphine; Blob, Richard W

2016-02-01

Locomotion imposes some of the highest loads upon the skeleton, and diverse bone designs have evolved to withstand these demands. Excessive loads can fatally injure organisms; however, bones have a margin of extra protection, called a 'safety factor' (SF), to accommodate loads that are higher than normal. The extent to which SFs might vary amongst an animal's limb bones is unclear. If the limbs are likened to a chain composed of bones as 'links', then similar SFs might be expected for all limb bones because failure of the system would be determined by the weakest link, and extra protection in other links could waste energetic resources. However, Alexander proposed that a 'mixed-chain' of SFs might be found amongst bones if: (1) their energetic costs differ, (2) some elements face variable demands, or (3) SFs are generally high. To test whether such conditions contribute to diversity in limb bone SFs, we compared the biomechanical properties and locomotor loading of the humerus and femur in the tiger salamander (Ambystoma tigrinum). Despite high SFs in salamanders and similar sizes of the humerus and femur that would suggest similar energetic costs, the humerus had lower bone stresses, higher mechanical hardness and larger SFs. SFs were greatest in the anatomical regions where yield stresses were highest in the humerus and lowest in the femur. Such intraspecific variation between and within bones may relate to their different biomechanical functions, providing insight into the emergence of novel locomotor capabilities during the invasion of land by tetrapods. © 2016. Published by The Company of Biologists Ltd.

Roentgenologic bone changes in phenylketonuria

International Nuclear Information System (INIS)

Zhang Xuezhe; Shang Yanning; Yu Weimin; Li Yongfa; Wang Yongchun; Wang Wu

2000-01-01

Objective: To report the bone X-ray changes in phenylketonuria. Methods: Thirty-seven cases of phenylketonuria were reported. Among the 37 cases, 25 were males and 12 were females. The age of this series ranged from 6 months to 9 years. X-ray examination of the hands, wrists, and knees and laboratory examination were performed in all cases. Results: The bone changes of the 37 cases were divided into 6 groups: no abnormal findings, osteoporosis, metaphyseal changes, special changes, the bone age method, and miscellaneous changes. Special changes included striations into the diaphysis (12 cases) and beak of the metaphyseal margin (21 cases). Conclusion: The mechanism causing the bone changes in phenylketonuria is not quite clear. The authors conclude that specific bone changes may be important X-ray signs suggestive of phenylketonuria

Effect of macro-design of immediately loaded implants on micromotion and stress distribution in surrounding bone using finite element analysis.

Science.gov (United States)

Fazel, Akbar; Aalai, Shima; Rismanchian, Mansour

2009-08-01

Macro-design influences the initial stability of implant and reduces micromotions. The aim of this study was to determine and compare micromotions and stress distribution in the bone around immediately loaded Maestro and Xive implants using finite element analysis. In this experimental study, accurate, clear photos were prepared of Xive and Maestro implants 12 and 13 mm long and 4 and 3.8 mm in diameter, respectively, using a Nikon Digital Camera with a resolution 5.24-megapixels with 8x Optical Zoom and 4x Digital Zoom. After accurate measurements, 3-D models of the implants inside the lower mandible (D2) were processed in Solidworks Version 2003 environment and transferred into Ansys for finite element analysis. After loading of 500 N angled at 70 degrees from the horizontal plane, the micromotion of the implant and Von Misses stresses around the bone were measured. The measured micromotion in Maestro implant was 148 mum and that in Xive was 284 mum. Stress distribution in the bone surrounding Maestro implant was better than Xive, but maximum stress surrounding Xive implants (30 MPa) was lower than Maestro (33 MPa). Based on the results obtained in the present study, maximum micromotion in maestro was less than that in Xive implants. This finding can guarantee the application of maestro implants for immediate loading.

Influence of different abutment diameter of implants on the peri-implant stress in the crestal bone: A three-dimensional finite element analysis--In vitro study.

Science.gov (United States)

Aradya, Anupama; Kumar, U Krishna; Chowdhary, Ramesh

2016-01-01

The study was designed to evaluate and compare stress distribution in transcortical section of bone with normal abutment and platform switched abutment under vertical and oblique forces in posterior mandible region. A three-dimensional finite element model was designed using ANSYS 13.0 software. The type of bone selection for the model was made of type II mandibular bone, having cortical bone thickness ranging from 0.595 mm to 1.515 mm with the crestal region measuring 1.5 mm surrounding dense trabecular bone. The implant will be modulated at 5 mm restorative platform and tapering down to 4.5 mm wide at the threads, 13 mm long with an abutment 3 mm in height. The models will be designed for two situations: (1) An implant with a 5 mm diameter abutment representing a standard platform in the posterior mandible region. (2) An implant with a 4.5 mm diameter abutment representing platform switching in the posterior mandible region. Force application was performed in both oblique and vertical conditions using 100 N as a representative masticatory force. For oblique loading, a force of 100 N was applied at 15° from the vertical axis. von Mises stress analysis was evaluated. The results of the study showed cortical stress in the conventional and platform switching model under oblique forces were 59.329 MPa and 39.952 MPa, respectively. Cortical stress in the conventional and platform switching model under vertical forces was 13.914 MPa and 12.793 MPa, respectively. Results from this study showed the platform switched abutment led to relative decrease in von Mises stress in transcortical section of bone compared to normal abutment under vertical and oblique forces in posterior mandible region.

A study of trabecular bone strength and morphometric analysis of bone microstructure from digital radiographic image

International Nuclear Information System (INIS)

Han, Seung Yun; Lee, Sun Bok; Oh, Sung Ook; Heo, Min Suk; Lee, Sam Sun; Choi, Soon Chul; Park, Tae Won; Kim, Jong Dae

2003-01-01

To evaluate the relationship between morphometric analysis of microstructure from digital radiographic image and trabecular bone strength. One hundred eleven bone specimens with 5 mm thickness were obtained from the mandibles of 5 pigs. Digital images of specimens were taken using a direct digital intraoral radiographic system. After selection of ROI(100 x 100 pixel) within the trabecular bone, mean gray level and standard deviation were obtained. Fractal dimension and the variants of morphometric analysis (trabecular area, periphery, length of skeletonized trabeculae, number of terminal point, number of branch point) were obtained from ROI. Punch sheer strength analysis was performed using Instron (model 4465, Instron Corp., USA). The loading force (loading speed 1mm/min) was applied to ROI of bone specimen by a 2 mm diameter punch. Stress-deformation curve was obtained from the punch sheer strength analysis and maximum stress, yield stress, Young's modulus were measured. Maximum stress had a negative linear correlation with mean gray level and fractal dimension significantly (p<0.05). Yield stress had a negative linear correlation with mean gray level, periphery, fractal dimension and the length of skeletonized trabeculae significantly (p<0.05). Young's modulus had a negative linear correlation with mean gray level and fractal dimension significantly (p<0.05). The strength of cancellous bone exhibited a significantly linear relationship between mean gray level, fractal dimension and morphometric analysis. The methods described above can be easily used to evaluate bone quality clinically.

Patterns of Intraosseous Recurrence After Stereotactic Body Radiation Therapy for Coxal Bone Metastasis.

Science.gov (United States)

Ito, Kei; Shimizuguchi, Takuya; Nihei, Keiji; Furuya, Tomohisa; Ogawa, Hiroaki; Tanaka, Hiroshi; Sasai, Keisuke; Karasawa, Katsuyuki

2018-01-01

To analyze the detailed pattern of intraosseous failure after stereotactic body radiation therapy (SBRT) for coxal bone metastasis. Patients treated with SBRT to coxal bone metastasis were identified by retrospective chart review. The SBRT doses were 30 Gy or 35 Gy in 5 fractions. A margin of 5 to 10 mm was added to the gross tumor volume to create the clinical target volume. We evaluated the presence or absence of intraosseous recurrence using magnetic resonance imaging. Intraosseous recurrences were assessed as "in-field" or "marginal/out-of-field." In addition, we measured the distance between the center of the recurrent tumor and the nearest edge of the initial bone metastasis in cases of marginal/out-of-field recurrence. Seventeen patients treated for 17 coxal bone metastases were included. Median age was 64 years (range, 48-79 years). Coxal lesions involved the ilium in 14 cases, pubis in 3, and ischium in 4 (3 lesions crossed over multiple regions). Patients most commonly had renal cell carcinoma (29.4%), followed by lung, hepatic cell, and colorectal cancers (23.5%, 11.8%, and 11.8%, respectively). Median follow-up after SBRT was 13 months (range, 2-44 months). Among all 17 cases, 7 cases developed 8 intraosseous recurrences, including in-field recurrence in 1 case and marginal/out-of-field recurrences in 7 cases. Median time to intraosseous recurrence was 10 months (range, 2-35 months). Among 7 cases with marginal/out-of-field recurrence, mean distance to the center of the recurrent tumor from the nearest edge of the initial bone metastasis was 34 mm (range, 15-55 mm). Most recurrences were observed out-of-field in the same coxal bone. These results suggest that defining the optimal clinical target volume in SBRT for coxal bone metastasis to obtain sufficient local tumor control is difficult. Copyright © 2017 Elsevier Inc. All rights reserved.

Long-term effects of vertical bone augmentation: a systematic review

Directory of Open Access Journals (Sweden)

Johan Anton Jochum Keestra

2016-02-01

Full Text Available ABSTRACT Extraction, periodontitis, or trauma can cause a reduction on the alveolar ridge. This could result in an insufficient alveolar bone width and height. Different techniques of vertical bone augmentation are described in literature. However, nowadays there is not enough evidence against lateral augmentation procedures to verify if these techniques are stable over a long period of time. Objective This review analyses the different techniques that are used to vertically augment the bone and evaluate if these techniques are stable over a long period of time. Material and Methods The MEDLINE-PubMed database was searched from its earliest records until December 22, 2014. The following search term was used: Alveolar Ridge augmentation [MESH]. Several journals were hand searched and some authors were contacted for additional information. The primary outcome measure that was analyzed was marginal bone level change around dental implants in the augmented sites, and the secondary outcomes were survival and success rates of dental implants placed in the augmented sites. Results The search yielded 203 abstracts. Ultimately, 90 articles were selected, describing 51 studies meeting the eligibility criteria. The marginal bone level change for the inlay technique and vertical guided bone regeneration are in agreement with the success criteria. Alveolar distraction showed more marginal bone level change after the first year of loading, and for the inlay technique very few studies were available. Conclusions Based on the available data in the current existing studies with a follow-up period of at least 4 to 5 years, one can summarize that there seems to be a trend that the onlay technique, alveolar distraction, and vertical guided bone regeneration are stable for at least 4 to 5 years.

Resveratrol induces antioxidant and heat shock protein mRNA expression in response to heat stress in black-boned chickens.

Science.gov (United States)

Liu, L L; He, J H; Xie, H B; Yang, Y S; Li, J C; Zou, Y

2014-01-01

This study investigated the effects of dietary resveratrol at 0, 200, 400, or 600 mg/kg of diet on the performance, immune organ growth index, serum parameters, and expression levels of heat shock protein (Hsp) 27, Hsp70, and Hsp90 mRNA in the bursa of Fabricius, thymus, and spleen of 42-d-old female black-boned chickens exposed to heat stress at 37 ± 2°C for 15 d. The results showed that heat stress reduced daily feed intake and BW gain; decreased serum glutathione (GSH), growth hormone, and insulin-like growth factor-1 levels; and inhibited GSH peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) activities compared with birds subjected to thermo-neutral circumstances. Chickens that were fed diets supplemented with resveratrol exhibited a linear increase in feed intake and BW gain (P stress. In contrast, serum malonaldehyde concentrations were decreased (P stress also reduced (P stress and coincided with an increase in supplemental resveratrol levels. The expression of Hsp27, Hsp70, and Hsp90 mRNA in the bursa of Fabricius and spleen were increased (P stress compared with no heat stress. Resveratrol attenuated the heat stress-induced overexpression of Hsp27, Hsp70, and Hsp90 mRNA in the bursa of Fabricius and spleen and increased the low expression of Hsp27 and Hsp90 mRNA in thymus upon heat stress. The results suggest that supplemental resveratrol improves growth performance and reduces oxidative stress in heat-stressed black-boned chickens by increasing serum growth hormone concentrations and modulating the expression of heat shock genes in organs of the immune system.

The Reliability and Validity of the Power-Load-Margin Inventory: A Rasch Analysis.

Science.gov (United States)

Hardigan, Patrick C; Cohen, Stanley R; Hagen, Kathleen P

2015-01-01

Margin is a function of the relationship of stress to strength. The greater the margin, the more likely students are able to successfully navigate academic structures. This study examined the psychometric properties of a newly created instrument designed to measure margin - the Power-Load-Margin Inventory (PLMI). The PLMI was created using eight domains: (A) Student's aptitude and ability, (B) Course structure, (C) External motivation, (D) Student health, (E) Instructor style, (F) Internal motivation, (G) Life opportunities, and (H) University support structure. A three-point response scale was used to measure the domains: (1) stress, (2) neither stress nor strength, and (3) strength. The PLMI was administered to 586 medical, dental, and pharmacy students. A Rasch rating scale model was used to examine the psychometric properties of the PLMI. The PLMI demonstrated acceptable psychometric properties for use with pharmacy, dental, and medical students. The PLMI's primary weakness was with the subscales' reliability. We attribute this to the small number of items per subscale.

Sustainable food production in marginal lands—Case of GDLA member countries

Directory of Open Access Journals (Sweden)

Shabbir A. Shahid

2013-06-01

Full Text Available Sustainable food production in the changing climate and dwindling water resources in the Global Dry Land Alliance (GDLA member countries is a real challenge, especially when considering marginal lands in dryland systems. The definition of marginal land is very vague and defined from different perspectives (pragmatism about marginal lands. Dryland itself indicates "marginality" due to water stress. In general, the abandoned agriculture land where food production is not economical, and has low inherent productivity potential is considered marginal; however, a land may be marginal for agriculture but vital for grazing. In this paper attempts have been made to give review of literature (water stress, extent of marginal saline lands, marginality. Policy matters (development of soil, water and agriculture strategies that GDLA and member countries should consider for future sustainable food production in their countries, including but not limited to, assessment of land resources for agriculture potential, defining, mapping and characterizing marginal lands, and use of innovative technologies (conservation agriculture, climate smart agriculture, integrated soil reclamation program and capacity building for food production, are discussed. The international perception (FAO, UNEP, CGIAR on marginal lands is also described. An innovative approach of using national biocapacity and ecological footprint is used to assess marginality of GDLA member countries. Ecological overshoot (using 1.5 earth planets and biocapacity debtor and creditor countries are highlighted. Challenges and best management practices for food production in marginal lands are included. Other important issues, like leasing land abroad, GDLA strategic food reserves and best management practices, innovative ideas for food production are shared. Finally recommendations are drafted for actions by GDLA, its member countries and the partners.

Construction of computational models for the stress analysis of the bones using CT imaging: application in the gleno-humeral joint

International Nuclear Information System (INIS)

Cisilino, Adrian; D'Amico, Diego; Buroni, Federico; Commisso, Pablo; Sammartino, Mario; Capiel, Carlos

2008-01-01

A methodology for the construction of computational models from CT images is presented in this work. Computational models serve for the stress analysis of the bones using the Finite Element Method. The elastic constants of the bone tissue are calculated using the density data obtained in from the CTs. The proposed methodology is demonstrated in the construction of a model for the gleno-humeral joint. (authors) [es

SIRT3/SOD2 maintains osteoblast differentiation and bone formation by regulating mitochondrial stress

OpenAIRE

Gao, Jing; Feng, Zhihui; Wang, Xueqiang; Zeng, Mengqi; Liu, Jing; Han, Shujun; Xu, Jie; Chen, Lei; Cao, Ke; Long, Jiangang; Li, Zongfang; Shen, Weili; Liu, Jiankang

2017-01-01

Recent studies have revealed robust metabolic changes during cell differentiation. Mitochondria, the organelles where many vital metabolic reactions occur, may play an important role. Here, we report the involvement of SIRT3-regulated mitochondrial stress in osteoblast differentiation and bone formation. In both the osteoblast cell line MC3T3-E1 and primary calvarial osteoblasts, robust mitochondrial biogenesis and supercomplex formation were observed during differentiation, accompanied by in...

Effect of roughened micro-threaded implant neck 
and platform switching on marginal bone loss: 
a multicenter retrospective study with 6-year follow-up.

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Di Stefano, Danilo Alessio; Giacometti, Edoardo; Greco, Gian Battista; Gastaldi, Giorgio; Gherlone, Enrico

2016-01-01

The aim of this retrospective study was to evaluate medium-term marginal peri-implant bone loss following placement of root-form implants featuring a micro-threaded rough-surfaced neck and a platform-switched implant-abutment connection. Records were identified of patients treated with such implants over a 3-year period at three Italian dental centers. Patient radiographs were digitized and subjected to computerized analysis of peri-implant bone resorption. Records of 112 patients who received 257 implants were analyzed. Although implant diameters and lengths varied, all had a 0.3-mm platform-switching width and a 2.5-mm high micro-threaded neck. All patients healed uneventfully, and no peri-implant infection, implant mobility, or radiolucency around the implant were detected at any follow-up control. At the 72-month control (average 71 ± 5 months) all implants were successful according to Albrektsson and Zarb's criteria. At implant level, average peri-implant bone resorption was 0.18 ± 0.12 mm at 6 months, 0.22 ± 0.15 mm at 12 months, 0.23 ± 0.16 mm at 24 months, 0.25 ± 0.17 mm at 36 months, 0.26 ± 0.15 mm at 48 months, and stable at subsequent controls, regardless of the implant diameter and length. At patient level, a similar trend was observed, with crestal bone loss stabilizing from 48 months onward. The surface, geometry, and platform-switching features of the implant under investigation allowed effective bone preservation on a medium-term basis.

Comparison of cone-beam computed tomography and ultrasonography on experimental bone lesion

International Nuclear Information System (INIS)

Kim, Min Sung; Park, Cheol Woo; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan

2010-01-01

This study was performed to evaluate the diagnostic ability of ultrasonography in detection of bone defects and new bone formation. Experimental bony defects were prepared on the parietal bone samples acquired from 3.5 kg New Zealand male rabbits. The defects were evaluated using ultrasonography and CBCT, and examined histologically at interval of 1, 3, 6, and 8 weeks. Ultrasonograph demonstrated hyperechogenicity in the defect area at 3 weeks and broadened hyperechogenicity from the margin of bone defect at 6 and 8 weeks due to new bone formation. On the CBCT images, new bone formation was first observed at 3 weeks around the margin of the defect, and showed gradually increase at 6 and 8 weeks. Histologic findings revealed existence of the fibroblasts and fibrous connective tissue with abundant capillary vessels only at 1 week, but osteoid tissue and newly formed trabecular bone at 3 weeks. Bone remodeling in the defect area was observed at 6 weeks and increased calcification and dense trabecular bone formation was observed at 8 weeks. Ultrasonograph proved to be a very useful diagnostic tool in detecting the bony defect and new bone formation. Additionally, ultrasonography provided valuable information regarding the blood supply around the defect area.

The transmission of stress to grafted bone inside a titanium mesh cage used in anterior column reconstruction after total spondylectomy: a finite-element analysis.

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Akamaru, Tomoyuki; Kawahara, Norio; Sakamoto, Jiro; Yoshida, Akira; Murakami, Hideki; Hato, Taizo; Awamori, Serina; Oda, Juhachi; Tomita, Katsuro

2005-12-15

A finite-element study of posterior alone or anterior/posterior combined instrumentation following total spondylectomy and replacement with a titanium mesh cage used as an anterior strut. To compare the effect of posterior instrumentation versus anterior/posterior instrumentation on transmission of the stress to grafted bone inside a titanium mesh cage following total spondylectomy. The most recent reconstruction techniques following total spondylectomy for malignant spinal tumor include a titanium mesh cage filled with autologous bone as an anterior strut. The need for additional anterior instrumentation with posterior pedicle screws and rods is controversial. Transmission of the mechanical stress to grafted bone inside a titanium mesh cage is important for fusion and remodeling. To our knowledge, there are no published reports comparing the load-sharing properties of the different reconstruction methods following total spondylectomy. A 3-dimensional finite-element model of the reconstructed spine (T10-L4) following total spondylectomy at T12 was constructed. A Harms titanium mesh cage (DePuy Spine, Raynham, MA) was positioned as an anterior replacement, and 3 types of the reconstruction methods were compared: (1) multilevel posterior instrumentation (MPI) (i.e., posterior pedicle screws and rods at T10-L2 without anterior instrumentation); (2) MPI with anterior instrumentation (MPAI) (i.e., MPAI [Kaneda SR; DePuy Spine] at T11-L1); and (3) short posterior and anterior instrumentation (SPAI) (i.e., posterior pedicle screws and rods with anterior instrumentation at T11-L1). The mechanical energy stress distribution exerted inside the titanium mesh cage was evaluated and compared by finite-element analysis for the 3 different reconstruction methods. Simulated forces were applied to give axial compression, flexion, extension, and lateral bending. In flexion mode, the energy stress distribution in MPI was higher than 3.0 x 10 MPa in 73.0% of the total volume inside

Effect of α-lipoic acid combined with nerve growth factor on bone metabolism, oxidative stress and nerve conduction function after femoral fracture surgery

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An-Jun Cao

2017-11-01

Full Text Available Objective: To discuss the effect of 毩 -lipoic acid combined with nerve growth factor on bone metabolism, oxidative stress and nerve conduction function after femoral fracture surgery. Methods: A total of 110 patients with femoral fracture who received surgical treatment in the hospital between January 2015 and January 2017 were collected and divided into the control group (n=55 and study group (n=55 by random number table. Control group received postoperative nerve growth factor therapy, and study group received postoperative 毩 -lipoic acid combined with nerve growth factor therapy. The differences in the contents of bone metabolism and oxidative stress indexes as well as the levels of nerve conduction function indexes were compared between the two groups before and after treatment. Results: Before treatment, the differences in the contents of bone metabolism and oxidative stress indexes as well as the levels of nerve conduction function indexes were not statistically significant between the two groups. After treatment, serum bone metabolism indexes BGP and PⅠNP contents of study group were higher than those of control group while CTX-Ⅰ and TRAP contents were lower than those of control group; serum oxidative stress indexes TAC, CAT and SOD contents of study group were higher than those of control group while MDA content was lower than that of control group; limb nerve conduction velocity SCV and MCV levels of study group were higher than those of control group. Conclusion: 毩 -lipoic acid combined with nerve growth factor therapy after femoral fracture surgery can effectively balance osteoblast/ osteoclast activity, reduce oxidative stress and improve limb nerve conduction velocity.

Perceptions of stress, burnout, and support systems in pediatric bone marrow transplantation nursing.

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Gallagher, Regan; Gormley, Denise K

2009-12-01

Bone marrow transplantation (BMT) is used to treat various conditions, ranging from immune disorders to many types of cancer. The critical complexity of patients and the environment in which BMT nurses work can lead to stress, burnout, and, ultimately, poor retention. This study aimed to investigate nurses' perceptions of work-related stress and burnout as well as current support systems for nurses. The study included 30 BMT staff nurses from a large pediatric medical center in the midwestern United States. Critical illness or acuity of patients was reported as the most stressful factor; long work hours was the least stressful factor. Most nurses perceived moderate to high levels of emotional exhaustion, and 33% reported moderate levels of depersonalization. Fifty percent perceived high levels of personal accomplishment, despite the critical illness or acuity of their patients, demanding patient families, rotating shifts, short staffing, and caring for dying patients. Most nurses felt that support systems were in place and that staff was accessible, but most respondents were undecided about the helpfulness of the support systems. Results suggest that support systems may significantly affect work satisfaction and feelings of accomplishment for BMT nurses.

Microgravity Stress: Bone and Connective Tissue.

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Bloomfield, Susan A; Martinez, Daniel A; Boudreaux, Ramon D; Mantri, Anita V

2016-03-15

The major alterations in bone and the dense connective tissues in humans and animals exposed to microgravity illustrate the dependency of these tissues' function on normal gravitational loading. Whether these alterations depend solely on the reduced mechanical loading of zero g or are compounded by fluid shifts, altered tissue blood flow, radiation exposure, and altered nutritional status is not yet well defined. Changes in the dense connective tissues and intervertebral disks are generally smaller in magnitude but occur more rapidly than those in mineralized bone with transitions to 0 g and during recovery once back to the loading provided by 1 g conditions. However, joint injuries are projected to occur much more often than the more catastrophic bone fracture during exploration class missions, so protecting the integrity of both tissues is important. This review focuses on the research performed over the last 20 years in humans and animals exposed to actual spaceflight, as well as on knowledge gained from pertinent ground-based models such as bed rest in humans and hindlimb unloading in rodents. Significant progress has been made in our understanding of the mechanisms for alterations in bone and connective tissues with exposure to microgravity, but intriguing questions remain to be solved, particularly with reference to biomedical risks associated with prolonged exploration missions. Copyright © 2016 John Wiley & Sons, Inc.

Meeting the expectations of your heritage culture: Links between attachment orientations, intragroup marginalization and psychological adjustment.

Science.gov (United States)

Ferenczi, Nelli; Marshall, Tara C

2016-02-01

Do insecurely attached individuals perceive greater rejection from their heritage culture? Few studies have examined the antecedents and outcomes of this perceived rejection - termed intragroup marginalization - in spite of its implications for the adjustment of cultural migrants to the mainstream culture. This study investigated whether anxious and avoidant attachment orientations among cultural migrants were associated with greater intragroup marginalization and, in turn, with lower subjective well-being and flourishing and higher acculturative stress. Anxious attachment was associated with heightened intragroup marginalization from friends and, in turn, with increased acculturative stress; anxious attachment was also associated with increased intragroup marginalization from family. Avoidant attachment was linked with increased intragroup marginalization from family and, in turn, with decreased subjective well-being.

Multifocal bone and bone marrow lesions in children - MRI findings

Energy Technology Data Exchange (ETDEWEB)

Raissaki, Maria; Demetriou, Stelios; Spanakis, Konstantinos; Skiadas, Christos; Karantanas, Apostolos H. [University of Crete, Faculty of Medicine, Department of Radiology, University Hospital of Heraklion, Heraklion, Crete (Greece); Katzilakis, Nikolaos; Stiakaki, Eftichia [University of Crete, Faculty of Medicine, Department of Pediatric Hematology-Oncology, University Hospital of Heraklion, Heraklion, Crete (Greece); Velivassakis, Emmanouil G. [University Hospital of Heraklion, Orthopedic Clinic, Heraklion, Crete (Greece)

2017-03-15

Polyostotic bone and bone marrow lesions in children may be due to various disorders. Radiographically, lytic lesions may become apparent after loss of more than 50% of the bone mineral content. Scintigraphy requires osteoblastic activity and is not specific. MRI may significantly contribute to the correct diagnosis and management. Accurate interpretation of MRI examinations requires understanding of the normal conversion pattern of bone marrow in childhood and of the appearances of red marrow rests and hyperplasia. Differential diagnosis is wide: Malignancies include metastases, multifocal primary sarcomas and hematological diseases. Benign entities include benign tumors and tumor-like lesions, histiocytosis, infectious and inflammatory diseases, multiple stress fractures/reactions and bone infarcts/ischemia. (orig.)

Marginal Zone Lymphoma Complicated by Protein Losing Enteropathy

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Nadine Stanek

2016-01-01

Full Text Available Protein losing enteropathy (PLE refers to excessive intestinal protein loss, resulting in hypoalbuminemia. Underlying pathologies include conditions leading to either reduced intestinal barrier or lymphatic congestion. We describe the case of a patient with long-lasting diffuse abdominal problems and PLE. Repetitive endoscopies were normal with only minimal lymphangiectasia in biopsies. Further evaluations revealed an indolent marginal zone lymphoma with minor bone marrow infiltration. Monotherapy with rituximab decreased bone marrow infiltration of the lymphoma but did not relieve PLE. Additional treatments with steroids, octreotide, a diet devoid of long-chain fatty-acids, and parenteral nutrition did not prevent further clinical deterioration with marked weight loss (23 kg, further reduction in albumin concentrations (nadir 8 g/L, and a pronounced drop in performance status. Finally, immunochemotherapy with rituximab and bendamustine resulted in hematological remission and remarkable clinical improvement. 18 months after therapy the patient remains free of gastrointestinal complaints and has regained his body weight with normal albumin levels. We demonstrate a case of PLE secondary to indolent marginal zone lymphoma. No intestinal pathologies were detected, contrasting a severe and almost lethal clinical course. Immunochemotherapy relieved lymphoma and PLE, suggesting that a high suspicion of lymphoma is warranted in otherwise unexplained cases of PLE.

Mechanical and morphological properties of trabecular bone samples obtained from third metacarpal bones of cadavers of horses with a bone fragility syndrome and horses unaffected by that syndrome.

Science.gov (United States)

Symons, Jennifer E; Entwistle, Rachel C; Arens, Amanda M; Garcia, Tanya C; Christiansen, Blaine A; Fyhrie, David P; Stover, Susan M

2012-11-01

To determine morphological and mechanical properties of trabecular bone of horses with a bone fragility syndrome (BFS; including silicate-associated osteoporosis). Cylindrical trabecular bone samples from the distal aspects of cadaveric third metacarpal bones of 39 horses (19 horses with a BFS [BFS bone samples] and 20 horses without a BFS [control bone samples]). Bone samples were imaged via micro-CT for determination of bone volume fraction; apparent and mean mineralized bone densities; and trabecular number, thickness, and separation. Bone samples were compressed to failure for determination of apparent elastic modulus and stresses, strains, and strain energy densities for yield, ultimate, and failure loads. Effects of BFS and age of horses on variables were determined. BFS bone samples had 25% lower bone volume fraction, 28% lower apparent density, 18% lower trabecular number and thickness, and 16% greater trabecular separation versus control bone samples. The BFS bone samples had 22% lower apparent modulus and 32% to 33% lower stresses, 10% to 18% lower strains, and 41 % to 52% lower strain energy densities at yield, ultimate, and failure loads, compared with control bone samples. Differences between groups of bone samples were not detected for mean mineral density and trabecular anisotropy. Results suggested that horses with a BFS had osteopenia and compromised trabecular bone function, consistent with bone deformation and pathological fractures that develop in affected horses. Effects of this BFS may be systemic, and bones other than those that are clinically affected had changes in morphological and mechanical properties.

Marginal Assessment of Crowns by the Aid of Parallel Radiography

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Farnaz Fattahi

2015-03-01

Full Text Available Introduction: Marginal adaptation is the most critical item in long-term prognosis of single crowns. This study aimed to assess the marginal quality as well asthe discrepancies in marginal integrity of some PFM single crowns of posterior teeth by employing parallel radiography in Shiraz Dental School, Shiraz, Iran. Methods: In this descriptive study, parallel radiographies were taken from 200 fabricated PFM single crowns of posterior teeth after cementation and before discharging the patient. To calculate the magnification of the images, a metallic sphere with the thickness of 4 mm was placed in the direction of the crown margin on the occlusal surface. Thereafter, the horizontal and vertical space between the crown margins, the margin of preparations and also the vertical space between the crown margin and the bone crest were measured by using digital radiological software. Results: Analysis of data by descriptive statistics revealed that 75.5% and 60% of the cases had more than the acceptable space (50µm in the vertical (130±20µm and horizontal (90±15µm dimensions, respectively. Moreover, 85% of patients were found to have either horizontal or vertical gap. In 77% of cases, the margins of crowns invaded the biologic width in the mesial and 70% in distal surfaces. Conclusion: Parallel radiography can be expedient in the stage of framework try-in to yield some important information that cannot be obtained by routine clinical evaluations and may improve the treatment prognosis

Complexity in modeling of residual stresses and strains during polymerization of bone cement: effects of conversion, constraint, heat transfer, and viscoelastic property changes.

