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Sample records for abnormal biomechanical properties

  1. Biomechanical properties of four dermal substitutes

    ZHANG Guo-an; NING Fang-gang; ZHAO Nan-ming

    2007-01-01

    @@ Many kinds of cell-free dermal substitutes have been developed during the past several years, however,their biomechanical properties, including hysteresis,stress relaxation, creep, and non-linear stress-strain, are still unknown. In this study, we tested these biomechanical characteristics of four dermal substitutes,and compared them with those of fresh human skin (FHS).

  2. Asymmetric cell-matrix and biomechanical abnormalities in elastin insufficiency induced aortopathy.

    Krishnamurthy, Varun K; Evans, Ashlie N; Wansapura, Janaka P; Osinska, Hanna; Maddy, Kelsey E; Biechler, Stefanie V; Narmoneva, Daria A; Goodwin, Richard L; Hinton, Robert B

    2014-10-01

    Aortopathy is characterized by vascular smooth muscle cell (VSMC) abnormalities and elastic fiber fragmentation. Elastin insufficient (Eln (+/-)) mice demonstrate latent aortopathy similar to human disease. We hypothesized that aortopathy manifests primarily in the aorto-pulmonary septal (APS) side of the thoracic aorta due to asymmetric cardiac neural crest (CNC) distribution. Anatomic (aortic root vs. ascending aorta) and molecular (APS vs. non-APS) regions of proximal aorta tissue were examined in adult and aged wild type (WT) and mutant (Eln (+/-)) mice. CNC, VSMCs, elastic fiber architecture, proteoglycan expression, morphometrics and biomechanical properties were examined using histology, 3D reconstruction, micropipette aspiration and in vivo magnetic resonance imaging (MRI). In the APS side of Eln (+/-) aorta, Sonic Hedgehog (SHH) is decreased while SM22 is increased. Elastic fiber architecture abnormalities are present in the Eln (+/-) aortic root and APS ascending aorta, and biglycan is increased in the aortic root while aggrecan is increased in the APS aorta. The Eln (+/-) ascending aorta is stiffer than the aortic root, the APS side is thicker and stiffer than the non-APS side, and significant differences in the individual aortic root sinuses are observed. Asymmetric structure-function abnormalities implicate regional CNC dysregulation in the development and progression of aortopathy.

  3. Biomechanical properties of soft tissues

    曾衍钧; 许传青; 杨坚; 徐小虎

    2003-01-01

    Viscoelasticity is the primary mechanical property of bio-soft tissues. It has been widely applied in basic research of biological tissues including cornea, lung, heart and blood vessels. Along with the development of tissue engineering research, the evaluation of soft tissue viscoelasticity is becoming more and more important. In this paper, using the Whittaker function, we give an approximate power series of the exponential integral E1(x) and the parameters c, ?1 and ?2 of the generalized relaxation function G(t) and generalized creep function J(t). With expanded skin as an example, the relationship between stress relaxation, creep and stress-strain finite deformation are studied.

  4. Biomechanical Properties of Bone and Biomechanics of Age - Related Fractures - Review

    Rezzan Günaydın

    2007-06-01

    Full Text Available From a biomechanical viewpoint, fractures are due to a structural failure of the bone. This failure occurs when the forces applied to the bone exceed its load – bearing capacity. The load – bearing capacity of a bone depends on the geometry (its size, shape and distribution of bone mass, and the material properties of a bone as well as the direction and magnitude of applied load. Bone fragility can be defined by biomechanical parameters such as strength, brittleness and work to failure. Strategies to reduce fracture risk must be based on a sound understanding of the cellular, molecular and biomechanical mechanisms that underlie the increased risk of fractures while aging. In this review biomechanics of bone and the etiology of age – related fractures from a biomechanical viewpoint have been discussed in the view of current literature. (From the World of Osteoporosis 2007;13:44-8

  5. Foot orthoses improve kinematic measurement in young women with biomechanical abnormality

    Maria Regina Rachmawati

    2015-12-01

    Foot pronation causes biomechanical abnormalities in the form of functional leg-length disparity. Foot orthoses are often used in the treatment of abnormal pronation. The aim of the study was to evaluate the effect of foot orthoses on abnormal kinematic chain the differences of pelvic height, step length, and walking distance on walking test in young women with biomechanical abnormality. METHODS A randomized double blind controlled clinical trial was conducted on 27 young adult women having abnormal biomechanical abnormalities. By random allocation the subjects were divided into the intervention group (14 subjects receiving correction of foot pronation using foot orthoses, and the control group (13 subjects receiving no orthoses. Before and during use of foot orthoses, we determined pelvic height difference (mm, step length difference (cm, and walking distance at maximal walking speed for 15 minutes. RESULTS Correction of foot pronation resulted in decreased pelvic height difference from 4.7 ± 2.1 mm to 1.7 ± 1.3 mm (p<0.001 and in a reduction in step length difference, from 4.9 ± 2.9 cm to 2.1 ± 1.5 cm (p=0.002. Walking test distance of the intervention group was 1318.5 ± 46.3 m, as compared with that of the control group of 1233 ± 114.7 m (p = 0.05. Walking distance of the intervention group rose steadily in the second test to 1369.3 ± 27 m, and in the third test to 1382.14 ± 10.5 m (p<0.001. CONCLUSIONS Foot orthoses improved the kinematic chain, resulting in a more symmetrical pelvic height, reduced step length difference, and increased functional walking ability.

  6. The biomechanical and structural properties of CS2 fimbriae

    Mortezaei, Narges; Zakrisson, Johan; Bullitt, Esther; Andersson, Magnus

    2015-01-01

    Enterotoxigenic Escherichia coli (ETEC) are a major cause of diarrhea worldwide, and infection of children in underdeveloped countries often leads to high mortality rates. Isolated ETEC express a plethora of colonization factors (fimbriae/pili), of which CFA/I and CFA/II that are assembled via the alternate chaperone pathway (ACP), are amongst the most common. Fimbriae are filamentous structures, whose shafts are primarily composed of helically arranged single pilin-protein subunits, with a unique biomechanical capability allowing them to unwind and rewind. A sustained ETEC infection, under adverse conditions of dynamic shear forces, is primarily attributed to this biomechanical feature of ETEC fimbriae. Recent understandings about the role of fimbriae as virulence factors are pointing to an evolutionary adaptation of their structural and biomechanical features. In this work, we investigated the biophysical properties of CS2 fimbriae from the CFA/II group. Homology modelling its major structural subunit CotA ...

  7. Biomechanical properties of peripheral nerve after acellular treatment

    MA Xin-long; SUN Xiao-lei; YANG Zhao; LI Xiu-lan; MA Jian-xiong; ZHANG Yang; YUAN Zhen-zhen

    2011-01-01

    Background Peripheral nerve injury causes a high rate of disability and a huge economic burden,and is currently one of the serious health problems in the world.The use of nerve grafts plays a vital role in repairing nerve defects.Acellular nerve grafts have been widely used in many experimental models as a peripheral nerve substitute.The purpose of this study was to test the biomechanical properties of acellular nerve grafts.Methods Thirty-four fresh sciatic nerves were obtained from 17 adult male Wistar rats (age of 3 months) and randomly assigned to 3 groups:normal control group,nerve segments underwent no treatment and were put in phosphate buffered saline (pH 7.4) and stored at 4℃ until further use; physical method group,nerve segments were frozen at -196℃ and then thawed at 37℃; and chemical method group,nerve segments were chemically extracted with the detergents Triton X-200,sulfobetaine-10 (SB-10) and sulfobetaine-16 (SB-16).After the acellularization process was completed,the structural changes of in the sciatic nerves in each group were observed by hematoxylin-eosin staining and field emission scanning electron microscopy,then biomechanical properties were tested using a mechanical apparatus (Endura TEC ELF 3200,Bose,Boston,USA).Results Hematoxylin-eosin staining and field emission scanning electron microscopy demonstrated that the effects of acellularization,demyelination,and integrity of nerve fiber tube of the chemical method were better than that of the physical method.Biomechanical testing showed that peripheral nerve grafts treated with the chemical method resulted in some decreased biomechanical properties (ultimate load,ultimate stress,ultimate strain,and mechanical work to fracture) compared with normal control nerves,but the differences were not statistically significant (P >0.05).Conclusion Nerve treated with the chemical method may be more appropriate for use in implantation than nerve treated with the physical method.

  8. Anatomical Characteristics and Biomechanical Properties of the Oblique Popliteal Ligament

    Wu, Xiang-Dong; Yu, Jin-Hui; Zou, Tao; Wang, Wei; LaPrade, Robert F.; Huang, Wei; Sun, Shan-Quan

    2017-01-01

    This anatomical study sought to investigate the morphological characteristics and biomechanical properties of the oblique popliteal ligament (OPL). Embalmed cadaveric knees were used for the study. The OPL and its surrounding structures were dissected; its morphology was carefully observed, analyzed and measured; its biomechanical properties were investigated. The origins and insertions of the OPL were relatively similar, but its overall shape was variable. The OPL had two origins: one originated from the posterior surface of the posteromedial tibia condyle, merged with fibers from the semimembranosus tendon, the other originated from the posteromedial part of the capsule. The two origins converged and coursed superolaterally, then attached to the fabella or to the tendon of the lateral head of the gastrocnemius and blended with the posterolateral joint capsule. The OPL was classified into Band-shaped, Y-shaped, Z-shaped, Trident-shaped, and Complex-shaped configurations. The mean length, width, and thickness of the OPL were 39.54, 22.59, and 1.44 mm, respectively. When an external rotation torque (18 N·m) was applied both before and after the OPL was sectioned, external rotation increased by 8.4° (P = 0.0043) on average. The OPL was found to have a significant role in preventing excessive external rotation and hyperextension of the knee. PMID:28205540

  9. Characterization of biomechanical properties of agar based tissue mimicking phantoms for ultrasound stiffness imaging techniques.

    Manickam, Kavitha; Machireddy, Ramasubba Reddy; Seshadri, Suresh

    2014-07-01

    Pathological changes of the body have been observed to change the mechanical properties of soft tissue types which can be imaged by ultrasound elastography. Though initial clinical results using ultrasound elastography in detection of tumors are promising, quantification of signal to noise ratio, resolution and strain image patterns are the best achieved under a controlled study using phantoms with similar biomechanical properties of normal and abnormal tissues. The purpose of this work is to characterize the biomechanical properties of agar based tissue mimicking phantoms by varying the agar concentration from 1.7 to 6.6% by weight and identify the optimum property to be used in classification of cancerous tissues. We performed quasi-static uniaxial compression test under a strain rate of 0.5mm/min up to 15% strain and measured Young's modulus of phantom samples which are from 50kPa to 450kPa. Phantoms show nonlinear stress-strain characteristics at finite strain which were characterized using hyperelastic parameters by fitting Neo-Hookean, Mooney Rivlin, Ogden and Veronda Westmann models. We also investigated viscoelastic parameters of the samples by conducting oscillatory shear rheometry at various precompression levels (2-5%). Loss modulus values are always less than storage modulus which represents the behavior of soft tissues. The increase in agar concentration increases the shear modulus of the samples as well as decreases the linear viscoelastic region. The results suggest that dynamic shear modul are more promising than linear and nonlinear elastic modul in differentiation of various classes of abnormal tissues.

  10. Effects of antibacterial nanostructured composite films on vascular stents: hemodynamic behaviors, microstructural characteristics, and biomechanical properties.

    Cheng, Han-Yi; Hsiao, Wen-Tien; Lin, Li-Hsiang; Hsu, Ya-Ju; Sinrang, Andi Wardihan; Ou, Keng-Liang

    2015-01-01

    The purpose of this research was to investigate stresses resulting from different thicknesses and compositions of hydrogenated Cu-incorporated diamond-like carbon (a-C:H/Cu) films at the interface between vascular stent and the artery using three-dimensional reversed finite element models (FEMs). Blood flow velocity variation in vessels with plaques was examined by angiography, and the a-C:H/Cu films were characterized by transmission electron microscopy to analyze surface morphology. FEMs were constructed using a computer-aided reverse design system, and the effects of antibacterial nanostructured composite films in the stress field were investigated. The maximum stress in the vascular stent occurred at the intersections of net-like structures. Data analysis indicated that the stress decreased by 15% in vascular stents with antibacterial nanostructured composite films compared to the control group, and the stress decreased with increasing film thickness. The present results confirmed that antibacterial nanostructured composite films improve the biomechanical properties of vascular stents and release abnormal stress to prevent restenosis. The results of the present study offer the clinical benefit of inducing superior biomechanical behavior in vascular stents.

  11. Changes in biomechanical properties during drop jumps of incremental height.

    Peng, Hsien-Te

    2011-09-01

    The purpose of this study was to investigate changing biomechanical properties with increasing drop jump height. Sixteen physically active college students participated in this study and performed drop jumps from heights of 20, 30, 40, 50, and 60 cm (DJ20-DJ60). Kinematic and kinetic data were collected using 11 Eagle cameras and 2 force platforms. Data pertaining to the dominant leg for each of 3 trials for each drop height were recorded and analyzed. Statistical comparisons of vertical ground reaction force (vGRF), impulse, moment, power, work, and stiffness were made between different drop jump heights. The peak vGRF of the dominant leg exceeded 3 times the body weight during DJ50 and DJ60; these values were significantly greater than those for DJ20, DJ30, and DJ40 (all p height jumped during DJ60 was significantly less than that during DJ20 and DJ30 (both p = 0.010). Both the landing impulse and total impulse during the contact phase were significantly different between each drop height (all p height. There were no significant differences in the takeoff impulse. Peak and mean power absorption and negative work at the knee and ankle joints during DJ40, DJ50, and DJ60 were significantly greater than those during DJ20 and DJ30 (all p heights >40 cm offered no advantages in terms of mechanical efficiency (SSC power output) and stiffness. Drop jumps from heights in excess of 60 cm are not recommended because of the lack of biomechanical efficiency and the potentially increased risk of injury.

  12. Biomechanical properties of acellular sciatic nerves treated with a modified chemical method

    Xinlong Ma; Zhao Yang; Xiaolei Sun; Jianxiong Ma; Xiulan Li; Zhenzhen Yuan; Yang Zhang; Honggang Guo

    2011-01-01

    Nerve grafts are able to adapt to surrounding biomechanical environments if the nerve graft itself exhibits appropriate biomechanical properties (load, elastic modulus, etc.). The present study was designed to determine the differences in biomechanical properties between fresh and chemically acellularized sciatic nerve grafts. Two different chemical methods were used to establish acellular nerve grafts. The nerve was chemically extracted in the Sondell method with a combination of Triton X-100 (nonionic detergent) and sodium deoxycholate (anionic detergent), and in the modified method with a combination of Triton X-200 (anionic detergent), sulfobetaine-10 (SB-10, amphoteric detergents), and sulfobetaine-16 (SB-16, amphoteric detergents). Following acellularization, hematoxylin-eosin staining and scanning electron microscopy demonstrated that the effect of acellularization via the modified method was similar to the traditional Sondell method. However, effects of demyelination and nerve fiber tube integrity were superior to the traditional Sondell method. Biomechanical testing showed that peripheral nerve graft treated using the chemical method resulted in decreased biomechanical properties (ultimate load, ultimate stress, ultimate strain, and mechanical work to fracture) compared with fresh nerves, but the differences had no statistical significance (P > 0.05). These results demonstrated no significant effect on biomechanical properties of nerves treated using the chemical method. In conclusion, nerve grafts treated via the modified method removed Schwann cells, preserved neural structures, and ensured biomechanical properties of the nerve graft, which could be more appropriate for implantation studies.

  13. The biomechanical properties of F1C pili

    Castelain, Mickaël; Klinth, Jeanna; Lindberg, Stina; Andersson, Magnus; Uhlin, Bernt Eric; Axner, Ove

    2014-01-01

    Uropathogenic Escherichia coli (UPEC) express various kinds of organelles, so-called pili or fimbriae, that mediate adhesion to host tissue in the urinary tract through specific receptor-adhesin interactions. The biomechanical properties of these pili have been considered important for the ability of bacteria to withstand shear forces from rinsing urine flows. Force measuring optical tweezers have been used to characterize individual organelles of F1C type expressed by UPEC bacteria with respect to such properties. Qualitatively, the force-vs.-elongation response was found to be similar to that of other types of helix-like pili expressed by UPEC, i.e. type 1, P, and S, with force-induced elongation in three regions of which one represents the important uncoiling mechanism of the helix-like quaternary structure. Quantitatively, the steady-state uncoiling force was assessed to 26.4(1.4) pN, which is similar to those of other pili (which range from 21 pN for SI to 30 pN for type 1). The corner velocity for dynam...

  14. Biomechanical properties of regenerated bone by mandibular distraction osteogenesis

    李继华; 胡静; 王大章; 唐正龙; 高占巍

    2002-01-01

    Objective: To study the biomechanical properties of the new bone generated by mandibular distractionosteogenesis (DO).Methods: A total of 11 healthy adult goats wererandomly divided into 2 groups, the experimental group (n=9) and the control group (n = 2). For the goats in theexperimental group, the bilateral mandibles were graduallylengthened for 10 mm with distraction appliances. Threegoats were sacrificed respectively at 2, 4 and 8 weeks aftercompletion of distraction. Compressive, three-pointbending and shearing tests were conducted on the standardregenerated bone samples and the whole unilateralmandibular specimens. For the goats in the control group,no operation was made and the whole unilateral mandiblewas taken as the test specimen.Results: The compressive strength and bendingstiffness of the new bone reached the normal level at 4 and 8weeks after completion of distraction, respectively. But theshearing strength remained significantly weaker than that of the controls at 8 weeks after distraction.Conclusions: The distraction appliance can beremoved and the lengthened mandible should be exposed toadaptive functional exercise at 8 weeks after completion ofdistraction.