Science.gov (United States)

Gilbert, Jeremy L

2006-12-15

Aseptic loosening of cemented joint prostheses remains a significant concern in orthopedic biomaterials. One possible contributor to cement loosening is the development of porosity, residual stresses, and local fracture of the cement that may arise from the in-situ polymerization of the cement. In-situ polymerization of acrylic bone cement is a complex set of interacting processes that involve polymerization reactions, heat generation and transfer, full or partial mechanical constraint, evolution of conversion- and temperature-dependent viscoelastic material properties, and thermal and conversion-driven changes in the density of the cement. Interactions between heat transfer and polymerization can lead to polymerization fronts moving through the material. Density changes during polymerization can, in the presence of mechanical constraint, lead to the development of locally high residual strain energy and residual stresses. This study models the interactions during bone cement polymerization and determines how residual stresses develop in cement and incorporates temperature and conversion-dependent viscoelastic behavior. The results show that the presence of polymerization fronts in bone cement result in locally high residual strain energies. A novel heredity integral approach is presented to track residual stresses incorporating conversion and temperature dependent material property changes. Finally, the relative contribution of thermal- and conversion-dependent strains to residual stresses is evaluated and it is found that the conversion-based strains are the major contributor to the overall behavior. This framework provides the basis for understanding the complex development of residual stresses and can be used as the basis for developing more complex models of cement behavior.

Effects of different loading patterns on the trabecular bone morphology of the proximal femur using adaptive bone remodeling.

Science.gov (United States)

Banijamali, S Mohammad Ali; Oftadeh, Ramin; Nazarian, Ara; Goebel, Ruben; Vaziri, Ashkan; Nayeb-Hashemi, Hamid

2015-01-01

In this study, the changes in the bone density of human femur model as a result of different loadings were investigated. The model initially consisted of a solid shell representing cortical bone encompassing a cubical network of interconnected rods representing trabecular bone. A computationally efficient program was developed that iteratively changed the structure of trabecular bone by keeping the local stress in the structure within a defined stress range. The stress was controlled by either enhancing existing beam elements or removing beams from the initial trabecular frame structure. Analyses were performed for two cases of homogenous isotropic and transversely isotropic beams.Trabecular bone structure was obtained for three load cases: walking, stair climbing and stumbling without falling. The results indicate that trabecular bone tissue material properties do not have a significant effect on the converged structure of trabecular bone. In addition, as the magnitude of the loads increase, the internal structure becomes denser in critical zones. Loading associated with the stumbling results in the highest density;whereas walking, considered as a routine daily activity, results in the least internal density in different regions. Furthermore, bone volume fraction at the critical regions of the converged structure is in good agreement with previously measured data obtained from combinations of dual X-ray absorptiometry (DXA) and computed tomography (CT). The results indicate that the converged bone architecture consisting of rods and plates are consistent with the natural bone morphology of the femur. The proposed model shows a promising means to understand the effects of different individual loading patterns on the bone density.

Bone changes in ridge split with immediate implant placement: A systematic review

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Mohamed M. Dohiem

2015-12-01

Conclusion: Alveolar ridge splitting might be considered a predictable approach that demonstrates a high implant survival rate, adequate horizontal bone gain and minimal postoperative complications. Weak evidence showed the effect of flap design and immediate implantation on marginal bone loss and survival rate.

Insight into the pathomorphology of the distal border of the equine navicular bone

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Martyna Frątczak

2017-01-01

Full Text Available Pathological changes of the equine navicular bone are found in a variety of forms in numerous old and also relatively young horses. Therefore, investigations on this small bone are of major practical significance. The current article presents a view of the alterations observed on the distal aspect of the bone and analyzes their origin and importance. As a result of pressure subjected by the deep digital flexor tendon and adaptive remodelling of the bone tissue, distal border of the navicular bone extends and becomes sharpened. Osseous distal border fragments may be a consequence of this phenomenon. However, the origin of fragments is also associated with the development of entheseophytes on the margins, which can result from stress induced by the distal impar sesamoid ligament. The authors are not unanimous about the clinical importance of fragments, but it seems that the most dangerous are large-sized ones, especially when occurring together with other lesions. An important issue is also the alterations of the nutrient foramina located on the distal border, due to the main role of this surface in blood supply. Changes in the size and shape of pathological synovial invaginations can be a sign of circulatory disturbances and abnormal turnover of the bone tissue. Some researchers link synovial invaginations to cases of lameness, but their importance is still enigmatic. Majority of studies focus on warmblood horses, and a lower interest in coldblood horses can be seen. Nonetheless, certain data are a strong argument that the breed and morphotype can affect the frequency of adverse changes.

In vitro investigation of marginal accuracy of implant-supported screw-retained partial dentures.

Science.gov (United States)

Koke, U; Wolf, A; Lenz, P; Gilde, H

2004-05-01

Mismatch occurring during the fabrication of implant-supported dentures may induce stress to the peri-implant bone. The purpose of this study was to investigate the influence of two different alloys and the fabrication method on the marginal accuracy of cast partial dentures. Two laboratory implants were bonded into an aluminium block so that the distance between their longitudinal axes was 21 mm. Frameworks designed for screw-retained partial dentures were cast either with pure titanium (rematitan) or with a CoCr-alloy (remanium CD). Two groups of 10 frameworks were cast in a single piece. The first group was made of pure titanium, and the second group of a CoCr-alloy (remanium CD). A third group of 10 was cast in two pieces and then laser-welded onto a soldering model. This latter group was also made of the CoCr-alloy. All the frameworks were screwed to the original model with defined torque. Using light microscopy, marginal accuracy was determined by measuring vertical gaps at eight defined points around each implant. Titanium frameworks cast in a single piece demonstrated mean vertical gaps of 40 microm (s.d. = 11 microm) compared with 72 microm (s.d. = 40 microm) for CoCr-frameworks. These differences were not significant (U-test, P = 0.124) because of a considerable variation of the values for CoCr-frameworks (minimum: 8 microm and maximum: 216 microm). However, frameworks cast in two pieces and mated with a laser showed significantly better accuracy in comparison with the other experimental groups (mean: 17 microm +/- 6; P laser welding. Manufacturing the framework pieces separately and then welding them together provides the best marginal fit.

Passive margins getting squeezed in the mantle convection vice

Science.gov (United States)

Yamato, Philippe; Husson, Laurent; Becker, Thorsten W.; Pedoja, Kevin

2014-05-01

Passive margins often exhibit uplift, exhumation and tectonic inversion. We speculate that the compression in the lithosphere gradually increased during the Cenozoic. In the same time, the many mountain belts at active margins that accompany this event seem readily witness this increase. However, how that compression increase affects passive margins remains unclear. In order to address this issue, we design a 2D viscous numerical model wherein a lithospheric plate rests above a weaker mantle. It is driven by a mantle conveyor belt, alternatively excited by a lateral downwelling on one side, an upwelling on the other side, or both simultaneously. The lateral edges of the plate are either free or fixed, representing the cases of free convergence, and collision or slab anchoring, respectively. This distinction changes the upper boundary condition for mantle circulation and, as a consequence, the stress field. Our results show that between these two regimes, the flow pattern transiently evolves from a free-slip convection mode towards a no-slip boundary condition above the upper mantle. In the second case, the lithosphere is highly stressed horizontally and deforms. For an equivalent bulk driving force, compression increases drastically at passive margins provided that upwellings are active. Conversely, if downwellings alone are activated, compression occurs at short distances from the trench and extension prevails elsewhere. These results are supported by Earth-like 3D spherical models that reveal the same pattern, where active upwellings are required to excite passive margins compression. These results support the idea that compression at passive margins, is the response to the underlying mantle flow, that is increasingly resisted by the Cenozoic collisions.

Bone tumors with an associated pathologic fracture: Differentiation between benign and malignant status using radiologic findings

International Nuclear Information System (INIS)

Bae, Ji Hyun; Lee, In Sook; Song, You Seon; Kim, Jeung Il; Lee, Moon Sung; Lee, Young Hwan; Song, Jong Woon

2015-01-01

To determine whether benign and malignant bone tumors with associated pathologic fractures can be differentiated using radiologic findings. Seventy-eight patients (47 men and 31 women, age range: 1-93 years) with a bone tumor and an associated pathologic fracture from 2004 to 2013 constituted the retrospective study cohort. The tumor size, margin, and enhancement patterns; the presence of sclerotic margin, the peritumoral bone marrow, soft tissue edema, extra-osseous soft tissue mass, intratumoral cystic/hemorrhagic/necrotic regions, mineralization/sclerotic regions, periosteal reaction and its appearance; and cortical change and its appearance were evaluated on all images. Differences between the imaging characteristics of malignant and benign pathologic fractures were compared using Pearson's chi-square test and the 2-sample t-test. There were 22 benign and 56 malignant bone tumors. Some factors were found to significantly differentiate between benign and malignant tumors; specifically, ill-defined tumor margin, the presence of sclerotic tumor margin and an extra-osseous soft tissue mass, the absence of cystic/necrotic/hemorrhagic portions in a mass, the homogeneous enhancement pattern, and the presence of a displaced fracture and of underlying cortical change were suggestive of malignant pathologic fractures. Some imaging findings were helpful for differentiating between benign and malignant pathologic fractures

Bone tumors with an associated pathologic fracture: Differentiation between benign and malignant status using radiologic findings

Energy Technology Data Exchange (ETDEWEB)

Bae, Ji Hyun; Lee, In Sook; Song, You Seon [Pusan National University School of Medicine, Pusan National University Hospital, Busan (Korea, Republic of); Kim, Jeung Il [Dept. of Radiology, Yeungnam University College of Medicine, Yeungnam University Medical Center, Daegu (Korea, Republic of); Lee, Moon Sung [Dept. of Radiology, Keimyung University College of Medicine, Dongsan Medical Center, Daegu (Korea, Republic of); Lee, Young Hwan [Dept. of Radiology, Catholic University of Daegu College of Medicine, Daegu Catholic University Hospital, Daegu (Korea, Republic of); Song, Jong Woon [Dept. of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan (Korea, Republic of)

2015-10-15

To determine whether benign and malignant bone tumors with associated pathologic fractures can be differentiated using radiologic findings. Seventy-eight patients (47 men and 31 women, age range: 1-93 years) with a bone tumor and an associated pathologic fracture from 2004 to 2013 constituted the retrospective study cohort. The tumor size, margin, and enhancement patterns; the presence of sclerotic margin, the peritumoral bone marrow, soft tissue edema, extra-osseous soft tissue mass, intratumoral cystic/hemorrhagic/necrotic regions, mineralization/sclerotic regions, periosteal reaction and its appearance; and cortical change and its appearance were evaluated on all images. Differences between the imaging characteristics of malignant and benign pathologic fractures were compared using Pearson's chi-square test and the 2-sample t-test. There were 22 benign and 56 malignant bone tumors. Some factors were found to significantly differentiate between benign and malignant tumors; specifically, ill-defined tumor margin, the presence of sclerotic tumor margin and an extra-osseous soft tissue mass, the absence of cystic/necrotic/hemorrhagic portions in a mass, the homogeneous enhancement pattern, and the presence of a displaced fracture and of underlying cortical change were suggestive of malignant pathologic fractures. Some imaging findings were helpful for differentiating between benign and malignant pathologic fractures.

Multistage bone-charged distraction osteogenesis for aesthetic reconstruction of an extensive bone deficiency in the mandible.

Science.gov (United States)

Watanabe, Yorikatsu; Sasaki, Ryo; Ando, Tomohiro; Okano, Teruo; Akizuki, Tanetaka

2012-01-01

Alveolar and mandibular bone defects impair occlusion and affect the aesthetics of facial contouring, making it difficult to obtain a satisfactory outcome. Treatment with distraction osteogenesis (DO) is particularly difficult in cases in which the defective region extends to close to the inferior margin of the mandible. To overcome the limits of current DO, we developed a method as follows. In the first stage, a submucosal space necessary for bone grafting was prepared by soft tissue expansion through DO. In the second stage, an iliac corticocancellous bone was transplanted with its cancellous side in close contact with the new bone in the space formed on the labial side into this new space. In the third stage, the grafted bone was distracted. This technique requires time, but each surgery is of minimum invasiveness and does not leave a visible scar; use of this technique may expand the limited indication of current DO and dental implants.

An unusual stress fracture: Bilateral posterior longitudinal stress fracture of tibia

OpenAIRE

Malkoc, Melih; Korkmaz, Ozgur; Ormeci, Tugrul; Oltulu, Ismail; Isyar, Mehmet; Mahirogulları, Mahir

2014-01-01

INTRODUCTION Stress fractures (SF) occur when healthy bone is subjected to cyclic loading, which the normal carrying range capacity is exceeded. Usually, stress fractures occur at the metatarsal bones, calcaneus, proximal or distal tibia and tends to be unilateral. PRESENTATION OF CASE This article presents a 58-year-old male patient with bilateral posterior longitudinal tibial stress fractures. A 58 years old male suffering for persistent left calf pain and decreased walking distance for las...

p38 MAPK mediated in compressive stress-induced chondrogenesis of rat bone marrow MSCs in 3D alginate scaffolds.

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Li, Juan; Zhao, Zhihe; Yang, Jingyuan; Liu, Jun; Wang, Jun; Li, Xiaoyu; Liu, Yurong

2009-12-01

Mesenchymal stem cells (MSCs) are well known to have the capability to form bone and cartilage, and chondrogenesis derived from MSCs is reported to be affected by mechanical stimuli. This research was aimed to study the effects of cyclic compressive stress on the chondrogenic differentiation of rat bone marrow-derived MSCs (BMSCs) which were encapsulated in alginate scaffolds and cultured with or without chondrogenic medium, and to investigate the role of p38 MAPK phospho-relay cascade in this process. The results show that the gene expression of chondrocyte-specific markers of Col2alpha1, aggrecan, Sox9, Runx2, and Ihh was upregulated by dynamic compressive stress introduced at the 8th day of chondrogenic differentiation in vitro. The p38 MAPK was activated by chondrogenic cytokines in a slow and lagged way, but activated by cyclic compressive stimulation in a rapid and transient manner. And inhibition of p38 activity with SB203580 suppressed gene expression of chondrocyte-specific genes stimulated by chondrogenic medium and (or) cyclic compressive stress. These findings suggest that p38 MAPK signal acts as an essential mediator in the mechano-biochemical transduction and subsequent transcriptional regulation in the process of chondrogenesis.

Numerical simulation of fluid field and in vitro three-dimensional fabrication of tissue-engineered bones in a rotating bioreactor and in vivo implantation for repairing segmental bone defects.

Science.gov (United States)

Song, Kedong; Wang, Hai; Zhang, Bowen; Lim, Mayasari; Liu, Yingchao; Liu, Tianqing

2013-03-01

In this paper, two-dimensional flow field simulation was conducted to determine shear stresses and velocity profiles for bone tissue engineering in a rotating wall vessel bioreactor (RWVB). In addition, in vitro three-dimensional fabrication of tissue-engineered bones was carried out in optimized bioreactor conditions, and in vivo implantation using fabricated bones was performed for segmental bone defects of Zelanian rabbits. The distribution of dynamic pressure, total pressure, shear stress, and velocity within the culture chamber was calculated for different scaffold locations. According to the simulation results, the dynamic pressure, velocity, and shear stress around the surface of cell-scaffold construction periodically changed at different locations of the RWVB, which could result in periodical stress stimulation for fabricated tissue constructs. However, overall shear stresses were relatively low, and the fluid velocities were uniform in the bioreactor. Our in vitro experiments showed that the number of cells cultured in the RWVB was five times higher than those cultured in a T-flask. The tissue-engineered bones grew very well in the RWVB. This study demonstrates that stress stimulation in an RWVB can be beneficial for cell/bio-derived bone constructs fabricated in an RWVB, with an application for repairing segmental bone defects.

The radiological diagnosis of stress fracture

International Nuclear Information System (INIS)

Li Yonggang; Wang Renfa; Zhang Jingfeng; Wang Min

2005-01-01

Objective: To study the radiological features and biomechanics of stress fracture. Methods: The X-ray, CT, MRI, and ECT signs in 20 cases of stress fracture and its correlation to biomechanics were analyzed. Results: Of the 20 cases, 14 cases occurred in the tibia, 2 cases in the metatarsal bone, 1 case in the rib, 1 case in the neck of femur and ribs, 1 case in the middle-inferior part of the femur, and 1 case in the fibula. Tow early cases of stress fracture demonstrated a characteristic sign of 'gray cortex'. The spherical or abnormal generation of bony callus and periosteum proliferation that demonstrated 'double cortex' sign in 2 cases were the sign of bone remodeling and the 'button sign' was the sign of bone healing. CT scan could clearly show the pathologic changes of bone and the soft tissue edema. Bone callus showed low signal on T 1 WI and slight high signal on T 2 WI. The area of bone edema on MRI that demonstrated low signal on T 1 WI and high signal on T 2 WI was larger than that on CT. MRI showed a linear band of low signal on both T 1 WI and T 2 WI in the area of bone fracture. ECT showed a focal area of increased uptake in the abnormal areas. The areas of bone stress fracture were characteristic and accorded with the biomechanical weak area in the bone. Conclusion: Stress fracture occurs in the special parts of the bone and has characteristic imaging features. X-ray should still be used to find the fracture of bones in the first inspection. CT and MRI are very helpful in the differentiation. Although sensitive, bone scan has lower specificity than either CT or MRI. (authors)

Increased periodontal bone loss in temporarily B lymphocyte-deficient rats

DEFF Research Database (Denmark)

Klausen, B; Hougen, H P; Fiehn, N E

1989-01-01

In order to study the role of T lymphocytes and B lymphocytes in the development of marginal periodontitis, experiments were performed on specific-pathogen-free (SPF) rats with various immunologic profiles. The study comprised nude (congenitally T lymphocyte-deficient), thymus-grafted nude (T-lym......-lymphocyte deficiency did not interfere with the development of periodontal disease in this model, whereas a temporary and moderate reduction in B-lymphocyte numbers seemed to predispose for aggravation of periodontal bone loss.......In order to study the role of T lymphocytes and B lymphocytes in the development of marginal periodontitis, experiments were performed on specific-pathogen-free (SPF) rats with various immunologic profiles. The study comprised nude (congenitally T lymphocyte-deficient), thymus-grafted nude (T...... had significantly less periodontal bone support than controls. Anti-mu treated inoculated rats had significantly less periodontal bone support than nude and normal rats, whereas no difference was found between normal, nude, and thymus-grafted rats. It is concluded that permanent T...

Periapical multilocular osteoporotic bone marrow defect

International Nuclear Information System (INIS)

Jung, Yun Hoa; Cho, Bong Hae; Nah, Kyung Soo

2005-01-01

A case of osteoporotic bone marrow defect, which appeared as a well-defined multilocular radiolucency overlapping the roots of mandibular right second molar, was reported. On periapical radiograph, a daughter cyst-like radiolucency was seen at the anterior margin of the lesion making it difficult to rule out odontogenic keratocyst.

Periapical multilocular osteoporotic bone marrow defect

Energy Technology Data Exchange (ETDEWEB)

Jung, Yun Hoa; Cho, Bong Hae; Nah, Kyung Soo [Pusan National University College of Medicine, Busan (Korea, Republic of)

2005-12-15

A case of osteoporotic bone marrow defect, which appeared as a well-defined multilocular radiolucency overlapping the roots of mandibular right second molar, was reported. On periapical radiograph, a daughter cyst-like radiolucency was seen at the anterior margin of the lesion making it difficult to rule out odontogenic keratocyst.

Effects of electromagnetic radiation exposure on bone mineral density, thyroid, and oxidative stress index in electrical workers

Directory of Open Access Journals (Sweden)

Kunt H

2016-02-01

Full Text Available Halil Kunt,1,* İhsan Şentürk,2,* Yücel Gönül,3,* Mehmet Korkmaz,4 Ahmet Ahsen,5 Ömer Hazman,6 Ahmet Bal,7 Abdurrahman Genç,8 Ahmet Songur3 1Department of Science Education, Faculty of Education, Dumlupinar University, Kütahya, 2Department of Orthopedics and Traumatology, 3Department of Anatomy, Faculty of Medicine, Afyon Kocatepe University, Afyonkarahisar, 4Department of Radiology, Faculty of Medicine, Dumlupinar University, Kütahya, 5Department of Nephrology, Faculty of Medicine, 6Department of Biochemistry, Faculty of Science and Arts, 7Department of General Surgery, 8Department of Physiology, Faculty of Medicine, Afyon Kocatepe University, Afyonkarahisar, Turkey *These authors contributed equally to this work Background: In the literature, some articles report that the incidence of numerous diseases increases among the individuals who live around high-voltage electric transmission lines (HVETL or are exposed vocationally. However, it was not investigated whether HVETL affect bone metabolism, oxidative stress, and the prevalence of thyroid nodule.Methods: Dual-energy X-ray absorptiometry (DEXA bone density measurements, serum free triiodothyronine (FT3, free thyroxine (FT4, RANK, RANKL, osteoprotegerin (OPG, alkaline phosphatase (ALP, phosphor, total antioxidant status (TAS, total oxidant status (TOS, and oxidative stress index (OSI levels were analyzed to investigate this effect.Results: Bone mineral density levels of L1–L4 vertebrae and femur were observed significantly lower in the electrical workers. ALP, phosphor, RANK, RANKL, TOS, OSI, and anteroposterior diameter of the left thyroid lobe levels were significantly higher, and OPG, TAS, and FT4 levels were detected significantly lower in the study group when compared with the control group.Conclusion: Consequently, it was observed that the balance between construction and destruction in the bone metabolism of the electrical workers who were employed in HVETL replaced toward

Success of dental implants in vascularised fibular osteoseptocutaneous flaps used as onlay grafts after marginal mandibulectomy.

Science.gov (United States)

Chang, Y-M; Pan, Y-H; Shen, Y-F; Chen, J-K; ALDeek, N F; Wei, F-C

2016-12-01

We have evaluated the survival of dental implants placed in vascularised fibular flap onlay grafts placed over marginal mandibulectomies and the effects on marginal bone loss of different types of soft tissue around implants under functional loading. From 2001-2009 we studied a total of 11 patients (1 woman and10 men), three of whom had had ameloblastoma and eight who had had squamous cell carcinomas resected. A total of 38 dental implants were placed either at the time of transfer of the vascularised fibular ostoseptocutaneous flaps (nine patients with 30 implants) or secondarily (two patients with eight implants). Four patients were given palatal mucosal grafts to replace intraoral skin flaps around the dental implants (n=13), and the other seven had the skin flaps around the dental implants thinned (n=25) at the second stage of implantation of the osteointegrated teeth. All vascularised fibular osteoseptocutaneous flaps were successfully transferred, and all implants survived a mean (range) of 73 (33-113) months after occlusal functional loading. The mean (SD) marginal bone loss was 0.5 (0.3) mm on both mesial and distal sides in patients who had palatal mucosal grafts, but 1.8 (1.6) mm, and 1.7 (1.5) mm, respectively, on the mesial and distal sides in the patients who had had thinning of their skin flaps. This difference is significant (p=0.008) with less resorption of bone in the group who had palatal mucosal grafts. Palatal mucosa around the implants helps to reduce resorption of bone after functional loading of implants. Copyright © 2016 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Finite Element Analysis of Bone Stress around Micro-Implants of Different Diameters and Lengths with Application of a Single or Composite Torque Force.

Science.gov (United States)

Lu, Ying-juan; Chang, Shao-hai; Ye, Jian-tao; Ye, Yu-shan; Yu, Yan-song

2015-01-01

Stress on the bone surrounding dental micro-implants affects implant success. To compare the stress on the bone surrounding a micro-implant after application of a single force (SF) of 200 g or a composite force (CF) of 200 g and 6 N.mm torque. Finite element models were developed for micro-implant diameters of 1.2, 1.6, and 2.0 mm, and lengths of 6, 8, 10, and 12 mm and either a SF or CF was applied. The maximum equivalent stress (Max EQS) of the bone surrounding the micro-implant was determined, and the relationships among type of force, diameter, and length were evaluated. The Max EQS of the CF exceeded that of the SF (Pimplant diameter, but not to implant length. The larger CF led to greater instability of the micro-implant and the effect was most pronounced at an implant diameter of 1.2 mm. The use of implant diameters of 1.6 mm and 2.0 mm produced no significant difference in implant stability when either a CF or SF was applied. When considering the use of an implant to perform three-dimensional control on the teeth, the implant diameter chosen should be > 1.2 mm.

Stress Fractures

Science.gov (United States)

Stress fractures Overview Stress fractures are tiny cracks in a bone. They're caused by repetitive force, often from overuse — such as repeatedly jumping up and down or running long distances. Stress fractures can also arise from normal use of ...

Cancer Metastases to Bone: Concepts, Mechanisms, and Interactions with Bone Osteoblasts

Directory of Open Access Journals (Sweden)

Alison B. Shupp

2018-06-01

Full Text Available The skeleton is a unique structure capable of providing support for the body. Bone resorption and deposition are controlled in a tightly regulated balance between osteoblasts and osteoclasts with no net bone gain or loss. However, under conditions of disease, the balance between bone resorption and deposition is upset. Osteoblasts play an important role in bone homeostasis by depositing new bone osteoid into resorption pits. It is becoming increasingly evident that osteoblasts additionally play key roles in cancer cell dissemination to bone and subsequent metastasis. Our laboratory has evidence that when osteoblasts come into contact with disseminated breast cancer cells, the osteoblasts produce factors that initially reduce breast cancer cell proliferation, yet promote cancer cell survival in bone. Other laboratories have demonstrated that osteoblasts both directly and indirectly contribute to dormant cancer cell reactivation in bone. Moreover, we have demonstrated that osteoblasts undergo an inflammatory stress response in late stages of breast cancer, and produce inflammatory cytokines that are maintenance and survival factors for breast cancer cells and osteoclasts. Advances in understanding interactions between osteoblasts, osteoclasts, and bone metastatic cancer cells will aid in controlling and ultimately preventing cancer cell metastasis to bone.

[Bone Cell Biology Assessed by Microscopic Approach. A mathematical approach to understand bone remodeling].

Science.gov (United States)

Kameo, Yoshitaka; Adachi, Taiji

2015-10-01

It is well known that bone tissue can change its outer shape and internal structure by remodeling according to a changing mechanical environment. However, the mechanism of bone functional adaptation induced by the collaborative metabolic activities of bone cells in response to mechanical stimuli remains elusive. In this article, we focus on the hierarchy of bone structure and function from the microscopic cellular level to the macroscopic tissue level. We provide an overview of a mathematical approach to understand the adaptive changes in trabecular morphology under the application of mechanical stress.

Planning Target Margin Calculations for Prostate Radiotherapy Based on Intrafraction and Interfraction Motion Using Four Localization Methods

International Nuclear Information System (INIS)

Beltran, Chris; Herman, Michael G.; Davis, Brian J.

2008-01-01

Purpose: To determine planning target volume (PTV) margins for prostate radiotherapy based on the internal margin (IM) (intrafractional motion) and the setup margin (SM) (interfractional motion) for four daily localization methods: skin marks (tattoo), pelvic bony anatomy (bone), intraprostatic gold seeds using a 5-mm action threshold, and using no threshold. Methods and Materials: Forty prostate cancer patients were treated with external radiotherapy according to an online localization protocol using four intraprostatic gold seeds and electronic portal images (EPIs). Daily localization and treatment EPIs were obtained. These data allowed inter- and intrafractional analysis of prostate motion. The SM for the four daily localization methods and the IM were determined. Results: A total of 1532 fractions were analyzed. Tattoo localization requires a SM of 6.8 mm left-right (LR), 7.2 mm inferior-superior (IS), and 9.8 mm anterior-posterior (AP). Bone localization requires 3.1, 8.9, and 10.7 mm, respectively. The 5-mm threshold localization requires 4.0, 3.9, and 3.7 mm. No threshold localization requires 3.4, 3.2, and 3.2 mm. The intrafractional prostate motion requires an IM of 2.4 mm LR, 3.4 mm IS and AP. The PTV margin using the 5-mm threshold, including interobserver uncertainty, IM, and SM, is 4.8 mm LR, 5.4 mm IS, and 5.2 mm AP. Conclusions: Localization based on EPI with implanted gold seeds allows a large PTV margin reduction when compared with tattoo localization. Except for the LR direction, bony anatomy localization does not decrease the margins compared with tattoo localization. Intrafractional prostate motion is a limiting factor on margin reduction

Load transfer in bovine plexiform bone determined by synchrotron x-ray diffraction

International Nuclear Information System (INIS)

Akhtar, R.; Daymond, M.; Almer, J.; Mummery, P.; The Univ. of Manchester; Queen's Univ.

2008-01-01

High-energy synchrotron x-ray diffraction (XRD) has been used to quantify load transfer in bovine plexiform bone. By using both wide-angle and small-angle XRD, strains in the mineral as well as the collagen phase of bone were measured as a function of applied compressive stress. We suggest that a greater proportion of the load is borne by the more mineralized woven bone than the lamellar bone as the applied stress increases. With a further increase in stress, load is shed back to the lamellar regions until macroscopic failure occurs. The reported data fit well with reported mechanisms of microdamage accumulation in bovine plexiform bone

Finite Element Analysis of Bone Stress for Miniscrew Implant Proximal to Root Under Occlusal Force and Implant Loading.

Science.gov (United States)

Shan, Li-Hua; Guo, Na; Zhou, Guan-jun; Qie, Hui; Li, Chen-Xi; Lu, Lin

2015-10-01

Because of the narrow interradicular spaces and varying oral anatomies of individual patients, there is a very high risk of root proximity during the mini implants inserting. The authors hypothesized that normal occlusal loading and implant loading affected the stability of miniscrew implants placed in proximity or contact with the adjacent root. The authors implemented finite element analysis (FEA) to examine the effectiveness of root proximity and root contact. Stress distribution in the bone was assessed at different degrees of root proximity by generating 4 finite element models: the implant touches the root surface, the implant was embedded in the periodontal membrane, the implant touches the periodontal surface, and the implant touches nothing. Finite element analysis was then carried out with simulations of 2 loading conditions for each model: condition A, involving only tooth loading and condition B, involving both tooth and implant loading. Under loading condition A, the maximum stress on the bone for the implant touching the root was the distinctly higher than that for the other models. For loading condition B, peak stress areas for the implant touching the root were the area around the neck of the mini implant and the point of the mini implant touches the root. The results of this study suggest that normal occlusal loading and implant loading contribute to the instability of the mini implant when the mini implant touches the root.

Stress fractures in military training

International Nuclear Information System (INIS)

Jofre, M.J.; Sierralta, M.P.