  15. Corneal Biomechanical Properties in Myopic Eyes Measured by a Dynamic Scheimpflug Analyzer

    Jingyi Wang

    2015-01-01

    Full Text Available Purpose. To evaluate the corneal biomechanical parameters in myopic and emmetropic eyes using Corneal Visualization Scheimpflug Technology (CorVis ST. Methods. 103 myopic and emmetropic eyes of 103 patients were examined. Corneal biomechanical parameters, axial length, and mean keratometry were measured using CorVis ST, IOL Master, and topography, respectively. Corneal biomechanical properties were compared within four groups. Bivariate correlation analysis was used to assess the relationship between corneal biomechanical parameters and ocular characteristics. Results. Four of ten corneal biomechanical parameters, namely, deformation amplitude (DA, first- and second-applanation time (A1-time, A2-time, and radius at highest concavity (HC radius, were significantly different within the four groups (P<0.05. In correlation analysis, DA was positively correlated with axial length (r=0.20, P=0.04; A2-time was positively correlated with spherical equivalent (SE (r=0.24, P=0.02; HC radius was positively correlated with SE (r=0.24, P=0.02 and was negatively correlated with mean keratometry (r=-0.20, P=0.046 and axial length (r=-0.21, P=0.03. Conclusions. The corneal refraction-related biomechanical alterations were associated with ocular characteristics. Highly myopic eyes exhibited longer DA and smaller HC radius than do moderately myopic eyes; the eyes with longer axial length tend to have less corneal stiffness and are easier to deform under stress.

  16. Patellofemoral anatomy and biomechanics.

    Sherman, Seth L; Plackis, Andreas C; Nuelle, Clayton W

    2014-07-01

    Patellofemoral disorders are common. There is a broad spectrum of disease, ranging from patellofemoral pain and instability to focal cartilage disease and arthritis. Regardless of the specific condition, abnormal anatomy and biomechanics are often the root cause of patellofemoral dysfunction. A thorough understanding of normal patellofemoral anatomy and biomechanics is critical for the treating physician. Recognizing and addressing abnormal anatomy will optimize patellofemoral biomechanics and may ultimately translate into clinical success.

  17. MR morphology of triangular fibrocartilage complex: correlation with quantitative MR and biomechanical properties

    Bae, Won C.; Chang, Eric Y.; Chung, Christine B. [VA San Diego Healthcare System, Radiology Service, San Diego, CA (United States); University of California-San Diego, Department of Radiology, San Diego, CA (United States); Ruangchaijatuporn, Thumanoon [Mahidol University, Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine Ramathibodi Hospital, Rachathewi, Bangkok (Thailand); Biswas, Reni; Du, Jiang; Statum, Sheronda [University of California-San Diego, Department of Radiology, San Diego, CA (United States)

    2016-04-15

    To evaluate pathology of the triangular fibrocartilage complex (TFCC) using high-resolution morphologic magnetic resonance (MR) imaging, and compare with quantitative MR and biomechanical properties. Five cadaveric wrists (22-70 years) were imaged at 3 T using morphologic (proton density weighted spin echo, PD FS, and 3D spoiled gradient echo, 3D SPGR) and quantitative MR sequences to determine T2 and T1rho properties. In eight geographic regions, morphology of TFC disc and laminae were evaluated for pathology and quantitative MR values. Samples were disarticulated and biomechanical indentation testing was performed on the distal surface of the TFC disc. On morphologic PD SE images, TFC disc pathology included degeneration and tears, while that of the laminae included degeneration, degeneration with superimposed tear, mucinous transformation, and globular calcification. Punctate calcifications were highly visible on 3D SPGR images and found only in pathologic regions. Disc pathology occurred more frequently in proximal regions of the disc than distal regions. Quantitative MR values were lowest in normal samples, and generally higher in pathologic regions. Biomechanical testing demonstrated an inverse relationship, with indentation modulus being high in normal regions with low MR values. The laminae studied were mostly pathologic, and additional normal samples are needed to discern quantitative changes. These results show technical feasibility of morphologic MR, quantitative MR, and biomechanical techniques to characterize pathology of the TFCC. Quantitative MRI may be a suitable surrogate marker of soft tissue mechanical properties, and a useful adjunct to conventional morphologic MR techniques. (orig.)

  18. Morphology and biomechanical properties of cerebellar arteries in adults

    Olga A. Fomkina

    2016-06-01

    Full Text Available The goal was to analyze the variability of a number of morphometric and biomechanical parameters of cerebellar arteries in adults aged 20-74 years. Material and Methods ― 179 samples of cerebellar arteries, obtained by autopsy of adults without acute cerebrovascular pathology have been studied; 24 preparations of arterial complexes «arterial circle – cerebral arteries» from scientific collection of Human Anatomy Department of Saratov State Medical University (Saratov, Russia have been also investigated. Research methods were: preparation, microscopy, experiments on uniaxial longitudinal stretching at a tensile testing machine Tira Test 28005 (TIRA GmbH, Germany. We studied outer diameter, angle of divergence, overall strength and maximal relative deformation of superior (SCA, anterior inferior (AICA and posterior inferior cerebellar arteries (PICA. Results and Conclusion ― It was revealed that SCA was characterized by the largest diameter and angle of divergence, the most strength and extensibility. AICA and PICA had no significant differences of the studied parameters. It was noted that AICA originated in the lower third part of basilar artery 1.5 times more likely than in the middle third part of this artery.

  19. Impaired Corneal Biomechanical Properties and the Prevalence of Keratoconus in Mitral Valve Prolapse

    Emine Kalkan Akcay

    2014-01-01

    Full Text Available Objective. To investigate the biomechanical characteristics of the cornea in patients with mitral valve prolapse (MVP and the prevalence of keratoconus (KC in MVP. Materials and Methods. Fifty-two patients with MVP, 39 patients with KC, and 45 control individuals were recruited in this study. All the participants underwent ophthalmologic examination, corneal analysis with the Sirius system (CSO, and the corneal biomechanical evaluation with Reichert ocular response analyzer (ORA. Results. KC was found in six eyes of four patients (5.7% and suspect KC in eight eyes of five patients (7.7% in the MVP group. KC was found in one eye of one patient (1.1% in the control group (P=0.035. A significant difference occurred in the mean CH and CRF between the MVP and control groups (P=0.006 and P=0.009, resp.. All corneal biomechanical and topographical parameters except IOPcc were significantly different between the KC-MVP groups (P<0.05. Conclusions. KC prevalence is higher than control individuals in MVP patients and the biomechanical properties of the cornea are altered in patients with MVP. These findings should be considered when the MVP patients are evaluated before refractive surgery.

  20. Mathematical functions and their properties as relevant to the biomechanical modeling of cell and tissue damage.

    Gefen, Amit

    2010-02-01

    The extrapolation of biological damage from a biomechanical model requires that a closed-form mathematical damage threshold function (DTF) be included in the model. A DTF typically includes a generic load variable, being the critical load (e.g., pressure, strain, temperature) causing irreversible tissue or cell damage, and a generic time variable, which represents the exposure to the load (e.g., duration, strain rate). Despite the central role that DTFs play in biomechanical studies, there is no coherent literature on how to formulate a DTF, excluding the field of heat-induced damage studies. This technical note describes six mathematical function types (Richards, Boltzmann, Morgan-Mercer-Flodin, Gompertz, Weibull, Bertalanffy) that are suitable for formulating a wide range of DTFs. These functions were adapted from the theory of restricted growth, and were fitted herein to describe biomechanical damage phenomena. Relevant properties of each adapted function type were extracted to allow efficient fitting of its parameters to empirical biomechanical data, and some practical examples are provided.

  1. Changes in Corneal Biomechanical Properties after Long-Term Topical Prostaglandin Therapy.

    Na Wu

    Full Text Available To compare corneal biomechanical properties, measured by a newly developed tonometer (Corneal Visualization Scheimpflug Technology, Corvis ST, in untreated primary open angle glaucoma (POAG patients, POAG patients with long-term topical prostaglandin analog (PGA therapy and in normal controls. Further is to investigate the potential effects of PGA on corneal biomechanics.In this case-control study, 35 consecutive medication naïve eyes with POAG, 34 POAG eyes with at least 2 years treatment by PGA and 19 normal eyes were included. Intraocular pressure (IOP, central corneal thickness (CCT and corneal biomechanical parameters, including deformation amplitude (DA, applanation time (AT1 and AT2, applanation length (AL1 and AL2, applanation velocity (AV1 and AV2, and peak distance and radius were measured using Corvis ST. Axial length and corneal curvature were measured with partial coherence interferometry (IOLMaster, Zeiss, Germany. General linear model analysis was performed to investigate the corneal biomechanical property changes among the normal controls, newly diagnosed POAG patients and POAG patients with long-term PGA treatment, and among the subgroups of different types of PGA treatment, including bimatoprost, latanoprost and travoprost. Furthermore, pairwise comparisons using Bonferroni correction for least squares means were employed.AT1 (p<0.0001, AV1 (p<0.0001, AT2 (p = 0.0001, AV2 (p<0.0001 and DA (p = 0.0004 in newly diagnosed glaucoma patients were significantly different from those in normal subjects and in patients underwent at least 2 years topical PGA therapy after adjusting for age and gender. After adjusting for age, gender, IOP, CCT, axial length and corneal curvature, a significant difference was detected for DA between glaucoma patients without PGA treatment and patients with long-term PGA therapy (p = 0.0387. Furthermore, there were no statistical significant differences in all of the corneal biomechanical parameters among

  2. Effects of refrigeration and freezing on the electromechanical and biomechanical properties of articular cartilage.

    Changoor, Adele; Fereydoonzad, Liah; Yaroshinsky, Alex; Buschmann, Michael D

    2010-06-01

    In vitro electromechanical and biomechanical testing of articular cartilage provide critical information about the structure and function of this tissue. Difficulties obtaining fresh tissue and lengthy experimental testing procedures often necessitate a storage protocol, which may adversely affect the functional properties of cartilage. The effects of storage at either 4°C for periods of 6 days and 12 days, or during a single freeze-thaw cycle at -20°C were examined in young bovine cartilage. Non-destructive electromechanical measurements and unconfined compression testing on 3 mm diameter disks were used to assess cartilage properties, including the streaming potential integral (SPI), fibril modulus (Ef), matrix modulus (Em), and permeability (k). Cartilage disks were also examined histologically. Compared with controls, significant decreases in SPI (to 32.3±5.5% of control values, prefrigeration at 4°C, but no significant changes were detected at day 6. A trend toward detecting a decrease in SPI (to 94.2±6.2% of control values, p=0.083) was identified following a single freeze-thaw cycle, but no detectable changes were observed for any biomechanical parameters. All numbers are mean±95% confidence interval. These results indicate that fresh cartilage can be stored in a humid chamber at 4°C for a maximum of 6 days with no detrimental effects to cartilage electromechanical and biomechanical properties, while one freeze-thaw cycle produces minimal deterioration of biomechanical and electromechanical properties. A comparison to literature suggested that particular attention should be paid to the manner in which specimens are thawed after freezing, specifically by minimizing thawing time at higher temperatures.

  3. Correlation of discoloration and biomechanical properties in porcine sclera induced by genipin

    Tai-Xiang; Liu; Xin; Luo; Yu-Wei; Gu; Bin; Yang; Zheng; Wang

    2014-01-01

    ·AIM: To study the feasibility of using the discoloration to evaluate the biomechanical properties after treating with genipin.·METHODS: Porcine cadaver eyes were treated for30 min with 1.0%(by w/v) genipin. Untreated samples were used as controls. After treatment, scleral strips of4.0 ×10.0-mm2 were cut. The denaturation temperature(Td) measurement and stress-strain test were performed after taking photograph to analyze the color.·RESULTS: Within 24 h after treating with genipin, the sclera exhibited a bluish color which became deeper with time. And the denaturation temperature also was increased gradually. Compared with untreated groups, at1, 6, 12, 24 and 36 h after treatment, the ultimate stress were increased by 56%, 153%, 173%, 225% and 211%respectively. The Young’s modulus at 10% strain also increased by 170%, 246%, 264%, 389% and 288%respectively. There were strong correlation between the discoloration and the biomechanical properties(ΔE-Ultimate stress:R2=0.892, P =0.00; ΔE-Young’s modulus:R2=0.602, P =0.00).·CONCLUSION: Genipin could be used to strengthen collagen gradually in a relatively short time span. And the biomechanical properties could be reliably evaluated via simple visible discoloration.

  4. In Vivo Corneal Biomechanical Properties with Corneal Visualization Scheimpflug Technology in Chinese Population

    Ying Wu

    2016-01-01

    Full Text Available Purpose. To determine the repeatability of recalculated corneal visualization Scheimpflug technology (CorVis ST parameters and to study the variation of biomechanical properties and their association with demographic and ocular characteristics. Methods. A total of 783 healthy subjects were included in this study. Comprehensive ophthalmological examinations were conducted. The repeatability of the recalculated biomechanical parameters with 90 subjects was assessed by the coefficient of variation (CV and intraclass correlation coefficient (ICC. Univariate and multivariate linear regression models were used to identify demographic and ocular factors. Results. The repeatability of the central corneal thickness (CCT, deformation amplitude (DA, and first/second applanation time (A1/A2-time exhibited excellent repeatability (CV% ≤ 3.312% and ICC ≥ 0.929 for all measurements. The velocity in/out (Vin/out, highest concavity- (HC- radius, peak distance (PD, and DA showed a normal distribution. Univariate linear regression showed a statistically significant correlation between Vin, Vout, DA, PD, and HC-radius and IOP, CCT, and corneal volume, respectively. Multivariate analysis showed that IOP and CCT were negatively correlated with Vin, DA, and PD, while there was a positive correlation between Vout and HC-radius. Conclusion. The ICCs of the recalculated parameters, CCT, DA, A1-time, and A2-time, exhibited excellent repeatability. IOP, CCT, and corneal volume significantly influenced the biomechanical properties of the eye.

  5. Comparison of Corneal Topographical and Biomechanical Properties in Cases with Atopic Dermatitis and Healthy Subjects

    Yusuf Yıldırım

    2013-06-01

    Full Text Available Pur po se: To compare the topographic, biomechanical, and thickness properties of corneas of patients with atopic dermatitis (AD and of healthy individuals. Ma te ri al and Met hod: In this prospective, cross-sectional, and comparative study, 28 healthy individuals (control group and 28 patients with AD (study group were enrolled. Corneal topographical measurements using Scheimpflug camera with a Placido disc topographer (Sirius, corneal biomechanical properties using Ocular Response Analyzer (ORA, and central corneal thickness (CCT using ultrasonic pachymeter were obtained for each participant. Re sults: Topographic parameters were not significantly different between both groups (p>0.05. Corneal hysteresis (CH and corneal resistance factor (CRF were found same in both groups. CCT measured with ultrasonic pachymeter was significantly lower in patients with AD compared to health controls (p<0.05. Dis cus si on: No significant difference was found between patients with AD and age-matched healthy individuals regarding the corneal topographic findings and corneal biomechanical parameters. CCT was found to be lower in cases with AD than in healthy controls. (Turk J Ophthalmol 2013; 43: 140-4

  6. An Atomic Force Microscopy based investigation of specific biomechanical properties for various types of neuronal cells

    Spedden, Elise; White, James; Kaplan, David; Staii, Cristian

    2012-02-01

    Here we describe the use of Atomic Force Microscope (AFM) based techniques to characterize and explore the influence of biochemical and biomechanical cues on the growth and interaction of neuronal cells with surrounding guidance factors. Specifically, we use AFM topography and AFM force spectroscopy measurements to systematically investigate the morphology, elasticity, and real time growth of neuronal processes in the presence of different types of extracellular matrix proteins and growth factors. We therefore create a series of systems containing specified neuron densities where the type of the underlying growth promoting protein is different from sample to sample. For each system we measure key biomechanical parameters related to neuronal growth such as height and elastic modulus at multiple growth points on several types of neurons. We show that systematic measurements of these parameters yield fundamental information about the role played by substrate-plated guidance factors in determining elastic and morphological properties of neurons during growth.

  7. Nanoscale characterization of the biomechanical properties of collagen fibrils in the sclera

    Papi, M. [Institute of Physics, Università Cattolica del Sacro Cuore, Largo F.Vito 1, 00168 Rome (Italy); Paoletti, P. [Centre for Engineering Dynamics, School of Engineering, Brownlow Hill, Liverpool, L69 3GH (United Kingdom); Geraghty, B.; Akhtar, R. [Centre for Materials and Structures, School of Engineering, Brownlow Hill, Liverpool, L69 3GH (United Kingdom)

    2014-03-10

    We apply the PeakForce Quantitative Nanomechanical Property Mapping (PFQNM) atomic force microscopy mode for the investigation of regional variations in the nanomechanical properties of porcine sclera. We examine variations in the collagen fibril diameter, adhesion, elastic modulus and dissipation in the posterior, equatorial and anterior regions of the sclera. The mean fibril diameter, elastic modulus and dissipation increased from the posterior to the anterior region. Collagen fibril diameter correlated linearly with elastic modulus. Our data matches the known macroscopic mechanical behavior of the sclera. We propose that PFQNM has significant potential in ocular biomechanics and biophysics research.

  8. Nanoscale characterization of the biomechanical properties of collagen fibrils in the sclera

    Papi, M.; Paoletti, P.; Geraghty, B.; Akhtar, R.

    2014-03-01

    We apply the PeakForce Quantitative Nanomechanical Property Mapping (PFQNM) atomic force microscopy mode for the investigation of regional variations in the nanomechanical properties of porcine sclera. We examine variations in the collagen fibril diameter, adhesion, elastic modulus and dissipation in the posterior, equatorial and anterior regions of the sclera. The mean fibril diameter, elastic modulus and dissipation increased from the posterior to the anterior region. Collagen fibril diameter correlated linearly with elastic modulus. Our data matches the known macroscopic mechanical behavior of the sclera. We propose that PFQNM has significant potential in ocular biomechanics and biophysics research.

  9. Might axial myofascial properties and biomechanical mechanisms be relevant to ankylosing spondylitis and axial spondyloarthritis?

    Masi, Alfonse T

    2014-01-01

    inflammatory mechanisms operate in both ankylosing spondylitis and degenerative disc disease but differ in relative degrees. The hypothesized biomechanical properties raised in this commentary require documentation of their association with the onset risk and course of ankylosing spondylitis and axial spondyloarthritis. If particular subsets of ankylosing spondylitis and axial spondyloarthritis patients are confirmed to have altered axial myofascial properties, their biological basis and underlying biomechanical mechanisms promise to become clarified. Understanding how biomechanical and physical properties can affect symptomatic and structural manifestations of these disorders could also improve their management.

  10. Effects of heat treatment of wood on hydroxylapatite type mineral precipitation and biomechanical properties in vitro.

    Rekola, J; Lassila, L V J; Hirvonen, J; Lahdenperä, M; Grenman, R; Aho, A J; Vallittu, P K

    2010-08-01

    Wood is a natural fiber reinforced composite. It structurally resembles bone tissue to some extent. Specially heat-treated birch wood has been used as a model material for further development of synthetic fiber reinforced composites (FRC) for medical and dental use. In previous studies it has been shown, that heat treatment has a positive effect on the osteoconductivity of an implanted wood. In this study the effects of two different heat treatment temperatures (140 and 200 degrees C) on wood were studied in vitro. Untreated wood was used as a control material. Heat treatment induced biomechanical changes were studied with flexural and compressive tests on dry birch wood as well as on wood after 63 days of simulated body fluid (SBF) immersion. Dimensional changes, SBF sorption and hydroxylapatite type mineral formation were also assessed. The results showed that SBF immersion decreases the biomechanical performance of wood and that the heat treatment diminishes the effect of SBF immersion on biomechanical properties. With scanning electron microscopy and energy dispersive X-ray analysis it was shown that hydroxylapatite type mineral precipitation formed on the 200 degrees C heat-treated wood. An increased weight gain of the same material during SBF immersion supported this finding. The results of this study give more detailed insight of the biologically relevant changes that heat treatment induces in wood material. Furthermore the findings in this study are in line with previous in vivo studies.

  11. Directional biases reveal utilization of arm's biomechanical properties for optimization of motor behavior.

    Goble, Jacob A; Zhang, Yanxin; Shimansky, Yury; Sharma, Siddharth; Dounskaia, Natalia V

    2007-09-01

    Strategies used by the CNS to optimize arm movements in terms of speed, accuracy, and resistance to fatigue remain largely unknown. A hypothesis is studied that the CNS exploits biomechanical properties of multijoint limbs to increase efficiency of movement control. To test this notion, a novel free-stroke drawing task was used that instructs subjects to make straight strokes in as many different directions as possible in the horizontal plane through rotations of the elbow and shoulder joints. Despite explicit instructions to distribute strokes uniformly, subjects showed biases to move in specific directions. These biases were associated with a tendency to perform movements that included active motion at one joint and largely passive motion at the other joint, revealing a tendency to minimize intervention of muscle torque for regulation of the effect of interaction torque. Other biomechanical factors, such as inertial resistance and kinematic manipulability, were unable to adequately account for these significant biases. Also, minimizations of jerk, muscle torque change, and sum of squared muscle torque were analyzed; however, these cost functions failed to explain the observed directional biases. Collectively, these results suggest that knowledge of biomechanical cost functions regarding interaction torque (IT) regulation is available to the control system. This knowledge may be used to evaluate potential movements and to select movement of "low cost." The preference to reduce active regulation of interaction torque suggests that, in addition to muscle energy, the criterion for movement cost may include neural activity required for movement control.

  12. Biomechanical properties of a novel biodegradable magnesium-based interference screw

    Marco Ezechieli

    2016-06-01

    Full Text Available Magnesium-based interference screws may be an alternative in anterior/posterior cruciate ligament reconstruction. The well-known osteoconductive effects of biodegradable magnesium alloys may be useful. It was the purpose of this study to evaluate the biomechanical properties of a magnesium based interference screw and compare it to a standard implant. A MgYREZr-alloy interference screw and a standard implant (Milagro®; De Puy Mitek, Raynham, MA, USA were used for graft fixation. Specimens were placed into a tensile loading fixation of a servohydraulic testing machine. Biomechanical analysis included pretensioning of the constructs at 20 N for 1 min following cyclic pretensioning of 20 cycles between 20 and 60 N. Biomechanical elongation was evaluated with cyclic loading of 1000 cycles between 50 and 200 N at 0.5 Hz. Maximum load to failure was 511.3±66.5 N for the Milagro® screw and 529.0±63.3 N for magnesium-based screw (ns, P=0.57. Elongations after preload, during cyclical loading and during failure load were not different between the groups (ns, P>0.05. Stiffness was 121.1±13.8 N/mm for the magnesiumbased screw and 144.1±18.4 for the Milagro® screw (ns, P=0.32. MgYREZr alloy interference screws show comparable results in biomechanical testing to standard implants and may be an alternative for anterior cruciate reconstruction in the future.

  13. Study the effects of radon inhalation on biomechanical properties of blood in rats

    Mostafa Fawzy Eissa

    2015-09-01

    Full Text Available Purpose: To investigate the effect of inhalation radon gas (Rn on the biomechanical properties of red blood cell of rats. Methods: 20 young healthy adult male albino rats were divided into equally 4 groups. The first group (0 served as control group, while the other three groups (I, II and III were exposed to Rn gas inside a chamber for 3, 5 and 7 weeks. The biomechanical properties of red blood cell of rats was performed by determine the rheological properties of blood and the osmotic fragility of red blood cells (RBCs. Results: The Rn doses received by every group of rats were found to 34.84, 58.07 and 81.30 mSv for 3, 5 and 7 weeks respectively (based on 12 exposure hours per week. The obtained results indicate that the viscosity, consistency index, yield stress and aggregation index increase with Rn doses. The osmotic fragility curves of irradiated groups shift toward lower values of NaCl concentration. The dispersion of hemolysis (S increased, at the same time an average osmotic fragility (H50% decreased. Conclusion: The results indicates that the exposure to radon alters the mechanical properties of red blood cells membrane (permeability and elasticity reflecting a change in its physiological properties. This mean that low levels of Rn gas are harmful to biological systems and the degree of damage was dose-dependent.

  14. Biomechanical properties of wheat grains: the implications on milling

    Reith, Martin

    2017-01-01

    Millennia of continuous innovation have driven ever increasing efficiency in the milling process. Mechanically characterizing wheat grains and discerning the structure and function of the wheat bran layers can contribute to continuing innovation. We present novel shear force and puncture force testing regimes to characterize different wheat grain cultivars. The forces endured by wheat grains during the milling process can be quantified, enabling us to measure the impact of commonly applied grain pretreatments, such as microwave heating, extended tempering, enzyme and hormone treatments on grains of different ‘hardness’. Using these methods, we demonstrate the importance of short tempering phases prior to milling and identify ways in which our methods can detect differences in the maximum force, energy and breaking behaviours of hard and soft grain types. We also demonstrate for the first time, endosperm weakening in wheat, through hormone stratification on single bran layers. The modern milling process is highly refined, meaning that small, cultivar specific, adjustments can result in large increases in downstream profits. We believe that methods such as these, which enable rapid testing of milling pretreatments and material properties can help to drive an innovation process that has been core to our industrial efforts since prehistory. PMID:28100826

  15. Assessment of Corneal Biomechanical Properties by CorVis ST in Patients with Dry Eye and in Healthy Subjects

    Qin Long

    2015-01-01

    Full Text Available Purpose. To investigate corneal biomechanical properties in patients with dry eye and in healthy subjects using Corneal Visualization Scheimpflug Technology (CorVis ST. Methods. Biomechanical parameters were measured using CorVis ST in 28 eyes of 28 patients with dry eye (dry eye group and 26 normal subjects (control group. The Schirmer I test value, tear film break-up time (TBUT, and corneal staining score (CSS were recorded for each eye. Biomechanical properties were compared between the two groups and bivariate correlation analysis was used to assess the relationship between biomechanical parameters and dry eye signs. Results. Only one of the ten biomechanical parameters was significantly different between the two groups. Patients in the dry eye group had significantly lower highest concavity time (HC-time (P=0.02 than the control group. Correlation analysis showed a significant negative correlation between HC-time and CSS with marginal P value (ρ=-0.39, P=0.04 in the dry eye group. Conclusions. The corneal biomechanical parameter of HC-time is reduced in dry eyes compared to normal eyes. There was also a very weak but significant negative correlation between HC-time and CSS in the dry eye group, indicating that ocular surface damage can give rise to a more compliant cornea in dry eyes.

  16. Biomechanical properties of osteoporotic rat femurs after different hormonal treatments: genistein, estradiol, and estradiol/progesterone

    Azboy İbrahim

    2016-01-01

    Full Text Available Introduction: The purpose of the study is to compare the effects of genistein, estradiol, estradiol/progesterone combination on the bone mineral density and biomechanical properties of ovariectomized rats’ bone. Methods: 50 female adult Sprague-Dawley rats were divided into five groups. Bilaterally ovaeriectomy were performed in all groups except the sham-operated group. Groups were a sham-operated group and a control group (water was given, estradiol treated group (17-β estradiol 0.015 mg/kg per day, genistein treated group (genistein 10 mg/kg per day, and an estradiol/progesterone combination group (17-β estradiol 0.015 mg/kg plus drosperinone 0.028 mg/kg per day. The water or hormones were implemented in relevant groups for eight weeks by orogasthric catheter. The bone mineral density and biomechanical properties of the femur were analyzed. Results: Genistein, estradiol, and estradiol/progesterone groups increased bone mineral density significantly compared to the control group. In diaphysis and metaphysis bending test, all groups had higher peak load values than the control group. There were statistically significant differences between the estrogen/progesterone group and control group in diaphysis bending with regard to peak load. There were statistically significant differences between the estradiol and control groups in metaphysis bending with regard to peak load. In axial rotation test, all groups had higher peak torque values than the control groups. Conclusions: Genistein, estradiol and estrogen/progesterone combination improved the biomechanical properties of the ovariectomized rat bone. Genistein which has less side effects may be considered as an alternative in the treatment of postmenopausal osteoporosis.

  17. Biomechanical properties of bone in a mouse model of Rett syndrome.

    Kamal, Bushra; Russell, David; Payne, Anthony; Constante, Diogo; Tanner, K Elizabeth; Isaksson, Hanna; Mathavan, Neashan; Cobb, Stuart R

    2015-02-01

    Rett syndrome (RTT) is an X-linked genetic disorder and a major cause of intellectual disability in girls. Mutations in the methyl-CpG binding protein 2 (MECP2) gene are the primary cause of the disorder. Despite the dominant neurological phenotypes, MECP2 is expressed ubiquitously throughout the body and a number of peripheral phenotypes such as scoliosis, reduced bone mineral density and skeletal fractures are also common and important clinical features of the disorder. In order to explore whether MeCP2 protein deficiency results in altered structural and functional properties of bone and to test the potential reversibility of any defects, we have conducted a series of histological, imaging and biomechanical tests of bone in a functional knockout mouse model of RTT. Both hemizygous Mecp2(stop/y) male mice in which Mecp2 is silenced in all cells and female Mecp2(stop/+) mice in which Mecp2 is silenced in ~50% of cells as a consequence of random X-chromosome inactivation, revealed significant reductions in cortical bone stiffness, microhardness and tensile modulus. Microstructural analysis also revealed alterations in both cortical and cancellous femoral bone between wild-type and MeCP2-deficient mice. Furthermore, unsilencing of Mecp2 in adult mice cre-mediated stop cassette deletion resulted in a restoration of biomechanical properties (stiffness, microhardness) towards wild-type levels. These results show that MeCP2-deficiency results in overt, but potentially reversible, alterations in the biomechanical integrity of bone and highlights the importance of targeting skeletal phenotypes in considering the development of pharmacological and gene-based therapies.

  18. Comparative transcriptional analysis of three human ligaments with distinct biomechanical properties

    Lorda-Diez, Carlos I; Canga-Villegas, Ana; Cerezal, Luis; Plaza, Santiago; Hurlé, Juan M; García-Porrero, Juan A; Montero, Juan A

    2013-01-01

    One major aim of regenerative medicine targeting the musculoskeletal system is to provide complementary and/or alternative therapeutic approaches to current surgical therapies, often involving the removal and prosthetic substitution of damaged tissues such as ligaments. For these approaches to be successful, detailed information regarding the cellular and molecular composition of different musculoskeletal tissues is required. Ligaments have often been considered homogeneous tissues with common biomechanical properties. However, advances in tissue engineering research have highlighted the functional relevance of the organisational and compositional differences between ligament types, especially in those with higher risks of injury. The aim of this study was to provide information concerning the relative expression levels of a subset of key genes (including extracellular matrix components, transcription factors and growth factors) that confer functional identity to ligaments. We compared the transcriptomes of three representative human ligaments subjected to different biomechanical demands: the anterior cruciate ligament (ACL); the ligamentum teres of the hip (LT); and the iliofemoral ligament (IL). We revealed significant differences in the expression of type I collagen, elastin, fibromodulin, biglycan, transforming growth factor β1, transforming growth interacting factor 1, hypoxia-inducible factor 1-alpha and transforming growth factor β-induced gene between the IL and the other two ligaments. Thus, considerable molecular heterogeneity can exist between anatomically distinct ligaments with differing biomechanical demands. However, the LT and ACL were found to show remarkable molecular homology, suggesting common functional properties. This finding provides experimental support for the proposed role of the LT as a hip joint stabiliser in humans. PMID:24128114

  19. Comparative transcriptional analysis of three human ligaments with distinct biomechanical properties.

    Lorda-Diez, Carlos I; Canga-Villegas, Ana; Cerezal, Luis; Plaza, Santiago; Hurlé, Juan M; García-Porrero, Juan A; Montero, Juan A

    2013-12-01

    One major aim of regenerative medicine targeting the musculoskeletal system is to provide complementary and/or alternative therapeutic approaches to current surgical therapies, often involving the removal and prosthetic substitution of damaged tissues such as ligaments. For these approaches to be successful, detailed information regarding the cellular and molecular composition of different musculoskeletal tissues is required. Ligaments have often been considered homogeneous tissues with common biomechanical properties. However, advances in tissue engineering research have highlighted the functional relevance of the organisational and compositional differences between ligament types, especially in those with higher risks of injury. The aim of this study was to provide information concerning the relative expression levels of a subset of key genes (including extracellular matrix components, transcription factors and growth factors) that confer functional identity to ligaments. We compared the transcriptomes of three representative human ligaments subjected to different biomechanical demands: the anterior cruciate ligament (ACL); the ligamentum teres of the hip (LT); and the iliofemoral ligament (IL). We revealed significant differences in the expression of type I collagen, elastin, fibromodulin, biglycan, transforming growth factor β1, transforming growth interacting factor 1, hypoxia-inducible factor 1-alpha and transforming growth factor β-induced gene between the IL and the other two ligaments. Thus, considerable molecular heterogeneity can exist between anatomically distinct ligaments with differing biomechanical demands. However, the LT and ACL were found to show remarkable molecular homology, suggesting common functional properties. This finding provides experimental support for the proposed role of the LT as a hip joint stabiliser in humans.

  20. Biomechanical properties of ileum after systemic treatment with epithelial growth factor

    Jian Yang; Jing-Bo Zhao; Yan-Jun Zeng; Hans Gregersen

    2003-01-01

    AIM:Systemic treatment with epidermal growth factor (EGF)leads to growth of all parts of the small intestine in normal functioning rats. In this study, we investigated the effect of this growth process on morphometric and biomechanical parameters of ileum.METHODS: Rats were treated with EGF (150 μg@kg-1day-1)or placebo via osmotic minipumps for 2, 4, 7, and 14 days.A segment of ileum was removed. The morphology at noload state and zero-stress state was measured and passive biomechanical properties were assessed using a biaxial test machine (combined inflation and axial stretching).RESULTS: The ileum weight increased after EGF administration. After 4 days' EGF treatment, the wall thickness was increased. Significantly smaller inner perimeters were seen in 4 day and 7 day EGF treatment groups. The opening angle and residual strain began to increase after 7 days' EGF treatment. Wall stiffness, evaluated from the stress-strain curves, showed a continuous decrease in circumferential direction during the first 7 days' EGF treatment. The longitudinal stiffness increased during the first 7 days. The stress-strain curves for both circumferential and longitudinal direction tended to shift back to normal 14days after starting EGF administration.CONCLUSION: EGF can cause significant changes both in the morphology and in the passive mechanical properties of the rat ileum.

  1. Flow-dependent porosity and other biomechanical properties of mysticete baleen.

    Werth, Alexander J

    2013-04-01

    Despite its vital function in a highly dynamic environment, baleen is typically assumed to be a static material. Its biomechanical and material properties have not previously been explored. Thus I tested sections of baleen from bowhead whales, Balaena mysticetus, and humpback whales, Megaptera novaeangliae, alone or in groups representing miniature 'racks', in a flow tank through which water and buoyant particles circulated with variable flow velocity. Kinematic sequences were recorded through an endoscopic camera or viewing window. One set of experiments investigated particle capture; another series analyzed biomechanical behavior, including fringe spacing, movement and interaction. Baleen fringe porosity directly correlates, in a mostly linear fashion, with velocity of incident water flow. However, undulation and interaction of fringes (especially of bowheads) at higher flow velocities can decrease porosity. Fringe porosity depends on distance from the baleen plate. Porosity also varies, with fringe length, by position along the length of an individual plate. Plate orientation, which varied from 0 to 90 deg relative to water flow, is crucial in fringe spacing and particle capture. At all flow velocities, porosity is lowest with plates aligned parallel to water flow. Turbulence introduced when plates rotate perpendicular to flow (as in cross-flow filtration) increases fringe interaction, so that particles more easily strike fringes yet more readily dislodge. Baleen of bowhead whales, which feed by continuous ram filtration, differs biomechanically from that of humpbacks, which use intermittent lunge filtration. The longer, finer fringes of bowhead baleen readily form a mesh-like mat, especially at higher flow velocities, to trap tiny particles.