2002-01-01

During military training, the incidence of overuse injuries like stress fractures increase. The aim of the study was to investigate the utility of bone scan in a military population with clinical suspected stress fractures or periostitis. Material and methods: A three-year retrospective analysis was made on patients who were clinically diagnosed with stress fractures at the Military Hospital Nuclear Medicine Department. Thirty-seven patients were studied (mean age 23. +/- 8 y.o; 31 males), 28 cases of which (76%) had tibial stress syndrome. Other localizations were lumbar spine, femoral, fibular, tarsal or metatarsal. Bone scintigraphy was performed injecting 1036 MBq of Tc99m-MDP i.v. Whole body images and lateral projections of lower extremities were done. Results: Bone scan in tibial syndrome was positive for 23 cases (82%), 65% of them were bilateral and 13% also had femoral injuries. X-rays were done in 10 cases and were all negative. In other localizations, the bone scans were negative, but demonstrated other degenerative lesions. All stress fractures were conservatively treated with non-steroidal anti-inflammatories and suspension of physical activity. Conclusions: Bone scan is a reliable confirmatory tool for tibial stress syndrome diagnosis. In addition, it helps to determine both the severity and extension of the injury as well as support the indication of rest in the military population

Stress fractures in military training

Energy Technology Data Exchange (ETDEWEB)

Jofre, M J; Sierralta, M P [Military Hospital Nuclear Medicine Department, Santiago (Chile)

2002-09-01

During military training, the incidence of overuse injuries like stress fractures increase. The aim of the study was to investigate the utility of bone scan in a military population with clinical suspected stress fractures or periostitis. Material and methods: A three-year retrospective analysis was made on patients who were clinically diagnosed with stress fractures at the Military Hospital Nuclear Medicine Department. Thirty-seven patients were studied (mean age 23. +/- 8 y.o; 31 males), 28 cases of which (76%) had tibial stress syndrome. Other localizations were lumbar spine, femoral, fibular, tarsal or metatarsal. Bone scintigraphy was performed injecting 1036 MBq of Tc99m-MDP i.v. Whole body images and lateral projections of lower extremities were done. Results: Bone scan in tibial syndrome was positive for 23 cases (82%), 65% of them were bilateral and 13% also had femoral injuries. X-rays were done in 10 cases and were all negative. In other localizations, the bone scans were negative, but demonstrated other degenerative lesions. All stress fractures were conservatively treated with non-steroidal anti-inflammatories and suspension of physical activity. Conclusions: Bone scan is a reliable confirmatory tool for tibial stress syndrome diagnosis. In addition, it helps to determine both the severity and extension of the injury as well as support the indication of rest in the military population.

Bone mineral density and bone scintigraphy in children and adolescents with osteomalacia

International Nuclear Information System (INIS)

El-Desouki, M.; Al-Jurayyan, N.

1997-01-01

In order to demonstrate the role of bone mineral density (BMD) measurement and bone scans in the management of patients with osteomalacia, radioisotope bone scintigraphy using technetium-99m methylene diphosphonate (MDP) and BMD measurements of the lumbar spine and femur by means of dual X-ray absorptiometry (DXA) were performed at the time of diagnosis and 6 months after therapy in 26 Saudi patients (17 females and nine males). Their mean age was 13.5 years (range, 5-16). BMD measurements were compared with those of normal Saudi subjects matched for age and sex. Bone scan showed an increase in tracer uptake throughout the skeleton (''superscan'') in all children and demonstrated multiple stress fractures in eight. The mean BMD for the lumbar spine was 0.53 g/cm 2 (Z-score, -3.1) and for the femoral neck 0.55 g/cm 2 (Z-score, -2.8). Repeated bone scan and BMD after 6 months of therapy with oral vitamin D, calcium and proper sun exposure demonstrated a significant increase (P <0.001) in BMD and healing of pseudofractures. In conclusion, as a non-invasive method with minimal radiation exposure, measurements of BMD in children with osteomalacia are to be recommended in the initial assessment of the severity of osteopenia and in the follow-up to monitor the response to therapy. Bone scintigraphy is valuable in demonstrating the site and severity of stress fractures. (orig.). With 2 figs., 1 tab

Bone mineral density and bone scintigraphy in children and adolescents with osteomalacia

Energy Technology Data Exchange (ETDEWEB)

El-Desouki, M. [College of Medicine and King Khalid University Hospital, King Saud University, Riyadh (Saudi Arabia); Al-Jurayyan, N. [College of Medicine and King Khalid University Hospital, King Saud University, Riyadh (Saudi Arabia)

1997-02-01

In order to demonstrate the role of bone mineral density (BMD) measurement and bone scans in the management of patients with osteomalacia, radioisotope bone scintigraphy using technetium-99m methylene diphosphonate (MDP) and BMD measurements of the lumbar spine and femur by means of dual X-ray absorptiometry (DXA) were performed at the time of diagnosis and 6 months after therapy in 26 Saudi patients (17 females and nine males). Their mean age was 13.5 years (range, 5-16). BMD measurements were compared with those of normal Saudi subjects matched for age and sex. Bone scan showed an increase in tracer uptake throughout the skeleton (``superscan``) in all children and demonstrated multiple stress fractures in eight. The mean BMD for the lumbar spine was 0.53 g/cm{sup 2}(Z-score, -3.1) and for the femoral neck 0.55 g/cm {sup 2}(Z-score, -2.8). Repeated bone scan and BMD after 6 months of therapy with oral vitamin D, calcium and proper sun exposure demonstrated a significant increase (P <0.001) in BMD and healing of pseudofractures. In conclusion, as a non-invasive method with minimal radiation exposure, measurements of BMD in children with osteomalacia are to be recommended in the initial assessment of the severity of osteopenia and in the follow-up to monitor the response to therapy. Bone scintigraphy is valuable in demonstrating the site and severity of stress fractures. (orig.). With 2 figs., 1 tab.

Primary bone tumours of the hand

International Nuclear Information System (INIS)

Kozlowski, K.; Azouz, E.M.; Campbell, J.; Marton, D.; Morris, L.; Padovani, J.; Sprague, P.; Beluffi, G.; Berzero, G.F.; Cherubino, P.; Adelaide Children's Hospital; Hospital for Children, Perth; Montreal Children's Hospital, Quebec; Saint Justine Hospital, Montreal, Quebec; Children's Hospital, Denver, CO; Hopital des Enfants, 13 - Marseille; Pavia Univ.; Pavia Univ.

1988-01-01

Twenty-one primary bone tumours of the hand in children from 8 paediatric hospitals are reported. Osteochondromas and enchondromas were not included. Our material consisted of 16 patients with common tumours (3 Ewing's sarcoma, 5 aneurysmal bone cyst, 6 osteoid osteoma and 2 epithelioma) and 5 patients with uncommon tumours (osteoma, simple bone cyst, haemangiopericytoma, capillary angiomatous tumour and benign ossifying fibroma or osteoblastoma). The X-ray diagnosis of the common tumours should have high concordance with histology, whereas that of uncommon tumours in much more difficult and uncertain. The characteristic features of Ewing's sarcoma are stressed as all our children with this tumour had a delayed diagnosis and a fatal outcome. Differential diagnosis with other short tubular bone lesions of the hand - specifically osteomyelitis - is discussed and the posibilities of microscopic diagnosis are stressed. (orig.)

Effect of implant position, angulation, and attachment height on peri-implant bone stress associated with mandibular two-implant overdentures: a finite element analysis.

Science.gov (United States)

Hong, Hae Ryong; Pae, Ahran; Kim, Yooseok; Paek, Janghyun; Kim, Hyeong-Seob; Kwon, Kung-Rock

2012-01-01

The aim of this study was to analyze and compare the level and distribution of peri-implant bone stresses associated with mandibular two-implant overdentures with different implant positions. Mathematical models of mandibles and overdentures were designed using finite element analysis software. Two intraosseous implants and ball attachment systems were placed in the interforaminal region. The overdenture, which was supported by the two implants, was designed to withstand bilateral and unilateral vertical masticatory loads (total 100 N). In all, eight types of models, which differed according to assigned implant positions, height of attachments, and angulation, were tested: MI (model with implants positioned in the lateral incisor sites), MC (implants in canine sites), MP (implants in premolar sites), MI-Hi (greater height of attachments), MC-M (canine implants placed with mesial inclination), MC-D (canine implants placed with distal inclination), MC-B (canine implants placed with buccal inclination), and MC-L (canine implants placed with lingual inclination). Peri-implant bone stress levels associated with overdentures retained by lateral incisor implants resulted in the lowest stress levels and the highest efficiency in distributing peri-implant stress. MI-Hi showed increased stress levels and decreased efficiency in stress distribution. As the implants were inclined, stress levels increased and the efficiency of stress distribution decreased. Among the inclined models, MC-B showed the lowest stress level and best efficiency in stress distribution. The lowest stress and the best stability of implants in mandibular two-implant overdentures were obtained when implants were inserted in lateral incisor areas with shorter attachments and were placed parallel to the long axes of the teeth.

Remodeling of the Mandibular Bone Induced by Overdentures Supported by Different Numbers of Implants.

Science.gov (United States)

Li, Kai; Xin, Haitao; Zhao, Yanfang; Zhang, Zhiyuan; Wu, Yulu

2016-05-01

The objective of this study was to investigate the process of mandibular bone remodeling induced by implant-supported overdentures. computed tomography (CT) images were collected from edentulous patients to reconstruct the geometry of the mandibular bone and overdentures supported by implants. Based on the theory of strain energy density (SED), bone remodeling models were established using the user material subroutine (UMAT) in abaqus. The stress distribution in the mandible and bone density change was investigated to determine the effect of implant number on the remodeling of the mandibular bone. The results indicated that the areas where high Mises stress values were observed were mainly situated around the implants. The stress was concentrated in the distal neck region of the distal-most implants. With an increased number of implants, the biting force applied on the dentures was almost all taken up by implants. The stress and bone density in peri-implant bone increased. When the stress reached the threshold of remodeling, the bone density began to decrease. In the posterior mandible area, the stress was well distributed but increased with decreased implant numbers. Changes in bone density were not observed in this area. The computational results were consistent with the clinical data. The results demonstrate that the risk of bone resorption around the distal-most implants increases with increased numbers of implants and that the occlusal force applied to overdentures should be adjusted to be distributed more in the distal areas of the mandible.

Stress fractures of ankle and wrist in childhood: nature and frequency

International Nuclear Information System (INIS)

Oestreich, Alan E.; Bhojwani, Nicholas

2010-01-01

Stress fractures of many etiologies are found not infrequently in various tarsal bones but are less commonly recognized in carpal bones. To assess the distribution of tarsal and carpal stress fractures. During the last three decades, the senior author collected locations of tarsal and carpal bone stress fracture callus seen on plain radiographs. 527 children with tarsal and carpal stress fractures were identified (88 children had multiple bones involved). The totals were: calcaneus 244, cuboid 188, talus 121, navicular 24, cuneiforms 23, capitate 18, lunate 1, and scaphoid 1. Stress fractures were more frequently seen once we became aware each particular bone could be involved. Tarsal and carpal stress fractures in children are not rare. Careful perusal of these bones is urged in all susceptible children with limping or wrist pain. (orig.)

Stress fractures of ankle and wrist in childhood: nature and frequency

Energy Technology Data Exchange (ETDEWEB)

Oestreich, Alan E. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Bhojwani, Nicholas [University of Cincinnati College of Medicine, Cincinnati, OH (United States)

2010-08-15

Stress fractures of many etiologies are found not infrequently in various tarsal bones but are less commonly recognized in carpal bones. To assess the distribution of tarsal and carpal stress fractures. During the last three decades, the senior author collected locations of tarsal and carpal bone stress fracture callus seen on plain radiographs. 527 children with tarsal and carpal stress fractures were identified (88 children had multiple bones involved). The totals were: calcaneus 244, cuboid 188, talus 121, navicular 24, cuneiforms 23, capitate 18, lunate 1, and scaphoid 1. Stress fractures were more frequently seen once we became aware each particular bone could be involved. Tarsal and carpal stress fractures in children are not rare. Careful perusal of these bones is urged in all susceptible children with limping or wrist pain. (orig.)

Operative treatment of primary bone tumours of the femur and the tibia

African Journals Online (AJOL)

The height of the bone sections was determined on the preoperative Magnetic Resonance Imaging (MRI), performed before chemotherapy if necessary, in order to leave a margin of two centimetres of healthy bone. Results: The average age of the series was 34.2 years (9 to 61 years). There were 8 (53.4%) female patients ...

Increased classical endoplasmic reticulum stress is sufficient to reduce chondrocyte proliferation rate in the growth plate and decrease bone growth.

Directory of Open Access Journals (Sweden)

Louise H W Kung

Full Text Available Mutations in genes encoding cartilage oligomeric matrix protein and matrilin-3 cause a spectrum of chondrodysplasias called multiple epiphyseal dysplasia (MED and pseudoachondroplasia (PSACH. The majority of these diseases feature classical endoplasmic reticulum (ER stress and activation of the unfolded protein response (UPR as a result of misfolding of the mutant protein. However, the importance and the pathological contribution of ER stress in the disease pathogenesis are unknown. The aim of this study was to investigate the generic role of ER stress and the UPR in the pathogenesis of these diseases. A transgenic mouse line (ColIITgcog was generated using the collagen II promoter to drive expression of an ER stress-inducing protein (Tgcog in chondrocytes. The skeletal and histological phenotypes of these ColIITgcog mice were characterised. The expression and intracellular retention of Tgcog induced ER stress and activated the UPR as characterised by increased BiP expression, phosphorylation of eIF2α and spliced Xbp1. ColIITgcog mice exhibited decreased long bone growth and decreased chondrocyte proliferation rate. However, there was no disruption of chondrocyte morphology or growth plate architecture and perturbations in apoptosis were not apparent. Our data demonstrate that the targeted induction of ER stress in chondrocytes was sufficient to reduce the rate of bone growth, a key clinical feature associated with MED and PSACH, in the absence of any growth plate dysplasia. This study establishes that classical ER stress is a pathogenic factor that contributes to the disease mechanism of MED and PSACH. However, not all the pathological features of MED and PSACH were recapitulated, suggesting that a combination of intra- and extra-cellular factors are likely to be responsible for the disease pathology as a whole.

Diagnosis of an isolated occult fracture of the posterior margin of the tibia with the SPECT/CT

International Nuclear Information System (INIS)

Bourdon, A.; Granier, P.; Mourad, M.

2007-01-01

We report the case of a 56-year-old woman, investigated for pains of the right ankle related to a trauma of an unspecified mechanism. The radiographic assessment was negative. The 99m Tc-HDP 3-phase bone scintigraphy highlighted, on the blood pool and the delayed images, a located lesion on the right ankle. The single photon emission computerized tomography guided by computerized tomography (SPECT-CT) showed a focused uptake on the posterior margin of the right tibia and a sharp lucent line within the tomo-scintigraphy spot of uptake. The diagnosis accepted was an isolated occult fracture of the posterior margin of the right tibia. The contribution of the 99m Tc-HDP 3-phase bone scintigraphy combined with the SPECT-CT in the diagnosis of the occult fractures is discussed. (N.C.)

Current diagnostic approach of bone tumors in childhood

International Nuclear Information System (INIS)

Torre, Marcia Barbosa; Scatigno Neto, Andre

1995-01-01

The authors analyze the magnetic resonance imaging (MRI) as the imaging modality of choice for evaluation of patients with bone tumors or soft tissue tumors. The advent of such a sensitive imaging modality is fortuitous and coincides with a recent change in the therapeutic approach to primary bone tumors. MRI is extremely valuable in monitoring the tumor response to the initial chemotherapy and is accurate defining the margins of tumor, facilitating planning of limb salvage surgical procedures. (author). 5 refs., 8 figs

[Biomaterials in bone repair].

Science.gov (United States)

Puska, Mervi; Aho, Allan J; Vallittu, Pekka K

2013-01-01

In orthopedics, traumatology, and craniofacial surgery, biomaterials should meet the clinical demands of bone that include shape, size and anatomical location of the defect, as well as the physiological load-bearing stresses. Biomaterials are metals, ceramics, plastics or materials of biological origin. In the treatment of large defects, metallic endoprostheses or bone grafts are employed, whereas ceramics in the case of small defects. Plastics are employed on the artificial joint surfaces, in the treatment of vertebral compression fractures, and as biodegradable screws and plates. Porosity, bioactivity, and identical biomechanics to bone are fundamental for achieving a durable, well-bonded, interface between biomaterial and bone. In the case of severe bone treatments, biomaterials should also imply an option to add biologically active substances.

A three-dimensional finite element analysis of a passive and friction fit implant abutment interface and the influence of occlusal table dimension on the stress distribution pattern on the implant and surrounding bone

Science.gov (United States)

Sarfaraz, Hasan; Paulose, Anoopa; Shenoy, K. Kamalakanth; Hussain, Akhter

2015-01-01

Aims: The aim of the study was to evaluate the stress distribution pattern in the implant and the surrounding bone for a passive and a friction fit implant abutment interface and to analyze the influence of occlusal table dimension on the stress generated. Materials and Methods: CAD models of two different types of implant abutment connections, the passive fit or the slip-fit represented by the Nobel Replace Tri-lobe connection and the friction fit or active fit represented by the Nobel active conical connection were made. The stress distribution pattern was studied at different occlusal dimension. Six models were constructed in PRO-ENGINEER 05 of the two implant abutment connection for three different occlusal dimensions each. The implant and abutment complex was placed in cortical and cancellous bone modeled using a computed tomography scan. This complex was subjected to a force of 100 N in the axial and oblique direction. The amount of stress and the pattern of stress generated were recorded on a color scale using ANSYS 13 software. Results: The results showed that overall maximum Von Misses stress on the bone is significantly less for friction fit than the passive fit in any loading conditions stresses on the implant were significantly higher for the friction fit than the passive fit. The narrow occlusal table models generated the least amount of stress on the implant abutment interface. Conclusion: It can thus be concluded that the conical connection distributes more stress to the implant body and dissipates less stress to the surrounding bone. A narrow occlusal table considerably reduces the occlusal overload. PMID:26929518

[Stress fractures of the ribs with acute thoracic pain in a young woman, diagnosed by the bone scan].

Science.gov (United States)

Georgitzikis, Athanasios; Siopi, Dimitra; Doumas, Argyrios; Mitka, Ekaterini; Antoniadis, Antonios

2010-01-01

We report the unusual case of a 29 -year old woman with emotional instability who presented with acute onset chest pain after severe chronic cough. The chest X-ray and the serological tests were normal but the CT scanning, and the bone scanning revealed multiple bilateral rib stress fractures, caused by severe coughing and physical activity and worsened by the patient's emotional instability.

Splenic marginal zone lymphoma: from genetics to management.

Science.gov (United States)

Arcaini, Luca; Rossi, Davide; Paulli, Marco

2016-04-28

Splenic marginal zone lymphoma (SMZL) is a rare B-cell malignancy involving the spleen, bone marrow, and frequently the blood. SMZL lymphomagenesis involves antigen and/or superantigen stimulation and molecular deregulation of genes (NOTCH2 and KLF2) involved in the physiological differentiation of spleen marginal zone B cells. Diagnosis requires either spleen histology or, alternatively, the documentation of a typical cell morphology and immunophenotype on blood cells coupled with the detection of intrasinusoidal infiltration by CD20(+) cells in the bone marrow. Among B-cell tumors, deletion of 7q and NOTCH2 mutations are almost specific lesions of SMZL, thus representing promising diagnostic biomarkers of this lymphoma. Although the majority of SMZLs show an indolent course with a median survival of approximately 10 years, nearly 30% of patients experience a poor outcome. No randomized trials are reported for SMZL, and few prospective trials are available. A watch-and-wait approach is advisable for asymptomatic patients. Treatment options for symptomatic patients ranges from splenectomy to rituximab alone or combined with chemotherapy. In some geographic areas, a subset of patients with SMZL associates with hepatitis C virus infection, prompting virus eradication as an effective lymphoma treatment. It would be worthwhile to explore deregulated cellular programs of SMZL as therapeutic targets in the future; improved clinical and biological prognostication will be essential for identifying patients who may benefit from novel approaches. © 2016 by The American Society of Hematology.

MR imaging of the bone marrow using short TI IR, 1. Normal and pathological intensity distribution of the bone marrow

Energy Technology Data Exchange (ETDEWEB)

Ishizaka, Hiroshi; Kurihara, Mikiko; Tomioka, Kuniaki; Kobayashi, Kanako; Sato, Noriko; Nagai, Teruo; Heshiki, Atsuko; Amanuma, Makoto; Mizuno, Hitomi.

1989-02-01

Normal vertebral bone marrow intensity distribution and its alteration in various anemias were evaluated on short TI IR sequences. Material consists of 73 individuals, 48 normals and 25 anemic patients excluding neoplastic conditions. All normal and reactive hypercellular bone marrow revealed characteristic intensity distribution; marginal high intensity and central low intensity, corresponding well to normal distribution of red and yellow marrows and their physiological or reactive conversion between red and yellow marrows. Aplastic anemia did not reveal normal intensity distribution, presumably due to autonomous condition.

Three-phase radionuclide bone imaging in sports medicine

International Nuclear Information System (INIS)

Rupani, H.D.; Holder, L.E.; Espinola, D.A.; Engin, S.I.

1985-01-01

Three-phase radionuclide bone (TPB) imaging was performed on 238 patients with sports-related injuries. A wide variety of lesions was encountered, but the most frequent lesions seen were stress fractures of the lower part of the leg at the junction of the middle and distal thirds of the posterior tibial cortex (42 of 79 lesions). There were no differences in the type, location, or distribution of lesions between males and females or between competitive and noncompetitive athletes. In 110 cases, bone stress lesions were often diagnosed when radiographs were normal, whereas subacute or chronic soft-tissue abnormalities had few specific scintigraphic features. TPB imaging provides significant early diagnostic information about bone stress lesions. Normal examination results (53 cases) exclude underlying osseous pathologic conditions

Evaluation of seismic margins for an in-plant piping system

International Nuclear Information System (INIS)

Kot, C.A.; Srinivasan, M.G.; Hsieh, B.J.

1991-01-01

Earthquake experience as well as experiments indicate that, in general, piping systems are quite rugged in resisting seismic loadings. Therefore there is a basis to hold that the seismic margin against pipe failure is very high for systems designed according to current practice. However, there is very little data, either from tests or from earthquake experience, on the actual margin or excess capacity (against failure from seismic loading) of in-plant piping systems. Design of nuclear power plant piping systems in the US is governed by the criteria given in the ASME Boiler and Pressure Vessel (B ampersand PV) Code, which assure that pipe stresses are within specified allowable limits. Generally linear elastic analytical methods are used to determine the stresses in the pipe and forces in pipe supports. The objective of this study is to verify that piping designed according to current practice does indeed have a large margin against failure and to quantify the excess capacity for piping and dynamic pipe supports on the basis of data obtained in a series of high-level seismic experiments (designated SHAM) on an in-plant piping system at the HDR (Heissdampfreaktor) Test Facility in Germany. Note that in the present context, seismic margin refers to the deterministic excess capacities of piping or supports compared to their design capacities. The excess seismic capacities or margins of a prototypical in-plant piping system and its components are evaluated by comparing measured inputs and responses from high-level simulated seismic experiments with design loads and allowables. Large excess capacities are clearly demonstrated against pipe and overall system failure with the lower bound being about four. For snubbers the lower bound margin is estimated at two and for rigid strut supports at five. 4 refs., 2 figs., 2 tabs

Bone scintigraphy for horses

International Nuclear Information System (INIS)

Jahn, Werner

2010-01-01

Scintigraphy (bone scan) is being used approximately since 1980 in the horse under general anaesthesia. With the construction of custom-made overhead gantries for gamma-cameras scintigraphy found widespread entry in big equine referral hospitals for bone-scanning of the standing horse. Indications for the use of a bone scan in the horse are inflammatory alterations in the locomotor apparatus. It is primarily used for diagnosis of lameness of unknown origin, suspect of stress fracture or hairline fracture and for horses with bad riding comfort with suspected painful lesions in the spine. (orig.)

Physical Processes Contributing To Small-scale Vertical Movements During Changing Inplane Stresses In Rift Basins and At Passive Continental Margins

Science.gov (United States)

Paulsen, G. E.; Nielsen, S. B.; Hansen, D. L.

The vertical movements during a regional stress reversal in a rifted basin or on a passive continental margin are examined using a numerical 2D thermo-mechanical finite element model with a visco-elastic-plastic rheology. Three different physical mechanisms are recognized in small-scale vertical movements at small inplane force variations: elastic dilatation, elastic flexure, and permanent deformation. Their rela- tive importance depend on the applied force, the duration of the force, and the thermal structure of the lithosphere. Elastic material dilatation occurs whenever the stress state changes. A reversal from extension to compression therefore immediately leads to elastic dilatation, and re- sults in an overall subsidence of the entire profile. Simultaneously with dilatation the lithosphere reacts with flexure. The significance of the flexural component strongly depends on the thermal structure of the lithosphere. The polarity and amplitude of the flexure depends on the initial (before compression) loading of the lithosphere. Gener- ally, the flexural effects lead to subsidence of the overdeep in the landward part of the basin and a small amount of uplift at the basin flanks. The amplitudes of the flexural response are small and comparable with the amplitudes of the elastic dilatation. With continuing compression permanent deformation and lithospheric thickening becomes increasingly important. Ultimately, the thickened part of the lithosphere stands out as an inverted zone. The amount of permanent deformation is directly connected with the size and duration of the applied force, but even a relatively small force leads to inversion tectonics in the landward part of the basin. The conclusions are: 1) small stress induced vertical movements in rift basins and at passive continental margins are the result of a complex interaction of at least three different processes, 2) the total sediment loaded amplitudes resulting from these pro- cesses are small (2-300 m) for

驯鹿头骨解剖%THE ANATOMY OF THE SKULL BONES OF REINDEER

Institute of Scientific and Technical Information of China (English)

都格尔斯仁; 刘为民; 苏布登格日勒; 杨银凤; 乔灵; 额尔德木图

2001-01-01

With cross anatomical method,the anatomy of the skull bones ofreindeer was studied and compared with that of camel,horse and cattle.The results were as follows:The vomer of reindeer is very developed.A group of ethmoidal cellules were formed among the lacrimal bone,frontal bone and nasal bone.The mandible is longer and narrower than that of cattle,horse and camel.The angle of mandible is obtuse.The lacrimal bone has a pair of lacrimal foramen which lie on the cranral part of orbital margin and separated by the lacrimal process.The reindeer has no lacrimal saccus fossa.On the ventral part of the orbital margin,the zygomatic bone formed a deep notch of the orbital margin.%运用大体解剖的方法对驯鹿头骨进行了形态学观察，并将其与双峰驼、牛、马的头骨进行了比较。结果表明：驯鹿的犁骨特别发达。泪骨，额骨和鼻骨之间围成一个狭长的筛鼻甲窦(部)。下颌骨比牛、马、驼窄而长，下颌角钝圆。泪骨的形态较特殊，颜而形成纵形深窝，泪孔有两个，位于眶缘上，并有尖状的泪突分开，眶缘与颧骨交界处有一个深切迹，无泪囊窝。

Clinical and Radiologic Outcomes of Submerged and Nonsubmerged Bone-Level Implants with Internal Hexagonal Connections in Immediate Implantation: A 5-Year Retrospective Study.

Science.gov (United States)

Wu, Shiyu; Wu, Xiayi; Shrestha, Rachana; Lin, Jinying; Feng, Zhicai; Liu, Yudong; Shi, Yunlin; Huang, Baoxin; Li, Zhipeng; Liu, Quan; Zhang, Xiaocong; Hu, Mingxuan; Chen, Zhuofan

2018-02-01

To evaluate the 5-year clinical and radiologic outcome of immediate implantation using submerged and nonsubmerged techniques with bone-level implants and internal hexagonal connections and the effects of potential influencing factors. A total of 114 bone-level implants (XiVE S plus) with internal hexagonal connections inserted into 72 patients were included. Patients were followed up for 5 years. A t-test was used to statistically evaluate the marginal bone loss between the submerged and nonsubmerged groups. The cumulative survival rate (CSR) was calculated according to the life table method and illustrated with Kaplan-Meier survival curves. Comparisons of the CSR between healing protocols, guided bone regeneration, implants with different sites, lengths, and diameters were performed using log-rank tests. The 5-year cumulative implant survival rates with submerged and nonsubmerged healing were 94% and 96%, respectively. No statistically significant differences in terms of marginal bone loss, healing protocol, application of guided bone regeneration, implant site, or length were observed. High CSRs and good marginal bone levels were achieved 5 years after immediate implantation of bone-level implants with internal hexagonal connections using both the submerged and nonsubmerged techniques. Factors such as implant length, site, and application of guided bone regeneration did not have an impact on the long-term success of the implants. © 2017 by the American College of Prosthodontists.

Three phase bone scan in sports injuries

International Nuclear Information System (INIS)

Chauhan, M.S.; Chowhan, M.

2007-01-01

Full text: Sports injuries are common in individual who participate in sports and exercise related activities. In majority of sports related injuries such as stress fracture, periosteitits, acute stress reaction of bone, the radiological investigations are usually normal in early stages. These injuries can lead to serious complications if not detected early and managed properly. This study was jointly carried out in premier medical institutes. All patients were referred from premier sports institute of the country and also by orthopedic surgeons. All patients were subjected for relevant radiological investigations and 3 phase bone scan. Total number of cases included in this study was 70 (N=70) among which bone scan was positive for stress fracture in 45 patients and shin splint was detected in 15 patients and avulsion injury seen in 3 patients. However, only one patient showed features of avulsion injury in X ray and in 1 patient X-ray was inconclusive. Conclusion:-The study shows that 3 phase bone scan is the most sensitive and relatively an inexpensive study. Bone scan has the ability for early detection of sports injuries and provide physiological information and evaluate multiple sites in single examination.SPECT study will help in the diagnostic specificity. (author)

Case report 534: Simple bone cyst of the acetabulum and ischium

International Nuclear Information System (INIS)

Abdelwahab, I.F.; Hermann, G.; Lewis, M.M.; Klein, M.H.

1989-01-01

A case is presented of a solitary bone cyst of the acetabulum in an eighteen year old female. The lesion was sharply defined with sclerosed margins and minimal expansion. Proof was obtained in an open biopsy which showed a hypocellular fibrous tissue lining the cyst wall. The classical appearance of simple bone cysts of the pelvis and the site of predilection have been described. (orig./GDG)

Bone Geometry as a Predictor of Tissue Fragility and Stress Fracture Risk

National Research Council Canada - National Science Library

Jepsen, Karl

2003-01-01

... and bone quality, such that slender bones are associated with more damageable bone tissue. We postulate that a similar reciprocal relationship between bone mass and bone material properties exists in the human skeleton...

Bone Geometry as a Predictor of Tissue Fragility and Stress Fracture Risk

National Research Council Canada - National Science Library

Jepsen, Karl J

2004-01-01

... and bone quality, such that slender bones are associated with more damageable bone tissue. We postulate that a similar reciprocal relationship between bone mass and bone material properties exists in the human skeleton...

Bone Geometry as a Predictor of Tissue Fragility and Stress Fracture Risk

National Research Council Canada - National Science Library

Jepsen, Karl J

2006-01-01

... and bone quality, such that slender bones are associated with more damageable bone tissue. We postulate that a similar reciprocal relationship between bone mass and bone material properties exists in the human skeleton...

Bone Geometry as a Predictor of Tissue Fragility and Stress Fracture Risk

National Research Council Canada - National Science Library

Jepsen, Karl

2002-01-01

... and bone quality, such that slender bones are associated with more damageable bone tissue. We postulate that a similar reciprocal relationship between bone mass and bone material properties exists in the human skeleton...

Stimulation of host bone marrow stromal cells by sympathetic nerves promotes breast cancer bone metastasis in mice.

Directory of Open Access Journals (Sweden)

J Preston Campbell

2012-07-01

Full Text Available Bone and lung metastases are responsible for the majority of deaths in patients with breast cancer. Following treatment of the primary cancer, emotional and psychosocial factors within this population precipitate time to recurrence and death, however the underlying mechanism(s remain unclear. Using a mouse model of bone metastasis, we provide experimental evidence that activation of the sympathetic nervous system, which is one of many pathophysiological consequences of severe stress and depression, promotes MDA-231 breast cancer cell colonization of bone via a neurohormonal effect on the host bone marrow stroma. We demonstrate that induction of RANKL expression in bone marrow osteoblasts, following β2AR stimulation, increases the migration of metastatic MDA-231 cells in vitro, independently of SDF1-CXCR4 signaling. We also show that the stimulatory effect of endogenous (chronic stress or pharmacologic sympathetic activation on breast cancer bone metastasis in vivo can be blocked with the β-blocker propranolol, and by knockdown of RANK expression in MDA-231 cells. These findings indicate that RANKL promotes breast cancer cell metastasis to bone via its pro-migratory effect on breast cancer cells, independently of its effect on bone turnover. The emerging clinical implication, supported by recent epidemiological studies, is that βAR-blockers and drugs interfering with RANKL signaling, such as Denosumab, could increase patient survival if used as adjuvant therapy to inhibit both the early colonization of bone by metastatic breast cancer cells and the initiation of the "vicious cycle" of bone destruction induced by these cells.