  2. Dynamic ultra high speed Scheimpflug imaging for assessing corneal biomechanical properties

    Renato Ambrósio Jr

    2013-04-01

    Full Text Available OBJECTIVE: To describe a novel technique for clinical characterization of corneal biomechanics using non-invasive dynamic imaging. METHODS: Corneal deformation response during non contact tonometry (NCT is monitored by ultra-high-speed (UHS photography. The Oculus Corvis ST (Scheimpflug Technology; Wetzlar, Germany has a UHS Scheimpflug camera, taking over 4,300 frames per second and of a single 8mm horizontal slit, for monitoring corneal deformation response to NCT. The metered collimated air pulse or puff has a symmetrical configuration and fixed maximal internal pump pressure of 25 kPa. The bidirectional movement of the cornea in response to the air puff is monitored. RESULTS: Measurement time is 30ms, with 140 frames acquired. Advanced algorithms for edge detection of the front and back corneal contours are applied for every frame. IOP is calculated based on the first applanation moment. Deformation amplitude (DA is determined as the highest displacement of the apex in the highest concavity (HC moment. Applanation length (AL and corneal velocity (CVel are recorded during ingoing and outgoing phases. CONCLUSION: Corneal deformation can be monitored during non contact tonometry. The parameters generated provide clinical in vivo characterization of corneal biomechanical properties in two dimensions, which is relevant for different applications in Ophthalmology.

  3. Evaluation of corneal biomechanical properties following penetrating keratoplasty using ocular response analyzer

    Vanathi Murugesan

    2014-01-01

    Full Text Available Purpose: To evaluate corneal biomechanical properties in eyes that has undergone penetrating keratoplasty (PK. Materials and Methods: Retrospective observational study in a tertiary care centre. Data recorded included ocular response analyzer (ORA values of normal and post-keratoplasty eyes [corneal hysteresis (CH, corneal resistance factor (CRF, Goldmann-correlated intraocular pressure (IOPg, and cornea-compensated intraocular pressure (IOPcc], corneal topography, and central corneal thickness (CCT. Wilcoxon signed rank test was used to analyze the difference in ORA parameter between post-PK eyes and normal eyes. Correlation between parameters was evaluated with Spearman′s rho correlation. Results: The ORA study of 100 eyes of 50 normal subjects and 54 post-keratoplasty eyes of 51 patients showed CH of 8.340 ± 1.85 and 9.923 ± 1.558, CRF of 8.846 ± 2.39 and 9.577 ± 1.631 in post-PK eyes and normal eyes, respectively. CH and CRF did not correlate with post-keratoplasty astigmatism (P = 0.311 and 0.276, respectively while a significant correlation was observed with IOPg (P = 0.004 and IOPcc (P < 0.001. Conclusion: Biomechanical profiles were significantly decreased in post-keratoplasty eyes with significant correlation with higher IOP as compared with that in normal eyes.

  4. Investigation of chemical and physical properties of carbon nanotubes and their effects on cell biomechanics

    Dong, Chenbo

    Cerasela Zoica Dinu, Effects of acid treatment on structure, properties and biocompatibility of carbon nanotubes, Applied Surface Science, 2013, 268, 261-268.) Chapter two shows how exposure to CNTs changes the biomechanical properties of fixed human lung epithelial cells (BEAS-2B cells). Specifically, by using Atomic Force Microscopy (AFM) nanoindentation technology, we demonstrated that cellular exposure to multi-walled carbon nanotubes (MWCNTs) for 24h induces significant changes in cellular biomechanics leading to increased cellular stiffness. The MWCNTs incubation also seemed to alter the surface area of the cells. Consequently, measures of the mechanical properties of the exposed cell could be used as indicators of its biological state and could offer valuable insights into the mechanisms associated with CNTs-induced genetic instability. (Publication: Chenbo Dong, Linda Sargent, Michael L Kashon, David Lowry, Jonathan S. Dordick, Steven H. Reynolds, Yon Rojanasakul and Cerasela Zoica Dinu, Expose to carbon nanotubes leads to change in cellular biomechanics, Advanced Healthcare Materials, 2013, 7, 945-951.) Chapter three links together the MWCNTs exposure duration, internalization and induced biomechanical changes in fixed cells. Our findings indicated that changes in biomechanical properties of the fixed cells are a function of the uptake and internalization of the MWCNTs as well as their uptake time. Specifically, short exposure time did not seem to lead to considerable changes in the elastic properties in the cellular system. However, longer cellular exposure to CNTs leads to a higher uptake and internalization of the nanotubes and a larger effect on the cell mechanics. Such changes could be related to CNTs interactions with cellular elements and could bring information on the CNT intrinsic toxicity. Chapter four talks about the potential of purified forms of CNTs with increased hydrophilicity to affect live human lung epithelial cells when used at occupational

  5. Current considerations concerning endodontically treated teeth: alteration of hard dental tissues and biomechanical properties following endodontic therapy.

    Dimitriu, Bogdan; Vârlan, Constantin; Suciu, Ioana; Vârlan, Virginia; Bodnar, Dana

    2009-01-01

    The aim of this general article is to present an overview of the current knowledge about composition and structural changes and also about specific biomechanical alterations related to vitality loss or endodontic therapy. For a long time, these issues have been controversially approached from a clinical standpoint and are therefore still confusing for many practitioners. Vitality loss or endodontic procedures seem to induce only negligible changes in hard dental tissue moisture. Physico-chemical properties of dentin can be modified by some of the endodontic chemical products used for chemo-mechanical debridement. On the other hand, tooth biomechanical behavior is affected, since tooth strength is reduced proportionally to coronal tissue loss, due to either pre-existent carious/non-carious lesions or cavity acces preparation, besides restorative procedures. The related literature shows the lack of accepted clinical standards and consensus regarding the optimal way of approaching the specific tooth biomechanics following endodontic therapy.

  6. Changes in biomechanical properties of the cornea after modified transepithelial crosslinking

    I. B. Medvedev

    2016-01-01

    Full Text Available The aim of the study was to evaluate changes in biomechanical properties of the cornea after conducting transepithelial crosslinking with the prior application of a 40 % glucose solution.Materials and methods. Just studied the biomechanical properties of the corneas of six rabbits breed Chinchilla (12 eyes. 4 rabbit entered in the experimental group, in which in one eye glucose solution was applied on the cornea and allowed to stay for 10 minutes, followed by the instillation of 0.1 % Riboflavin solution for 30 minutes. On a couple of the rabbit eye was applied a solution of Riboflavin without prior instillation of glucose. Then carried out the procedure of irradiation according to the conventional technology with UV with a wavelength of 370 μm and a beam energy of 3.0 mW / cm2. Two rabbits (4 eyes were included in the control group, in which crosslinking was not performed. After 1 month the euthanasia of the animals was performed with subsequent enucleation for corneal research on a tensile testing machine. In the control and experimental group compared, the relaxation curves and the following parameters were analyzed: initial stress (MPa, equilibrium stress (MPa modulus of elasticity.Results and their discussion. After the crosslinking the rise of the initial stress (in the control group and 0.7+0.1 MPa, in the experimental and 1.5+0.2 1.3+0.3 MPa, respectively. The stress relaxation is fast (equilibrium stress value is reached after 250 sec. and after the administration of glucose for approximately 75 seconds, which means a greater rigidity of experimental group of samples. In the experimental groups significantly changed and the modulus of elasticity: its value has increased approximately in 2 times in comparison with control samples. The equilibrium stress values in the experimental groups were different from the zero value that also indicates a change in the chemical structure of the samples.Conclusions. Holding transepithelial of

  7. Impaired physical function, loss of muscle mass and assessment of biomechanical properties in critical ill patients

    Poulsen, Jesper Brøndum

    2012-01-01

    Intensive care unit (ICU) admission is associated with muscle weakness and ICU survivors report sustained limitation of physical capacity for years after discharge. Limited information is available on the underlying biomechanical properties responsible for this muscle function impairment....... A plausible contributor to the accentuated catabolic drive in ICU patients is a synergistic response to inflammation and inactivity leading to loss of muscle mass. As these entities are predominantly present in the early phase of ICU stay, interventions employed during this time frame may exhibit the greatest...... potential to counteract loss of muscle mass. Despite the obvious clinical significance of muscle atrophy for the functional impairment observed in ICU survivors, no preventive therapies have been identified as yet. The overall aim of the present dissertation is to characterize aspects of physical function...

  8. Effects of gamma irradiation on the biomechanical properties of peroneus tendons

    Aguila CM

    2016-09-01

    Full Text Available Christopher M Aguila,1 Gaëtan J-R Delcroix,2–5 David N Kaimrajh,6 Edward L Milne,6 H Thomas Temple,5,7 Loren L Latta2,6 1Department of Biological Sciences, Florida International University, Miami, FL, USA; 2Department of Orthopaedics, Miller School of Medicine, University of Miami, Miami, FL, USA; 3Research Service & Geriatric Research, Education, and Clinical Center, Bruce W. Carter Veterans Affairs Medical Center, Miami, FL, USA; 4Interdisciplinary Stem Cell Institute, University of Miami, Miami, FL, USA; 5Vivex Biomedical Inc., Marietta, GA, USA; 6Max Biedermann Institute for Biomechanics, Miami Beach, FL, USA; 7Translational Research and Economic Development, Nova Southeastern University, Fort-Lauderdale, FL, USA Purpose: This study was designed to investigate the biomechanical properties of nonirradiated (NI and irradiated (IR peroneus tendons to determine if they would be suitable allografts, in regards to biomechanical properties, for anterior cruciate ligament reconstruction after a dose of 1.5–2.5 Mrad.Methods: Seven pairs of peroneus longus (PL and ten pairs of peroneus brevis (PB tendons were procured from human cadavers. The diameter of each allograft was measured. The left side of each allograft was IR at 1.5–2.5 Mrad, whereas the right side was kept aseptic and NI. The allografts were thawed, kept wet with saline, and attached in a single-strand fashion to custom freeze grips using liquid nitrogen. A preload of 10 N was then applied and, after it had reached steady state, the allografts were pulled at 4 cm/sec. The parameters recorded were the displacement and force.Results: The elongation at the peak load was 10.3±2.3 mm for the PB NI side and 13.5±3.3 mm for the PB IR side. The elongation at the peak load was 17.4±5.3 mm for the PL NI side and 16.3±2.0 mm for the PL IR side. For PL, the ultimate load was 2,091.6±148.7 N for NI and 2,122.8±380.0 N for IR. The ultimate load for the PB tendons was 1,485.7±209.3 N for

  9. Assessment of Corneal Biomechanical Properties and Intraocular Pressure in Myopic Spanish Healthy Population

    María A. del Buey

    2014-01-01

    Full Text Available Purpose. To examine biomechanical parameters of the cornea in myopic eyes and their relationship with the degree of myopia in a western healthy population. Methods. Corneal hysteresis (CH, corneal resistance factor (CRF, Goldmann correlated intraocular pressure (IOP, and corneal compensated IOP (IOPcc were measured using the ocular response analyzer (ORA in 312 eyes of 177 Spanish subjects aged between 20 and 56 years. Refraction was expressed as spherical equivalent (SE, which ranged from 0 to −16.50 diopters (D (mean: −3.88±2.90 D. Subjects were divided into four groups according to their refractive status: group 1 or control group: emmetropia (-0.50≤SE0.05; nevertheless, IOPcc was significantly higher in the moderately myopic (15.47±2.47 mmHg and highly myopic (16.14±2.59 mmHg groups than in the emmetropia (15.15±2.06 mmHg and low myopia groups (14.53±2.37 mmHg. No correlation between age and the measured parameters was found. CH and IOPcc were weakly but significantly correlated with SE (r=0.171, P=0.002 and r=-0.131, P=0.021, resp.. Conclusions. Present study showed only a very weak, but significant, correlation between CH and refractive error, with CH being lower in both moderately and highly myopic eyes than that in the emmetropic and low myopic eyes. These changes in biomechanical properties of the cornea may have an impact on IOP measurement, increasing the risk of glaucoma.

  10. Relationship among bone mineral density, collagen composition, and biomechanical properties of callus in the healing of osteoporotic fracture

    SHEN Bin; MU Jian-xiong; PEI Fu-xing

    2007-01-01

    Objective: To study the change and relationship among bone mineral density (BMD), collagen composition and biomechanical properties of the callus in the healing process of osteoporotic fracture.Methods: The osteoporotic rat model and fracture model were established through bilateral ovariectomy(OVX) and osteotomy of the middle shaft of the right hind tibiae, respectively. Ninety female SD rats were randomly divided into OVX group and sham group. With the samples of blood and callus, roentgenoraphic and histological observation were performed for the assessment of the healing progress of the fracture, and the serum concentration of TRAP-5b, proportion of type Ⅰ collagen,BMD and biomechanical properties of the callus were measured.Results: The OVX group experienced a significant delay of fracture healing. The mean serum concentration of TRAP-5b of rats in the OVX group was much higher than that in the sham group after the operation (P < 0.05), but the difference at the same time point after fracture was smaller than that before fracture (P < 0.05 ). The BMD of the callus in both groups reached the peak value at the 6 th week after fracture while the proportion of the type Ⅰ collagen and the biomechanical strength reached the peak at the 8th week.Conclusions: The deficiency of estrogen after the ovariectomy could induce the up-regulation of the osteoclasts activities, whereas the potency of further activation after fracture was depressed. Although the synthesis of collagen together with its mineralization determines the biomechanical properties of new bone, the accumulation of collagen could be assessed as an index in the prediction of biomechanical strength of bones independent of the bone mineral deposition.

  11. Effects of gamma irradiation on the biomechanical properties of peroneus tendons

    Aguila, Christopher M; Delcroix, Gaëtan J-R; Kaimrajh, David N; Milne, Edward L; Temple, H Thomas; Latta, Loren L

    2016-01-01

    Purpose This study was designed to investigate the biomechanical properties of nonirradiated (NI) and irradiated (IR) peroneus tendons to determine if they would be suitable allografts, in regards to biomechanical properties, for anterior cruciate ligament reconstruction after a dose of 1.5–2.5 Mrad. Methods Seven pairs of peroneus longus (PL) and ten pairs of peroneus brevis (PB) tendons were procured from human cadavers. The diameter of each allograft was measured. The left side of each allograft was IR at 1.5–2.5 Mrad, whereas the right side was kept aseptic and NI. The allografts were thawed, kept wet with saline, and attached in a single-strand fashion to custom freeze grips using liquid nitrogen. A preload of 10 N was then applied and, after it had reached steady state, the allografts were pulled at 4 cm/sec. The parameters recorded were the displacement and force. Results The elongation at the peak load was 10.3±2.3 mm for the PB NI side and 13.5±3.3 mm for the PB IR side. The elongation at the peak load was 17.4±5.3 mm for the PL NI side and 16.3±2.0 mm for the PL IR side. For PL, the ultimate load was 2,091.6±148.7 N for NI and 2,122.8±380.0 N for IR. The ultimate load for the PB tendons was 1,485.7±209.3 N for NI and 1,318.4±296.9 N for the IR group. The ultimate stress calculations for PL were 90.3±11.3 MPa for NI and 94.8±21.0 MPa for IR. For the PB, the ultimate stress was 82.4±19.0 MPa for NI and 72.5±16.6 MPa for the IR group. The structural stiffness was 216.1±59.0 N/mm for the NI PL and 195.7±51.4 N/mm for the IR side. None of these measures were significantly different between the NI and IR groups. The structural stiffness was 232.1±45.7 N/mm for the NI PB and 161.9±74.0 N/mm for the IR side, and this was the only statistically significant difference found in this study (P=0.034). Conclusion Our statistical comparisons found no significant differences in terms of elongation, ultimate load, or ultimate stress between IR and NI

  12. Corneal biomechanical properties after femtosecond laser assisted LASIK with the corneal visualization Scheimpflug technology and ocular response analyzer

    Jing Li

    2017-02-01

    Full Text Available AIM: To investigate the changes of corneal biomechanical properties before and after femtosecond laser assisted LASIK(FS-LASIKusing Corneal Visualisation Scheimpflug Technology(Corvis STand Ocular Response Analyzer(ORA, and the correlation with other myopic parameters. METHODS:Sixty three patients(63 eyeswho had myopic femtosecond laser assisted LASIK(FS-LASIKwere enrolled in the study. The right eye of each patient was analyzed in this study. The corneal biomechanical parameters pre-operative and 1mo post-operative was measured with the Corvis ST(Oculus, Wetzlar, Germanyand ORA(Reichert, Buffalo, New York, USA. Comparison of the biomechanical property values before and after surgery was peformed using Paired t-test or Mann-Whitney U. Pearson or Spearman correlations were used to evaluate the relationship between parameters.RESULTS: The postoperative 1st A-time, Vin, 2nd A length, Vout, HC time and Radius demonstrate significant decreases comparing with preoperative values(P=0.00, P=0.00, P=0.00, P=0.00, P=0.00, P=0.00 respectively. The postoperative 2nd A-time, DA and PD significantly increases(P=0.00, P=0.00, P=0.00, however, the 1st A length had no significant difference after surgery. The CH and CRF were significantly lower after FS-LASIK(P=0.00, P=0.00. A statistically significant correlation coefficient was found between preoperative central corneal thickness(CCTwith postoperative-preoperative changes of 1st A-time, 2nd A-time, DA and Radius respectively(P=0.01, P=0.04, P=0.03, P=0.01. CONCLUSION:There were significantly changes of corneal biomechanical properties after FS-LASIK surgery. The changes of corneal biomechanical properties after FS-LASIK can be reflected by some parameters of Corvis ST and ORA. The mainly influence of corneal biomechanical alteration was possibly correlation with corneal thickness.