Stimulation of host bone marrow stromal cells by sympathetic nerves promotes breast cancer bone metastasis in mice.

Science.gov (United States)

Campbell, J Preston; Karolak, Matthew R; Ma, Yun; Perrien, Daniel S; Masood-Campbell, S Kathryn; Penner, Niki L; Munoz, Steve A; Zijlstra, Andries; Yang, Xiangli; Sterling, Julie A; Elefteriou, Florent

2012-07-01

Bone and lung metastases are responsible for the majority of deaths in patients with breast cancer. Following treatment of the primary cancer, emotional and psychosocial factors within this population precipitate time to recurrence and death, however the underlying mechanism(s) remain unclear. Using a mouse model of bone metastasis, we provide experimental evidence that activation of the sympathetic nervous system, which is one of many pathophysiological consequences of severe stress and depression, promotes MDA-231 breast cancer cell colonization of bone via a neurohormonal effect on the host bone marrow stroma. We demonstrate that induction of RANKL expression in bone marrow osteoblasts, following β2AR stimulation, increases the migration of metastatic MDA-231 cells in vitro, independently of SDF1-CXCR4 signaling. We also show that the stimulatory effect of endogenous (chronic stress) or pharmacologic sympathetic activation on breast cancer bone metastasis in vivo can be blocked with the β-blocker propranolol, and by knockdown of RANK expression in MDA-231 cells. These findings indicate that RANKL promotes breast cancer cell metastasis to bone via its pro-migratory effect on breast cancer cells, independently of its effect on bone turnover. The emerging clinical implication, supported by recent epidemiological studies, is that βAR-blockers and drugs interfering with RANKL signaling, such as Denosumab, could increase patient survival if used as adjuvant therapy to inhibit both the early colonization of bone by metastatic breast cancer cells and the initiation of the "vicious cycle" of bone destruction induced by these cells.

[Osteoporosis and stress].

Science.gov (United States)

Kumano, Hiroaki

2005-09-01

There may be three ways of relationship between stress and osteoporosis. The first is that stress induces some physiological changes leading to osteoporosis. The second is that stress induces behavioral distortion of eating, drinking, exercise, and sleep habits, which leads to osteoporosis. The third is that osteoporosis, on the other hand, brings about anxiety, depression, loss of social roles, and social isolation, which leads to stress. The susceptible sex and age groups are postmenopausal women and young women. The abrupt decrease of estrogen in postmenopausal women promotes reabsorption of bone, and it was also reported that the increase of interleukin-6 (IL-6) that is downstream of estrogen was related to the production of osteoclast and to the development of disability of the aged. Regarding the association with stress, while it was reported that depression or depressive states directly increased inflammation-induced cytokines including IL-6, it was also pointed out that stress-induced easy infectious may produce chronic infection, which indirectly increases inflammation-induced cytokines. Anorexia Nervosa that is assumed to be associated with adolescent developmental stress is noteworthy in young women. Amenorrhea is always present in this disease, and in addition to bone reabsorption associated with estrogen deficiency, the decrease of bone formation associated with malnutrition may be related to the development of osteoporosis.

Pedicular stress fracture in the lumbar spine

International Nuclear Information System (INIS)

Chong, V.F.H.; Htoo, M.M.

1997-01-01

Spondylolisthesis with or without spondylolysis is common in the lumbar spine. Associated fracture in the pedicle ('pediculolysis') is unusual. The margins of pedicular stress fractures, like spondylolysis, usually appear sclerotic. A patient with a pedicular stress fracture with minimal marginal sclerosis suggesting an injury of recent onset is presented here. There was associated bilateral spondylolysis. The findings in this patient suggest that established pediculolysis probably represents a stress fracture that has failed to heal. (authors)

Olive oil and vitamin D synergistically prevent bone loss in mice.

Directory of Open Access Journals (Sweden)

Camille Tagliaferri

Full Text Available As the Mediterranean diet (and particularly olive oil has been associated with bone health, we investigated the impact of extra virgin oil as a source of polyphenols on bone metabolism. In that purpose sham-operated (SH or ovariectomized (OVX mice were subjected to refined or virgin olive oil. Two supplementary OVX groups were given either refined or virgin olive oil fortified with vitamin D3, to assess the possible synergistic effects with another liposoluble nutrient. After 30 days of exposure, bone mineral density and gene expression were evaluated. Consistent with previous data, ovariectomy was associated with increased bone turnover and led to impaired bone mass and micro-architecture. The expression of oxidative stress markers were enhanced as well. Virgin olive oil fortified with vitamin D3 prevented such changes in terms of both bone remodeling and bone mineral density. The expression of inflammation and oxidative stress mRNA was also lower in this group. Overall, our data suggest a protective impact of virgin olive oil as a source of polyphenols in addition to vitamin D3 on bone metabolism through improvement of oxidative stress and inflammation.

Bone and/or joint attachment is a risk factor for local recurrence of myxofibrosarcoma

International Nuclear Information System (INIS)

Kaya, Mitsunori; Wada, Takuro; Nagoya, Satoshi; Yamashita, Toshihiko

2011-01-01

Myxofibrosarcoma is characterized by a high local recurrence rate despite optimal surgical treatment. The definition of prognostic factors for recurrence offers high-risk patients a closer follow-up and a multidisciplinary therapeutic approach. A cohort of 23 patients treated for primary myxofibrosarcoma was retrospectively analyzed. The patients (sex and age), tumors (size, stage, tumor location, bone and/or joint attachment), radiological findings (abnormal signal extension in MRI), histological findings (FNCLCC grade and microscopic extension along the muscle fascia), and treatment (surgical margin) characteristics were included in univariate prognostic factor analysis. After a median follow-up of 63.3 months (range 15-191), the overall recurrence rate was 34.7%. Median time between initial surgery and recurrence was 24.8 months (range 8-52). Inadequate surgical margins (p=0.026) and bone and/or joint attachment (p=0.001) were associated with an increased recurrence rate. For the further improvement of local recurrence-free survival of patients with myxofibrosarcoma, accurate diagnosis of the tumor extension and adequate planning for the surgical margin should be focused on in cases with bone and/or joint attachment. (author)

Pedicular stress fracture in the lumbar spine

Energy Technology Data Exchange (ETDEWEB)

Chong, V.F.H.; Htoo, M.M. [Singapore General Hospital, Singapore, (Singapore). Department of Diagnostic Radiology

1997-08-01

Spondylolisthesis with or without spondylolysis is common in the lumbar spine. Associated fracture in the pedicle (`pediculolysis`) is unusual. The margins of pedicular stress fractures, like spondylolysis, usually appear sclerotic. A patient with a pedicular stress fracture with minimal marginal sclerosis suggesting an injury of recent onset is presented here. There was associated bilateral spondylolysis. The findings in this patient suggest that established pediculolysis probably represents a stress fracture that has failed to heal. (authors). 10 refs., 2 figs.

Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion

Science.gov (United States)

Lee, Scott

2015-01-01

In our first article on scaling in theropod dinosaurs, the longitudinal stress in the leg bones due to supporting the weight of the animal was studied and found not to control the dimensions of the femur. As a continuation of our study of elasticity in dinosaur bones, we now examine the transverse stress in the femur due to locomotion and find…

Firn thickness variations across the Northeast Greenland Ice Stream margins indicating nonlinear densification rates

Science.gov (United States)

Riverman, K. L.; Anandakrishnan, S.; Alley, R. B.; Peters, L. E.; Christianson, K. A.; Muto, A.

2013-12-01

Northeast Greenland Ice Stream (NEGIS) is the largest ice stream in Greenland, draining approximately 8.4% of the ice sheet's area. The flow pattern and stability mechanism of this ice stream are unique to others in Greenland and Antarctica, and merit further study to ascertain the sensitivity of this ice stream to future climate change. Geophysical methods are valuable tools for this application, but their results are sensitive to the structure of the firn and any spatial variations in firn properties across a given study region. Here we present firn data from a 40-km-long seismic profile across the upper reaches of NEGIS, collected in the summer of 2012 as part of an integrated ground-based geophysical survey. We find considerable variations in firn thickness that are coincident with the ice stream shear margins, where a thinner firn layer is present within the margins, and a thicker, more uniform firn layer is present elsewhere in our study region. Higher accumulation rates in the marginal surface troughs due to drift-snow trapping can account for some of this increased densification; however, our seismic results also highlight enhanced anisotropy within the firn and upper ice column that is confined to narrow bands within the shear margins. We thus interpret these large firn thickness variations and abrupt changes in anisotropy as indicators of firn densification dependent on the effective stress state as well as the overburden pressure, suggesting that the strain rate increases nonlinearly with stress across the shear margins. A GPS strain grid maintained for three weeks across both margins observed strong side shearing, with rapid stretching and then compression along particle paths, indicating large deviatoric stresses in the margins. This work demonstrates the importance of developing a high-resolution firn densification model when conducting geophysical field work in regions possessing a complex ice flow history; it also motivates the need for a more

Augmented reality in bone tumour resection

Science.gov (United States)

Park, Y. K.; Gupta, S.; Yoon, C.; Han, I.; Kim, H-S.; Choi, H.; Hong, J.

2017-01-01

Objectives We evaluated the accuracy of augmented reality (AR)-based navigation assistance through simulation of bone tumours in a pig femur model. Methods We developed an AR-based navigation system for bone tumour resection, which could be used on a tablet PC. To simulate a bone tumour in the pig femur, a cortical window was made in the diaphysis and bone cement was inserted. A total of 133 pig femurs were used and tumour resection was simulated with AR-assisted resection (164 resection in 82 femurs, half by an orthropaedic oncology expert and half by an orthopaedic resident) and resection with the conventional method (82 resection in 41 femurs). In the conventional group, resection was performed after measuring the distance from the edge of the condyle to the expected resection margin with a ruler as per routine clinical practice. Results The mean error of 164 resections in 82 femurs in the AR group was 1.71 mm (0 to 6). The mean error of 82 resections in 41 femurs in the conventional resection group was 2.64 mm (0 to 11) (p Augmented reality in bone tumour resection: An experimental study. Bone Joint Res 2017;6:137–143. PMID:28258117

Effects of Neuropeptides and Mechanical Loading on Bone Cell Resorption in Vitro

Directory of Open Access Journals (Sweden)

Yeong-Min Yoo

2014-04-01

Full Text Available Neuropeptides such as vasoactive intestinal peptide (VIP and calcitonin gene-related peptide (CGRP are present in nerve fibers of bone tissues and have been suggested to potentially regulate bone remodeling. Oscillatory fluid flow (OFF-induced shear stress is a potent signal in mechanotransduction that is capable of regulating both anabolic and catabolic bone remodeling. However, the interaction between neuropeptides and mechanical induction in bone remodeling is poorly understood. In this study, we attempted to quantify the effects of combined neuropeptides and mechanical stimuli on mRNA and protein expression related to bone resorption. Neuropeptides (VIP or CGRP and/or OFF-induced shear stress were applied to MC3T3-E1 pre-osteoblastic cells and changes in receptor activator of nuclear factor kappa B (NF-κB ligand (RANKL and osteoprotegerin (OPG mRNA and protein levels were quantified. Neuropeptides and OFF-induced shear stress similarly decreased RANKL and increased OPG levels compared to control. Changes were not further enhanced with combined neuropeptides and OFF-induced shear stress. These results suggest that neuropeptides CGRP and VIP have an important role in suppressing bone resorptive activities through RANKL/OPG pathway, similar to mechanical loading.

[CHARACTERISTICS OF OSTEOCYTE CELL LINES FROM BONES FORMED AS A RESULT OF MEMBRANOUS (SKULL BONES) AND CHONDRAL (LONG BONES) OSSIFICATION].

Science.gov (United States)

Avrunin, A S; Doktorov, A A

2016-01-01

The aim of this work was to analyze the literature data and the results of authors' own research, to answer the question--if the osteocytes of bone tissues resulting from membranous and chondral ossification, belong to one or to different cell lines. The differences between the cells of osteocyte lines derived from bones resulting from membranous and chondral ossification were established in: 1) the magnitude of the mechanical signal, initiating the development of the process of mechanotransduction; 2) the nature of the relationship between the magnitude of the mechanical signal that initiates the reorganization of the architecture of bone structures and the resource of their strength; in membranous bones significantly lower mechanical signal caused a substantially greater increment of bone strength resource; 3) the biological activity of bone structures, bone fragments formed from membranous tissue were more optimal for transplantation; 4) the characteristics of expression of functional markers of bone cells at different stages of their differentiation; 5) the nature of the reaction of bone cells to mechanical stress; 6) the sensitivity of bone cells to one of the factors controlling the process of mechanotransduction (PGI2); 7) the functioning of osteocytes during lactation. These differences reflect the functional requirements to the bones of the skeleton--the supporting function in the bones of the limbs and the shaping and protection in the bones of the cranial vault. These data suggest that the results of research conducted on the bones of the skull, should not be transferred to the entire skeleton as a whole.

Air-sea interactions in the marginal ice zone

Directory of Open Access Journals (Sweden)

Seth Zippel

2016-03-01

Full Text Available Abstract The importance of waves in the Arctic Ocean has increased with the significant retreat of the seasonal sea-ice extent. Here, we use wind, wave, turbulence, and ice measurements to evaluate the response of the ocean surface to a given wind stress within the marginal ice zone, with a focus on the local wind input to waves and subsequent ocean surface turbulence. Observations are from the Beaufort Sea in the summer and early fall of 2014, with fractional ice cover of up to 50%. Observations showed strong damping and scattering of short waves, which, in turn, decreased the wind energy input to waves. Near-surface turbulent dissipation rates were also greatly reduced in partial ice cover. The reductions in waves and turbulence were balanced, suggesting that a wind-wave equilibrium is maintained in the marginal ice zone, though at levels much less than in open water. These results suggest that air-sea interactions are suppressed in the marginal ice zone relative to open ocean conditions at a given wind forcing, and this suppression may act as a feedback mechanism in expanding a persistent marginal ice zone throughout the Arctic.

Prediction of mechanical properties of trabecular bone using quantitative MRI

International Nuclear Information System (INIS)

Lammentausta, E; Hakulinen, M A; Jurvelin, J S; Nieminen, M T

2006-01-01

Techniques for quantitative magnetic resonance imaging (MRI) have been developed for non-invasive estimation of the mineral density and structure of trabecular bone. The R* 2 relaxation rate (i.e. 1/T* 2 ) is sensitive to bone mineral density (BMD) via susceptibility differences between trabeculae and bone marrow, and by binarizing MRI images, structural variables, such as apparent bone volume fraction, can be assessed. In the present study, trabecular bone samples of human patellae were investigated in vitro at 1.5 T to determine the ability of MRI-derived variables (R* 2 and bone volume fraction) to predict the mechanical properties (Young's modulus, yield stress and ultimate strength). Further, the MRI variables were correlated with reference measurements of volumetric BMD and bone area fraction as determined with a clinical pQCT system. The MRI variables correlated significantly (p 2 and MRI-derived bone volume fraction further improved the prediction of yield stress and ultimate strength. Although pQCT showed a trend towards better prediction of the mechanical properties, current results demonstrate the feasibility of combined MR imaging of marrow susceptibility and bone volume fraction in predicting the mechanical strength of trabecular bone and bone mineral density

Effect of alpha-calciferol on bone mineral density, bone histomorphometry and bone biomechanics in rats by radiative injury to kidney

International Nuclear Information System (INIS)

Zhu Feipeng; Wang Hongfu; Gao Linfeng; Jin Weifang

2003-01-01

The work is to study the effects of alpha-calciferol on bone mineral density, histomorphometry and biomechanics in rats with osteoporosis induced by irradiation of the rat kidney. 32 male SD rats of six months in age were randomly divided into 4 groups (8 rats per group), i.e. the model group, the sham group, the bone one group and the fosamax group. Osteoporosis was developed in the rats by irradiating the kidney. Then the rats were administrated orally as follows in a 90 days, 0.1 g·kg -1 BW.d of alpha-calciferol for the bone one group, 10 mg·kg -1 BW.d of alendronate sodium in 1 mL CMC for the fosamax group, and 1 mL CMC for both the model group and sham group. BMD of L1-4, bone histomorphometry and the bone biomechanical properties were measured. Compared with the model group, both the bone one group and the fosamax group were characterized with significantly higher BMD of L1-4 (p<0.01), significantly larger volume and width of bone trabecula, smaller space of bone trabecula (p<0.05, p<0.01), and significantly larger maximal stress of femur and lumbar vertebra (p<0.05, p<0.01). It is concluded that Alpha-calciferol can improve BMD, bone histomorphometry and bone biomechanical properties in rat osteoporosis induced by kidney irradiation

The effect of concentrated bone marrow aspirate in operative treatment of fifth metatarsal stress fractures; a double-blind randomized controlled trial

NARCIS (Netherlands)

Weel, Hanneke; Mallee, Wouter H.; van Dijk, C. Niek; Blankevoort, Leendert; Goedegebuure, Simon; Goslings, J. Carel; Kennedy, John G.; Kerkhoffs, Gino M. M. J.

2015-01-01

Fifth metatarsal (MT-V) stress fractures often exhibit delayed union and are high-risk fractures for non-union. Surgical treatment, currently considered as the gold standard, does not give optimal results, with a mean time to fracture union of 12-18 weeks. In recent studies, the use of bone marrow

Growth, immune, antioxidant, and bone responses of heat stress-exposed broilers fed diets supplemented with tomato pomace

Science.gov (United States)

Hosseini-Vashan, S. J.; Golian, A.; Yaghobfar, A.

2016-08-01

A study was conducted to investigate the effects of supplementation of dried tomato pomace (DTP) on growth performance, relative weights of viscera, serum biological parameters, antioxidant status, immune response, and bone composition of broilers exposed to a high ambient temperature. A total of 352 one-day-old male broiler chickens were randomly divided into four groups consisting of four replicates with 22 birds each. One group was reared under the thermoneutral zone and fed a corn-soybean meal basal diet. The other three groups were subjected to a cyclic heat stress from 29 to 42 days of age (34 ± 1 °C, 55 % RH, 5 h/day). These birds were fed corn-soybean meal basal diet or the same diet supplemented with 3 % DTP (420 mg lycopene/kg diet) or 5 % (708 mg lycopene/kg diet) of DTP. Blood samples were collected on days 28 and 42, and the birds were slaughtered at the same times. Supplementation of 5 % of DTP increased body weight and production index and decreased feed conversion ratio during 1-28 days of age. On day 28, the broilers supplemented with 5 % DTP had lower serum triglycerides and higher high-density lipoprotein (HDL) cholesterol concentration than those on the other dietary treatments. The activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) were higher and the concentration of malondialdehyde (MDA) was lower in the broilers fed 5 % TP than those of the broilers fed other diets at 28 days of age. The effects of heat stress (HS) were impaired body weight, enhanced serum activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lipase, and MDA concentration while reducing the activities of GPx and SOD. Dried tomato pomace supplementation did not influence growth performance under HS but ameliorated the negative effects of HS on the serum enzyme activities, GPx activity, and lipid peroxidation. Heat stress did not change the relative weights of the lymphoid organs but reduced the total and IgG titers

The "rising bubble" sign: a new aid in the diagnosis of unicameral bone cysts.

Science.gov (United States)

Jordanov, Martin I

2009-06-01

The observation of a bubble of gas at the most non-dependent margin of a lytic bone lesion which has sustained a pathologic fracture implies that the lesion is hollow and can assist the radiologist in making the diagnosis of a unicameral bone cyst. The imaging studies of two patients who sustained pathologic fractures through unicameral bone cysts and exhibited the "rising bubble" sign are shown. The sign's basis, proper utilization, and potential pitfalls are discussed.

The ''rising bubble'' sign: a new aid in the diagnosis of unicameral bone cysts

International Nuclear Information System (INIS)

Jordanov, Martin I.

2009-01-01

The observation of a bubble of gas at the most non-dependent margin of a lytic bone lesion which has sustained a pathologic fracture implies that the lesion is hollow and can assist the radiologist in making the diagnosis of a unicameral bone cyst. The imaging studies of two patients who sustained pathologic fractures through unicameral bone cysts and exhibited the ''rising bubble'' sign are shown. The sign's basis, proper utilization, and potential pitfalls are discussed. (orig.)

The biodegradation of hydroxyapatite bone graft substitutes in vivo.

Science.gov (United States)

Rumpel, E; Wolf, E; Kauschke, E; Bienengräber, V; Bayerlein, T; Gedrange, T; Proff, P

2006-02-01

Hydroxyapatite (HA) ceramics are widely used for bone reconstruction. They are osteoconductive and serve as structural scaffolds for the deposition of new bone. Generally, scaffold materials should be degradable as they affect the mechanical properties of the reconstructed bone negatively. Degradation by osteoclasts during the bone remodelling process is desirable but often does not take place. In the current study we analysed by light microscopy the degradation of two granular HA implants in critically sized defects in the mandibula of Goettingen mini-pigs five weeks after implantation. Bio-Oss consists of sintered bovine bone and NanoBone is a synthetic HA produced in a sol-gel process in the presence of SiO2. We found that both biomaterials were degraded by osteoclasts with ruffled borders and acid phosphatase activity. The osteoclasts created resorption lacunae and resorptive trails and contained mineral particles. Frequently, resorption surfaces were in direct contact with bone formative surfaces on one granule. Granules, especially of NanoBone, were also covered by osteoclasts if located in vascularised connective tissue distant from bone tissue. However, this usually occurred without the creation of resorption lacunae. The former defect margins consisted of newly formed bone often without remnants of bone substitutes. Our results show that the degradation of both biomaterials corresponds to the natural bone degradation processes and suggest the possibility of complete resorption during bone remodelling.

Pharmacological activation of aldehyde dehydrogenase 2 promotes osteoblast differentiation via bone morphogenetic protein-2 and induces bone anabolic effect

Energy Technology Data Exchange (ETDEWEB)

Mittal, Monika; Pal, Subhashis; China, Shyamsundar Pal; Porwal, Konica [Division of Endocrinology and Centre for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Lucknow 226031 (India); Dev, Kapil [Division of Medicinal and Process Chemistry, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Shrivastava, Richa [Division of Toxicology, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Raju, Kanumuri Siva Rama; Rashid, Mamunur [Pharmaceutics Division, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Trivedi, Arun Kumar; Sanyal, Sabyasachi [Biochemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Wahajuddin, Muhammad [Pharmaceutics Division, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Bhaduria, Smrati [Division of Toxicology, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Maurya, Rakesh [Division of Medicinal and Process Chemistry, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Chattopadhyay, Naibedya, E-mail: n_chattopadhyay@cdri.res.in [Division of Endocrinology and Centre for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Lucknow 226031 (India)

2017-02-01

Aldehyde dehydrogenases (ALDHs) are a family of enzymes involved in detoxifying aldehydes. Previously, we reported that an ALDH inhibitor, disulfiram caused bone loss in rats and among ALDHs, osteoblast expressed only ALDH2. Loss-of-function mutation in ALDH2 gene is reported to cause bone loss in humans which suggested its importance in skeletal homeostasis. We thus studied whether activating ALDH2 by N-(1, 3-benzodioxol-5-ylmethyl)-2, 6-dichlorobenzamide (alda-1) had osteogenic effect. We found that alda-1 increased and acetaldehyde decreased the differentiation of rat primary osteoblasts and expressions of ALDH2 and bone morphogenetic protein-2 (BMP-2). Silencing ALDH2 in osteoblasts abolished the alda-1 effects. Further, alda-1 attenuated the acetaldehyde-induced lipid-peroxidation and oxidative stress. BMP-2 is essential for bone regeneration and alda-1 increased its expression in osteoblasts. We then showed that alda-1 (40 mg/kg dose) augmented bone regeneration at the fracture site with concomitant increase in BMP-2 protein compared with control. The osteogenic dose (40 mg/kg) of alda-1 attained a bone marrow concentration that was stimulatory for osteoblast differentiation, suggesting that the tissue concentration of alda-1 matched its pharmacologic effect. In addition, alda-1 promoted modeling-directed bone growth and peak bone mass achievement, and increased bone mass in adult rats which reiterated its osteogenic effect. In osteopenic ovariectomized (OVX) rats, alda-1 reversed trabecular osteopenia with attendant increase in serum osteogenic marker (procollagen type I N-terminal peptide) and decrease in oxidative stress. Alda-1 has no effect on liver and kidney function. We conclude that activating ALDH2 by alda-1 had an osteoanabolic effect involving increased osteoblastic BMP-2 production and decreased OVX-induced oxidative stress. - Highlights: • Alda-1 induced osteoblast differentiation that involved upregulation of ALDH2 and BMP-2 • Alda-1

Can experimental data in humans verify the finite element-based bone remodeling algorithm?

DEFF Research Database (Denmark)

Wong, C.; Gehrchen, P.M.; Kiaer, T.

2008-01-01

STUDY DESIGN: A finite element analysis-based bone remodeling study in human was conducted in the lumbar spine operated on with pedicle screws. Bone remodeling results were compared to prospective experimental bone mineral content data of patients operated on with pedicle screws. OBJECTIVE......: The validity of 2 bone remodeling algorithms was evaluated by comparing against prospective bone mineral content measurements. Also, the potential stress shielding effect was examined using the 2 bone remodeling algorithms and the experimental bone mineral data. SUMMARY OF BACKGROUND DATA: In previous studies...... operated on with pedicle screws between L4 and L5. The stress shielding effect was also examined. The bone remodeling results were compared with prospective bone mineral content measurements of 4 patients. They were measured after surgery, 3-, 6- and 12-months postoperatively. RESULTS: After 1 year...

Biomechanical study of the bone tissue with dental implants interaction

Directory of Open Access Journals (Sweden)

Navrátil P.

2011-12-01

Full Text Available The article deals with the stress-strain analysis of human mandible in the physiological state and after the dental implant application. The evaluation is focused on assessing of the cancellous bone tissue modeling-level. Three cancellous bone model-types are assessed: Non-trabecular model with homogenous isotropic material, nontrabecular model with inhomogeneous material obtained from computer tomography data using CT Data Analysis software, and trabecular model built from mandible section image. Computational modeling was chosen as the most suitable solution method and the solution on two-dimensional level was carried out. The results show that strain is more preferable value than stress in case of evaluation of mechanical response in cancellous bone. The non-trabecular model with CT-obtained material model is not acceptable for stress-strain analysis of the cancellous bone for singularities occurring on interfaces of regions with different values of modulus of elasticity.

Unicameral (simple) bone cysts.

Science.gov (United States)

Baig, Rafath; Eady, John L

2006-09-01

Since their original description by Virchow, simple bone cysts have been studied repeatedly. Although these defects are not true neoplasms, simple bone cysts may create major structural defects of the humerus, femur, and os calcis. They are commonly discovered incidentally when x-rays are taken for other reasons or on presentation due to a pathologic fracture. Various treatment strategies have been employed, but the only reliable predictor of success of any treatment strategy is the age of the patient; those being older than 10 years of age heal their cysts at a higher rate than those under age 10. The goal of management is the formation of a bone that can withstand the stresses of use by the patient without evidence of continued bone destruction as determined by serial radiographic follow-up. The goal is not a normal-appearing x-ray, but a functionally stable bone.

Quasi-static and ratcheting properties of trabecular bone under uniaxial and cyclic compression.

Science.gov (United States)

Gao, Li-Lan; Wei, Chao-Lei; Zhang, Chun-Qiu; Gao, Hong; Yang, Nan; Dong, Li-Min

2017-08-01

The quasi-static and ratcheting properties of trabecular bone were investigated by experiments and theoretical predictions. The creep tests with different stress levels were completed and it is found that both the creep strain and creep compliance increase rapidly at first and then increase slowly as the creep time goes by. With increase of compressive stress the creep strain increases and the creep compliance decreases. The uniaxial compressive tests show that the applied stress rate makes remarkable influence on the compressive behaviors of trabecular bone. The Young's modulus of trabecular bone increases with increase of stress rate. The stress-strain hysteresis loops of trabecular bone under cyclic load change from sparse to dense with increase of number of cycles, which agrees with the change trend of ratcheting strain. The ratcheting strain rate rapidly decreases at first, and then exhibits a relatively stable and small value after 50cycles. Both the ratcheting strain and ratcheting strain rate increase with increase of stress amplitude or with decrease of stress rate. The creep model and the nonlinear viscoelastic constitutive model of trabecular bone were proposed and used to predict its creep property and rate-dependent compressive property. The results show that there are good agreements between the experimental data and predictions. Copyright © 2017 Elsevier B.V. All rights reserved.

Three-Dimensional Finite Element Analysis of Maxillary Sinus Floor Augmentation with Optimal Positioning of a Bone Graft Block

Directory of Open Access Journals (Sweden)

Peter Schuller-Götzburg

2018-01-01

Full Text Available Purpose: the aim of the computational 3D-finite element study is to evaluate the influence of an augmented sinus lift with additional inserted bone grafting. The bone graft block stabilizes the implant in conjunction with conventional bone augmentation. Two finite element models were applied: the real geometry based bone models and the simplified geometry models. The bone graft block was placed in three different positions. The implants were loaded first with an axial force and then with forces simulating laterotrusion and protrusion. This study examines whether the calculated stress behavior is symmetrical for both models. Having established a symmetry between the primary axis, the laterotrusion and protrusion behavior reduces calculation efforts, by simplifying the model. Material and Methods: a simplified U-shaped 3D finite element model of the molar region of the upper jaw and a more complex anatomical model of the left maxilla with less cortical bone were created. The bone graft block was placed in the maxillary sinus. Then the von Mises stress distribution was calculated and analyzed at three block positions: at contact with the sinus floor, in the middle of the implant helix and in the upper third of the implant. The two finite element models were then compared to simplify the modelling. Results: the position of the bone graft block significantly influences the magnitude of stress distribution. A bone graft block positioned in the upper third or middle of the implant reduces the quantity of stress compared to the reference model without a bone graft block. The low bone graft block position is clearly associated with lower stress distribution in compact bone. We registered no significant differences in stress in compact bone with regard to laterotrusion or protrusion. Conclusions: maximum values of von Mises stresses in compact bone can be reduced significantly by using a bone graft block. The reduction of stress is nearly the same for

Reconstructing the tectonic history of Fennoscandia from its margins: The past 100 million years

International Nuclear Information System (INIS)

Muir Wood, R.

1995-12-01

In the absence of onland late Mesozoic and Cenozoic geological formations the tectonic history of the Baltic Shield over the past 100 million years can most readily be reconstructed from the thick sedimentary basins that surround Fennoscandia on three sides. Tectonic activity around Fennoscandia through this period has been diverse but can be divided into four main periods: a. pre North Atlantic spreading ridge (100-60 Ma) when transpressional deformation on the southern margins of Fennoscandia and transtensional activity to the west was associated with a NNE-SSW maximum compressive stress direction; b. the creation of the spreading ridge (60-45 Ma) when there was rifting along the western margin; c. the re-arrangement of spreading axes (45-25 Ma) when there was a radial compression around Fennoscandia, and d. the re-emergence of the Iceland hot-spot (25-0 Ma) when the stress-field has come to accord with ridge or plume 'push'. Since 60 Ma the Alpine plate boundary has had little influence on Fennoscandia. The highest levels of deformation on the margins of Fennoscandia were achieved around 85 Ma, 60-55 Ma, with strain-rates around 10 -9 /year. Within the Baltic Shield long term strain rates have been around 10 -1 1/year, with little evidence for evidence for significant deformations passing into the shield from the margins. Fennoscandian Border Zone activity, which was prominent from 90-60 Ma, was largely abandoned following the creation of the Norwegian Sea spreading ridge, and with the exception of the Lofoten margin, there is subsequently very little evidence for deformation passing into Fennoscandia. Renewal of modest compressional deformation in the Voering Basin suggest that the 'Current Tectonic Regime' is of Quaternary age although the orientation of the major stress axis has remained approximately consistent since around 10 Ma. The past pattern of changes suggest that in the geological near-future variations are to be anticipated in the magnitude rather

Reconstructing the tectonic history of Fennoscandia from its margins: The past 100 million years

Energy Technology Data Exchange (ETDEWEB)

Muir Wood, R [EQE International Ltd (United Kingdom)

1995-12-01

In the absence of onland late Mesozoic and Cenozoic geological formations the tectonic history of the Baltic Shield over the past 100 million years can be reconstructed from the thick sedimentary basins that surround Fennoscandia on three sides. Tectonic activity around Fennoscandia through this period has been diverse but can be divided into four main periods: a. pre North Atlantic spreading ridge (100-60 Ma) when transpressional deformation on the southern margins of Fennoscandia and transtensional activity to the west was associated with a NNE-SSW maximum compressive stress direction; b. the creation of the spreading ridge (60-45 Ma) when there was rifting along the western margin; c. the re-arrangement of spreading axes (45-25 Ma) when there was a radial compression around Fennoscandia, and d. the re-emergence of the Iceland hot-spot (25-0 Ma) when the stress-field has come to accord with ridge or plume `push`. Since 60 Ma the Alpine plate boundary has had little influence on Fennoscandia. The highest levels of deformation on the margins of Fennoscandia were achieved around 85 Ma, 60-55 Ma, with strain-rates around 10{sup -9}/year. Within the Baltic Shield long term strain rates have been around 10{sup -1}1/year, with little evidence for significant deformations passing into the shield from the margins. Fennoscandian Border Zone activity, which was prominent from 90-60 Ma, was largely abandoned following the creation of the Norwegian Sea spreading ridge, and with the exception of the Lofoten margin, there is subsequently little evidence for deformation passing into Fennoscandia. Renewal of modest compressional deformation in the Voering Basin suggest that the `Current Tectonic Regime` is of Quaternary age although the orientation of the major stress axis has remained consistent since around 10 Ma. The past pattern of changes suggest that in the geological near-future variations are to be anticipated in the magnitude rather than the orientation of stresses.

Radioisotopic and Radiological Evaluation in Patient with Stress Fracture

International Nuclear Information System (INIS)

Ko, Kwang Seop; Kim, Jai Young; Kang, Sung Koo; Kim, So Yon; Lee, Gwon Jun

1987-01-01

The stress fracture is a disease caused by and abnormal stress to the normal bone with constant, repeated pull. Early detection of stress fracture plays an important role in treatment and prevention of its complication. Bone scintigraphy was performed to evaluate 18 patients with stress fracture of the lower extremities from May, 1985 to April, 1987, in the Department of Internal Medicine of National Police Hospital. The results were as follows: 1) Seventeen of the 18 cases showed positive bone scans at the initial study performed from 1 week to 5 months after the onset of symptom. 2) Ten of the 18 patients had findings of stress fracture at the initial X-ray film. Two out of 8 negative case revealed positive findings in the follow-up studies. 3) The bone scans in the 2 cases taken 5 months after the onset of symptom; the one showed only slightly increased radio uptake, the other showed no abnormal findings. In conclusion, bone scanning is a more sensitive indicator of early stress fracture than radiologic study, The healing phase is characterized by a gradual decline in radioactivity at the fracture site in concordance with subsidence of symptom.

Correlation between bone mineral density and oxidative stress in postmenopausal women

Directory of Open Access Journals (Sweden)

Tripti Sharma

2015-01-01

Full Text Available Background: Postmenopausal osteoporosis affects large fraction of elderly women. Oxidative stress (OS appears to be involved in its pathogenesis. The scarcity of human studies focusing on the correlation between bone mineral density (BMD and OS in postmenopausal women has prompted us to study on this issue. Materials and Methods: We conducted a cross sectional study in 95 subjects, between 21-65 years of age, including postmenopausal osteoporotic females (n = 35, healthy postmenopausal females (n = 30 and healthy females in reproductive age group (n = 30. We measured serum antioxidant activity of superoxide dismutase (SOD, catalase, glutathione peroxidase (GPx, and total antioxidant power (TAP. BMD was obtained at lumbar spine and femur neck by dual-energy X-ray absorptiometry scan. Osteoporosis was considered when subjects had a BMD of 2.5 standard deviations or more below the mean value for young adults. Results: Serum GPx, SOD, catalase and TAP level were found significantly lower in osteoporotic postmenopausal group as compared to healthy postmenopausal women and women in healthy reproductive age group healthy reproductive women (P 0.005. Conclusion: These findings support that oxidative stress plays an important role in pathogenesis of postmenopausal osteoporosis. We did not find any significant association between BMD and serum level of antioxidants (P > 0.05. The failure to detect this association does not preclude the role of OS in osteoporosis because OS is complex and dynamic process.

Determination of the effects of organic antioxidants and fat sources on performance, carcass and bone characteristics of broilers under heat stress

Directory of Open Access Journals (Sweden)

seyyed javad Hosseini-vashan

2016-11-01

Full Text Available Introduction Heat stress is one of the major environmental stressors that negatively influence feed intake, body weight gain, feed conversion ratio, nutrient digestion, absorption, and retention in the poultry production. In the two last decades, several researches were done to find approaches for decreasing the undesirable effects of high ambient temperatures. Supplementation of powder, extract and essence of some medicinal plants were proposed that could be used in poultry production to improve the performance, immune system and antioxidant status in heat stress condition. Turmeric powder is known as a natural antioxidant, because it has several antioxidant component specially curcumin that prevent the oxidative reaction and the free radicals production in the live body. On the other hand, some of by-products in food industry may also be used in heat stressed birds. Tomato pomace is a reachable source of vit E, C and A and several carotenoids specially lycopene that has antimutagenic, anticancer and antioxidant properties. Therefore the objective of this research was to investigate the effects of organic antioxidants including turmeric powder and tomato pomace and fat sources including soybean oil, canola oil and tallow on performance, carcass and bone characteristics of broilers under heat stress. Materials and Methods An experiment with factorial arrangement 3× 2× 2 (3 oils involved: canola, soybean, tallow, 2 turmeric powder (TRP levels involved 0.4, 0.8% and 2 tomato pomace (TP levels 3, 5 of TP% in a completely randomized design in heat stressed birds was done. Five hundred four one-d-old male Ross broilers were randomly allocated to 36 experimental units with 12 dietary treatments (3 replicates with 12 birds in each. The feed and water were supplied ad libitum. All diets were balanced to meet the nutrient requirement proposed by the Ross committee. A daily heat stressed (HS schedule (33oC for 5 h was applied from 29 to 42d of

Computational modelling of the mechanics of trabecular bone and marrow using fluid structure interaction techniques.

Science.gov (United States)

Birmingham, E; Grogan, J A; Niebur, G L; McNamara, L M; McHugh, P E

2013-04-01

Bone marrow found within the porous structure of trabecular bone provides a specialized environment for numerous cell types, including mesenchymal stem cells (MSCs). Studies have sought to characterize the mechanical environment imposed on MSCs, however, a particular challenge is that marrow displays the characteristics of a fluid, while surrounded by bone that is subject to deformation, and previous experimental and computational studies have been unable to fully capture the resulting complex mechanical environment. The objective of this study was to develop a fluid structure interaction (FSI) model of trabecular bone and marrow to predict the mechanical environment of MSCs in vivo and to examine how this environment changes during osteoporosis. An idealized repeating unit was used to compare FSI techniques to a computational fluid dynamics only approach. These techniques were used to determine the effect of lower bone mass and different marrow viscosities, representative of osteoporosis, on the shear stress generated within bone marrow. Results report that shear stresses generated within bone marrow under physiological loading conditions are within the range known to stimulate a mechanobiological response in MSCs in vitro. Additionally, lower bone mass leads to an increase in the shear stress generated within the marrow, while a decrease in bone marrow viscosity reduces this generated shear stress.

Effects of metformin on inflammation, oxidative stress, and bone loss in a rat model of periodontitis.

Science.gov (United States)

Araújo, Aurigena Antunes de; Pereira, Aline de Sousa Barbosa Freitas; Medeiros, Caroline Addison Carvalho Xavier de; Brito, Gerly Anne de Castro; Leitão, Renata Ferreira de Carvalho; Araújo, Lorena de Souza; Guedes, Paulo Marcos Matta; Hiyari, Sarah; Pirih, Flávia Q; Araújo Júnior, Raimundo Fernandes de

2017-01-01

To evaluate the effects of metformin (Met) on inflammation, oxidative stress, and bone loss in a rat model of ligature-induced periodontitis. Male albino Wistar rats were divided randomly into five groups of twenty-one rats each, and given the following treatments for 10 days: (1) no ligature + water, (2) ligature + water, (3) ligature + 50 mg/kg Met, (4) ligature + 100 mg/kg Met, and (5) ligature + 200 mg/kg Met. Water or Met was administered orally. Maxillae were fixed and scanned using Micro-computed Tomography (μCT) to quantitate linear and bone volume/tissue volume (BV/TV) volumetric bone loss. Histopathological characteristics were assessed through immunohistochemical staining for MMP-9, COX-2, the RANKL/RANK/OPG pathway, SOD-1, and GPx-1. Additionally, confocal microscopy was used to analyze osteocalcin fluorescence. UV-VIS analysis was used to examine the levels of malondialdehyde, glutathione, IL-1β and TNF-α from gingival tissues. Quantitative RT-PCR reaction was used to gene expression of AMPK, NF-κB (p65), and Hmgb1 from gingival tissues. Significance among groups were analysed using a one-way ANOVA. A p-value of ploss after 50 mg/kg Met compared to the ligature and Met 200 mg/kg groups. The same pattern was observed volumetrically in BV/TV and decreased osteoclast number (ploss in ligature-induced periodontitis in rats.

[Researches on biomechanics of micro-implant-bone interface and optimum design of micro implant's neck].

Science.gov (United States)

Deng, Feng; Zhang, Lei; Zhang, Yi; Song, Jin-lin; Fan, Yuboa

2007-07-01

To compare and analyze the stress distribution at the micro-implant-bone interface based on the different micro-implant-bone conditioned under orthodontic load, and to optimize the design of micro implant's neck. An adult skull with all tooth was scanned by spiral CT, and the data were imported into computer for three-dimensional reconstruction with software Mimics 9.0. The three dimensional finite element models of three micro-implant-bone interfaces(initial stability, full osseointegration and fibrous integration) were analyzed by finite element analysis software ABAQUS6.5. The primary stress distributions of different micro-implant-bone conditions were evaluated when 2N force was loaded. Then the diameter less than 1.5 mm of the micro implant's neck was added with 0.2 mm, to compare the stress distribution of the modified micro-implant-bone interface with traditional type. The stress mostly concentrated on the neck of micro implant and the full osseointegration interface in all models showed the lowest strain level. Compared with the traditional type, the increasing diameter neck of the micro implant obviously decreased the stress level in all the three conditions. The micro-implant-bone interface and the diameter of micro implant's neck both are the important influence factors to the stress distribution of micro implant.

Adaptive Bone Remodeling of the Femoral Bone After Tumor Resection Arthroplasty With an Uncemented Proximally Hydroxyapatite-Coated Stem

DEFF Research Database (Denmark)

Andersen, Mikkel R.; Petersen, Michael M.

2016-01-01

-fluted 125-mm uncemented press-fit titanium alloy stem with hydroxyapatite coating of the proximal part of the stem. Measurements of bone mineral density (BMD; g/cm2) were done postoperatively and after 3, 6, and 12 mo in the part of the femur bone containing the Global Modular Replacement System stem using...... of 8%-9% during the first postoperative year was seen along the femoral stem, but in the bone containing the hydroxyapatite-coated part of the stem, the decrease in BMD was 14%, thus indicating that stress shielding of this part of the bone may play a role for the adaptive bone remodeling....

Bone health in endurance athletes: runners, cyclists, and swimmers.

Science.gov (United States)

Scofield, Kirk L; Hecht, Suzanne

2012-01-01

Weight-bearing exercise has been recognized widely to be beneficial for long-term bone health. However inherent differences in bone-loading characteristics and energy expenditure during participation in endurance sports place many endurance athletes at a relative disadvantage with regard to bone health compared with other athletes. Adolescents and adults who participate in endurance sports, such as running, and non-weight-bearing sports, such as biking and swimming, often have lower bone mineral density (BMD) than athletes participating in ball and power sports, and sometimes their BMD is lower than their inactive peers. Low BMD increases the risk of stress and fragility fractures, both while an athlete is actively competing and later in life. This article reviews the variable effects of distance running, cycling, swimming, and triathlons on bone health; the evaluation of stress and fragility fractures; and the diagnosis, management, and prevention of low BMD in endurance athletes.

Peritumoral bone marrow edema accompanying benign giant cell tumor

International Nuclear Information System (INIS)

Kim, Sung Hun; Park, Jeong Mi; Kim, Ji Yong; Gi, Won Hee; Sung, Mi Suk; Lee, Jae Mun; Shin, Kyung Sub

1998-01-01

To evaluate the frequency of peritumoral bone marrow(BM) edema accompanying benign giant cell tumor(GCT) of the appendicular bone by magnetic resonance(MR) imaging and to correlate MRI findings with those of plain radiography and bone scintigraphy. Eighteen cases of pathologically proven benign GCT of the appendicular bone were retrospectively analyzed using MR images, plain radiographs and bone scintigrams. A plain radiography was available in 15 cases, and a scintigram in six. Marrow edema was defined as peritumoral signal changes which were of homogeneous intermediate or low signal intensity(SI) onT1WI and high SI on T2WI, relative to the SI of normal BM, and homogeneous enhancement on Gd-DTPA -enhanced T1WI. The transition zone, sclerotic margin and aggressiveness of the lesion were assessed on the basis of plain radiographs. BM edema seen on MR images was correlated with plain radiographic and scintigraphic findings. 1. Peritumoral BM edema was seen on MR images in 10 of 18 cases (55.5%). 2. In 8 of 15 cases for which plain radiographs were available, MR imaging revealed BM edema. In six of these eight, transition zone was wide, while in two it was narrow. Six of seven patients without marrow edema showed a wide transition zone, and in one this was narrow. There was significant correlation between BM edema shown by MR imaging and the transition zone seen on plain radiographs (x 2 , p<0.05). But the aggressiveness shown by plain radiographs correlated only marginally while the presence of sclerotic rim did not correlate. 3. All six cases for which a bone scintigram was available showed an extended uptake pattern. In five of the six, MR imaging revealed edema. Peritumoral BM edema was frequently seen (55.5%) in the GCTs of appendicular bone; it was more often shown in association with a wide transition zone by plain radiographs.=20

A novel transgenic mouse model of growth plate dysplasia reveals that decreased chondrocyte proliferation due to chronic ER stress is a key factor in reduced bone growth

Directory of Open Access Journals (Sweden)

Benedetta Gualeni

2013-11-01

Disease mechanisms leading to different forms of chondrodysplasia include extracellular matrix (ECM alterations and intracellular stress resulting in abnormal changes to chondrocyte proliferation and survival. Delineating the relative contribution of these two disease mechanisms is a major challenge in understanding disease pathophysiology in genetic skeletal diseases and a prerequisite for developing effective therapies. To determine the influence of intracellular stress and changes in chondrocyte phenotype to the development of chondrodysplasia, we targeted the expression of the G2320R mutant form of thyroglobulin to the endoplasmic reticulum (ER of resting and proliferating chondrocytes. Previous studies on this mutant protein have shown that it induces intracellular aggregates and causes cell stress and death in the thyroid gland. The expression and retention of this exogenous mutant protein in resting and proliferating chondrocytes resulted in a chronic cell stress response, growth plate dysplasia and reduced bone growth, without inducing any alterations to the architecture and organization of the cartilage ECM. More significantly, the decreased bone growth seemed to be the direct result of reduced chondrocyte proliferation in the proliferative zone of growth plates in transgenic mice, without transcriptional activation of a classical unfolded protein response (UPR or apoptosis. Overall, these data show that mutant protein retention in the ER of resting and proliferative zone chondrocytes is sufficient to cause disrupted bone growth. The specific disease pathways triggered by mutant protein retention do not necessarily involve a prototypic UPR, but all pathways impact upon chondrocyte proliferation in the cartilage growth plate.

Perioperative fractionated high-dose rate brachytherapy for malignant bone and soft tissue tumors

International Nuclear Information System (INIS)

Koizumi, Masahiko; Inoue, Takehiro; Yamazaki, Hideya; Teshima, Teruki; Tanaka, Eiichi; Yoshida, Ken; Imai, Atsushi; Shiomi, Hiroya; Kagawa, Kazufumi; Araki, Nobuto; Kuratsu, Shigeyuki; Uchida, Atsumasa; Inoue, Toshihiko

1999-01-01

Purpose: To investigate the viability of perioperative fractionated HDR brachytherapy for malignant bone and soft tissue tumors, analyzing the influence of surgical margin. Methods and Materials: From July 1992 through May 1996, 16 lesions of 14 patients with malignant bone and soft tissue tumors (3 liposarcomas, 3 MFHs, 2 malignant schwannomas, 2 chordomas, 1 osteosarcoma, 1 leiomyosarcoma, 1 epithelioid sarcoma, and 1 synovial sarcoma) were treated at the Osaka University Hospital. The patients' ages ranged from 14 to 72 years (median: 39 years). Treatment sites were the pelvis in 6 lesions, the upper limbs in 5, the neck in 4, and a lower limb in 1. The resection margins were classified as intracapsular in 5 lesions, marginal in 5, and wide in 6. Postoperative fractionated HDR brachytherapy was started on the 4th-13th day after surgery (median: 6th day). The total dose was 40-50 Gy/7-10 fr/ 4-7 day (bid) at 5 or 10 mm from the source. Follow-up periods were between 19 and 46 months (median: 30 months). Results: Local control rates were 75% at 1 year and 48% in 2 years, and ultimate local control was achieved in 8 (50%) of 16 lesions. Of the 8 uncontrolled lesions, 5 (63%) had intracapsular (macroscopically positive) resection margins, and all the 8 controlled lesions (100%) had marginal (microscopically positive) or wide (negative) margins. Of the total, 3 patients died of both tumor and metastasis, 3 of metastasis alone, 1 of tumor alone, and 7 showed no evidence of disease. Peripheral nerve palsy was seen in one case after this procedure, but no infection or delayed wound healing caused by tubing or irradiation has occurred. Conclusion: Perioperative fractionated HDR brachytherapy is safe, well tolerated, and applicable to marginal or wide surgical margin cases

Stress Erythropoiesis Model Systems.

Science.gov (United States)

Bennett, Laura F; Liao, Chang; Paulson, Robert F

2018-01-01

Bone marrow steady-state erythropoiesis maintains erythroid homeostasis throughout life. This process constantly generates new erythrocytes to replace the senescent erythrocytes that are removed by macrophages in the spleen. In contrast, anemic or hypoxic stress induces a physiological response designed to increase oxygen delivery to the tissues. Stress erythropoiesis is a key component of this response. It is best understood in mice where it is extramedullary occurring in the adult spleen and liver and in the fetal liver during development. Stress erythropoiesis utilizes progenitor cells and signals that are distinct from bone marrow steady-state erythropoiesis. Because of that observation many genes may play a role in stress erythropoiesis despite having no effect on steady-state erythropoiesis. In this chapter, we will discuss in vivo and in vitro techniques to study stress erythropoiesis in mice and how the in vitro culture system can be extended to study human stress erythropoiesis.

Comparison of marginal bone loss between internal- and external-connection dental implants in posterior areas without periodontal or peri-implant disease.

Science.gov (United States)

Kim, Dae-Hyun; Kim, Hyun Ju; Kim, Sungtae; Koo, Ki-Tae; Kim, Tae-Il; Seol, Yang-Jo; Lee, Yong-Moo; Ku, Young; Rhyu, In-Chul

2018-04-01

The purpose of this retrospective study with 4-12 years of follow-up was to compare the marginal bone loss (MBL) between external-connection (EC) and internal-connection (IC) dental implants in posterior areas without periodontal or peri-implant disease on the adjacent teeth or implants. Additional factors influencing MBL were also evaluated. This retrospective study was performed using dental records and radiographic data obtained from patients who had undergone dental implant treatment in the posterior area from March 2006 to March 2007. All the implants that were included had follow-up periods of more than 4 years after loading and satisfied the implant success criteria, without any peri-implant or periodontal disease on the adjacent implants or teeth. They were divided into 2 groups: EC and IC. Subgroup comparisons were conducted according to splinting and the use of cement in the restorations. A statistical analysis was performed using the Mann-Whitney U test for comparisons between 2 groups and the Kruskal-Wallis test for comparisons among more than 2 groups. A total of 355 implants in 170 patients (206 EC and 149 IC) fulfilled the inclusion criteria and were analyzed in this study. The mean MBL was 0.47 mm and 0.15 mm in the EC and IC implants, respectively, which was a statistically significant difference ( P <0.001). Comparisons according to splinting (MBL of single implants: 0.34 mm, MBL of splinted implants: 0.31 mm, P =0.676) and cement use (MBL of cemented implants: 0.27 mm, MBL of non-cemented implants: 0.35 mm, P =0.178) showed no statistically significant differences in MBL, regardless of the implant connection type. IC implants showed a more favorable bone response regarding MBL in posterior areas without peri-implantitis or periodontal disease.

[Research advances of fluid bio-mechanics in bone].

Science.gov (United States)

Chen, Zebin; Huo, Bo

2017-04-01

It has been found for more than one century that when experiencing mechanical loading, the structure of bone will adapt to the changing mechanical environment, which is called bone remodeling. Bone remodeling is charaterized as two processes of bone formation and bone resorption. A large number of studies have confirmed that the shear stress is resulted from interstitial fluid flow within bone cavities under mechanical loading and it is the key factor of stimulating the biological responses of bone cells. This review summarizes the major research progress during the past years, including the biological response of bone cells under fluid flow, the pressure within bone cavities, the theoretical modeling, numerical simulation and experiments about fluid flow within bone, and finally analyzes and predicts the possible tendency in this field in the future.

Comparison of prostate set-up accuracy and margins with off-line bony anatomy corrections and online implanted fiducial-based corrections.

Science.gov (United States)

Greer, P B; Dahl, K; Ebert, M A; Wratten, C; White, M; Denham, J W

2008-10-01

The aim of the study was to determine prostate set-up accuracy and set-up margins with off-line bony anatomy-based imaging protocols, compared with online implanted fiducial marker-based imaging with daily corrections. Eleven patients were treated with implanted prostate fiducial markers and online set-up corrections. Pretreatment orthogonal electronic portal images were acquired to determine couch shifts and verification images were acquired during treatment to measure residual set-up error. The prostate set-up errors that would result from skin marker set-up, off-line bony anatomy-based protocols and online fiducial marker-based corrections were determined. Set-up margins were calculated for each set-up technique using the percentage of encompassed isocentres and a margin recipe. The prostate systematic set-up errors in the medial-lateral, superior-inferior and anterior-posterior directions for skin marker set-up were 2.2, 3.6 and 4.5 mm (1 standard deviation). For our bony anatomy-based off-line protocol the prostate systematic set-up errors were 1.6, 2.5 and 4.4 mm. For the online fiducial based set-up the results were 0.5, 1.4 and 1.4 mm. A prostate systematic error of 10.2 mm was uncorrected by the off-line bone protocol in one patient. Set-up margins calculated to encompass 98% of prostate set-up shifts were 11-14 mm with bone off-line set-up and 4-7 mm with online fiducial markers. Margins from the van Herk margin recipe were generally 1-2 mm smaller. Bony anatomy-based set-up protocols improve the group prostate set-up error compared with skin marks; however, large prostate systematic errors can remain undetected or systematic errors increased for individual patients. The margin required for set-up errors was found to be 10-15 mm unless implanted fiducial markers are available for treatment guidance.

Bone scintigraphy in bone stress. A technical consideration and correlation of the findings to clinical symptoms especially to the pain

International Nuclear Information System (INIS)

Kuusela, T.; Vorne, M.; Vahatalo, S.

1983-01-01

The purpose of this investigation was to find out a reliable scintigraphic method to investigate different fatigue phenomena in bone and to correlate the scintigraphic findings to the development of clinical symptoms. The gamma-imaging after the injection of bone seeking tracers is recommended to be performed after a period of 1-3 hours. The experiments indicate that in active bone tissue, might it be a healing fracture or a remodeling bone, the tracer uptake still increases after 1-3 hours. The delayed gamma-imaging can therefore be useful, especially if it is important to investigate faint physiological changes in bone tissue. It seems, that the capacity of emission energy in the diagnosis of bone affections is superior to the radiology because of its excellent histo-functional resolution especially in detecting and localizing bone affections

Late Cenozoic flexural deformation of the middle U.S. Atlantic passive margin

Science.gov (United States)

Pazzaglia, Frank J.; Gardner, Thomas, W.

1994-01-01

Despite the century-long recognition of regional epeirogeny along the middle Atlantic passive margin, relatively few studies have focused on understanding postrift uplift mechanisms. Here, we demonstrate that epeirogenic uplift of the central Appalachian Piedmont and subsidence of the Salisbury Embayment represent first-order, flexural isostatic processes driven by continental denudation and offshore deposition. Our results show that regional epeirogenic processes, present on all Atlantic-type passive margins, are best resolved by specific stratigraphic and geomorphic relationships, rather than topography. A simple one-dimensional geodynamic model, constrained by well-dated Baltimore Canyon trough, Coastal Plain, and lower Susquehanna River (piedmont) stratigraphy, simulates flexural deforamtion of the U.S. Atlantic margin. The model represents the passive margin lithosphree as a uniformly thick elastic plate, without horizontal compressive stresses, that deforms flexurally under the stress of strike-averaged, vertically applied line loads. Model results illustrate a complex interaction among margin stratigraphy and geomorphology, the isostatic repsonse to denudational and depositional processes, and the modulating influence of exogenic forces such as eustasy. The current elevation, with respect to modern sea level, of fluvial terraces and correlateive Coastal Plain deposits or unconformities is successfully predicted through the synthesis of paleotopography, eustatic change, and margin flexure. Results suggest that the middle U.S. Atlantic margin landward of East Coast Magnetic Anomaly is underlain by lithoshpere with an average elastic thickness of 40 km (flexural rigidity, D = 4 X 10(exp 23) N m), the margin experience an average, long-term denudation rate of approximately 10m/m.y., and the Piedmont has been flexurally upwaped between 35 and 130 meters in the last 15 m.y. Long term isostatic continental uplift resulting rom denudation and basin subsidence

Bone-Cement: The New Medical Quick Fix

Directory of Open Access Journals (Sweden)

Dinesh Bhatia

2010-01-01

Full Text Available

margin-bottom: .0001pt; text-align: justify; line-height: normal;">Bone Cement is being widely used in vertebroplasty, a minimally invasive surgical procedure to treat spinal fractures and collapsed vertebrae. It is being labeled as a concrete success in medical field. It is being used to treat fractures due to osteoporosis, menopause, steroids, hyperthyroidism and chronic obstructive pulmonary diseases.  In this technique a needle with bone cement (PMMA, polymethylmethacrylate is injected into the collapsed vertebra after administering local anesthesia to patient. It solidifies within few minutes and provides support to damaged bone resulting in relief to the patient. It also prevents the movement between different parts of the broken bone. Hence it requires a short hospital stay for the patient and the procedure can be performed with much ease and at significant lower costs. Patient can resume normal activity within a day or so. Bone cement is now being referred to as the quick medical fix material for early repair of fractures.

Finite element analysis of functionally graded bone plate at femur bone fracture site

Science.gov (United States)

Satapathy, Pravat Kumar; Sahoo, Bamadev; Panda, L. N.; Das, S.

2018-03-01

This paper focuses on the analysis of fractured Femur bone with functionally graded bone plate. The Femur bone is modeled by using the data from the CT (Computerized Tomography) scan and the material properties are assigned using Mimics software. The fracture fixation plate used here is composed of Functionally Graded Material (FGM). The functionally graded bone plate is considered to be composed of different layers of homogeneous materials. Finite element method approach is adopted for analysis. The volume fraction of the material is calculated by considering its variation along the thickness direction (z) according to a power law and the effective properties of the homogeneous layers are estimated. The model developed is validated by comparing numerical results available in the literature. Static analysis has been performed for the bone plate system by considering both axial compressive load and torsional load. The investigation shows that by introducing FG bone plate instead of titanium, the stress at the fracture site increases by 63 percentage and the deformation decreases by 15 percentage, especially when torsional load is taken into consideration. The present model yields better results in comparison with the commercially available bone plates.

Methodological model of chronic stress associated with ligature-induced periodontitis in rats: a radiographic study

Directory of Open Access Journals (Sweden)

Alex Semenoff Segundo

2010-12-01

Full Text Available This study evaluated the time efficiency of stress associated with ligature-induced periodontitis in rats. Sixty adult Wistar rats, housed in temperature-controlled rooms and receiving water and food ad libitum, were randomly separated into stress (n = 30 or control groups (n = 30. All animals were anesthetized, and nylon ligatures were placed at the gingival margin level of the maxillary right second molars. After the induction of periodontitis, rats in the stress group were subjected to physical restraint for 12 hours daily. The animals were euthanized after 7, 15 and 30 days by anesthetic overdose (10 animals per group per period. The right hemimaxillae were stored in formalin solution for 48 hours. Parallel radiographic images of the hemimaxillae were taken and processed following standard procedures. Radiographic examination was performed by a blinded and previously calibrated investigator. Bone height level was measured, and data were submitted to analysis of variance and post hoc Bonferroni tests (p 0.05. Restraint stress modulates the short-term progression of periodontal disease in rats. Therefore, the 12-hour daily physical restraint stress model in rats applied for up to 15 days is suitable for the investigation of the combined effect of ligation and restraint stress on periodontal degradation.

Effect of Margin Designs on the Marginal Adaptation of Zirconia Copings.

Science.gov (United States)

Habib, Syed Rashid; Al Ajmi, Mohammed Ginan; Al Dhafyan, Mohammed; Jomah, Abdulrehman; Abualsaud, Haytham; Almashali, Mazen

2017-09-01

The aim of this in vitro study was to investigate the effect of Shoulder versus Chamfer margin design on the marginal adaptation of zirconia (Zr) copings. 40 extracted molar teeth were mounted in resin and prepared for zirconia crowns with two margin preparation designs (20=Shoulder and 20=Chamfer). The copings were manufactured by Cercon® (DeguDent GmbH, Germany) using the CAD/CAM system for each tooth. They were tried on each tooth, cemented, thermocycled, re-embedded in resin and were subsequently cross sectioned centrally into two equal mesial and distal halves. They were examined under electron microscope at 200 X magnification and the measurements were recorded at 5 predetermined points in micrometers (µm). The o verall mean marginal gap for the two groups was found to be 206.98+42.78µm with Shoulder margin design (Marginal Gap=199.50+40.72µm) having better adaptation compared to Chamfer (Marginal Gap=214.46+44.85µm). The independent-samples t-test showed a statistically non-significant difference (p=.113) between the means of marginal gap for Shoulder and Chamfer margin designs and the measurements were recorded at 5 predetermined points for the two groups. The Chamfer margin design appeared to offer the same adaptation results as the Shoulder margin design.