  13. Influence of Physical Exercise and Food Restriction on the Biomechanical Properties of the Femur of Ageing Male Rats

    Thomsen, Jesper Skovhus; Skalicky, Monika; Viidik, Andrus

    2008-01-01

    were used: baseline (BL), voluntarily running in wheels (RW), food restriction to attain pair weight with RW animals (PW), forced running in treadmills (TM), and sedentary controls (SE). The biomechanical properties of femoral neck, diaphysis, and distal metaphysis were measured. RESULTS: While......BACKGROUND: Voluntary running in wheels as well as food reduction increase the life spans of rats. Disparate parameters such as the collagen biomarker of ageing and the development of kidney pathologies are decreased by voluntary exercise. There are few reports on the influence of physical exercise...... restriction on the biomechanical properties of bone tissue of ageing male rats with the interventions starting at the age of 5 months with the end point at 23 months. This enables the study of the influence of these interventions on the ageing of the skeleton. METHODS: Five groups of male Sprague-Dawley rats...

  14. Leaf biomechanical properties in Arabidopsis thaliana polysaccharide mutants affect drought survival.

    Balsamo, Ronald; Boak, Merewyn; Nagle, Kayla; Peethambaran, Bela; Layton, Bradley

    2015-11-26

    Individual sugars are the building blocks of cell wall polysaccharides, which in turn comprise a plant׳s overall architectural structure. But which sugars play the most prominent role in maintaining a plant׳s mechanical stability during large cellular deformations induced by drought? We investigated the individual contributions of several genes that are involved in the synthesis of monosaccharides which are important for cell wall structure. We then measured drought tolerance and mechanical integrity during simulated drought in Arabidopsis thaliana. To assess mechanical properties, we designed a small-scale tensile tester for measuring failure strain, ultimate tensile stress, work to failure, toughness, and elastic modulus of 6-week-old leaves in both hydrated and drought-simulated states. Col-0 mutants used in this study include those deficient in lignin, cellulose, components of hemicellulose such as xylose and fucose, the pectic components arabinose and rhamnose, as well as mutants with enhanced arabinose and total pectin content. We found that drought tolerance is correlated to the mechanical and architectural stability of leaves as they experience dehydration. Of the mutants, S096418 with mutations for reduced xylose and galactose was the least drought tolerant, while the arabinose-altered CS8578 mutants were the least affected by water loss. There were also notable correlations between drought tolerance and mechanical properties in the diminished rhamnose mutant, CS8575 and the dehydrogenase-disrupted S120106. Our findings suggest that components of hemicellulose and pectins affect leaf biomechanical properties and may play an important role in the ability of this model system to survive drought.

  15. The role of cryopreservation in the biomechanical properties of the intervertebral disc

    SKL Lam

    2011-12-01

    Full Text Available Implantation of intervertebral disc (IVD allograft or tissue engineered disc constructs in the spine has emerged as an alternative to artificial disc replacement for the treatment of severe degenerative disc disease (DDD. Establishment of a bank of cryopreserved IVD allografts enables size matching and facilitates logistics for effective clinical management. However, the biomechanical properties of cryopreserved IVDs have not been previously reported. This study aimed to assess if cryopreservation with different concentrations of cryopreservant agents (CPA would affect the dynamic viscoelastic properties of the IVD. Whole porcine lumbar IVDs (n = 40 were harvested and processed using various concentrations of CPA, 0 % CPA, 10 % CPA and 20 % CPA. The discs were cryopreserved using a stepwise freezing protocol and stored in liquid nitrogen. After four weeks of storage, the cryopreserved IVDs were quickly thawed at 37 °C for dynamic viscoelastic testing. The apparent modulus, elastic modulus (G’, viscous modulus (G” and loss modulus (G”/G’ were calculated and compared to a fresh control group. Cryopreserved IVD without cryopreservants was significantly stiffer than the control. In the dynamic viscoelastic testing, cryopreservation with the use of CPA was able to preserve both G’ and G” of an IVD. No significant differences were found between fresh IVD and IVD cryopreserved with 10 % CPA or 20 % CPA. This study demonstrated that CPAs at an optimal concentration could preserve the mechanical properties of the IVD allograft and can provide further credence for the application of long-term storage of IVD allografts for disc transplantation or tissue engineered construct applications.

  16. Effect of Elastic Modulus on Biomechanical Properties of Lumbar Interbody Fusion Cage

    Yue Zhu; Fusheng Li; Shujun Li; Yulin Hao; Rui Yang

    2009-01-01

    This work focuses on the influence of elastic modulus on biomechanical properties of lumbar interbody fusion cages by selecting two titanium alloys with different elastic modulus.They were made by a new β type alloy with chemical composition of Ti-24Nb-4Zr-7.6Sn having low Young's modulus ~50 GPa and by a conventional biomedical alloy Ti-6Al-4V having Young's modulus ~110 GPa.The results showed that the designed cages with low modulus (LMC) and high modulus (HMC) can keep identical compression load ~9.8 kN and endure fatigue cycles higher than 5× 106 without functional or mechanical failure under 2.0 kN axial compression.The anti-subsidence ability of both group cages were examined by axial compression of thoracic spine specimens (T9~T10) dissected freshly from the calf with averaged age of 6 months.The results showed that the LMC has better anti-subsidence ability than the HMC (p<0.05).The above results suggest that the cage with low elastic modulus has great potential for clinical applications.

  17. Altered Biomechanical Properties of Gastrocnemius Tendons of Turkeys Infected with Turkey Arthritis Reovirus

    Tamer A. Sharafeldin

    2016-01-01

    Full Text Available Turkey arthritis reovirus (TARV causes lameness and tenosynovitis in commercial turkeys and is often associated with gastrocnemius tendon rupture by the marketing age. This study was undertaken to characterize the biomechanical properties of tendons from reovirus-infected turkeys. One-week-old turkey poults were orally inoculated with O’Neil strain of TARV and observed for up to 16 weeks of age. Lameness was first observed at 8 weeks of age, which continued at 12 and 16 weeks. At 4, 8, 12, and 16 weeks of age, samples were collected from legs. Left intertarsal joint with adjacent gastrocnemius tendon was collected and processed for histological examination. The right gastrocnemius tendon’s tensile strength and elasticity modulus were analyzed by stressing each tendon to the point of rupture. At 16 weeks of age, gastrocnemius tendons of TARV-infected turkeys showed significantly reduced (P<0.05 tensile strength and modulus of elasticity as compared to those of noninfected control turkeys. Gastrocnemius tendons revealed lymphocytic tendinitis/tenosynovitis beginning at 4 weeks of age, continuing through 8 and 12 weeks, and progressing to fibrosis from 12 to 16 weeks of age. We propose that tendon fibrosis is one of the key features contributing to reduction in tensile strength and elasticity of gastrocnemius tendons in TARV-infected turkeys.

  18. Changes in corneal topography and biomechanical properties after collagen cross linking for keratoconus: 1-year results

    Mohammadreza Sedaghat

    2015-01-01

    Full Text Available Purpose: To evaluate changes in corneal topography and biomechanical properties after collagen cross-linking (CXL for progressive keratoconus. Patients and Methods: Collagen cross-linking was performed on 97 eyes. We assessed uncorrected visual acuity (UCVA and best corrected visual acuity (BCVA. Corneal topography indices were evaluated using placido disc topography, scanning slit anterior topography (Orbscan II, and rotating Scheimpflug topography (Pentacam. Specular microscopy and corneal biomechanics were evaluated. Results: A 1-year-follow-up results revealed that UCVA improved from 0.31 to 0.45 and BCVA changed from 0.78 to 0.84 (P < 0.001. The mean of average keratometry value decreased from 49.62 to 47.95 D (P < 0.001. Astigmatism decreased from 4.84 to 4.24 D (P < 0.001. Apex corneal thickness decreased from 458.11 to 444.46 mm. Corneal volume decreased from 56.66 to 55.97 mm 3 (P < 0.001. Posterior best fit sphere increased from 55.50 to 46.03 mm (P = 0.025. Posterior elevation increased from 99.2 to 112.22 mm (P < 0.001. Average progressive index increased from 2.26 to 2.56 (P < 0.001. A nonsignificant decrease was observed in mean endothelial count from 2996 to 2928 cell/mm 2 (P = 0.190. Endothelial coefficient of variation (CV increased nonsignificantly from 18.26 to 20.29 (P = 0.112. Corneal hysteresis changed from 8.18 to 8.36 (P = 0.552 and corneal resistance factor increased from 6.98 to 7.21(P = 0.202, so these changes were not significant. Conclusion: Visual acuity and K values improved after CXL. In spite of the nonsignificant increase in endothelial cell count and increase in the CV, CLX seems to be a safe treatment for keratoconus. Further studies with larger sample sizes and longer follow-up periods are recommended.

  19. Fetal Growth Restriction Induces Heterogeneous Effects on Vascular Biomechanical and Functional Properties in Guinea Pigs (Cavia porcellus)

    Cañas, Daniel; Herrera, Emilio A.; García-Herrera, Claudio; Celentano, Diego; Krause, Bernardo J.

    2017-01-01

    Aim: Fetal growth restriction (FGR) is associated with a variety of cardiometabolic diseases in adulthood which could involve remodeling processes of the vascular walls that could start in the fetal period. However, there is no consensus whether this remodeling affects in a similar way the whole vascular system. We aimed to determine the effects of FGR on the vasoactive and biomechanical properties of umbilical and systemic vessels in fetal guinea pigs. Methods: FGR was induced by implanting ameroid occluders at mid-gestation in uterine arteries of pregnant guinea pigs, whilst the control group was exposed to simulated surgery. At the term of gestation, systemic arteries (aorta, carotid and femoral) and umbilical vessels were isolated to determine ex vivo contractile and biomechanical responses (stretch-stress until rupture) on a wire myograph, as well as opening angle and residual stresses. Histological characteristics in tissue samples were measured by van Gieson staining. Results: Aorta and femoral arteries from FGR showed an increased in biomechanical markers of stiffness (p < 0.01), contractile capacity (p < 0.05) and relative media thickness (p < 0.01), but a reduced internal diameter (p < 0.001), compared with controls. There were no differences in the biomechanical properties of carotid and umbilical from control and FGR fetuses, but FGR umbilical arteries had a decreased contractile response to KCl (p < 0.05) along with a reduced relative media thickness (p < 0.05). Conclusion: Altogether, these changes in functional, mechanical and morphological properties suggest that FGR is associated with a heterogeneous pro-constrictive vascular remodeling affecting mainly the lower body fetal arteries. These effects would be set during a pathologic pregnancy in order to sustain the fetal blood redistribution in the FGR and may persist up to adulthood increasing the risk of a cardiovascular disease. PMID:28344561

  20. Effect of Biometric Characteristics on the Change of Biomechanical Properties of the Human Cornea due to Cataract Surgery

    Xuefei Song

    2014-01-01

    Full Text Available Purpose. To determine the impact of biometric characteristics on changes of biomechanical properties of the human cornea due to standard cataract surgery using biomechanical analysis. Patients and Methods. This prospective consecutive cross-sectional study comprised 54 eyes with cataract in stages I or II that underwent phacoemulsification and IOL implantation. CH, CRF, IOPg, and IOPcc intraocular pressure were measured by biomechanical analysis preoperatively and at 1 month postoperatively. Changes (Δ were calculated as preoperative value versus postoperative value. Biometrical data were extracted from TMS-5 (CSI and SAI, IOLMaster (AL, and EM-3000 (CCT and ECC preoperatively. Results. The average values of the changes were ΔCH=-0.45±1.27 mmHg, ΔCRF=-0.88±1.1 mmHg, ΔIOPg=-1.58±3.15 mmHg, and ΔIOPcc=-1.45±3.93 mmHg. The higher the CSI the smaller the decrease in CH (r=0.302, P=0.028. The higher the CCT the larger the decrease in CRF (r=-0.371, P=0.013. The higher the AL the smaller the decrease in IOPg (r=0.417, P=0.005. The higher the AL, SAI, and EEC the smaller the decrease in IOPcc (r=0.351, P=0.001; r=-0.478, P<0.001; r=0.339, P=0.013. Conclusions. Corneal biomechanical properties were affected by comprehensive factors after cataract surgery, including corneal endothelium properties, biometry, and geometrical characteristics.

  1. The Effect of Phospholipids (Surfactant) on Adhesion and Biomechanical Properties of Tendon: A Rat Achilles Tendon Repair Model.

    Dabak, T Kursat; Sertkaya, Omer; Acar, Nuray; Donmez, B Ozgur; Ustunel, Ismail

    2015-01-01

    Adhesion of the tendon is a major challenge for the orthopedic surgeon during tendon repair. Manipulation of biological environment is one of the concepts to prevent adhesion. Lots of biochemicals have been studied for this purpose. We aimed to determine the effect of phospholipids on adhesion and biomechanical properties of tendon in an animal tendon repair model. Seventy-two Wistar rats were divided into 4 groups. Achilles tendons of rats were cut and repaired. Phospholipids were applied at two different dosages. Tendon adhesion was determined histopathologically and biomechanical test was performed. At macroscopic evaluation of adhesion, there are statistically significant differences between multiple-dose phospholipid injection group and Control group and also hyaluronic acid group and Control group (p 0.008). Ultimate strength was highest at hyaluronic acid injection group and lowest at multiple-dose phospholipid injection group. Single-dose phospholipids (surfactant) application may have a beneficial effect on the tendon adhesion. Although multiple applications of phospholipids seem the most effective regime to reduce the tendon adhesion among groups, it deteriorated the biomechanical properties of tendon.

  2. Effect of pathological myopia on biomechanical properties : a study by ocular response analyzer

    Veysi; ?ner; Mehmet; Tas; Erdal; ?zkaya; Yavuz; Oru?

    2015-01-01

    AIM: To evaluate the ocular response analyzer(ORA)measurements of patients with pathological myopia in comparison with those of emmetropic control subjects,and to investigate the correlation between these ORA measurements and spherical equivalent(SE).METHODS: Measurements of 53 eyes of 53 subjects with pathological myopia(SE >-6.00 D) were compared with those of 60 eyes of 60 emmetropic controls. Corneal hysteresis(CH), corneal resistance factor(CRF),noncontact tonometer intraocular pressure(IOPg), and corneal-compensated IOP(IOPcc) were obtained for each subject. The refractive error value was determined as SE via a cycloplegic refraction test.RESULTS: The mean age was 54.1±18.9y(ranging from5 to 88) in the pathological myopic group and 56.2±19.0y(ranging from 6 to 89) in the control group. There were no significant differences between the groups concerning age and sex. CH and CRF were significantly lower in the pathological myopic group than in the control group(P <0.001, P =0.005, respectively). IOPcc and IOPg were significantly higher in the pathological myopic group than in the control group(P <0.001, P =0.009,respectively). There were significantly positive correlations between CH and SE(r =0.565, P <0.001) and between CRF and SE(r =0.364, P =0.007). There were significantly negative correlations between IOPcc and SE(r =-0.432, P =0.001) and between IOPg and SE(r =-0.401,P =0.003).CONCLUSION: The present study displayed that pathological myopia affected biomechanical properties measured by ORA. The results of corneal biomechanicalproperties measured by ORA may need to be appreciated by taking refraction into account. Further, pathological myopia might be related with the increased IOP.

  3. Abnormal white matter properties in adolescent girls with anorexia nervosa

    Travis, Katherine E.; Golden, Neville H.; Feldman, Heidi M.; Solomon, Murray; Nguyen, Jenny; Mezer, Aviv; Yeatman, Jason D.; Dougherty, Robert F.

    2015-01-01

    Anorexia nervosa (AN) is a serious eating disorder that typically emerges during adolescence and occurs most frequently in females. To date, very few studies have investigated the possible impact of AN on white matter tissue properties during adolescence, when white matter is still developing. The present study evaluated white matter tissue properties in adolescent girls with AN using diffusion MRI with tractography and T1 relaxometry to measure R1 (1/T1), an index of myelin content. Fifteen adolescent girls with AN (mean age = 16.6 years ± 1.4) were compared to fifteen age-matched girls with normal weight and eating behaviors (mean age = 17.1 years ± 1.3). We identified and segmented 9 bilateral cerebral tracts (18) and 8 callosal fiber tracts in each participant's brain (26 total). Tract profiles were generated by computing measures for fractional anisotropy (FA) and R1 along the trajectory of each tract. Compared to controls, FA in the AN group was significantly decreased in 4 of 26 white matter tracts and significantly increased in 2 of 26 white matter tracts. R1 was significantly decreased in the AN group compared to controls in 11 of 26 white matter tracts. Reduced FA in combination with reduced R1 suggests that the observed white matter differences in AN are likely due to reductions in myelin content. For the majority of tracts, group differences in FA and R1 did not occur within the same tract. The present findings have important implications for understanding the neurobiological factors underlying white matter changes associated with AN and invite further investigations examining associations between white matter properties and specific physiological, cognitive, social, or emotional functions affected in AN. PMID:26740918

  4. Abnormal white matter properties in adolescent girls with anorexia nervosa

    Katherine E. Travis

    2015-01-01

    Full Text Available Anorexia nervosa (AN is a serious eating disorder that typically emerges during adolescence and occurs most frequently in females. To date, very few studies have investigated the possible impact of AN on white matter tissue properties during adolescence, when white matter is still developing. The present study evaluated white matter tissue properties in adolescent girls with AN using diffusion MRI with tractography and T1 relaxometry to measure R1 (1/T1, an index of myelin content. Fifteen adolescent girls with AN (mean age = 16.6 years ± 1.4 were compared to fifteen age-matched girls with normal weight and eating behaviors (mean age = 17.1 years ± 1.3. We identified and segmented 9 bilateral cerebral tracts (18 and 8 callosal fiber tracts in each participant's brain (26 total. Tract profiles were generated by computing measures for fractional anisotropy (FA and R1 along the trajectory of each tract. Compared to controls, FA in the AN group was significantly decreased in 4 of 26 white matter tracts and significantly increased in 2 of 26 white matter tracts. R1 was significantly decreased in the AN group compared to controls in 11 of 26 white matter tracts. Reduced FA in combination with reduced R1 suggests that the observed white matter differences in AN are likely due to reductions in myelin content. For the majority of tracts, group differences in FA and R1 did not occur within the same tract. The present findings have important implications for understanding the neurobiological factors underlying white matter changes associated with AN and invite further investigations examining associations between white matter properties and specific physiological, cognitive, social, or emotional functions affected in AN.