On-line fatigue monitoring and margins probabilistic assessment

International Nuclear Information System (INIS)

Fournier, I.; Morilhat, P.

1993-01-01

An on-line computer aided system has been developed by Electricite de France, the French utility, for a fatigue monitoring of critical locations in the nuclear steam supply system. This tool, called fatiguemeter, includes as input data only existing plant parameters and is based on some conservative assumptions at several steps of the damage assessment (thermal boundary conditions, stress computation...). This paper presents recent developments performed toward a better assessing of margins involved in the complete analysis. The methodology is enlightened with an example showing the influence of plant parameters incertitude on the final stress computed at a PWR 900 MW unit pressurizer surge line nozzle. (author)

Vascularized fibular graft in infected tibial bone loss

Directory of Open Access Journals (Sweden)

C Cheriyan Kovoor

2011-01-01

Full Text Available Background : The treatment options of bone loss with infections include bone transport with external fixators, vascularized bone grafts, non-vascularized autogenous grafts and vascularized allografts. The research hypothesis was that the graft length and intact ipsilateral fibula influenced hypertrophy and stress fracture. We retrospectively studied the graft hypertrophy in 15 patients, in whom vascularized fibular graft was done for post-traumatic tibial defects with infection. Materials and Methods : 15 male patients with mean age 33.7 years (range 18 - 56 years of post traumatic tibial bone loss were analysed. The mean bony defect was 14.5 cm (range 6.5 - 20 cm. The mean length of the graft was 16.7 cm (range 11.5 - 21 cm. The osteoseptocutaneous flap (bone flap with attached overlying skin flap from the contralateral side was used in all patients except one. The graft was fixed to the recipient bone at both ends by one or two AO cortical screws, supplemented by a monolateral external fixator. A standard postoperative protocol was followed in all patients. The hypertrophy percentage of the vascularized fibular graft was calculated by a modification of the formula described by El-Gammal. The followup period averaged 46.5 months (range 24 - 164 months. The Pearson correlation coefficient (r was worked out, to find the relationship between graft length and hypertrophy. The t-test was performed to find out if there was any significant difference in the graft length of those who had a stress fracture and those who did not and to find out whether there was any significant difference in hypertrophy with and without ipsilateral fibula union. The Chi square test was performed to identify whether there was any association between the stress fracture and the fibula union. Given the small sample size we have not used any statistical analysis to determine the relation between the percentage of the graft hypertrophy and stress fracture. Results : Graft

The use of bone turnover markers in chronic kidney disease-mineral and bone disorders.

Science.gov (United States)

Chiang, Cherie

2017-03-01

Bone turnover markers assist in fracture risk prediction, management and monitoring of osteoporosis in patients without chronic kidney disease (CKD). The use in CKD-mineral bone disorder (MBD) has been limited as many of these markers and breakdown products are renally excreted, including the most commonly used and well standardized procollagen type I N propeptide and C-terminal cross-linking telopeptide of type I collagen. Of the markers unaffected by renal function, bone specific alkaline phosphatase is associated with mortality and fracture rate in CKD subjects and is now available on several automated analysers. When used in combination with PTH, bone specific alkaline phosphatase as a bone formation marker correlated well with bone biopsy histomorphometry in predicting adynamic bone disease. Tartrate-resistant acid phosphatase 5b is a resorption marker that is under development for automation. Both high and low bone turnover in CKD-MBD patients are associated with increased fracture and mortality risk. Bone biopsy as the gold standard to differentiate between adynamic bone disease and osteitis fibrosa is limited by availability and cost. Appropriate use of bone turnover markers is vital in the decision to commence anti-resorptive agents, and to monitor efficacy in order to avoid over suppression of bone turnover, which may lead to stress fractures. Further efforts are required to develop markers unaffected by renal function with standardized cut-off values and fracture as well as vascular calcification end-points. © 2017 Asian Pacific Society of Nephrology.

A three-dimensional finite element analysis of a passive and friction fit implant abutment interface and the influence of occlusal table dimension on the stress distribution pattern on the implant and surrounding bone

Directory of Open Access Journals (Sweden)

Hasan Sarfaraz

2015-01-01

Conclusion : It can thus be concluded that the conical connection distributes more stress to the implant body and dissipates less stress to the surrounding bone. A narrow occlusal table considerably reduces the occlusal overload.

Bone scan in diagnosis of infectious osteoarthritis

International Nuclear Information System (INIS)

Marandian, M.H.; Mortazavi, H.; Behvad, A.; Haghigat, H.; Lessani, M.; Youssefian, B.

1979-01-01

Bone scan with Technetium 99m is harmless method of evaluation of skeletal lesions. It is safe in pediatrics age group and it can be used in early diagnosis of infectious osteoarthritis. Bone scan differentiate osteomyelitis from cellulitis, and also it may help in diagnosis of subclinical involvement of rheumatoid arthritis, benign and malignant bone tumors, stress fractures and periostitis. We report results of bone scan in 30 pediatrics patients as follow: osteomyelitis 9 cases, cellulitis 4 cases, infectious arthritis 7 cases, tuberculous osteoarthritis 2 cases, rheumatoid arthritis 2 cases, and other different diseases 9 cases [fr

Oxidative Stress, Bone Marrow Failure, and Genome Instability in Hematopoietic Stem Cells

Directory of Open Access Journals (Sweden)

Christine Richardson

2015-01-01

Full Text Available Reactive oxygen species (ROS can be generated by defective endogenous reduction of oxygen by cellular enzymes or in the mitochondrial respiratory pathway, as well as by exogenous exposure to UV or environmental damaging agents. Regulation of intracellular ROS levels is critical since increases above normal concentrations lead to oxidative stress and DNA damage. A growing body of evidence indicates that the inability to regulate high levels of ROS leading to alteration of cellular homeostasis or defective repair of ROS-induced damage lies at the root of diseases characterized by both neurodegeneration and bone marrow failure as well as cancer. That these diseases may be reflective of the dynamic ability of cells to respond to ROS through developmental stages and aging lies in the similarities between phenotypes at the cellular level. This review summarizes work linking the ability to regulate intracellular ROS to the hematopoietic stem cell phenotype, aging, and disease.

Catastrophic scapular fractures in Californian racehorses: pathology, morphometry and bone density.

Science.gov (United States)

Vallance, S A; Spriet, M; Stover, S M

2011-11-01

To enhance understanding of the nature and pathogenesis of scapular fractures in racehorses. Scapular fractures in racehorses have a consistent configuration related to sites of pre-existing stress modelling and remodelling. Fractured and intact scapulae collected post mortem were examined visually and with computed tomography (CT). Scapular fracture configuration, bone modelling changes and standardised CT morphometry and density measurements were recorded. Statistical comparisons were made between fractured, nonfractured contralateral and control scapulae. Thirty-nine scapulae from 10 Thoroughbred (TB) and 10 Quarter Horse (QH) racehorses were obtained. All 14 fractured scapulae (from 12 horses) had a consistent comminuted fracture configuration. A complete fracture coursed transversely through the neck of the scapula at the level of the distal aspect of the spine (8.9 ± 0.9 cm proximal to the lateral articular margin of the glenoid cavity). The distal fragment of 13 fractured scapulae was split into 2 major fragments by a fracture in the frontal plane that entered the glenoid cavity (2.8 ± 0.4 cm caudal to the cranial articular margin). Focal areas of periosteal proliferation and/or radiolucency were present in the distal aspect of the scapular spine of all fractured and intact contralateral scapulae, but less commonly (Phorses without a scapular fracture. Fractured scapulae had 7-10% lower mean density and 46-104% greater density heterogeneity in the spine adjacent to the transverse fracture compared to control scapulae (Pfracture configuration that is associated with pre-existing pathology of the distal aspect of the spine. This location is consistent with scapular stress fractures diagnosed in lame TB racehorses. Catastrophic fracture is the acute manifestation of a more chronic process. Consequently, there are opportunities for early detection and prevention of fatalities. © 2010 EVJ Ltd.

Human dental pulp cells exhibit bone cell-like responsiveness to fluid shear stress

NARCIS (Netherlands)

Kraft, D.C.E.; Bindslev, D.A.; Melsen, B.; Klein-Nulend, J.

2011-01-01

Background aims. For engineering bone tissue to restore, for example, maxillofacial defects, mechanosensitive cells are needed that are able to conduct bone cell-specific functions, such as bone remodelling. Mechanical loading affects local bone mass and architecture in vivo by initiating a cellular

Development and application of a direct method to observe the implant/bone interface using simulated bone.

Science.gov (United States)

Yamaguchi, Yoko; Shiota, Makoto; FuJii, Masaki; Sekiya, Michi; Ozeki, Masahiko

2016-01-01

Primary stability after implant placement is essential for osseointegration. It is important to understand the bone/implant interface for analyzing the influence of implant design on primary stability. In this study rigid polyurethane foam is used as artificial bone to evaluate the bone-implant interface and to identify where the torque is being generated during placement. Five implant systems-Straumann-Standard (ST), Straumann-Bone Level (BL), Straumann-Tapered Effect (TE), Nobel Biocare-Brånemark MKIII (MK3), and Nobel Biocare-Brånemark MKIV (MK4)-were used for this experiment. Artificial bone blocks were prepared and the implant was installed. After placement, a metal jig and one side artificial bone block were removed and then the implant embedded in the artificial bone was exposed for observing the bone-implant interface. A digital micro-analyzer was used for observing the contact interface. The insertion torque values were 39.35, 23.78, 12.53, 26.35, and 17.79 N cm for MK4, BL, ST, TE, and MK3, respectively. In ST, MK3, TE, MK4, and BL the white layer areas were 61 × 103 μm(2), 37 × 103 μm(2), 103 × 103 μm(2) in the tapered portion and 84 × 03 μm(2) in the parallel portion, 134 × 103 μm(2), and 98 × 103 μm(2) in the tapered portion and 87 × 103 μm(2) in the parallel portion, respectively. The direct observation method of the implant/artificial bone interface is a simple and useful method that enables the identification of the area where implant retention occurs. A white layer at the site of stress concentration during implant placement was identified and the magnitude of the stress was quantitatively estimated. The site where the highest torque occurred was the area from the thread crest to the thread root and the under and lateral aspect of the platform. The artificial bone debris created by the self-tapping blade accumulated in both the cutting chamber and in the space between the threads and artificial bone.

Fixed and mobile-bearing total ankle prostheses: Effect on tibial bone strain.

Science.gov (United States)

Terrier, Alexandre; Fernandes, Caroline Sieger; Guillemin, Maïka; Crevoisier, Xavier

2017-10-01

Total ankle replacement is associated to a high revision rate. To improve implant survival, the potential advantage of prostheses with fixed bearing compared to mobile bearing is unclear. The objective of this study was to test the hypothesis that fixed and mobile bearing prostheses are associated with different biomechanical quantities typically associated to implant failure. With a validated finite element model, we compared three cases: a prosthesis with a fixed bearing, a prosthesis with a mobile bearing in a centered position, and a prosthesis with mobile bearing in an eccentric position. Both prostheses were obtained from the same manufacturer. They were tested on seven tibias with maximum axial compression force during walking. We tested the hypothesis that there was a difference of bone strain, bone-implant interfacial stress, and bone support between the three cases. We also evaluated, for the three cases, the correlations between bone support, bone strain and bone-implant interfacial stress. There were no statistically significant differences between the three cases. Overall, bone support was mainly trabecular, and less effective in the posterior side. Bone strain and bone-implant interfacial stress were strongly correlated to bone support. Even if slight differences are observed between fixed and mobile bearing, it is not enough to put forward the superiority of one of these implants regarding their reaction to axial compression. When associated to the published clinical results, our study provides no argument to warn surgeons against the use of two-components fixed bearing implants. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Three-dimensional finite element analysis on mechanical behavior of the bone remodeling and bone integration between the bone-implant interface after hip replacement].

Science.gov (United States)

Li, Yong-Jiang; Zhang, Li-Cheng; Zhang, Mei-Chao; Yang, Guo-Jing; Lin, Rui-Xin; Cai, Chun-Yuan; Zhong, Shi-Zhen

2014-04-01

To discuss the primary stability of the fixed interface between the cementless prosthesis and femur, and its influence on bone ingrowth and secondary stability under the roughened surface and press fit of different prostheses by finite element analysis. :A three-dimensional finite element module of total hip arthroplasty (THA) was developed with Mimics software. There was a collection of data when simulating hip arthroplasty. The frictional coefficient between the fixed interface was 0,0.15,0.40 and 1.00 representing the roughness of prosthesis surface. The press fit was 0, 0.01,0.05 and 0.10 mm according to the operation. The Vion Mises stress distribution and the contact pressure,friction stress and relative sliding displacement between the interface were analysed and compared when simulating the maneuver of climbing stairs. At a fixed press fit of 0.05 mm,the contact pressure between the interface was 230 , 231, 222 and 275 MN under four different frictional coefficient (0,0. 15,0.40 and 1.00) with little change; the relative sliding displacement was 0.529, 0.129, 0.107 and 0.087 mm with a consistent and obvious decline. As the fixed frictional coefficient was 0.40,the contact pressure between the interface were 56.0,67.7 ,60.4 and 49.6 MN under four different press fit (0, 0.01, 0.05 and 0.10 mm) with a reduction; the relative sliding displacement was 0.064,0.062,0.043 and 0.042 mm with an obvious decline, and there was a maximal friction stress when press fit of 0.01 mm. There is a dynamic process of the bone remodeling and bone integration between the interface after hip replacement, determining the long-term outcome. The interface clearance and the frictional coefficient are the key factors of the bone integration.

Age variations in the properties of human tibial trabecular bone

DEFF Research Database (Denmark)

Ding, Ming; Dalstra, M; Danielsen, CC

1997-01-01

We tested in compression specimens of human proximal tibial trabecular bone from 31 normal donors aged from 16 to 83 years and determined the mechanical properties, density and mineral and collagen content. Young's modulus and ultimate stress were highest between 40 and 50 years, whereas ultimate...... strain and failure energy showed maxima at younger ages. These age-related variations (except for failure energy) were non-linear. Tissue density and mineral concentration were constant throughout life, whereas apparent density (the amount of bone) varied with ultimate stress. Collagen density (the...... amount of collagen) varied with failure energy. Collagen concentration was maximal at younger ages but varied little with age. Our results suggest that the decrease in mechanical properties of trabecular bone such as Young's modulus and ultimate stress is mainly a consequence of the loss of trabecular...

Comparative evaluation of the effectiveness of the implantation in the lateral part of the mandible between short tissue level (TE) and bone level (BL) implant systems.

Science.gov (United States)

Hadzik, Jakub; Botzenhart, Ute; Krawiec, Maciej; Gedrange, Tomasz; Heinemann, Friedhelm; Vegh, Andras; Dominiak, Marzena

2017-09-01

Short dental implants can be an alternative method of treatment to a vertical bone augmentation procedure at sites of reduced alveolar height. However, for successful treatment, an implant system that causes a minimal marginal bone loss (MBL) should be taken into consideration. The aim of the study has been to evaluate implantation effectiveness for bone level and tissue level short implants provided in lateral aspects of partially edentulous mandible and limited alveolar ridge height. The MBL and primary as well as secondary implant stability were determined in the study. Patients were randomly divided into two groups according to the method of treatment provided. Sixteen short Bone Level Implants (OsseoSpeed TX, Astra tech) and 16 short Tissue Level Implants (RN SLActive ® , Straumann) were successfully placed in the edentulous part of the mandible. The determination of the marginal bone level was based on radiographic evaluation after 12 and 36 weeks. Implant stability was measured immediately after insertion and after 12 weeks. The marginal bone level of Bone Level Implants was significantly lower compared to Tissue Level Implants. Furthermore, the Bone Level Implants had greater primary and secondary stability in comparison with Tissue Level Implants (Primary: 77.8 ISQ versus 66.5 ISQ; Secondary: 78.9 ISQ versus 73.9 ISQ, respectively). Since short Bone Level Implants showed a significantly decreased MBL 12 and 36 weeks after implantation as well as better results for the primary stability compared to Tissue Level Implants, they should preferentially be used for this mentioned indication. Copyright © 2017 Elsevier GmbH. All rights reserved.

[Scanning electron microscopy of heat-damaged bone tissue].

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Harsanyl, L

1977-02-01

Parts of diaphyses of bones were exposed to high temperature of 200-1300 degrees C. Damage to the bone tissue caused by the heat was investigated. The scanning electron microscopic picture seems to be characteristic of the temperature applied. When the bones heated to the high temperature of 700 degrees C characteristic changes appear on the periostal surface, higher temperatura on the other hand causes damage to the compact bone tissue and can be observed on the fracture-surface. Author stresses the importance of this technique in the legal medicine and anthropology.

Vitamin D and Bone Disease

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S. Christodoulou

2013-01-01

Full Text Available Vitamin D is important for normal development and maintenance of the skeleton. Hypovitaminosis D adversely affects calcium metabolism, osteoblastic activity, matrix ossification, bone remodeling and bone density. It is well known that Vit. D deficiency in the developing skeleton is related to rickets, while in adults is related to osteomalacia. The causes of rickets include conditions that lead to hypocalcemia and/or hypophosphatemia, either isolated or secondary to vitamin D deficiency. In osteomalacia, Vit. D deficiency leads to impairment of the mineralisation phase of bone remodeling and thus an increasing amount of the skeleton being replaced by unmineralized osteoid. The relationship between Vit. D and bone mineral density and osteoporosis are still controversial while new evidence suggests that Vit. D may play a role in other bone conditions such as osteoarthritis and stress fractures. In order to maintain a “good bone health” guidelines concerning the recommended dietary intakes should be followed and screening for Vit. D deficiency in individuals at risk for deficiency is required, followed by the appropriate action.

Numerical evaluation of bone remodelling and adaptation considering different hip prosthesis designs.

Science.gov (United States)

Levadnyi, Ievgen; Awrejcewicz, Jan; Gubaua, José Eduardo; Pereira, Jucélio Tomás

2017-12-01

The change in mechanical properties of femoral cortical bone tissue surrounding the stem of the hip endoprosthesis is one of the causes of implant instability. We present an analysis used to determine the best conditions for long-term functioning of the bone-implant system, which will lead to improvement of treatment results. In the present paper, a finite element method coupled with a bone remodelling model is used to evaluate how different three-dimensional prosthesis models influence distribution of the density of bone tissue. The remodelling process begins after the density field is obtained from a computed tomography scan. Then, an isotropic Stanford model is employed to solve the bone remodelling process and verify bone tissue adaptation in relation to different prosthesis models. The study results show that the long-stem models tend not to transmit loads to proximal regions of bone, which causes the stress-shielding effect. Short stems or application in the calcar region provide a favourable environment for transfer of loads to the proximal region, which allows for maintenance of bone density and, in some cases, for a positive variation, which causes absence of the aseptic loosening of an implant. In the case of hip resurfacing, bone mineral density changes slightly and is closest to an intact femur. Installation of an implant modifies density distribution and stress field in the bone. Thus, bone tissue is stimulated in a different way than before total hip replacement, which evidences Wolff's law, according to which bone tissue adapts itself to the loads imposed on it. The results suggest that potential stress shielding in the proximal femur and cortical hypertrophy in the distal femur may, in part, be reduced through the use of shorter stems, instead of long ones, provided stem fixation is adequate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Initiation of Extension in South China Continental Margin during the Active-Passive Margin Transition: Thermochronological and Kinematic Constraints

Science.gov (United States)

Zuo, X.; Chan, L. S.

2015-12-01

The South China continental margin is characterized by a widespread magmatic belt, prominent NE-striking faults and numerous rifted basins filled by Cretaceous-Eocene sediments. The geology denotes a transition from active to passive margin, which led to rapid modifications of crustal stress configuration and reactivation of older faults in this area. Our zircon fission-track data in this region show two episodes of exhumation: The first episode, occurring during 170-120Ma, affected local parts of the Nanling Range. The second episode, a more regional exhumation event, occurred during 115-70Ma, including the Yunkai Terrane and the Nanling Range. Numerical geodynamic modeling was conducted to simulate the subduction between the paleo-Pacific plate and the South China Block. The modeling results could explain the fact that exhumation of the granite-dominant Nanling Range occurred earlier than that of the gneiss-dominant Yunkai Terrane. In addition to the difference in rock types, the heat from Jurassic-Early Cretaceous magmatism in Nanling may have softened the upper crust, causing the area to exhume more readily than Yunkai. Numerical modeling results also indicate that (1) high lithospheric geothermal gradient, high slab dip angle and low convergence velocity favor the reversal of crustal stress state from compression to extension in the upper continental plate; (2) late Mesozoic magmatism in South China was probably caused by a slab roll-back; and (3) crustal extension could have occurred prior to the cessation of plate subduction. The inversion of stress regime in the continental crust from compression to crustal extension imply that the Late Cretaceous-early Paleogene red-bed basins in South China could have formed during the late stage of the subduction, accounting for the occurrence of volcanic events in some sedimentary basins. We propose that the rifting started as early as Late Cretaceous, probably before the cessation of subduction process.

Immediate implant placement into posterior sockets with or without buccal bone dehiscence defects: A retrospective cohort study.

Science.gov (United States)

Hu, Chen; Gong, Ting; Lin, Weimin; Yuan, Quan; Man, Yi

2017-10-01

To evaluate bone reconstruction and soft tissue reactions at immediate implants placed into intact sockets and those with buccal bone dehiscence defects. Fifty-nine internal connection implants from four different manufacturers were immediately placed in intact sockets(non-dehiscence group, n=40), and in alveoli with buccal bone dehiscence defects: 1) Group 1(n= N10), the defect depth measured 3-5 mm from the gingival margin. 2) Group 2(n=9), the depth ranged from 5mm to 7mm. The surrounding bony voids were grafted with deproteinized bovine bone mineral (DBBM) particles. Cone beam computed tomography(CBCT) was performed immediately after surgery (T1), and at 6 months later(T2). Radiographs were taken at prosthesis placement and one year postloading(T3). Soft tissue parameters were measured at baseline (T0), prosthesis placement and T3. No implants were lost during the observation period. For the dehiscence groups, the buccal bone plates were radiographically reconstructed to comparable horizontal and vertical bone volumes compared with the non-dehiscence group. Marginal bone loss occurred between the time of final restoration and 1-year postloading was not statistically different(P=0.732) between groups. Soft tissue parameters did not reveal inferior results for the dehiscence groups. Within the limitations of this study, flapless implant placement into compromised sockets in combination with DBBM grafting may be a viable technique to reconstitute the defected buccal bone plates due to space maintenance and primary socket closure provided by healing abutments and bone grafts. Immediate implants and DBBM grafting without using membranes may be indicated for sockets with buccal bone defects. Copyright © 2017 Elsevier Ltd. All rights reserved.

[The radiological findings of caisson-induced bone infarcts. The relationship between acute arthralgia and bone infarcts (author's transl)].

Science.gov (United States)

Horváth, V F

1978-07-01

The radiological features, such as calcification in long bones due to infarcts, resulting from Caisson disease are described by the author on the basis of an extensive experience. The similar localisation of acute "arthralgia" and bone infarcts make it appear probable that the infarcts play a primary role in the production of "osteo-articular" pain. The author stresses the advisability of examining the adjacent portions of the tibia and femur at the initial pre-employment examination, since bone infarcts can be caused by a variety of conditions other than work in Caissons.

14 CFR 33.62 - Stress analysis.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Stress analysis. 33.62 Section 33.62... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.62 Stress analysis. A stress analysis must be performed on each turbine engine showing the design safety margin of each turbine...

Bioarchaeology of adaptation to a marginal environment in bronze age Western China.

Science.gov (United States)

Berger, Elizabeth; Wang, Hui

2017-07-08

This study examines human adaptation to the 4000 BP climate change event, which is said to have increased the marginality of Inner Asian environments. We propose to define "marginal" environments not in relation to a specific economic activity (e.g., agriculture), but in relation to whether humans living there are physiologically stressed. Three sites in the Hexi Corridor of Gansu were studied, one from the early and two from the late Bronze Age (N = 125). The study includes three indicators of physiological stress: linear enamel hypoplasias (LEH); tibial periosteal lesions; and fertility. The early and late Bronze Age groups were compared to examine whether human physiological stress increased. The percent of individuals with LEH declined dramatically, indicating fewer growth disruptions. Tibial periosteal reactions also changed, from mostly active to mostly healing at the time of death, indicating that frailty declined. Fertility, which is sensitive to changes in population health and resource availability, did not change significantly. Counter to the dominant narrative of environmental deterioration and subsistence system collapse, the Bronze Age residents of the Hexi Corridor show no skeletal evidence that they suffered from resource shortages or struggled to adapt in the fluctuating climate that pertained after the 4000 BP climate event. In fact, this study found that people suffered from less frailty and fewer growth disruptions after the unstable climate had persisted for some time. Therefore, in human biological terms, the Hexi Corridor did not become more marginal for human habitation during the Bronze Age. © 2017 Wiley Periodicals, Inc.

Stress fractures in athletes

International Nuclear Information System (INIS)

Steingruber, I.E.; Wolf, C.; Gruber, H.; Czermak, B.V.; Mallouhi, A.; Jaschke, W.; Gabriel, M.

2002-01-01

Stress fractures may pose a diagnostic dilemma for radiologists since they are sometimes difficult to demonstrate on plain films and may simulate a tumour. They were first described in military personnel and professional athletes. Recently, there is an increasing incidence in the general population due to increasing sportive activities. Stress fractures occur most often in the lower extremities, especially in the tibia, the tarsal bone, the metatarsal bone, the femur and the fibula. In the upper extremities, they are commonly found in the humerus, the radius and the ulna. Some fractures of the lower extremities appear to be specific for particular sports, for example, fractures of the tibia affect mostly distance runners. Whereas stress fractures of the upper extremities are generally associated with upper limb-dominated sports. A correct diagnosis requires a careful clinical evaluation. The initial plain radiography may be normal. Further radiological evaluation could be performed by means of computerised tomography, magnetic resonance imaging and bone scanning. The latter two techniques are especially helpful for establishing a correct initial diagnosis. (orig.) [de

Stress fractures in athletes

International Nuclear Information System (INIS)

Kirschberger, R.; Henning, A.; Graff, K.H.

1984-01-01

The early exclusion of the presence of a stress fracture may be decisive for the success of an athlete. Scintigraphy with a bone-seeking radiopharmaceutical is suitable for the early detection of stress lesions. Of 30 athletes, fractures were demonstrated in 17 whereas in 6 they were excluded. We found most fractures in the tarsal bones such as os naviculare pedis, ossa cuneiformia and talus. The type of sport engaged in appears to be an important factor in determining the location of the fracture. Scintiphotos were taken in several views using region of interest techniques and two phase-scintigraphy. This method is considered to be useful for localization and follow-up of skeletal stress lesions as well as for differential diagnosis. (orig.) [de

Stress fractures in athletes

Energy Technology Data Exchange (ETDEWEB)

Kirschberger, R; Henning, A; Graff, K H

1984-12-01

The early exclusion of the presence of a stress fracture may be decisive for the success of an athlete. Scintigraphy with a bone-seeking radiopharmaceutical is suitable for the early detection of stress lesions. Of 30 athletes, fractures were demonstrated in 17 whereas in 6 they were excluded. We found most fractures in the tarsal bones such as os naviculare pedis, ossa cuneiformia and talus. The type of sport engaged in appears to be an important factor in determining the location of the fracture. Scintiphotos were taken in several views using region of interest techniques and two phase-scintigraphy. This method is considered to be useful for localization and follow-up of skeletal stress lesions as well as for differential diagnosis.

Matthew and marginality

Directory of Open Access Journals (Sweden)

Denis C. Duling

1995-12-01

Full Text Available This article explores marginality theory as it was first proposed in  the social sciences, that is related to persons caught between two competing cultures (Park; Stonequist, and, then, as it was developed in sociology as related to the poor (Germani and in anthropology as it was related to involuntary marginality and voluntary marginality (Victor Turner. It then examines a (normative scheme' in antiquity that creates involuntary marginality at the macrosocial level, namely, Lenski's social stratification model in an agrarian society, and indicates how Matthean language might fit with a sample inventory  of socioreligious roles. Next, it examines some (normative schemes' in  antiquity for voluntary margi-nality at the microsocial level, namely, groups, and examines how the Matthean gospel would fit based on indications of factions and leaders. The article ,shows that the author of the Gospel of Matthew has an ideology of (voluntary marginality', but his gospel includes some hope for (involuntary  marginals' in  the  real world, though it is somewhat tempered. It also suggests that the writer of the Gospel is a (marginal man', especially in the sense defined by the early theorists (Park; Stone-quist.

Increased physical activity ameliorates high fat diet-induced bone resorption in mice

Science.gov (United States)

It has been recognized that mechanical stresses associated with physical activity (PA) have beneficial effects on increasing bone mineral density (BMD) and improving bone quality. On the other hand, high fat diet (HFD) and obesity increase bone marrow adiposity leading to increased excretion of pro-...

Comparing the influence of crestal cortical bone and sinus floor cortical bone in posterior maxilla bi-cortical dental implantation: a three-dimensional finite element analysis.

Science.gov (United States)

Yan, Xu; Zhang, Xinwen; Chi, Weichao; Ai, Hongjun; Wu, Lin

2015-05-01

This study aimed to compare the influence of alveolar ridge cortical bone and sinus floor cortical bone in sinus areabi-cortical dental implantation by means of 3D finite element analysis. Three-dimensional finite element (FE) models in a posterior maxillary region with sinus membrane and the same height of alveolar ridge of 10 mm were generated according to the anatomical data of the sinus area. They were either with fixed thickness of crestal cortical bone and variable thickness of sinus floor cortical bone or vice versa. Ten models were assumed to be under immediate loading or conventional loading. The standard implant model based on the Nobel Biocare implant system was created via computer-aided design software. All materials were assumed to be isotropic and linearly elastic. An inclined force of 129 N was applied. Von Mises stress mainly concentrated on the surface of crestal cortical bone around the implant neck. For all the models, both the axial and buccolingual resonance frequencies of conventional loading were higher than those of immediate loading; however, the difference is less than 5%. The results showed that bi-cortical implant in sinus area increased the stability of the implant, especially for immediately loading implantation. The thickness of both crestal cortical bone and sinus floor cortical bone influenced implant micromotion and stress distribution; however, crestal cortical bone may be more important than sinus floor cortical bone.

Section modulus is the optimum geometric predictor for stress fractures and medial tibial stress syndrome in both male and female athletes.

Science.gov (United States)

Franklyn, Melanie; Oakes, Barry; Field, Bruce; Wells, Peter; Morgan, David

2008-06-01

Various tibial dimensions and geometric parameters have been linked to stress fractures in athletes and military recruits, but many mechanical parameters have still not been investigated. Sedentary people, athletes with medial tibial stress syndrome, and athletes with stress fractures have smaller tibial geometric dimensions and parameters than do uninjured athletes. Cohort study; Level of evidence, 3. Using a total of 88 subjects, male and female patients with either a tibial stress fracture or medial tibial stress syndrome were compared with both uninjured aerobically active controls and uninjured sedentary controls. Tibial scout radiographs and cross-sectional computed tomography images of all subjects were scanned at the junction of the midthird and distal third of the tibia. Tibial dimensions were measured directly from the films; other parameters were calculated numerically. Uninjured exercising men have a greater tibial cortical cross-sectional area than do their sedentary and injured counterparts, resulting in a greater value of some other cross-sectional geometric parameters, particularly the section modulus. However, for women, the cross-sectional areas are either not different or only marginally different, and there are few tibial dimensions or geometric parameters that distinguish the uninjured exercisers from the sedentary and injured subjects. In women, the main difference between the groups was the distribution of cortical bone about the centroid as a result of the different values of section modulus. Last, medial tibial stress syndrome subjects had smaller tibial cross-sectional dimensions than did their uninjured exercising counterparts, suggesting that medial tibial stress syndrome is not just a soft-tissue injury but also a bony injury. The results show that in men, the cross-sectional area and the section modulus are the key parameters in the tibia to distinguish exercise and injury status, whereas for women, it is the section modulus only.

Comparison of prostate set-up accuracy and margins with off-line bony anatomy corrections and online implanted fiducial-based corrections

International Nuclear Information System (INIS)

Greer, P. B.; Dahl, K.; Ebert, M. A.; Wratten, C.; White, M.; Denham, K. W.

2008-01-01

Full text: The aim of the study was to determine prostate set-up accuracy and set-up margins with off-line bony anatomy-based imaging protocols, compared with online implanted fiducial marker-based imaging with daily corrections. Eleven patients were treated with implanted prostate fiducial markers and online set-up corrections. Pretreatment orthogonal electronic portal images were acquired to determine couch shifts and verification images were acquired during treatment to measure residual set-up error. The prostate set-up errors that would result from skin marker set-up, off-line bony anatomy-based protocols and online fiducial marker-based corrections were determined. Set-up margins were calculated for each set-up technique using the percentage of encompassed isocentres land a margin recipe. The prostate systematic set-up errors in the medial-lateral, superior-inferior and anterior-I posterior directions for skin marker set-up were 2.2, 3.6 and 4.5 mm (1 standard deviation). For our bony anatomy-I based off-line protocol the prostate systematic set-up errors were 1.6, 2.5 and 4.4 mm. For the online fiducial based set-up the results were 0.5, 1.4 and 1.4 mm. A prostate systematic error of 10.2 mm was uncorrected by the off-line bone protocol in one patient. Set-up margins calculated to encompass 98% of prostate set-up shifts were 111-14 mm with bone off-line set-up and 4-7 mm with online fiducial markers. Margins from the van Herk margin I recipe were generally 1-2 mm smaller. Bony anatomy-based set-up protocols improve the group prostate set-up error compared with skin marks; however, large prostate systematic errors can remain undetected or systematic (errors increased for individual patients. The margin required for set-up errors was found to be 10-15 mm unless I implanted fiducial markers are available for treatment guidance.

The effects of orally administered diacerein on cartilage and subchondral bone in an ovine model of osteoarthritis.

Science.gov (United States)

Hwa, S Y; Burkhardt, D; Little, C; Ghosh, P

2001-04-01

An ovine model of osteoarthritis (OA) induced by bilateral lateral meniscectomy (BLM) was used to evaluate in vivo effects of the slow acting antiarthritic drug diacerein (DIA) on degenerative changes in cartilage and subchondral bone of the operated joints. Twenty of 30 adult age matched Merino wethers were subjected to BLM in the knee joints and the remainder served as non-operated controls (NOC). Half of the BLM group (n = 10) were given DIA (25 mg/kg orally) daily for 3 mo, then 50 mg/kg daily for a further 6 mo. The remainder of the meniscectomized (MEN) group served as OA controls. Five DIA, 5 MEN, and 5 NOC animals were sacrificed at 3 mo and the remainder at 9 mo postsurgery. One knee joint of each animal was used for bone mineral density (BMD) studies. Osteochondral slabs from the lateral femoral condyle and lateral tibial plateau were cut from the contralateral joint and were processed for histological and histomorphometric examination to assess the cartilage and subchondral bone changes. No significant difference was observed in the modified Mankin scores for cartilage from the DIA and MEN groups at 3 or 9 mo. However, in animals treated with DIA, the thickness of cartilage (p = 0.05) and subchondral bone (p = 0.05) in the lesion (middle) zone of the lateral tibial plateau were decreased relative to the corresponding zone of the MEN group at 3 mo (p = 0.05). At 9 mo subchondral bone thickness in this zone remained the same as NOC but BMD, which included both subchondral and trabecular bone, was significantly increased relative to the NOC group (p = 0.01). In contrast, the subchondral bone thickness of the outer zone of lateral tibial plateau and lateral femoral condyle of both MEN and DIA groups increased after 9 mo, while BMD remained the same as in the NOC. DIA treatment of meniscectomized animals mediated selective responses of cartilage and subchondral bone to the altered mechanical stresses induced across the joints by this procedure. While

Bone mineral as an electrical energy reservoir.

Science.gov (United States)

Nakamura, Miho; Hiratai, Rumi; Yamashita, Kimihiro

2012-05-01

Mechanical stress in bone induces an electrical potential generated by piezoelectricity arising from displacement of collagen fibrils. Where and for how long the potential is stored in bone; however, are still poorly understood. We investigated the electrical properties of collagen fibrils and apatite minerals and found that bone, when polarized electrically by applying an external voltage, depolarizes by two mechanisms. Plots of thermally stimulated depolarization current show two significant peaks: one at 100°C, attributed to collagen fibrils because decalcified bone exhibits depolarization peak at 100°C, and the other at 500°C, attributed to apatite minerals because calcined bone exhibits depolarization peak at 500°C and has activation energy similar to that for synthesized apatite. The crystallographic c-axis orientation of calcined bone depends on the direction in which the bone is cut, either transverse or longitudinal, and strongly affects the polarization efficacy. Copyright © 2012 Wiley Periodicals, Inc.

Splenic marginal zone lymphoma: a review of the clinical presentation, pathology, molecular biology, and management

Directory of Open Access Journals (Sweden)

Teixeira Mendes LS

2014-07-01

Full Text Available Larissa Sena Teixeira Mendes,1 Ming-Qing Du,2 Estella Matutes,3 Andrew Wotherspoon11Histopathology Department, Royal Marsden Hospital, London, UK; 2Molecular Malignancy Laboratory and Department of Histopathology, University Hospital NHS Foundation Trust/Division of Molecular Histopathology, Department of Pathology, University of Cambridge, Cambridge, UK; 3Hematopathology Unit, Hospital Clinic, Barcelona University, Barcelona, Spain Abstract: Splenic marginal zone lymphoma is a distinct low grade B-cell lymphoma primarily occurring in the spleen and separate from nodal marginal zone lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue. It is characterized by a relative indolent course, splenomegaly, moderate lymphocytosis, and an intrasinusoidal pattern of involvement, especially in the bone marrow. It is postulated that the neoplastic clone originates from persistent antigenic stimulation of marginal zone B-cells. Molecular and cytogenetic studies have failed to show specific alterations. There is no standard criterion to initiate treatment, which may include a watch and wait policy, splenectomy, or chemo/immunotherapy. This review highlights the main features of this entity, reassessing the guidelines for diagnosis, prognostic factors, staging, and management published by the SMZL Working Group (2008. Keywords: splenectomy, villous lymphocytes, guidelines

An unusual stress fracture: Bilateral posterior longitudinal stress fracture of tibia.

Science.gov (United States)

Malkoc, Melih; Korkmaz, Ozgur; Ormeci, Tugrul; Oltulu, Ismail; Isyar, Mehmet; Mahirogulları, Mahir

2014-01-01

Stress fractures (SF) occur when healthy bone is subjected to cyclic loading, which the normal carrying range capacity is exceeded. Usually, stress fractures occur at the metatarsal bones, calcaneus, proximal or distal tibia and tends to be unilateral. This article presents a 58-year-old male patient with bilateral posterior longitudinal tibial stress fractures. A 58 years old male suffering for persistent left calf pain and decreased walking distance for last one month and after imaging studies posterior longitudinal tibial stress fracture was detected on his left tibia. After six months the patient was admitted to our clinic with the same type of complaints in his right leg. All imaging modalities and blood counts were performed and as a result longitudinal posterior tibial stress fractures were detected on his right tibia. Treatment of tibial stress fracture includes rest and modified activity, followed by a graded return to activity commensurate with bony healing. We have applied the same treatment protocol and our results were acceptable but our follow up time short for this reason our study is restricted for separate stress fractures of the posterior tibia. Although the main localization of tibial stress fractures were unilateral, anterior and transverse pattern, rarely, like in our case, the unusual bilateral posterior localization and longitudinal pattern can be seen. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

A 5-year clinical and computerized tomographic implant follow-up in sinus-lifted maxillae and native bone.

Science.gov (United States)

Sbordone, Carolina; Toti, Paolo; Ramaglia, Luca; Guidetti, Franco; Sbordone, Ludovico; Martuscelli, Ranieri

2014-09-01

The present study analysed apical and marginal bone remodelling around dental implants placed in both maxillary (sinus elevated with particulated autogenous osseous graft) and corresponding native bone areas, with a follow-up of 5 years. The clinical survival of implants was also observed. In this retrospective chart review, 27 patients were enrolled, with 55 dental implants inserted from 2000 to 2006, 26 of which were followed (one implant per patient); if required, patients were treated via sinus lift with autogenous bone and particulate technique. The internal controls were implants positioned in native areas beneath the sinus. Radiologic survey was assessed via computerized tomographic analysis measuring apical bone level (ABL) and marginal bone level (MBL), at 1- (T1 ), 3- (T2 ) and 5 years (T3 ), around implants (buccal, b; palatal, p; mesial, m; and distal sides, d). Clinical probing depth (CPD) and clinical attachment level (CAL) for all the four peri-implant aspects were measured. Cumulative survival rate (CSR) and survival rate (SR) of implants were calculated. Significances for paired and unpaired comparisons were searched for. A significant degree of apical resorption was recorded between T1 and T3 for the mesial particulate group; again, a significant difference was discovered between the native and particulate procedures for mABL. A further feature was discovered for the particulate procedure, for which ABLs resulted negative at least for three of the aspects. Regarding MBL measurements, similar behaviours were revealed using time-comparison analysis for the two procedures at the buccal aspect. Comparisons among diameters, irrespective of the procedure, showed that resorption times for the bMBL were shorter as the diameter of the implant became wider. The implant CSR was 92% in native areas (two failures/25 implants) and 93.3% in sinuses lifted with particulate bone (two failures/30 implants). The results suggest that a protrusion of the implant

Stimulation of Host Bone Marrow Stromal Cells by Sympathetic Nerves Promotes Breast Cancer Bone Metastasis in Mice

OpenAIRE

Campbell, J. Preston; Karolak, Matthew R.; Ma, Yun; Perrien, Daniel S.; Masood-Campbell, S. Kathryn; Penner, Niki L.; Munoz, Steve A.; Zijlstra, Andries; Yang, Xiangli; Sterling, Julie A.; Elefteriou, Florent

2012-01-01

Bone and lung metastases are responsible for the majority of deaths in patients with breast cancer. Following treatment of the primary cancer, emotional and psychosocial factors within this population precipitate time to recurrence and death, however the underlying mechanism(s) remain unclear. Using a mouse model of bone metastasis, we provide experimental evidence that activation of the sympathetic nervous system, which is one of many pathophysiological consequences of severe stress and depr...

The reversal phase of the bone-remodeling cycle

DEFF Research Database (Denmark)

Delaisse, Jean-Marie

2014-01-01

coincides with decreased osteoblast recruitment and impaired initiation of bone formation, that is, uncoupling. Overall, this review stresses that coupling does not only depend on molecules able to activate osteogenesis, but that it also demands the presence of osteoprogenitors and ordered cell......The reversal phase couples bone resorption to bone formation by generating an osteogenic environment at remodeling sites. The coupling mechanism remains poorly understood, despite the identification of a number of 'coupling' osteogenic molecules. A possible reason is the poor attention...

Influence of PEEK Coating on Hip Implant Stress Shielding: A Finite Element Analysis

Directory of Open Access Journals (Sweden)

Jesica Anguiano-Sanchez

2016-01-01

Full Text Available Stress shielding is a well-known failure factor in hip implants. This work proposes a design concept for hip implants, using a combination of metallic stem with a polymer coating (polyether ether ketone (PEEK. The proposed design concept is simulated using titanium alloy stems and PEEK coatings with thicknesses varying from 100 to 400 μm. The Finite Element analysis of the cancellous bone surrounding the implant shows promising results. The effective von Mises stress increases between 81 and 92% for the complete volume of cancellous bone. When focusing on the proximal zone of the implant, the increased stress transmission to the cancellous bone reaches between 47 and 60%. This increment in load transferred to the bone can influence mineral bone loss due to stress shielding, minimizing such effect, and thus prolonging implant lifespan.

Mutual associations among microstructural, physical and mechanical properties of human cancellous bone

DEFF Research Database (Denmark)

Ding, Ming; Odgaard, A; Danielsen, CC

2002-01-01

structure and mechanical properties. In this study, 160 cancellous bone specimens were produced from 40 normal human tibiae aged from 16 to 85 years at post-mortem. The specimens underwent micro-CT and the microstructural properties were calculated using unbiased three-dimensional methods. The specimens...... were tested to determine the mechanical properties and the physical/compositional properties were evaluated. The type of structure together with anisotropy correlated well with Young's modulus of human tibial cancellous bone. The plate-like structure reflected high mechanical stress and the rod......-like structure low mechanical stress. There was a strong correlation between the type of trabecular structure and the bone-volume fraction. The most effective microstructural properties for predicting the mechanical properties of cancellous bone seem to differ with age....

Bone tumours in children and juveniles

International Nuclear Information System (INIS)

Meister, P.

1978-01-01

The auther stresses the importance 1) of clinical data (e.g. age of the patient, localisation of the lesion, type and duration of the symptoms), 2) of radiographic findings and 3) of anatomicopathological changes which must all be taken into account especially in the judgment of bone tumours. Radiographic examination is of importance here also as a morphological method as it gives a picture of the 'mosaic' of a bone change. Biopsy material alone may contain only isolated parts with ambiguous histological findings, so that the true nature of the bone lesion can only be recognized by comparsion with the X-ray findings. (orig.) [de

The Effects of Silymarin on Oxidative Status and Bone Characteristics in Japanese Quail Subjected to Oxidative Stress Induced by Carbon Tetrachloride

Directory of Open Access Journals (Sweden)

Moradi F

2017-10-01

Full Text Available This experiment was conducted to assess the effects of Silymarin on oxidative status, bone characteristics, and some blood parameters in Japanese quail subjected to oxidative stress induced by carbon tetrachloride (CCl4. The experiment was performed as a completely randomized design with four replicates, each with 30 birds, using a 2 × 2 factorial arrangement with two doses of Silymarin (0 and 1 mL/kg BW and CCl4 (0 and 1 mL/kg BW. Results revealed that the interaction between Silymarin and CCl4on concentrations of total cholesterol, triglycerides, glucose, albumin, calcium, and alkaline phosphatase were significant (P < 0.05. In contrast, concentrations of phosphorus, total protein, and high density lipoprotein-cholesterol in blood serum did not differ between experimental treatments. Experimental treatments had a significant effect on superoxide dismutase activity in blood serum (P < 0.05, but not on glutathione peroxide activity and malondialdehyde concentration. Experimental treatments significantly affected the weight, thickness, and external and internal diameters of tibia bone (P < 0.05, but not its length, ash, volume, and density. This study shows that Silymarin has potential to attenuate adverse effects of oxidative stress induced by CCl4 in Japanese quail.

Augmented reality in bone tumour resection: An experimental study.

Science.gov (United States)

Cho, H S; Park, Y K; Gupta, S; Yoon, C; Han, I; Kim, H-S; Choi, H; Hong, J

2017-03-01

We evaluated the accuracy of augmented reality (AR)-based navigation assistance through simulation of bone tumours in a pig femur model. We developed an AR-based navigation system for bone tumour resection, which could be used on a tablet PC. To simulate a bone tumour in the pig femur, a cortical window was made in the diaphysis and bone cement was inserted. A total of 133 pig femurs were used and tumour resection was simulated with AR-assisted resection (164 resection in 82 femurs, half by an orthropaedic oncology expert and half by an orthopaedic resident) and resection with the conventional method (82 resection in 41 femurs). In the conventional group, resection was performed after measuring the distance from the edge of the condyle to the expected resection margin with a ruler as per routine clinical practice. The mean error of 164 resections in 82 femurs in the AR group was 1.71 mm (0 to 6). The mean error of 82 resections in 41 femurs in the conventional resection group was 2.64 mm (0 to 11) (p Augmented reality in bone tumour resection: An experimental study. Bone Joint Res 2017;6:137-143. © 2017 Cho et al.

Living with the unknown: Posttraumatic stress disorder in pediatric bone marrow transplantation survivors and their mothers.

Science.gov (United States)

Taskıran, Gülseren; Sürer Adanır, Aslı; Özatalay, Esin

2016-04-01

Bone marrow transplantation (BMT) is used to treat children with various hematologic, oncologic, and metabolic diseases. Although the treatment can be lifesaving, it is also physically and psychologically demanding for both the child and caregivers. In previous studies, BMT is found to be related with anxiety, posttraumatic stress disorder (PTSD), depression, and psychosocial problems both in children and parents. The aim of this study was to investigate PTSD in pediatric BMT survivors and their mothers compared with the healthy controls. Twenty-seven BMT survivors and their mothers and 28 healthy peers and their mothers were recruited as the study group and as the comparison group, respectively. All children were interviewed using Child Posttraumatic Stress Disorder-Reaction Index (CPTSD-RI) for assessing posttraumatic stress responses. As for mothers, Clinician-Administered PTSD Scale (CAPS) was used. In healthy children and mothers, instead of BMT, the most important traumatic event reported by them was included. All data were analyzed by a neutral statistician from the Department of Biostatistics of the university. The BMT group, both children and mothers, obtained significantly higher PTSD rates than the control group (66.5% and 17.8%, respectively, in children; 57.6% and 7%, respectively, in mothers). However, there was a weak correlation between survivors' and mothers' posttraumatic stress responses. These findings suggest that BMT is a significant stressor for both children and mothers. Clinicians should be aware of psychiatric symptoms of children who underwent such a life-threatening condition. Combination of medical treatment with psychosocial support is imperative.

Estimates of margins in ASME Code strength values for stainless steel nuclear piping

International Nuclear Information System (INIS)

Ware, A.G.

1995-01-01

The margins in the ASME Code stainless steel allowable stress values that can be attributed to the variations in material strength are evaluated for nuclear piping steels. Best-fit curves were calculated for the material test data that were used to determine allowable stress values for stainless steels in the ASME Code, supplemented by more recent data, to estimate the mean stresses. The mean yield stresses (on which the stainless steel S m values are based) from the test data are about 15 to 20% greater than the ASME Code yield stress values. The ASME Code yield stress values are estimated to approximately coincide with the 97% confidence limit from the test data. The mean and 97% confidence limit values can be used in the probabilistic risk assessments of nuclear piping

The ''rising bubble'' sign: a new aid in the diagnosis of unicameral bone cysts

Energy Technology Data Exchange (ETDEWEB)

Jordanov, Martin I. [Vanderbilt University Medical Center, Department of Radiology and Radiological Sciences, Nashville, TN (United States)

2009-06-15

The observation of a bubble of gas at the most non-dependent margin of a lytic bone lesion which has sustained a pathologic fracture implies that the lesion is hollow and can assist the radiologist in making the diagnosis of a unicameral bone cyst. The imaging studies of two patients who sustained pathologic fractures through unicameral bone cysts and exhibited the ''rising bubble'' sign are shown. The sign's basis, proper utilization, and potential pitfalls are discussed. (orig.)

The relationship of depression, anxiety and stress with low bone mineral density in post-menopausal women.

Science.gov (United States)

Erez, Hany Burstein; Weller, Aron; Vaisman, Nachum; Kreitler, Shulamith

2012-01-01

The goal of the present study was to examine the relationships of depression, anxiety and stress with bone mineral density (BMD). We hypothesized negative relations between those mood variables and BMD in three assessed areas. The study showed association between depression and decreased BMD. The hypothesis regarding anxiety and stress was partially confirmed. In the last decade, the relationship of osteoporosis to psychological variables has been increasingly studied. The accumulating evidence from these studies supports the conclusion that depression is related to decreased BMD. Nevertheless, several studies found no support for this relationship. Moreover, only a small number of studies examined the association between anxiety or stress and decreased BMD. The goal of the present study was to examine the relationships of depression, anxiety and stress with BMD by means of adequate measuring instruments, while controlling for background factors known to be related to BMD decrease (e.g., body mass index, family history). The study included 135 post-menopausal female participants, who arrived for BMD screening, between the years 2006 and 2009. Several days prior to the examination, participants completed a series of questionnaires assessing depression and anxiety. BMD was measured using DXA, in spine, right and left hip. The study showed negative associations between depression and BMD variables in the three assessed areas. There were negative correlations between anxiety, stress and spine BMD, as well as a tendency towards negative relations in the right and left hip BMD. Concurrent hierarchical regressions showed that the addition of the three psychological variables increased the explained variance by 6–8 %. In addition, depression was found to have a unique significant contribution to the explained variance in right and left hip BMD. The findings provide supporting evidence for the existence of associations between mood variables and decreased BMD. Further

Marginal and happy? The need for uniqueness predicts the adjustment of marginal immigrants.

Science.gov (United States)

Debrosse, Régine; de la Sablonnière, Roxane; Rossignac-Milon, Maya

2015-12-01

Marginalization is often presented as the strategy associated with the worst adjustment for immigrants. This study identifies a critical variable that buffers marginal immigrants from the negative effects of marginalization on adjustment: The need for uniqueness. In three studies, we surveyed immigrants recruited on university campuses (n = 119, n = 116) and in the field (n = 61). Among marginal immigrants, a higher need for uniqueness predicted higher self-esteem (Study 1), affect (Study 2), and life satisfaction (Study 3), and marginally higher happiness (Study 2) and self-esteem (Study 3). No relationship between the need for uniqueness and adjustment was found among non-marginal immigrants. The adaptive value of the need for uniqueness for marginal immigrants is discussed. © 2015 The British Psychological Society.

Internal Distraction Osteogenesis With Piezosurgery Oblique Osteotomy of Supraorbital Margin of Frontal Bone for the Treatment of Unilateral Coronal Synostosis.

Science.gov (United States)

Shen, Weimin; Cui, Jie; Chen, Jianbing; Ji, Yi; Kong, Liangliang

2017-05-01

To assess the utility of internal distraction osteogenesis with Piezosurgery oblique osteotomy of supraorbital margin of frontal bone for the treatment of unilateral coronal synostosis and to study the outcome and complications of this procedure. Oblique osteotomy allows for entry into the cranial cavity, and along with parallel cut to the roof of the orbit, avoids the need to cut into the orbit which forms the frontal flap. Oblique osteotomy was performed along the supraorbital rim to do a frontal suture of the glabella (ages of patients were less than 1 year) or on the opposite side of the supraorbital rim (ages of patients were older than 1 year) after performing a suturectomy of the effected coronal suture. Two internal distraction devices were subsequently placed across the osteotomized, fused coronal suture. Finally, the cranium pieces were divided in the middle and placed in the middle of the frontal bone using biological glue. Five days after the operation, a 0.6-mm distraction was done twice daily. The distraction was removed 6 months after reaching 2 to 3 cm. Internal distraction osteogenesis with supraorbital oblique osteotomy was performed in 9 patients suffering from unilateral coronal synostosis. Eight patients had no postoperative infections around the shaft puncture wounds. One patient had infection in the rods around the distraction during the period of fixed, but was cured with antibiotic treatment. During a mean follow-up period of 12 months (5-26 months), all patients were satisfied with the cosmetic and functional results. No complications, including fixed screw displacement, penetration of the cranium and dura mater or retraction of distraction devices, occurred. The devices were exposed in 1 patient, resulting in a postoperative scar. Despite these complications, the cranium was successfully expanded in all patients. Use of this procedure avoids the need for frontal osteotomy to move the orbit forward. Adding 2 cranium strips can be used to

The diagnosis of stress fractures of runners by an isotope scintigraphy

International Nuclear Information System (INIS)

Karvonen, J.; Nieminen, M.

1988-01-01

By means of isotope scintigraphy the suspected stress fractures in the lower limb bones of ten competitive runners were verified in nine cases (9/10). In all cases the X-rays were normal. By conservative treatment avoiding excessive stress, the intensive local isotope uptake in the bone and pain symptoms of the stress fracture disappeared after 2-4 months. (orig.)

Proximal tibial stress fracture associated with mild osteoarthritis of the knee: case report.

Science.gov (United States)

Curković, Marko; Kovac, Kristina; Curković, Bozidar; Babić-Naglić, Durda; Potocki, Kristina

2011-03-01

Stress fractures are considered as multifactorial overuse injuries occurring in 0.3%-0.8% of patients suffering from rheumatic diseases, with rheumatoid arthritis being the most common underlying condition. Stress fractures can be classified according to the condition of the bone affected as: 1) fatigue stress fractures occurring when normal bone is exposed to repeated abnormal stresses; and 2) insufficiency stress fractures that occur when normal stress is applied to bone weakened by an underlying condition. Stress fractures are rarely associated with severe forms of knee osteoarthritis, accompanied with malalignment and obesity. We present a patient with a proximal tibial stress fracture associated with mild knee osteoarthritis without associated malalignment or obesity. Stress fracture should be considered when a patient with osteoarthritis presents with sudden deterioration, severe localized tenderness to palpation and localized swelling or periosteal thickening at the pain site and elevated local temperature. The diagnosis of stress fractures in patients with rheumatic diseases may often be delayed because plain film radiographs may not reveal a stress fracture soon after the symptom onset; moreover, evidence of a fracture may never appear on plain radiographs. Triple phase nuclear bone scans and magnetic resonance imaging are more sensitive in the early clinical course than plain films for initial diagnosis.

Bone Disease in Axial Spondyloarthritis.

Science.gov (United States)

Van Mechelen, Margot; Gulino, Giulia Rossana; de Vlam, Kurt; Lories, Rik

2018-05-01

Axial spondyloarthritis is a chronic inflammatory skeletal disorder with an important burden of disease, affecting the spine and sacroiliac joints and typically presenting in young adults. Ankylosing spondylitis, diagnosed by the presence of structural changes to the skeleton, is the prototype of this disease group. Bone disease in axial spondyloarthritis is a complex phenomenon with the coexistence of bone loss and new bone formation, both contributing to the morbidity of the disease, in addition to pain caused by inflammation. The skeletal structural changes respectively lead to increased fracture risk and to permanent disability caused by ankylosis of the sacroiliac joints and the spine. The mechanism of this new bone formation leading to ankylosis is insufficiently known. The process appears to originate from entheses, specialized structures that provide a transition zone in which tendon and ligaments insert into the underlying bone. Growth factor signaling pathways such as bone morphogenetic proteins, Wnts, and Hedgehogs have been identified as molecular drivers of new bone formation, but the relationship between inflammation and activation of these pathways remains debated. Long-standing control of inflammation appears necessary to avoid ankylosis. Recent evidence and concepts suggest an important role for biomechanical factors in both the onset and progression of the disease. With regard to new bone formation, these processes can be understood as ectopic repair responses secondary to inflammation-induced bone loss and instability. In this review, we discuss the clinical implications of the skeletal changes as well as the underlying molecular mechanisms, the relation between inflammation and new bone formation, and the potential role of biomechanical stress.

Biomechanical effects of two different collar implant structures on stress distribution under cantilever fixed partial dentures.

Science.gov (United States)

Merıç, Gökçe; Erkmen, Erkan; Kurt, Ahmet; Eser, Atilim; özden, Ahmet Utku

2011-11-01

The purpose of the study was to compare the effects of two distinct collar geometries of implants on stress distribution in the bone around the implants supporting cantilever fixed partial dentures (CFPDs) as well as in the implant-abutment complex and superstructures. The three-dimensional finite element method was selected to evaluate the stress distribution. CFPDs which was supported by microthread collar structured (MCS) and non-microthread collar structured (NMCS) implants was modeled; 300 N vertical, 150 N oblique and 60 N horizontal forces were applied to the models separately. The stress values in the bone, implant-abutment complex and superstructures were calculated. In the MCS model, higher stresses were located in the cortical bone and implant-abutment complex in the case of vertical load while decreased stresses in cortical bone and implant-abutment complex were noted within horizontal and oblique loading. In the case of vertical load, decreased stresses have been noted in cancellous bone and framework. Upon horizontal and oblique loading, a MCS model had higher stress in cancellous bone and framework than the NMCS model. Higher von Mises stresses have been noted in veneering material for NMCS models. It has been concluded that stress distribution in implant-supported CFPDs correlated with the macro design of the implant collar and the direction of applied force.

Bone scintigraphy for horses; Die Skelettszintigrafie beim Pferd

Energy Technology Data Exchange (ETDEWEB)

Jahn, Werner [Pferdeklinik Bargteheide (Germany)

2010-03-15

Scintigraphy (bone scan) is being used approximately since 1980 in the horse under general anaesthesia. With the construction of custom-made overhead gantries for gamma-cameras scintigraphy found widespread entry in big equine referral hospitals for bone-scanning of the standing horse. Indications for the use of a bone scan in the horse are inflammatory alterations in the locomotor apparatus. It is primarily used for diagnosis of lameness of unknown origin, suspect of stress fracture or hairline fracture and for horses with bad riding comfort with suspected painful lesions in the spine. (orig.)

Cone-Beam Computed Tomography as a Diagnostic Method for Determination of Gingival Thickness and Distance between Gingival Margin and Bone Crest

Directory of Open Access Journals (Sweden)

Germana Jayme Borges

2015-01-01

Full Text Available The objective of the present study was to assess cone-beam computed tomography (CBCT as a diagnostic method for determination of gingival thickness (GT and distance between gingival margin and vestibular (GMBC-V and interproximal bone crests (GMBC-I. GT and GMBC-V were measured in 348 teeth and GMBC-I was measured in 377 tooth regions of 29 patients with gummy smile. GT was assessed using transgingival probing (TP, ultrasound (US, and CBCT, whereas GMBC-V and GMBC-I were assessed by transsurgical clinical evaluation (TCE and CBCT. Statistical analyses used independent t-test, Pearson’s correlation coefficient, and simple linear regression. Difference was observed for GT: between TP, CBCT, and US considering all teeth; between TP and CBCT and between TP and US in incisors and canines; between TP and US in premolars and first molars. TP presented the highest means for GT. Positive correlation and linear regression were observed between TP and CBCT, TP and US, and CBCT and US. Difference was observed for GMBC-V and GMBC-I using TCE and CBCT, considering all teeth. Correlation and linear regression results were significant for GMBC-V and GMBC-I in incisors, canines, and premolars. CBCT is an effective diagnostic method to visualize and measure GT, GMBC-V, and GMBC-I.

High-strength mineralized collagen artificial bone

Science.gov (United States)

Qiu, Zhi-Ye; Tao, Chun-Sheng; Cui, Helen; Wang, Chang-Ming; Cui, Fu-Zhai

2014-03-01

Mineralized collagen (MC) is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal's cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in vivo implantation assay demonstrated good biocompatibility of the material, and in vivo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load-bearing sites.

Risk factors for stress fractures.

Science.gov (United States)

Bennell, K; Matheson, G; Meeuwisse, W; Brukner, P

1999-08-01

Preventing stress fractures requires knowledge of the risk factors that predispose to this injury. The aetiology of stress fractures is multifactorial, but methodological limitations and expediency often lead to research study designs that evaluate individual risk factors. Intrinsic risk factors include mechanical factors such as bone density, skeletal alignment and body size and composition, physiological factors such as bone turnover rate, flexibility, and muscular strength and endurance, as well as hormonal and nutritional factors. Extrinsic risk factors include mechanical factors such as surface, footwear and external loading as well as physical training parameters. Psychological traits may also play a role in increasing stress fracture risk. Equally important to these types of analyses of individual risk factors is the integration of information to produce a composite picture of risk. The purpose of this paper is to critically appraise the existing literature by evaluating study design and quality, in order to provide a current synopsis of the known scientific information related to stress fracture risk factors. The literature is not fully complete with well conducted studies on this topic, but a great deal of information has accumulated over the past 20 years. Although stress fractures result from repeated loading, the exact contribution of training factors (volume, intensity, surface) has not been clearly established. From what we do know, menstrual disturbances, caloric restriction, lower bone density, muscle weakness and leg length differences are risk factors for stress fracture. Other time-honoured risk factors such as lower extremity alignment have not been shown to be causative even though anecdotal evidence indicates they are likely to play an important role in stress fracture pathogenesis.