  5. Biomechanical properties of the pelvic floor muscles of continent and incontinent women using an inverse finite element analysis.

    Silva, M E T; Brandão, S; Parente, M P L; Mascarenhas, T; Natal Jorge, R M

    2017-03-17

    Pelvic disorders can be associated with changes in the biomechanical properties in the muscle, ligaments and/or connective tissue form fascia and ligaments. In this sense, the study of their mechanical behavior is important to understand the structure and function of these biological soft tissues. The aim of this study was to establish the biomechanical properties of the pelvic floor muscles of continent and incontinent women, using an inverse finite element analysis (FEA). The numerical models, including the pubovisceral muscle and pelvic bones were built from magnetic resonance (MR) images acquired at rest. The numerical simulation of Valsalva maneuver was based on the finite element method and the material constants were determined for different constitutive models (Neo-Hookean, Mooney-Rivlin and Yeoh) using an iterative process. The material constants (MPa) for Neo-Hookean (c1) were 0.039 ± 0.022 and 0.024 ± 0.004 for continent vs. incontinent women. For Mooney-Rivlin (c1) the values obtained were 0.026 ± 0.010 vs. 0.016 ± 0.003, and for Yeoh (c1) the values obtained were 0.031 ± 0.023 vs. 0.016 ± 0.002, (p pelvic floor muscles, leading to a relationship between them for the continent and incontinent women in a non-invasive manner.

  6. Biomechanics of foetal movement.

    Nowlan, N C

    2015-01-02

    Foetal movements commence at seven weeks of gestation, with the foetal movement repertoire including twitches, whole body movements, stretches, isolated limb movements, breathing movements, head and neck movements, jaw movements (including yawning, sucking and swallowing) and hiccups by ten weeks of gestational age. There are two key biomechanical aspects to gross foetal movements; the first being that the foetus moves in a dynamically changing constrained physical environment in which the freedom to move becomes increasingly restricted with increasing foetal size and decreasing amniotic fluid. Therefore, the mechanical environment experienced by the foetus affects its ability to move freely. Secondly, the mechanical forces induced by foetal movements are crucial for normal skeletal development, as evidenced by a number of conditions and syndromes for which reduced or abnormal foetal movements are implicated, such as developmental dysplasia of the hip, arthrogryposis and foetal akinesia deformation sequence. This review examines both the biomechanical effects of the physical environment on foetal movements through discussion of intrauterine factors, such as space, foetal positioning and volume of amniotic fluid, and the biomechanical role of gross foetal movements in human skeletal development through investigation of the effects of abnormal movement on the bones and joints. This review also highlights computational simulations of foetal movements that attempt to determine the mechanical forces acting on the foetus as it moves. Finally, avenues for future research into foetal movement biomechanics are highlighted, which have potential impact for a diverse range of fields including foetal medicine, musculoskeletal disorders and tissue engineering.

  7. Biomechanics of foetal movement

    N.C. Nowlan

    2015-01-01

    Full Text Available Foetal movements commence at seven weeks of gestation, with the foetal movement repertoire including twitches, whole body movements, stretches, isolated limb movements, breathing movements, head and neck movements, jaw movements (including yawning, sucking and swallowing and hiccups by ten weeks of gestational age. There are two key biomechanical aspects to gross foetal movements; the first being that the foetus moves in a dynamically changing constrained physical environment in which the freedom to move becomes increasingly restricted with increasing foetal size and decreasing amniotic fluid. Therefore, the mechanical environment experienced by the foetus affects its ability to move freely. Secondly, the mechanical forces induced by foetal movements are crucial for normal skeletal development, as evidenced by a number of conditions and syndromes for which reduced or abnormal foetal movements are implicated, such as developmental dysplasia of the hip, arthrogryposis and foetal akinesia deformation sequence. This review examines both the biomechanical effects of the physical environment on foetal movements through discussion of intrauterine factors, such as space, foetal positioning and volume of amniotic fluid, and the biomechanical role of gross foetal movements in human skeletal development through investigation of the effects of abnormal movement on the bones and joints. This review also highlights computational simulations of foetal movements that attempt to determine the mechanical forces acting on the foetus as it moves. Finally, avenues for future research into foetal movement biomechanics are highlighted, which have potential impact for a diverse range of fields including foetal medicine, musculoskeletal disorders and tissue engineering.

  8. Raman spectroscopy detects deterioration in biomechanical properties of bone in a glucocorticoid-treated mouse model of rheumatoid arthritis

    Maher, Jason R.; Takahata, Masahiko; Awad, Hani A.; Berger, Andrew J.

    2011-08-01

    Although glucocorticoids are frequently prescribed for the symptomatic management of inflammatory disorders such as rheumatoid arthritis, extended glucocorticoid exposure is the leading cause of physician-induced osteoporosis and leaves patients at a high risk of fracture. To study the biochemical effects of glucocorticoid exposure and how they might affect biomechanical properties of the bone, Raman spectra were acquired from ex vivo tibiae of glucocorticoid- and placebo-treated wild-type mice and a transgenic mouse model of rheumatoid arthritis. Statistically significant spectral differences were observed due to both treatment regimen and mouse genotype. These differences are attributed to changes in the overall bone mineral composition, as well as the degree of phosphate mineralization in tibial cortical bone. In addition, partial least squares regression was used to generate a Raman-based prediction of each tibia's biomechanical strength as quantified by a torsion test. The Raman-based predictions were as accurate as those produced by microcomputed tomography derived parameters, and more accurate than the clinically-used parameter of bone mineral density. These results suggest that Raman spectroscopy could be a valuable tool for monitoring bone biochemistry in studies of bone diseases such as osteoporosis, including tests of drugs being developed to combat these diseases.

  9. The Analysis of Biomechanical Properties of Proximal Femur after Implant Removal

    Yang, Jae Hyuk; Jung, Tae Gon; Honnurappa, Arjun Rupanagudi; Cha, Jae Min; Ham, Chang Hwa; Kim, Tae Yoon

    2016-01-01

    Introduction. To compare the biomechanical stability of the femur following the removal of proximal femoral nail antirotation (PFNA-II) and dynamic hip screw (DHS). Material and Methods. 56 paired cadaveric femurs were used as experimental and control groups. In the experimental group, PFNA-II and DHS were randomly inserted into femurs on both sides and then removed. Thereafter, compression load was applied until fracture occurred; biomechanical stability of the femurs and associated fracture patterns were studied. Results. The ultimate load and stiffness of the control group were 6227.8 ± 1694.1 N and 990.5 ± 99.8 N/mm, respectively. These were significantly higher than experimental group (p = 0.014, fracture patterns were different between two devices, intertrochanteric and subtrochanteric fractures. Conclusions. Mechanical stability of the proximal femurs does not differ after the removal of 2 different of fixation devices regardless of the age. However, it was significantly lower compared to an intact femur. Different fracture patterns have been shown following the removal of different fixation devices as there are variations in the site of stress risers for individual implants. PMID:27597807

  10. The Corneoscleral Shell of the Eye: an Age-Related Analysis of Structural Biomechanical Properties. Literature review

    E. N. Iomdina

    2016-01-01

    Full Text Available Structural biomechanical properties of the ocular corneoscleral shell largely determine its anatomic and optical parameters and its supporting and protective function. Therefore, changes related to age restructuring processes may affect the state of the cornea and the sclera, which should be taken into account in diagnosing eye diseases, especially age-related. According to actual literary data, age-related changes of the corneoscleral shell affecting its biomechanical properties involve all connective tissue components of the extracellular matrix: fibrous proteins (collagen and elastin and intermediate substance components (proteoglycans and glycosaminoglycans. Aged patients have a larger diameter of elastic fiber fibrils in the external part of the sclera and a lower density of fibrils in the center as compared to young patients, which is an evidence of elastin damage at the molecular level and fibril degeneration. Age-related changes of proteoglycans are primarilymanifested in hydration loss, which leads to an increase in corneal and sclera density and regional thinning of tissues. Agerelated changes of collagen are less expressed than those of elastin and proteoglycans. Yet, the distance between collagen fibrils in the cornea becomes smaller with age; they are subject to destruction, and small spaces devoid of collagen tend to appear in the posterior stroma. The most pronounced age-related degenerative changes of collagen in the deeper layers of the corneal stroma occur in the limb, which accumulates more cross striated collagen fibrils. Recent years of research have shown that the formation of cross-linked chemical bonds, i.e. intra- and intermolecular cross links of collagen is the most important structural factor. It is this particular process that is responsible for structural stability of the corneal and scleral tissue, which tends to change with age or due to certain eye diseases, such as keratoconus or progressive myopia

  11. Biomechanics of chiasmal compression: Sensitivity of the mechanical behaviors of nerve fibers to variations in material property and geometry

    Wang, Xiaofei; Neely, Andrew J.; McIlwaine, Gawn G.; Lueck, Christian J.

    2016-05-01

    The mechanism of bitemporal hemianopia is still unclear. Previous research suggested that the nerve fiber packing pattern may contribute to the selective damage of nasal (crossed) nerve fibers. Numerical models were built using finite element modeling to study the biomechanics of optic nerve fibers. The sensitivity of the mechanical behaviors of the nerve fibers to variations of five parameters in the nerve fiber model were investigated using design of experiments (DOE). Results show that the crossing angle is a very significant factor that affects a wide range of responses of the model. The strain difference between the crossed and the uncrossed nerve fibers may account for the phenomenon of bitemporal hemianopia. This work also highlights the need for more accurate material properties of the tissues in the model and an improved understanding of the microstructure of the optic chiasm.

  12. The Analysis of Biomechanical Properties of Proximal Femur after Implant Removal

    Jae Hyuk Yang

    2016-01-01

    Full Text Available Introduction. To compare the biomechanical stability of the femur following the removal of proximal femoral nail antirotation (PFNA-II and dynamic hip screw (DHS. Material and Methods. 56 paired cadaveric femurs were used as experimental and control groups. In the experimental group, PFNA-II and DHS were randomly inserted into femurs on both sides and then removed. Thereafter, compression load was applied until fracture occurred; biomechanical stability of the femurs and associated fracture patterns were studied. Results. The ultimate load and stiffness of the control group were 6227.8±1694.1 N and 990.5±99.8 N/mm, respectively. These were significantly higher than experimental group (p=0.014, <0.001 following the removal of PFNA-II (4085.6±1628.03 N and 656.3±155.3 N/mm and DHS (4001.9±1588.3 N and 656.3±155.3 N/mm. No statistical differences in these values were found between the 2 device groups (p=0.84, 0.71, regardless of age groups. However, fracture patterns were different between two devices, intertrochanteric and subtrochanteric fractures. Conclusions. Mechanical stability of the proximal femurs does not differ after the removal of 2 different of fixation devices regardless of the age. However, it was significantly lower compared to an intact femur. Different fracture patterns have been shown following the removal of different fixation devices as there are variations in the site of stress risers for individual implants.

  13. Detection of the early keratoconus based on corneal biomechanical properties in the refractive surgery candidates

    Zofia Pniakowska

    2016-01-01

    Full Text Available Context: Subclinical keratoconus is contraindication to refractive surgery. The currently used methods of preoperative screening do not always allow differentiating between healthy eyes and those with subclinical keratoconus. Aim: To evaluate biomechanical parameters of the cornea, waveform score (WS, and intraocular pressure (IOP as potentially useful adjuncts to the diagnostic algorithm for precise detection of the early keratoconus stages and selection of refractive surgery candidates. Settings and Design: Department of Ophthalmology and prospective cross-sectional study. Patients and Methods: Patients enrolled in the study were diagnosed with refractive disorders. We assessed parameters of corneal biomechanics such as corneal hysteresis (CH, corneal resistance factor (CRF, Goldman-correlated IOP (IOPg, corneal compensated IOP, WS, and keratoconus match index (KMI. They were classified into one of three groups based on the predefined KMI range: Group 1 (from 0.352 to 0.757 – 45 eyes, Group 2 (from −0.08 to 0.313 – 52 eyes, and Group 0 - control group (from 0.761 to 1.642 – 80 eyes. Results: In both study groups, IOPg, CRF, and CH were decreased when compared to control (P < 0.0001. In control group, there was positive correlation between CH and KMI (P < 0.05, with no correlations in any of the two study groups. CRF correlated positively with KMI in control (P < 0.0001 and in Group 2 (P < 0.05. Conclusions: CH and CRF, together with WS and IOPg, consist a clinically useful adjunct to detect subclinical keratoconus in patients referred for refractive surgery when based on KMI staging.

  14. Evolution of bone biomechanical properties at the micrometer scale around titanium implant as a function of healing time

    Vayron, Romain; Matsukawa, Mami; Tsubota, Ryo; Mathieu, Vincent; Barthel, Etienne; Haiat, Guillaume

    2014-03-01

    The characterization of the biomechanical properties of newly formed bone tissue around implants is important to understand the osseointegration process. The objective of this study is to investigate the evolution of elastic properties of newly formed bone tissue as a function of healing time. To do so, nanoindentation and micro-Brillouin scattering techniques are coupled following a multimodality approach using histological analysis. Coin-shaped implants were placed in vivo at a distance of 200 µm from the cortical bone surface, leading to an initially empty cavity. Two rabbits were sacrificed after 7 and 13 weeks of healing time. The histological analyses allow us to distinguish mature and newly formed bone tissue. The bone mechanical properties were measured in mature and newly formed bone tissue. Analysis of variance and Tukey-Kramer tests reveals a significant effect of healing time on the indentation modulus and ultrasonic velocities of bone tissue. The results show that bone mass density increases by 12.2% (2.2% respectively) between newly formed bone at 7 weeks (13 weeks respectively) and mature bone. The dependence of bone properties on healing time may be explained by the evolution of bone microstructure and mineralization.

  15. Cryogenic abnormal thermal expansion properties of carbon-doped La(Fe,Si)13 compounds.

    Li, Shaopeng; Huang, Rongjin; Zhao, Yuqiang; Wang, Wei; Li, Laifeng

    2015-12-14

    Recently, La(Fe,Si)13-based compounds have attracted much attention due to their isotropic and tunable abnormal thermal expansion (ATE) properties as well as bright prospects for practical applications. In this research, we have prepared cubic NaZn13-type carbon-doped La(Fe,Si)13 compounds by the arc-melting method, and their ATE and magnetic properties were investigated by means of variable-temperature X-ray diffraction, strain gauge and the physical property measurement system (PPMS). The experimental results indicate that both micro and macro negative thermal expansion (NTE) behaviors gradually weaken with the increase of interstitial carbon atoms. Moreover, the temperature region with the most remarkable NTE properties has been broadened and near zero thermal expansion (NZTE) behavior occurs in the bulk carbon-doped La(Fe,Si)13 compounds.

  16. Foraging on individual leaves by an intracellular feeding insect is not associated with leaf biomechanical properties or leaf orientation.

    Justin Fiene

    Full Text Available Nearly all herbivorous arthropods make foraging-decisions on individual leaves, yet systematic investigations of the adaptive significance and ecological factors structuring these decisions are rare with most attention given to chewing herbivores. This study investigated why an intracellular feeding herbivore, Western flower thrips (WFT Frankliniella occidentalis Pergande, generally avoids feeding on the adaxial leaf surface of cotton cotyledons. WFT showed a significant aversion to adaxial-feeding even when excised-cotyledons were turned up-side (abaxial-side 'up', suggesting that negative-phototaxis was not a primary cause of thrips foraging patterns. No-choice bioassays in which individual WFT females were confined to either the abaxial or adaxial leaf surface showed that 35% fewer offspring were produced when only adaxial feeding was allowed, which coincided with 32% less plant feeding on that surface. To test the hypothesis that leaf biomechanical properties inhibited thrips feeding on the adaxial surface, we used a penetrometer to measure two variables related to the 'toughness' of each leaf surface. Neither variable negatively co-varied with feeding. Thus, while avoiding the upper leaf surface was an adaptive foraging strategy, the proximate cause remains to be elucidated, but is likely due, in part, to certain leaf properties that inhibit feeding.

  17. The acute effect of bipolar radiofrequency energy thermal chondroplasty on intrinsic biomechanical properties and thickness of chondromalacic human articular cartilage.

    Dutcheshen, Nicholas; Maerz, Tristan; Rabban, Patrick; Haut, Roger C; Button, Keith D; Baker, Kevin C; Guettler, Joseph

    2012-08-01

    Radio frequency energy (RFE) thermal chondroplasty has been a widely-utilized method of cartilage debridement in the past. Little is known regarding its effect on tissue mechanics. This study investigated the acute biomechanical effects of bipolar RFE treatment on human chondromalacic cartilage. Articular cartilage specimens were extracted (n = 50) from femoral condyle samples of patients undergoing total knee arthroplasty. Chondromalacia was graded with the Outerbridge classification system. Tissue thicknesses were measured using a needle punch test. Specimens underwent pretreatment load-relaxation testing using a spherical indenter. Bipolar RFE treatment was applied for 45 s and the indentation protocol was repeated. Structural properties were derived from the force-time data. Mechanical properties were derived using a fibril-reinforced biphasic cartilage model. Statistics were performed using repeated measures ANOVA. Cartilage thickness decreased after RFE treatment from a mean of 2.61 mm to 2.20 mm in Grade II, II-III, and III specimens (P resistance to shear and tension could be compromised due to removal of the superficial layer and decreased fibril modulus, RFE treatment increases matrix modulus and decreases tissue permeability which may restore the load- bearing capacity of the cartilage.

  18. Changes in geometrical and biomechanical properties of immature male and female rat tibia

    Zernicke, Ronald F.; Hou, Jack C.-H.; Vailas, Arthur C.; Nishimoto, Mitchell; Patel, Sanjay

    1990-01-01

    The differences in the geometry and mechanical properties of immature male and female rat tibiae were detailed in order to provide comparative data for spaceflight, exercise, or disease experiments that use immature rats as an animal model. The experiment focuses on the particularly rapid period of growth that occurs in the Sprague-Dawley rat between 40 and 60 d of age. Tibial length and middiaphysical cross-sectional data were analyzed for eight different groups of rats according to age and sex, and tibial mechanical properties were obtained via three-point bending tests to failure. Results indicate that, during the 15 d period of rapid growth, changes in rat tibial geometry are more important than changes in bone material properties for influencing the mechanical properties of the tibia. Male tibiae changed primarily in structural properties, while in the female rats major changes in mechanical properties of the tibia were only attributable to changes in the structural properties of the bone.

  19. Anatomy and biomechanical properties of the plantar aponeurosis: a cadaveric study.

    Da-wei Chen

    Full Text Available OBJECTIVES: To explore the anatomy of the plantar aponeurosis (PA and its biomechanical effects on the first metatarsophalangeal (MTP joint and foot arch. METHODS: Anatomic parameters (length, width and thickness of each central PA bundle and the main body of the central part were measured in 8 cadaveric specimens. The ratios of the length and width of each bundle to the length and width of the central part were used to describe these bundles. Six cadaveric specimens were used to measure the range of motion of the first MTP joint before and after releasing the first bundle of the PA. Another 6 specimens were used to evaluate simulated static weight-bearing. Changes in foot arch height and plantar pressure were measured before and after dividing the first bundle. RESULTS: The average width and thickness of the origin of the central part at the calcaneal tubercle were 15.45 mm and 2.79 mm respectively. The ratio of the length of each bundle to the length of the central part was (from medial to lateral 0.29, 0.30, 0.28, 0.25, and 0.27, respectively. Similarly, the ratio of the widths was 0.26, 0.25, 0.23, 0.19 and 0.17. The thickness of each bundle at the bifurcation of the PA into bundles was (from medial to lateral 1.26 mm, 1.04 mm, 0.91 mm, 0.84 mm and 0.72 mm. The average dorsiflexion of the first MTP joint increased 10.16° after the first bundle was divided. Marked acute changes in the foot arch height and the plantar pressure were not observed after division. CONCLUSIONS: The first PA bundle was not the longest, widest, or the thickest bundle. Releasing the first bundle increased the range of motion of the first MTP joint, but did not acutely change foot arch height or plantar pressure during static load testing.

  20. Abnormal Photoluminescence Properties of Polycrystalline ZnO Nanowire Arrays Synthesized by Electrodeposition

    XUE De-Sheng; GONG Yu

    2006-01-01

    @@ Large-scale ZnO nanowire arrays are synthesized by electrodeposition with subsequent heat treatment in atmosphere ambient at 450-650℃. Photoluminescence (PL) is investigated at 295K. Abnormal PL properties of an unusual sharp emission at 485nm and a broad ultraviolet emission which are different from the other works of ZnO PL before are observed. Field emission scanning electronic microscopy and transmission electron microscopy results show that the length of ZnO nanowires is nearly 5μm and their diameter is about 70 nm. X-ray diffraction and electron diffraction results reveal that the ZnO nanowires are a polycrystalline structure.

  1. Dynamic Observation on the Effects of Different Suture Techniques on the Biomechanical Properties in the Healing of Tendons

    2005-01-01

    To identify the best suture techniques for the tendon repair, the biomechanical properties of tendons sutured by different methods were dynamically examined. 140 chickens were divided into 2 groups equally: group A and group B. The tendon of the right side was subjected to injury-repair process, and the tendons of the left sides served as controls in both groups. In group A, "figure-of8" suture, modified Kessler suture and Bunnell suture were used for the 2nd to 4th paws respectively, while in group B, Kleinert suture, Tsuge suture and Ikuta suture were used. On the day 0, 3,7, 14, 21, 28, 42 after operation, 10 animals were sacrificed and the flexor tendons of both sides were harvested for strength test. The results showed that the initial strength of the repaired tendons and the strength after 6 weeks following tendon cut were far below those of intact tendons, irrespective of suture techniques used. With the 6 techniques, the Pmax of tendons repaired by Tsuge suture was increased continually, reaching the highest value on the 42nd day. The Pmax of tendons sutured by the modified Kessler suture was slightly lower than that by Tsuge suture, but it was increased steadily in healing. The tendons repaired by figure-of-8 suture yielded the lowest Pmax. It was concluded that Tsuge suture and modified Kessler suture were the best techniques for tendon repair.

  2. Exogenous normal lymph alleviates microcirculation disturbances and abnormal hemorheological properties in rats with disseminated intravascular coagulation

    Niu, Chun-Yu; Zhao, Zi-Gang; Zhang, Yu-Ping [Institute of Microcirculation, Hebei North University, Zhangjiakou (China); Hou, Ya-Li [Department of Clinical Laboratory, First Affiliated Hospital, Hebei North University, Zhangjiakou (China); Li, Jun-Jie; Jiang, Hua; Zhang, Jing [Institute of Microcirculation, Hebei North University, Zhangjiakou (China)

    2013-02-01

    Disturbances of the microcirculation and abnormal hemorheological properties are important factors that play an important role in disseminated intravascular coagulation (DIC) and result in organ dysfunction or failure. In the present study, we established an animal model of DIC using intravenous Dextran 500 in rats, and used exogenous normal lymph corresponding to 1/15 of whole blood volume for injection through the left jugular vein. We found that normal lymph could improve the blood pressure and survival time of rats with DIC. The results regarding the mesenteric microcirculation showed that the abnormality of the diameter of mesenteric microvessels and micro-blood flow speed in the DIC+lymph group was significantly less than in the DIC+saline group. Whole blood viscosity, relative viscosity, plasma viscosity, hematocrit (Hct), erythrocyte sedimentation rate (ESR), and electrophoresis time of erythrocytes were significantly increased in the DIC+saline group compared to the control group. The electrophoretic length and migration of erythrocytes from the DIC+saline and DIC+lymph groups were significantly slower than the control group. Blood relative viscosity, Hct, ESR, and electrophoretic time of erythrocytes were significantly increased in the DIC+lymph group compared to the control group. Whole blood viscosity, relative viscosity and reduced viscosity were significantly lower in the DIC+lymph group than in the DIC+saline group, and erythrocyte deformability index was also significantly higher than in the DIC+saline and control groups. These results suggest that exogenous normal lymph could markedly improve the acute microcirculation disturbance and the abnormal hemorheological properties in rats with DIC induced by Dextran 500.

  3. Magnetic hyperthermia dosimetry by biomechanical properties revealed in magnetomotive optical coherence elastography (MM-OCE) (Conference Presentation)

    Huang, Pin-Chieh; Marjanovic, Marina; Spillman, Darold R.; Odintsov, Boris M.; Boppart, Stephen A.

    2016-03-01

    Magnetic nanoparticles (MNPs) have been utilized in magnetic hyperthermia to treat solid tumors. Under an appropriate AC magnetic field, energy can be transferred to the MNPs to heat up the intended tissue target while sparing non-targeted healthy tissue. However, a sensitive monitoring technique for the dose of MNP thermal therapy is desirable in order to prevent over-treatment and collateral injury. Typical hyperthermia dosimetry often relies on changes in imaging properties or temperature measurements based on the thermal distribution. Alternative dosimetric indicators can include the biomechanical properties of the tissue, reflecting the changes due to protein denaturation, coagulation, and tissue dehydration during hyperthermia treatments. Tissue stiffness can be probed by elastography modalities including MRI, ultrasound imaging, and optical coherence elastography (OCE), with OCE showing the highest displacement sensitivity (tens of nanometers). Magnetomotive optical coherence elastography (MM-OCE) is one type of OCE that utilizes MNPs as internal force transducers to probe the tissue stiffness. Therefore, we examined the feasibility of evaluating the hyperthermia dose based on the elasticity changes revealed by MM-OCE. Superparamagnetic MNPs were applied to ex vivo tissue specimens for both magnetic hyperthermia and MM-OCE experiments, where temperature and elastic modulus were obtained. A correlation between temperature rise and measured stiffness was observed. In addition, we found that with repetitive sequential treatments, tissue stiffness increased, while temperature rise remained relatively constant. These results potentially suggest that MM-OCE could indicate the irreversible changes the tissue undergoes during thermal therapy, which supports the idea for MM-OCE-based hyperthermia dosage control in future applications.

  4. Establishing the biomechanical properties of the pelvic soft tissues through an inverse finite element analysis using magnetic resonance imaging.

    Silva, M E T; Brandão, S; Parente, M P L; Mascarenhas, T; Natal Jorge, R M

    2016-04-01

    The mechanical characteristics of the female pelvic floor are relevant when explaining pelvic dysfunction. The decreased elasticity of the tissue often causes inability to maintain urethral position, also leading to vaginal and rectal descend when coughing or defecating as a response to an increase in the internal abdominal pressure. These conditions can be associated with changes in the mechanical properties of the supportive structures-namely, the pelvic floor muscles-including impairment. In this work, we used an inverse finite element analysis to calculate the material constants for the passive mechanical behavior of the pelvic floor muscles. The numerical model of the pelvic floor muscles and bones was built from magnetic resonance axial images acquired at rest. Muscle deformation, simulating the Valsalva maneuver with a pressure of 4 KPa, was compared with the muscle displacement obtained through additional dynamic magnetic resonance imaging. The difference in displacement was of 0.15 mm in the antero-posterior direction and 3.69 mm in the supero-inferior direction, equating to a percentage error of 7.0% and 16.9%, respectively. We obtained the shortest difference in the displacements using an iterative process that reached the material constants for the Mooney-Rivlin constitutive model (c10=11.8 KPa and c20=5.53 E-02 KPa). For each iteration, the orthogonal distance between each node from the group of nodes which defined the puborectal muscle in the numerical model versus dynamic magnetic resonance imaging was computed. With the methodology used in this work, it was possible to obtain in vivo biomechanical properties of the pelvic floor muscles for a specific subject using input information acquired non-invasively.

  5. Measuring the biomechanical properties of the actin in MCF-7 breast cancer cell with a combined system of AFM and SIM

    You, Minghai; Chen, Jianling; Wang, Yuhua; Jiang, Ningcheng; Xie, Shusen; Yang, Hongqin

    2016-10-01

    Biomechanics of cell plays an important role in the behavior and development of diseases, which has a profound influence on the health, structural integrity, and function of cells. In this study, we proposed a method to assess the biomechanical properties in single breast cancer cell line MCF-7 by combining structured illumination microscopy (SIM) with atomic force microscopy (AFM). High resolution optical image of actin in MCF-7 cell and its elastography were obtained. The result shows that the quantitative resolution was improved by SIM, with 490 nm of conventional fluorescence image and 285 nm of reconstructed SIM image, which could give a precise location for AFM measurement. The elasticity of actin is about in the range of 10 1000 kPa. The proposed methods will be helpful in the understanding and clinical diagnosis of diseases at single cell level.

  6. Study of biomechanical, anatomical, and physiological properties of scorpion stingers for developing biomimetic materials.

    Zhao, Zi-Long; Shu, Tao; Feng, Xi-Qiao

    2016-01-01

    Through natural selection, many animal organs have evolved superior mechanical properties and elegant hierarchical structures adaptive to their multiple biological functions. We combine experiments and theory to investigate the composition-structure-property-function relations of scorpion stingers. Their hierarchical structures and functionally gradient mechanical properties were revealed. Slow motion analysis of the penetration process of a scorpion stinger was performed to examine the refined survival skills of scorpions. An experiment-based mechanics model of the stinger was proposed, the results of which revealed an optimized range of penetration angle in an insertion event. Both theoretical and numerical results are in good agreement with our experimental measurements. The analysis method and physical insights of this work are potentially important for investigating a general class of sharp-edge biological materials, e.g., cattle horns, spider fangs, cat claws, and plant thorns.

  7. Contribution of collagen fiber undulation to regional biomechanical properties along porcine thoracic aorta.

    Zeinali-Davarani, Shahrokh; Wang, Yunjie; Chow, Ming-Jay; Turcotte, Raphaël; Zhang, Yanhang

    2015-05-01

    As major extracellular matrix components, elastin, and collagen play crucial roles in regulating the mechanical properties of the aortic wall and, thus, the normal cardiovascular function. The mechanical properties of aorta, known to vary with age and multitude of diseases as well as the proximity to the heart, have been attributed to the variations in the content and architecture of wall constituents. This study is focused on the role of layer-specific collagen undulation in the variation of mechanical properties along the porcine descending thoracic aorta. Planar biaxial tensile tests are performed to characterize the hyperelastic anisotropic mechanical behavior of tissues dissected from four locations along the thoracic aorta. Multiphoton microscopy is used to image the associated regional microstructure. Exponential-based and recruitment-based constitutive models are used to account for the observed mechanical behavior while considering the aortic wall as a composite of two layers with independent properties. An elevated stiffness is observed in distal regions compared to proximal regions of thoracic aorta, consistent with sharper and earlier collagen recruitment estimated for medial and adventitial layers in the models. Multiphoton images further support our prediction that higher stiffness in distal regions is associated with less undulation in collagen fibers. Recruitment-based models further reveal that regardless of the location, collagen in the media is recruited from the onset of stretching, whereas adventitial collagen starts to engage with a delay. A parameter sensitivity analysis is performed to discriminate between the models in terms of the confidence in the estimated model parameters.

  8. Biomechanical properties of an advanced new carbon/flax/epoxy composite material for bone plate applications.

    Bagheri, Zahra S; El Sawi, Ihab; Schemitsch, Emil H; Zdero, Rad; Bougherara, Habiba

    2013-04-01

    This work is part of an ongoing program to develop a new carbon fiber/flax/epoxy (CF/flax/epoxy) hybrid composite material for use as an orthopaedic long bone fracture plate, instead of a metal plate. The purpose of this study was to evaluate the mechanical properties of this new novel composite material. The composite material had a "sandwich structure", in which two thin sheets of CF/epoxy were attached to each outer surface of the flax/epoxy core, which resulted in a unique structure compared to other composite plates for bone plate applications. Mechanical properties were determined using tension, three-point bending, and Rockwell hardness tests. Also, scanning electron microscopy (SEM) was used to characterize the failure mechanism of specimens in tension and three-point bending tests. The results of mechanical tests revealed a considerably high ultimate strength in both tension (399.8MPa) and flexural loading (510.6MPa), with a higher elastic modulus in bending tests (57.4GPa) compared to tension tests (41.7GPa). The composite material experienced brittle catastrophic failure in both tension and bending tests. The SEM images, consistent with brittle failure, showed mostly fiber breakage and fiber pull-out at the fractured surfaces with perfect bonding at carbon fibers and flax plies. Compared to clinically-used orthopaedic metal plates, current CF/flax/epoxy results were closer to human cortical bone, making the material a potential candidate for use in long bone fracture fixation.

  9. Dinosaur biomechanics

    Alexander, R. McNeill

    2006-01-01

    Biomechanics has made large contributions to dinosaur biology. It has enabled us to estimate both the speeds at which dinosaurs generally moved and the maximum speeds of which they may have been capable. It has told us about the range of postures they could have adopted, for locomotion and for feeding, and about the problems of blood circulation in sauropods with very long necks. It has made it possible to calculate the bite forces of predators such as Tyrannosaurus, and the stresses they imp...

  10. Pulsed electromagnetic field treatment enhances healing callus biomechanical properties in an animal model of osteoporotic fracture.

    Androjna, Caroline; Fort, Brian; Zborowski, Maciej; Midura, Ronald J

    2014-09-01

    Delayed bone healing has been noted in osteoporosis patients and in the ovariectomized (OVX) rat model of estrogen-depletion osteopenia. Pulsed electromagnetic field (PEMF) devices are clinically approved as an adjunct to cervical fusion surgery in patients at high risk for non-fusion and for the treatment of fracture non-unions. These bone growth stimulating devices also accelerate the healing of fresh fracture repair in skeletally mature normal rats but have not been tested for efficacy to accelerate and/or enhance the delayed bone repair process in OVX rats. The current study tested the hypothesis that daily PEMF treatments would improve the fracture healing response in skeletally mature OVX rats. By 6 weeks of healing, PEMF treatments resulted in improved hard callus elastic modulus across fibula fractures normalizing the healing process in OVX rats with respect to this mechanical property. Radiographic evidence showed an improved hard callus bridging across fibula fractures in OVX rats treated with PEMF as compared to sham treatments. These findings provide a scientific rationale for investigating whether PEMF might improve bone-healing responses in at-risk osteoporotic patients.

  11. The effects of strain rate on the properties of the medial collateral ligament in skeletally immature and mature rabbits: a biomechanical and histological study.

    Woo, S L; Peterson, R H; Ohland, K J; Sites, T J; Danto, M I

    1990-09-01

    The effects of strain rate on the structural properties of the femur-medial collateral ligament-tibia complex (FMTC) and on the mechanical (material) properties of the medial collateral ligament (MCL) of skeletally immature and skeletally mature rabbits were studied. The FMTCs were tested in tension to failure, at five extension rates (0.008 mm/s-113 mm/s). For the FMTCs from the skeletally immature animals, values of load, elongation, and energy absorbed at failure increased substantially with extension rates. Such increases also existed for skeletally mature animals, but they were much less in magnitude. All samples from the skeletally immature animals failed by tibial avulsion, whereas samples from the skeletally mature animals failed within the ligament substance. The mechanical properties of the ligament substance were minimally strain-rate sensitive for both groups. Histological sections of the ligament substance and insertion sites from the failed samples were examined, and these observations were correlated with the biomechanical findings. For the rabbit model used in this study, we conclude that skeletal maturity has more influence on the biomechanical properties of the MCL than does strain rate.