Cortical bone drilling: An experimental and numerical study.

Science.gov (United States)

Alam, Khurshid; Bahadur, Issam M; Ahmed, Naseer

2014-12-16

Bone drilling is a common surgical procedure in orthopedics, dental and neurosurgeries. In conventional bone drilling process, the surgeon exerts a considerable amount of pressure to penetrate the drill into the bone tissue. Controlled penetration of drill in the bone is necessary for safe and efficient drilling. Development of a validated Finite Element (FE) model of cortical bone drilling. Drilling experiments were conducted on bovine cortical bone. The FE model of the bone drilling was based on mechanical properties obtained from literature data and additionally conducted microindentation tests on the cortical bone. The magnitude of stress in bone was found to decrease exponentially away from the lips of the drill in simulations. Feed rate was found to be the main influential factor affecting the force and torque in the numerical simulations and experiments. The drilling thrust force and torque were found to be unaffected by the drilling speed in numerical simulations. Simulated forces and torques were compared with experimental results for similar drilling conditions and were found in good agreement.CONCLUSIONS: FE schemes may be successfully applied to model complex kinematics of bone drilling process.

Distinguishing stress fractures from pathologic fractures: a multimodality approach

International Nuclear Information System (INIS)

Fayad, Laura M.; Kamel, Ihab R.; Kawamoto, Satomi; Bluemke, David A.; Fishman, Elliot K.; Frassica, Frank J.

2005-01-01

Whereas stress fractures occur in normal or metabolically weakened bones, pathologic fractures occur at the site of a bone tumor. Unfortunately, stress fractures may share imaging features with pathologic fractures on plain radiography, and therefore other modalities are commonly utilized to distinguish these entities. Additional cross-sectional imaging with CT or MRI as well as scintigraphy and PET scanning is often performed for further evaluation. For the detailed assessment of a fracture site, CT offers a high-resolution view of the bone cortex and periosteum which aids the diagnosis of a pathologic fracture. The character of underlying bone marrow patterns of destruction can also be ascertained along with evidence of a soft tissue mass. MRI, however, is a more sensitive technique for the detection of underlying bone marrow lesions at a fracture site. In addition, the surrounding soft tissues, including possible involvement of adjacent muscle, can be well evaluated with MRI. While bone scintigraphy and FDG-PET are not specific, they offer a whole-body screen for metastases in the case of a suspected malignant pathologic fracture. In this review, we present select examples of fractures that underscore imaging features that help distinguish stress fractures from pathologic fractures, since accurate differentiation of these entities is paramount. (orig.)

Bone tissue engineering: the role of interstitial fluid flow

Science.gov (United States)

Hillsley, M. V.; Frangos, J. A.

1994-01-01

It is well established that vascularization is required for effective bone healing. This implies that blood flow and interstitial fluid (ISF) flow are required for healing and maintenance of bone. The fact that changes in bone blood flow and ISF flow are associated with changes in bone remodeling and formation support this theory. ISF flow in bone results from transcortical pressure gradients produced by vascular and hydrostatic pressure, and mechanical loading. Conditions observed to alter flow rates include increases in venous pressure in hypertension, fluid shifts occurring in bedrest and microgravity, increases in vascularization during the injury-healing response, and mechanical compression and bending of bone during exercise. These conditions also induce changes in bone remodeling. Previously, we hypothesized that interstitial fluid flow in bone, and in particular fluid shear stress, serves to mediate signal transduction in mechanical loading- and injury-induced remodeling. In addition, we proposed that a lack or decrease of ISF flow results in the bone loss observed in disuse and microgravity. The purpose of this article is to review ISF flow in bone and its role in osteogenesis.

On-line fatigue monitoring and probabilistic assessment of margins

Energy Technology Data Exchange (ETDEWEB)

Fournier, I. [Electricite de France, 93 - Saint-Denis (France). Direction des Etudes et Recherches; Morilhat, P. [Electricite de France, 93 - Saint-Denis (France). Direction des Etudes et Recherches

1995-01-01

An on-line computer-aided system has been developed by Electricite de France, the French utility, for fatigue monitoring of critical locations in the nuclear steam supply system. This tool, called a fatigue meter, includes as input data plant parameters and is based on some conservative assumptions at several steps of the damage assessment (thermal boundary conditions, stress computation,..). In this paper we present recent developments performed towards a better assessment of margins involved in the complete analysis. The methodology is illustrated with an example showing the influence of uncertainty in plant parameters on the final stress computed at a pressurized water reactor 900MW unit pressurizer surge line nozzle. A second example is shown to illustrate the possibility of defining some transient archetypes. ((orig.)).

Electron microscopic observations and DNA chain fragmentation studies on apoptosis in bone tumor cells induced by 153Sm-EDTMP

International Nuclear Information System (INIS)

Zhu Shoupeng; Xiao Dong; Han Xiaofeng

1997-01-01

The morphological changes observed by electron microscopy indicate that after internal irradiation with 153 Sm-EDTMP bone tumor cells displayed feature of apoptosis, such as margination of condensed chromatin, chromatin fragmentation, as well as the membrane bounded apoptotic bodies formation. The quantification analysis of fragmentation DNA for bone tumor cells induced by 153 Sm-EDTMP shows that the DNA fragmentation is enhanced with the prolongation of internally irradiated time. These characteristics suggest that 153 Sm-EDTMP internal irradiation could induce bone tumor cells to go to apoptosis

Radiographic study of bone changes on TMJ arthrosis

International Nuclear Information System (INIS)

You, Dong Soo

1982-01-01

The author analyzed the morphologic changes of bone structures from 1256 radiographs of 314 patients with temporomandibular joint arthrosis, which were obtained by the oblique-lateral projection and orthopantomography. The interrelations of the bone changes and clinical symptoms were examined. Also, the positional relationships of condylar head, articular fossa and articular eminence in the mouth open and closed state were observed in the patients with bone changes. The results were as follows; 1. The most frequent bone change in the TMJ arthrosis was eburnation of cortical bone (35.64%) of total cases. Then came bone surface erosion and localized radiolucency (26.18%), marginal proliferation (9.7%) and flattening of articular surface (9.58%) in that order. 2. The most frequent site of bone change was articular eminence (41.70%). The came condylar head (21.09%) and articular fossa (20.73%) in that order. 3. In the patients with bone changes, their clinical symptoms were pain (51.55%), clicking sound during mandibular movement (37.71%) and limited mandibular movement (10.73%). In the patients complaining pain, their radiographs showed eburnation of cortical bone (30.68%), bone surface erosion and localized radiolucency (27.45%) and flattening in the (30.68%), bone surface erosion and localized radiolucency (27.45%) and flattening of articular surface (10.68%). 4. The condylar positional changes in the TMJ arthrosis patients with bone changes were as follows: in the mouth closed state, there were the widening of joint space in 624 cases (50.00%), the narrowing of joint space in 543 cases (43.47%) and bone on bone relationships in 82 cases (6.57%). In the mouth open state, there were forward positioning of the condyle in 332 cases (28.55%), limitation of movement in 332 cases (28.55%), bone on bone relationships in 248 cases (21.31%) and downward positioning of condyle in 217 cases (18.66%). Bone on bone relationships in 248 cases (21.32%) and downward positioning of

Radiographic study of bone changes on TMJ arthrosis

Energy Technology Data Exchange (ETDEWEB)

You, Dong Soo [Dept. of Radiology, College of Dentistry, Seoul National University, Seoul (Korea, Republic of)

1982-11-15

The author analyzed the morphologic changes of bone structures from 1256 radiographs of 314 patients with temporomandibular joint arthrosis, which were obtained by the oblique-lateral projection and orthopantomography. The interrelations of the bone changes and clinical symptoms were examined. Also, the positional relationships of condylar head, articular fossa and articular eminence in the mouth open and closed state were observed in the patients with bone changes. The results were as follows; 1. The most frequent bone change in the TMJ arthrosis was eburnation of cortical bone (35.64%) of total cases. Then came bone surface erosion and localized radiolucency (26.18%), marginal proliferation (9.7%) and flattening of articular surface (9.58%) in that order. 2. The most frequent site of bone change was articular eminence (41.70%). The came condylar head (21.09%) and articular fossa (20.73%) in that order. 3. In the patients with bone changes, their clinical symptoms were pain (51.55%), clicking sound during mandibular movement (37.71%) and limited mandibular movement (10.73%). In the patients complaining pain, their radiographs showed eburnation of cortical bone (30.68%), bone surface erosion and localized radiolucency (27.45%) and flattening in the (30.68%), bone surface erosion and localized radiolucency (27.45%) and flattening of articular surface (10.68%). 4. The condylar positional changes in the TMJ arthrosis patients with bone changes were as follows: in the mouth closed state, there were the widening of joint space in 624 cases (50.00%), the narrowing of joint space in 543 cases (43.47%) and bone on bone relationships in 82 cases (6.57%). In the mouth open state, there were forward positioning of the condyle in 332 cases (28.55%), limitation of movement in 332 cases (28.55%), bone on bone relationships in 248 cases (21.31%) and downward positioning of condyle in 217 cases (18.66%). Bone on bone relationships in 248 cases (21.32%) and downward positioning of

Imaging of bone tumors: evaluation of direct magnification radiography

International Nuclear Information System (INIS)

Link, T.M.; Hillmann, A.; Erlemann, R.; Groenefeld, A.; Haeussler, M.; Heppe, A.E.; Vestring, T.; Peters, P.E.

1996-01-01

Objective. To evaluate the potentials of magnification radiography as compared with conventional radiography in diagnosing bone tumors. Design and patients. Sixty-two patients with primary bone tumors and tumorlike lesions underwent radiography with both conventional (non-magnified) and magnification (fivefold) techniques. All radiographs were analyzed by four radiologists and the findings correlated with the histopathology findings. The microfocal X-ray unit used for magnification radiography had a focal spot size of 20-130 μm. Digital luminescence radiography was employed with magnification, while normal film-screen systems were used with conventional radiography. Results. The diagnosis of benign and malignant lesions as well as the individual tumor diagnosis were determined with higher accuracy using magnification compared with conventional radiography (88% vs 75% and 71% vs 52%, p<0.01). Margins of destruction, periosteal reactions and matrix patterns were evaluated with higher certainty by all of the radiologists (p<0.01). Conclusion. Magnification radiography may improve the evaluation and diagnosis of bone tumors. (orig.). With 6 tabs

Effects of Nrf2 Deficiency on Bone Microarchitecture in an Experimental Model of Osteoporosis

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Lidia Ibáñez

2014-01-01

Full Text Available Objective. Redox imbalance contributes to bone fragility. We have evaluated the in vivo role of nuclear factor erythroid derived 2-related factor-2 (Nrf2, an important regulator of cellular responses to oxidative stress, in bone metabolism using a model of postmenopausal osteoporosis. Methods. Ovariectomy was performed in both wild-type and mice deficient in Nrf2 (Nrf2−/−. Bone microarchitecture was analyzed by μCT. Serum markers of bone metabolism were also measured. Reactive oxygen species production was determined using dihydrorhodamine 123. Results. Sham-operated or ovariectomized Nrf2−/− mice exhibit a loss in trabecular bone mineral density in femur, accompanied by a reduction in cortical area in vertebrae. Nrf2 deficiency tended to increase osteoblastic markers and significantly enhanced osteoclastic markers in sham-operated animals indicating an increased bone turnover with a main effect on bone resorption. We have also shown an increased production of oxidative stress in bone marrow-derived cells from sham-operated or ovariectomized Nrf2−/− mice and a higher responsiveness of bone marrow-derived cells to osteoclastogenic stimuli in vitro. Conclusion. We have demonstrated in vivo a key role of Nrf2 in the maintenance of bone microarchitecture.

Material model of pelvic bone based on modal analysis: a study on the composite bone.

Science.gov (United States)

Henyš, Petr; Čapek, Lukáš

2017-02-01

Digital models based on finite element (FE) analysis are widely used in orthopaedics to predict the stress or strain in the bone due to bone-implant interaction. The usability of the model depends strongly on the bone material description. The material model that is most commonly used is based on a constant Young's modulus or on the apparent density of bone obtained from computer tomography (CT) data. The Young's modulus of bone is described in many experimental works with large variations in the results. The concept of measuring and validating the material model of the pelvic bone based on modal analysis is introduced in this pilot study. The modal frequencies, damping, and shapes of the composite bone were measured precisely by an impact hammer at 239 points. An FE model was built using the data pertaining to the geometry and apparent density obtained from the CT of the composite bone. The isotropic homogeneous Young's modulus and Poisson's ratio of the cortical and trabecular bone were estimated from the optimisation procedure including Gaussian statistical properties. The performance of the updated model was investigated through the sensitivity analysis of the natural frequencies with respect to the material parameters. The maximal error between the numerical and experimental natural frequencies of the bone reached 1.74 % in the first modal shape. Finally, the optimised parameters were matched with the data sheets of the composite bone. The maximal difference between the calibrated material properties and that obtained from the data sheet was 34 %. The optimisation scheme of the FE model based on the modal analysis data provides extremely useful calibration of the FE models with the uncertainty bounds and without the influence of the boundary conditions.

Can medio-lateral baseplate position and load sharing induce asymptomatic local bone resorption of the proximal tibia? A finite element study

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Wong Pius

2009-07-01

Full Text Available Abstract Background Asymptomatic local bone resorption of the tibia under the baseplate can occasionally be observed after total knee arthroplasty (TKA. Its occurrence is not well documented, and so far no explanation is available. We report the incidence of this finding in our practice, and investigate whether it can be attributed to specific mechanical factors. Methods The postoperative radiographs of 500 consecutive TKA patients were analyzed to determine the occurrence of local medial bone resorption under the baseplate. Based on these cases, a 3D FE model was developed. Cemented and cementless technique, seven positions of the baseplate and eleven load sharing conditions were considered. The average VonMises stress was evaluated in the bone-baseplate interface, and the medial and lateral periprosthetic region. Results Sixteen cases with local bone resorption were identified. In each, bone loss became apparent at 3 months post-op and did not increase after one year. None of these cases were symptomatic and infection screening was negative for all. The FE analysis demonstrated an influence of baseplate positioning, and also of load sharing, on stresses. The average stress in the medial periprosthetic region showed a non linear decrease when the prosthetic baseplate was shifted laterally. Shifting the component medially increased the stress on the medial periprosthetic region, but did not significantly unload the lateral side. The presence of a cement layer decreases the stresses. Conclusion Local bone resorption of the proximal tibia can occur after TKA and might be attributed to a stress shielding effect. This FE study shows that the medial periprosthetic region of the tibia is more sensitive than the lateral region to mediolateral positioning of the baseplate. Medial cortical support of the tibial baseplate is important for normal stress transfer to the underlying bone. The absence of medial cortical support of the tibial baseplate may lead

Stress fractures: pathophysiology, clinical presentation, imaging features, and treatment options.

Science.gov (United States)

Matcuk, George R; Mahanty, Scott R; Skalski, Matthew R; Patel, Dakshesh B; White, Eric A; Gottsegen, Christopher J

2016-08-01

Stress fracture, in its most inclusive description, includes both fatigue and insufficiency fracture. Fatigue fractures, sometimes equated with the term "stress fractures," are most common in runners and other athletes and typically occur in the lower extremities. These fractures are the result of abnormal, cyclical loading on normal bone leading to local cortical resorption and fracture. Insufficiency fractures are common in elderly populations, secondary to osteoporosis, and are typically located in and around the pelvis. They are a result of normal or traumatic loading on abnormal bone. Subchondral insufficiency fractures of the hip or knee may cause acute pain that may present in the emergency setting. Medial tibial stress syndrome is a type of stress injury of the tibia related to activity and is a clinical syndrome encompassing a range of injuries from stress edema to frank-displaced fracture. Atypical subtrochanteric femoral fracture associated with long-term bisphosphonate therapy is also a recently discovered entity that needs early recognition to prevent progression to a complete fracture. Imaging recommendations for evaluation of stress fractures include initial plain radiographs followed, if necessary, by magnetic resonance imaging (MRI), which is preferred over computed tomography (CT) and bone scintigraphy. Radiographs are the first-line modality and may reveal linear sclerosis and periosteal reaction prior to the development of a frank fracture. MRI is highly sensitive with findings ranging from periosteal edema to bone marrow and intracortical signal abnormality. Additionally, a brief description of relevant clinical management of stress fractures is included.

Titanium-Based Biomaterials for Preventing Stress Shielding between Implant Devices and Bone

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M. Niinomi

2011-01-01

Full Text Available β-type titanium alloys with low Young's modulus are required to inhibit bone atrophy and enhance bone remodeling for implants used to substitute failed hard tissue. At the same time, these titanium alloys are required to have high static and dynamic strength. On the other hand, metallic biomaterials with variable Young's modulus are required to satisfy the needs of both patients and surgeons, namely, low and high Young's moduli, respectively. In this paper, we have discussed effective methods to improve the static and dynamic strength while maintaining low Young's modulus for β-type titanium alloys used in biomedical applications. Then, the advantage of low Young's modulus of β-type titanium alloys in biomedical applications has been discussed from the perspective of inhibiting bone atrophy and enhancing bone remodeling. Further, we have discussed the development of β-type titanium alloys with a self-adjusting Young's modulus for use in removable implants.

Bone Growth, Mechanical Stimulus and IGF-1

National Research Council Canada - National Science Library

Gilsanz, Vicente

2006-01-01

... in the weight bearing skeleton of young adult females with low bone density. Ultimately, this information could be of great benefit to enhance musculoskeletal development and decrease the risk for stress fractures in military recruits...

Oral Contraceptives and Bone Health in Female Runners

National Research Council Canada - National Science Library

Kelsey, Jennifer L

2007-01-01

.... Previous cross-sectional research has shown that women with exercise-induced menstrual irregularities have a significantly higher frequency of stress fractures and low bone mass than normally menstruating controls...

PORTRAIT GRAFFITI IN MARGINS OF ANTIQUE LITHUANIAN BOOKS

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Burba, Domininkas

2006-12-01

Full Text Available This article presents and discusses fourteen drawings that portray a human and were found in manuscripts and printed books (documents that were actively used in Lithuania from 17th to 19th centuries. All the drawings were made in the margins of the documents. For the authors the drawings were not planned work but more like quips, scribbles and doodles. Therefore the terms portrait graffiti and (as a synonym portrait marginalia are used to describe the discussed portraits. According to the formal classification of marginal drawings (suggested by J. Liskeviciene two of the examined marginal portraits (no. 10 and 14 are classed as seperate and finished works with their own composition; ten marginal portraits (no. 2, 4, 5, 6, 7, 8, 9, 11, 12 and 13 represent the readers (document users sketch like drawings. Two other portraits (no. 1 and 3 are just scribbles that have nothing to do with artictic perception and are very close to book graffiti. From the artistic approcah the most sophisticated of the marginal portraits are “the hunt scene” (no. 14 and the late (first half of the 19th century “portrait of the teacher” (no. 13. In the viewpoint of documentary and social communication the discussed marginal drawings did not have a direct addressee. They were made not for public but for personal use. Paleographical, structural and content analysis of the document showed that the author of the “bearded nobleman” portrait (no. 2 could have been the elder of Merkine Antanas Kazimieras Sapiega. The political realia of Grand Duchy of Lithuania (from now GDL are reflected by the heart shaped portrait of a youngster who we can guess is portrayed weeping over the countries misfortunes and internal disagreements duringthe period of foreight military interventions in the years from 1733 to 1736. It was forbiden for scribes to daub on court files and other official GDL documents therefore the discussed graffiti could be linked to psychological stress and

Piezosurgical osteotomy for harvesting intraoral block bone graft

Science.gov (United States)

Lakshmiganthan, Mahalingam; Gokulanathan, Subramanium; Shanmugasundaram, Natarajan; Daniel, Rajkumar; Ramesh, Sadashiva B.

2012-01-01

The use of ultrasonic vibrations for the cutting of bone was first introduced two decades ago. Piezoelectric surgery is a minimally invasive technique that lessens the risk of damage to surrounding soft tissues and important structures such as nerves, vessels, and mucosa. It also reduces damage to osteocytes and permits good survival of bony cells during harvesting of bone. Grafting with intraoral bone blocks is a good way to reconstruct severe horizontal and vertical bone resorption in future implants sites. The piezosurgery system creates an effective osteotomy with minimal or no trauma to soft tissue in contrast to conventional surgical burs or saws and minimizes a patient's psychological stress and fear during osteotomy under local anesthesia. The purpose of this article is to describe the harvesting of intraoral bone blocks using the piezoelectric surgery device. PMID:23066242

Piezosurgical osteotomy for harvesting intraoral block bone graft

Directory of Open Access Journals (Sweden)

Mahalingam Lakshmiganthan

2012-01-01

Full Text Available The use of ultrasonic vibrations for the cutting of bone was first introduced two decades ago. Piezoelectric surgery is a minimally invasive technique that lessens the risk of damage to surrounding soft tissues and important structures such as nerves, vessels, and mucosa. It also reduces damage to osteocytes and permits good survival of bony cells during harvesting of bone. Grafting with intraoral bone blocks is a good way to reconstruct severe horizontal and vertical bone resorption in future implants sites. The piezosurgery system creates an effective osteotomy with minimal or no trauma to soft tissue in contrast to conventional surgical burs or saws and minimizes a patient′s psychological stress and fear during osteotomy under local anesthesia. The purpose of this article is to describe the harvesting of intraoral bone blocks using the piezoelectric surgery device.

Mathematical model of mechanical testing of bone-implant (4.5 mm LCP construct

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Lucie Urbanová

2012-01-01

Full Text Available The study deals with the possibility of substituting time- and material-demanding mechanical testing of a bone defect fixation by mathematical modelling. Based on the mechanical model, a mathematical model of bone-implant construct stabilizing experimental segmental femoral bone defect (segmental ostectomy in a miniature pig ex vivo model using 4.5 mm titanium LCP was created. It was subsequently computer-loaded by forces acting parallel to the long axis of the construct. By the effect of the acting forces the displacement vector sum of individual construct points occurred. The greatest displacement was noted in the end segments of the bone in close proximity to ostectomy and in the area of the empty central plate hole (without screw at the level of the segmental bone defect. By studying the equivalent von Mises stress σEQV on LCP as part of the tested construct we found that the greatest changes of stress occur in the place of the empty central plate hole. The distribution of this strain was relatively symmetrical along both sides of the hole. The exceeding of the yield stress value and irreversible plastic deformations in this segment of LCP occurred at the acting of the force of 360 N. These findings are in line with the character of damage of the same construct loaded during its mechanic testing. We succeeded in creating a mathematical model of the bone-implant construct which may be further used for computer modelling of real loading of similar constructs chosen for fixation of bone defects in both experimental and clinical practice.

"We call ourselves marginalized"

DEFF Research Database (Denmark)

Jørgensen, Nanna Jordt

2014-01-01

of the people we refer to as marginalized. In this paper, I discuss how young secondary school graduates from a pastoralist community in Kenya use and negotiate indigeneity, marginal identity, and experiences of marginalization in social navigations aimed at broadening their current and future opportunities. I...

Proximal alveolar bone loss in a longitudinal radiographic investigation

International Nuclear Information System (INIS)

Bolin, A.; Lavstedt, S.; Henrikson, C.O.; Frithiof, L.

1986-01-01

In Sweden people in all age groups now have more remaining teeth than previosly. An investigation has been made to identify some predictors of alveolar bone loss in a 10-year period in subjects with at least 20 remaining teeth. The material consisted of 349 individuals, examined radiographically, clinically and by interview in 1970 and in 1980. These subjects, born in 1904-1952, constituted a subgroup, with regard to remaining teeth, of an unselected sample of the population of the old county of Stockholm. In the unselected sample statistically significant predictors of alveolar bone loss found in a stepwise multiple regression analysis were 1) alveolar bone loss in 1970, 2) age, 3) number of lost teeth and 4) Russell's Periodontol Index (PI). In the subgroup the predictors were in the order 1) Russell's PI and 2) smoking. The prediction values (R 2 ) of further variables were marginal. The analyses showed that there was an interaction between PI and smoking, implying that the effect of smoking on alveolar bone loss was increased in individuals with high PI values. Furthermore, a tendency was found for a dose-response effect of tobacco consumption. This tendency almost disappeared when controlling for PI

Bone density does not reflect mechanical properties in early-stage arthrosis

DEFF Research Database (Denmark)

Ding, Ming; Danielsen, CC; Hvid, I

2001-01-01

: medial arthrosis, lateral control, normal medial and normal lateral controls. The specimens were tested in compression to determine mechanical properties and then physical/compositional properties. Compared to the normal medial control, we found reductions in ultimate stress, Young's modulus, and failure...... cancellous bone and the 3 controls. None of the mechanical properties of arthrotic cancellous bone could be predicted by the physical/compositional properties measured. The increase in bone tissue in early-stage arthrotic cancellous bone did not make up for the loss of mechanical properties, which suggests...

Modes of failures: primary and secondary stresses

International Nuclear Information System (INIS)

Roche, R.L.

1987-07-01

The paper begins with a reminder that the purpose of stress classification is to ensure suitable margins with respect to failure modes. The distinction between primary stresses and secondary stresses is then examined and a method is given for assessing the degree of elastic follow up in the elastic plastic field. The importance of elastic follow up is then highlighted by an examination of the effect of primary and secondary stresses on crack behavior

Adaptive scapula bone remodeling computational simulation: Relevance to regenerative medicine

International Nuclear Information System (INIS)

Sharma, Gulshan B.; Robertson, Douglas D.

2013-01-01

Shoulder arthroplasty success has been attributed to many factors including, bone quality, soft tissue balancing, surgeon experience, and implant design. Improved long-term success is primarily limited by glenoid implant loosening. Prosthesis design examines materials and shape and determines whether the design should withstand a lifetime of use. Finite element (FE) analyses have been extensively used to study stresses and strains produced in implants and bone. However, these static analyses only measure a moment in time and not the adaptive response to the altered environment produced by the therapeutic intervention. Computational analyses that integrate remodeling rules predict how bone will respond over time. Recent work has shown that subject-specific two- and three dimensional adaptive bone remodeling models are feasible and valid. Feasibility and validation were achieved computationally, simulating bone remodeling using an intact human scapula, initially resetting the scapular bone material properties to be uniform, numerically simulating sequential loading, and comparing the bone remodeling simulation results to the actual scapula’s material properties. Three-dimensional scapula FE bone model was created using volumetric computed tomography images. Muscle and joint load and boundary conditions were applied based on values reported in the literature. Internal bone remodeling was based on element strain-energy density. Initially, all bone elements were assigned a homogeneous density. All loads were applied for 10 iterations. After every iteration, each bone element’s remodeling stimulus was compared to its corresponding reference stimulus and its material properties modified. The simulation achieved convergence. At the end of the simulation the predicted and actual specimen bone apparent density were plotted and compared. Location of high and low predicted bone density was comparable to the actual specimen. High predicted bone density was greater than

Prosthodontic rehabilitation of patient with marginal mandibular resection using attachment supported prostheses: A clinical report

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Kailas Mundhe

2014-01-01

Full Text Available Marginal mandibular resection to treat neoplasms leads to loss of alveolar bone and teeth at the affected side. Consequently patient suffers with poor masticatory performance and esthetic disfigurement, which we need to restore with the help of prosthodontic rehabilitation. The success of rehabilitation of these patients depends on strategic treatment planning and choice of most suitable treatment modality. In this article, case of a patient has been presented who underwent marginal mandibular resection and reported with many limiting factors like obliterated buccal and lingual sulci, attachment of lingual frenum and lower lip at the level of alveolar ridge and Macroglossia. Impression making and fabrication of a retentive prosthesis were the main challenges. Therefore, a modified impression technique was used to fabricate mandibular cast partial denture with extracoronal semi precision attachments to enhance the retention of the prosthesis.

Multiple stress fractures in a young female runner.

Science.gov (United States)

Dusek, T; Pećina, M; Loncar-Dusek, M; Bojanic, I

2004-01-01

The effect of exercise on female's bone metabolism has received much attention in recent years. We report on unusual case of a female runner with low body mass and amenorrhea, who suffered 4 stress fractures. Three of the stress fractures occurred during her sports career, and the fourth occurred 7 years after the cessation of sports activities. It seems that exercise-induced amenorrhea together with food restriction in the young age may cause long-term consequences on bone metabolism.

Marginal Matter

Science.gov (United States)

van Hecke, Martin

2013-03-01

All around us, things are falling apart. The foam on our cappuccinos appears solid, but gentle stirring irreversibly changes its shape. Skin, a biological fiber network, is firm when you pinch it, but soft under light touch. Sand mimics a solid when we walk on the beach but a liquid when we pour it out of our shoes. Crucially, a marginal point separates the rigid or jammed state from the mechanical vacuum (freely flowing) state - at their marginal points, soft materials are neither solid nor liquid. Here I will show how the marginal point gives birth to a third sector of soft matter physics: intrinsically nonlinear mechanics. I will illustrate this with shock waves in weakly compressed granular media, the nonlinear rheology of foams, and the nonlinear mechanics of weakly connected elastic networks.

Chondroblastoma of the temporal bone

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Yuko; Murakami, Ryusuke; Toba, Masahiro; Ichikawa, Taro [Dept. of Radiology, Nippon Medical School, Tokyo (Japan); Kanazawa, Ryuzaburo; Sanno, Naoko; Shimura, Toshiro [Dept. of Neurosurgery, Nippon Medical School, Tokyo (Japan); Sawada, Namie; Hosone, Masaru [Dept. of Pathology, Nippon Medical School, Tokyo (Japan); Kumazaki, Tatsuo [Dept. of Radiology, Nippon Medical School, Tokyo (Japan)

2001-12-01

A rare case of chondroblastoma arising from the temporal bone that occurred in a 60-year-old woman is reported. The tumor appeared well demarcated and osteolytic on the radiographs. CT scan clearly depicted marginal and central calcification in the tumor. MR imaging demonstrated two components in the tumor: a solid component with predominantly low signal intensities on both T1- and T2-weighted sequences, and a multilocular cystic component with T1- and T2-elongation and fluid-fluid levels on the T2-weighted images. Postcontrast MR imaging revealed marked enhancement in the solid component and the septa of the cystic component. (orig.)

Morphological experimental study of bone stress at the interface acetabular bone/prosthetic cup in the bipolar hip prosthesis.

Science.gov (United States)

Anuşca, D; Pleşea, I E; Iliescu, N; Tomescu, P; Poenaru, F; Dascălu, V; Pop, O T

2006-01-01

By calculating the tension and distortion of the elements composing the bipolar prosthesis under extreme conditions encountered in real life using a special post-processing program, we established the variation curves of the contact pressure at the hip bone-cup, armor-cup and cup-femoral head interface. By comparing the data obtained from all the examined cases, important conclusions were drawn regarding the influence of tension and pressure distribution on the structural integrity and biomechanics of the prosthesis, as well as the acetabular wear and tear, in order to assess its reliability. The experimentally determined tension and distortion status at the acetabular bone-metal armour interface, lead to the wear and tear phenomenon, which can be explained by three mechanisms and theories incompletely reflecting the overall process. The histopathologic study of the acetabular bone tissue using FEM (finite elements method) on surgically removed specimens will probably lead to the identification of a series of factors that could reduce the rate of the wear and tear process.

Marginalization of the Youth