  12. Waves and high nutrient loads jointly decrease survival and separately affect morphological and biomechanical properties in the seagrass

    La Nafie, Y.A.; de los Santos, C.B.; Brun, F.G.; van Katwijk, M.M.; Bouma, T.J.

    2012-01-01

    In an 8-week aquarium experiment, we investigated the interactive effects of waves (present vs. absent) and water-column nutrient level (high vs. low) on the survival, growth, morphology, and biomechanics of the seagrass, Zostera noltii. Survival was reduced when plants were exposed to both waves an

  13. Mineral density and biomechanical properties of bone tissue from male Arctic foxes (Vulpes lagopus) exposed to organochlorine contaminants and emaciation

    Sonne, Christian; Wolkers, Hans; Rigét, Frank F;

    2008-01-01

    We investigated the impact from dietary OC (organochlorine) exposure and restricted feeding (emaciation) on bone mineral density (BMD; g hydroxy-apatite cm(-2)) in femoral, vertebrate, skull and baculum osteoid tissue from farmed Arctic blue foxes (Vulpes lagopus). For femur, also biomechanical...

  14. Sterilization with electron beam irradiation influences the biomechanical properties and the early remodeling of tendon allografts for reconstruction of the anterior cruciate ligament (ACL).

    Schmidt, Tanja; Hoburg, Arnd; Broziat, Christine; Smith, Mark D; Gohs, Uwe; Pruss, Axel; Scheffler, Sven

    2012-08-01

    Although allografts for anterior cruciate ligament (ACL) replacement have shown advantages compared to autografts, their use is limited due to the risk of disease transmission and the limitations of available sterilization methods. Gamma sterilization has shown detrimental effects on graft properties at the high doses required for sufficient pathogen inactivation. In our previous in vitro study on human patellar tendon allografts, Electron beam (Ebeam) irradiation showed less detrimental effects compared to gamma sterilization (Hoburg et al. in Am J Sports Med 38(6):1134-1140, 2010). To investigate the biological healing and restoration of the mechanical properties of a 34 kGy Ebeam treated tendon allograft twenty-four sheep underwent ACL replacement with either a 34 kGy Ebeam treated allograft or a non-sterilized fresh frozen allograft. Biomechanical testing of stiffness, ultimate failure load and AP-laxity as well as histological analysis to investigate cell, vessel and myofibroblast-density were performed after 6 and 12 weeks. Native sheep ACL and hamstring tendons (HAT, each n = 9) served as controls. The results of a previous study analyzing the remodeling of fresh frozen allografts (n = 12) and autografts (Auto, n = 18) with the same study design were also included in the analysis. Statistics were performed using Mann-Whitney U test followed by Bonferroni-Holm correction. Results showed significantly decreased biomechanical properties during the early remodeling period in Ebeam treated grafts and this was accompanied with an increased remodeling activity. There was no recovery of biomechanical function from 6 to 12 weeks in this group in contrast to the results observed in fresh frozen allografts and autografts. Therefore, high dose Ebeam irradiation investigated in this paper cannot be recommended for soft tissue allograft sterilization.

  15. Methods and Techniques for the Measurement of Biomechanical Properties of Eye Tissues%眼生物力学性质的测量技术与方法

    张佳莹; 田磊; 王立科; 郑永平

    2015-01-01

    角膜与晶状体是眼的主要屈光成分,且均为不均匀、各向异性的生物粘弹性组织器官,其生物力学特性是保持眼正常形态与屈光功能的结构基础。针对角膜、晶状体的生物力学测量方法将为相关疾病的早期诊断及开发有效治疗策略提供新的思路。传统生物力学测量方法多数为有创的离体方式;而临床中仅有的在体测量仪器,其正确性与实用性尚需探讨。近年来,伴随光学先进技术手段的发展,如利用声辐射力结合超快激光技术或光学相干断层扫描技术等,期待能够在传统的测量方式上加以改进,从而实现对角膜、晶状体生物力学更加精确、实用的在体测量。本文着力于对该领域作一个全景式的概括,使相关人员通过阅读本文获得对该领域的整体把握。%Cornea and crystalline lens are the major refraction components of eyes.The cornea and lens exhibited inhomogeneous, anisotropic and viscoelastic characteristics. Quantitative measurement of this biomechanical properties of cornea and lens can facilitate the early diagnosis and creative strategy for related diseases. Traditional methods for measuring biomechanical properties of cornea and lens are almost invasive and in vitro. Moreover the accuracy and performance of the only few clinical instruments for corneal biomechanics measurements are still need to be proven further. Based on the improvement of the traditional methods with the rapid development of related optical techniques, such as the combination of ultrasound radiation force, ultrafast laser and optical coherence tomography technique, the biomechanical properties of cornea and lens can be potentially measured more effcient and accurate in vivo. In this review, a comprehensive generalization was summarized to introduce a general knowledge of this ifeld.

  16. The biomechanics of seed germination.

    Steinbrecher, Tina; Leubner-Metzger, Gerhard

    2016-12-07

    From a biomechanical perspective, the completion of seed (and fruit) germination depends on the balance of two opposing forces: the growth potential of the embryonic axis (radicle-hypocotyl growth zone) and the restraint of the seed-covering layers (endosperm, testa, and pericarp). The diverse seed tissues are composite materials which differ in their dynamic properties based on their distinct cell wall composition and water uptake capacities. The biomechanics of embryo cell growth during seed germination depend on irreversible cell wall loosening followed by water uptake due to the decreasing turgor, and this leads to embryo elongation and eventually radicle emergence. Endosperm weakening as a prerequisite for radicle emergence is a widespread phenomenon among angiosperms. Research into the biochemistry and biomechanics of endosperm weakening has demonstrated that the reduction in puncture force of a seed's micropylar endosperm is environmentally and hormonally regulated and involves tissue-specific expression of cell wall remodelling proteins such as expansins, diverse hydrolases, and the production of directly acting apoplastic reactive oxygen. The endosperm-weakening biomechanics and its underlying cell wall biochemistry differ between the micropylar (ME) and chalazal (CE) endosperm domains. In the ME, they involve cell wall loosening, cell separation, and programmed cell death to provide decreased and localized ME tissue resistance, autolysis, and finally the formation of an ME hole required for radicle emergence. Future work will further unravel the molecular mechanisms, environmental regulation, and evolution of the diverse biomechanical cell wall changes underpinning the control of germination by endosperm weakening.

  17. Abnormal thermal expansion properties of cubic NaZn13-type La(Fe,Al)13 compounds.

    Li, Wen; Huang, Rongjin; Wang, Wei; Zhao, Yuqiang; Li, Shaopeng; Huang, Chuanjun; Li, Laifeng

    2015-02-28

    The cubic NaZn13-type La(Fe,Al)13 compounds were synthesized, and their linear thermal expansion properties were investigated in the temperature range of 4.2-300 K. It was found that these compounds exhibit abnormal thermal expansion behavior, i.e., pronounced negative thermal expansion (NTE) or zero thermal expansion (ZTE) behavior, below the Curie temperature due to the magnetovolume effect (MVE). Moreover, in the La(Fe,Al)13 compounds, the modification of the coefficient of thermal expansion (CTE) as well as the abnormal thermal expansion (ATE) temperature-window is achieved through optimizing the proportion of Fe and Al. Typically, the average CTE of the LaFe13-xAlx compounds with x = 1.8 reaches as large as -10.47 × 10(-6) K(-1) between 100 and 225 K (ΔT = 125 K). Also, the ZTE temperature-window of the LaFe13-xAlx compounds with x = 2.5 and x = 2.7 could be broadened to 245 K (from 5 to 250 K). Besides, the magnetic properties of these compounds were measured and correlated with the abnormal thermal expansion behavior. The present results highlight the potential application of such La(Fe,Al)13 compounds with abnormal thermal expansion properties in cryogenic engineering.

  18. Dinosaur biomechanics.

    Alexander, R McNeill

    2006-08-07

    Biomechanics has made large contributions to dinosaur biology. It has enabled us to estimate both the speeds at which dinosaurs generally moved and the maximum speeds of which they may have been capable. It has told us about the range of postures they could have adopted, for locomotion and for feeding, and about the problems of blood circulation in sauropods with very long necks. It has made it possible to calculate the bite forces of predators such as Tyrannosaurus, and the stresses they imposed on its skull; and to work out the remarkable chewing mechanism of hadrosaurs. It has shown us how some dinosaurs may have produced sounds. It has enabled us to estimate the effectiveness of weapons such as the tail spines of Stegosaurus. In recent years, techniques such as computational tomography and finite element analysis, and advances in computer modelling, have brought new opportunities. Biomechanists should, however, be especially cautious in their work on animals known only as fossils. The lack of living specimens and even soft tissues oblige us to make many assumptions. It is important to be aware of the often wide ranges of uncertainty that result.

  19. Biomechanics in Schools.

    Vincent, J. F. V.

    1980-01-01

    Examines current usage of the term "biomechanics" and emphasizes the importance of differentiating between structure and material. Describes current prolects in biomechanics and lists four points about the educational significance of the field. (GS)

  20. Fruit biomechanics based on anatomy: a review

    Li, Zhiguo; Yang, Hongling; Li, Pingping; Liu, Jizhan; Wang, Jizhang; Xu, Yunfeng

    2013-01-01

    Fruit biomechanics is needed for quality determination, multiscale modelling and engineering design of fruit processes and equipments. However, these determined fruit biomechanics data often have obvious differences for the same fruit or tissue. In order to investigate it, the fruit biomechanics based on anatomy was reviewed in this paper. First, the anatomical characteristics of fruit biomaterials were described at the macroscopic `tissue' level and microscopic `cellular' level. Subsequently, the factors affecting fruit biomechanics based on anatomy and the relationships between fruit biomechanics, texture and mechanical damage were summarised according to the published literature. Fruit biomechanics is mainly affected by size, number and arrangement of cells, quantity and volume of intracellular spaces, structure, thickness, chemical composition and permeability of cell walls, and pectin degradation level and turgor pressure within cells based on microanatomy. Four test methods and partial determined results of fruit biomechanics were listed and reviewed. The determined mechanical properties data of fruit are only approximate values by using the existing four test methods, owing to the fruit biomaterials being non-homogeneous and living. Lastly, further aspects for research on fruit biomechanics were proposed for the future.

  1. Research Techniques in Biomechanics.

    Ward, Terry

    Biomechanics involves the biological human beings interacting with his/her mechanical environment. Biomechanics research is being done in connection with sport, physical education, and general motor behavior, and concerns mechanics independent of implements. Biomechanics research falls in the following two general categories: (1) that specific…

  2. Changes in bone microarchitecture and biomechanical properties in the th3 thalassemia mouse are associated with decreased bone turnover and occur during the period of bone accrual.

    Vogiatzi, Maria G; Tsay, Jaime; Verdelis, Kostas; Rivella, Stefano; Grady, Robert W; Doty, Stephen; Giardina, Patricia J; Boskey, Adele L

    2010-06-01

    Osteoporosis and fractures occur frequently in patients with beta-thalassemias, a group of congenital hemolytic anemias characterized by decreased synthesis of the beta chain of hemoglobin. In this study, we determined the bone abnormalities of the th3 thalassemia mouse, generated by deletion of the mouse beta-chain genes. The heterozygous th3/+ mouse has moderate anemia and serves as a model of beta-thalassemia intermedia, which represents the mild thalassemia phenotype. The th3/th3 mouse has lethal anemia and is a model of beta-thalassemia major, which is characterized by life-threatening anemia requiring regular transfusions to sustain life. Compared to controls, (1) microCT of trabecular bone showed decreased bone volume fraction, number of trabeculae, and trabecular thickness in both th3/+ and th3/th3 (P < 0.05); (2) cortical bone analysis showed thinner cortices and increased marrow area in th3/+ (P < 0.05); (3) microCT abnormalities in th3/+ mice were present by 2 months and did not worsen with age; (4) histomorphometry was significant for decreased bone formation and resorption in both th3/+ and th3/th3, and expression of cathepsin K and osteocalcin from bone of both th3/+ and th3/th3 animals was reduced (P < 0.05); (5) biomechanics showed reduced maximum load, maximum moment, and structural stiffness in both th3/+ and th3/th3 (P < 0.01). In conclusion, the th3 mouse model of thalassemia manifests bone changes reminiscent of those in humans and can be used for further bone studies in thalassemia. Bone changes are associated with decreased bone turnover and develop early during the period of bone accrual.

  3. 髌骨骨折内固定板的生物力学性能%Biomechanical properties of internal fixation plate for patellar fracture

    管志海; 王勤业; 王以进; 罗亚平; 常小波; 冯夏莺

    2014-01-01

    背景:目前治疗髌骨骨折的各种手术方法均有优缺点,不能更好地满足患者的需求。  目的:评价髌骨内固定板固定髌骨骨折的生物力学性能,为临床应用提供基础理论依据。  方法:根据国人髌骨数据,采用钛合金制成蜘蛛形内固定板。采集6具新鲜尸体膝关节标本,随机分为两组,制成粉碎性骨折模型,分别采用髌骨内固定板和NiTi聚髌器固定,行生物力学实验,比较两种内固定物的生物力学性能。  结果与结论:两种不同内固定方法均能满足1 kN股四头肌收缩力,髌骨内固定板固定后髌骨的分离位移、肌力和关节力以及髌骨关节接触面力学特征均优于常用聚髌器内固定,统计两者力学指标差异有显著性意义(P OBJECTIVE:To evaluate biomechanical properties of internal fixation plate to treat patel ar fracture and to provide theoretical evidence for clinical application. METHODS:According to the statistics of patel a in the Chinese population, a titanium al oy spider internal fixation plate was designed and manufactured for the treatment of patel ar fractures. Knee joint specimens in six fresh cadavers were randomly divided into two groups and the comminuted fracture model of patel a were established. The models were fixed with internal fixation plate of patel a and NiTi patel ar concentrator. Biomechanical tests were carried out to compare the biomechanical properties. RESULTS AND CONCLUSION:Both the two fixation methods could meet the 1-kN quadriceps femoris contraction. The internal fixation plate of patel a was superior to NiTi patel ar concentrator in the patel ar isolation shift, muscle strength and joint strength, as wel as mechanical properties of patel a-point surface. There were significant differences between the two groups (P<0.05). The internal fixation plate of patel a is designed in accordance with the anatomical and biomechanical properties of the

  4. Research method and progresses of biomechanical properties of human spine%人体脊柱生物力学特性的研究方法及进展

    张恩泽; 廖振华; 刘伟强

    2016-01-01

    背景:随着脊椎融合术和人工椎间盘植入手术的不断发展,近年来研究者们利用各种医疗仪器设备和研究方法,对脊椎的各项特性展开研究。生物力学研究需要更真实的模拟人体生理环境和运动方式。  目的:综述国内外相关文献,从测量主体和测量内容角度总结脊柱生物力学研究方法的优势与不足。  方法:以“biomechanical and (properties or study or evaluation), spinal biomechanics, spine mechanical test, spine and (kinematics or motion)”为英文检索词检索PubMed、Web of Science、Springer数据库,以“生物力学特性,生物力学研究评估,脊柱生物力学,脊柱力学测试,脊柱动力学,脊柱运动”为检索词检索中文期刊全文数据库,纳入脊柱力学、运动学、动力学研究相关文献,主要整理近5年来该领域内的经典文献,排除重复性工作,重点对38篇文献进行分析讨论。  结果与结论:近30年来研究者从多个结构细节对脊柱机械特性展开了研究,仿照人体运动研究了基本工况下脊柱的运动形式,掌握了大量脊柱力学与动力学特性。未来还需要对脊柱特性进行更加深入的了解,如力学方面椎间盘的阻尼特性、运动学方面脊柱的空间耦合运动规律等,才能有助于设计性能更加优良的脊椎病治疗产品,更好地修复脊椎疾病。%BACKGROUND:With the gradual development of spine fusion surgery and artificial disc implant surgery, researchers have studied the characteristics of spine in various ways using many kinds of medical equipment in recent years. Biomechanical studies of more realistic simulation of human physiological environment and human movement are needed. OBJECTIVE:To review domestic and foreign documents and sum up the advantage and disadvantage of spinal biomechanics research methods from the aspects of measurement subjects and measurement methods

  5. FUNDAMENTALS OF BIOMECHANICS

    Duane Knudson

    2007-09-01

    Full Text Available DESCRIPTION This book provides a broad and in-depth theoretical and practical description of the fundamental concepts in understanding biomechanics in the qualitative analysis of human movement. PURPOSE The aim is to bring together up-to-date biomechanical knowledge with expert application knowledge. Extensive referencing for students is also provided. FEATURES This textbook is divided into 12 chapters within four parts, including a lab activities section at the end. The division is as follows: Part 1 Introduction: 1.Introduction to biomechanics of human movement; 2.Fundamentals of biomechanics and qualitative analysis; Part 2 Biological/Structural Bases: 3.Anatomical description and its limitations; 4.Mechanics of the musculoskeletal system; Part 3 Mechanical Bases: 5.Linear and angular kinematics; 6.Linear kinetics; 7.Angular kinetics; 8.Fluid mechanics; Part 4 Application of Biomechanics in Qualitative Analysis :9.Applying biomechanics in physical education; 10.Applying biomechanics in coaching; 11.Applying biomechanics in strength and conditioning; 12.Applying biomechanics in sports medicine and rehabilitation. AUDIENCE This is an important reading for both student and educators in the medicine, sport and exercise-related fields. For the researcher and lecturer it would be a helpful guide to plan and prepare more detailed experimental designs or lecture and/or laboratory classes in exercise and sport biomechanics. ASSESSMENT The text provides a constructive fundamental resource for biomechanics, exercise and sport-related students, teachers and researchers as well as anyone interested in understanding motion. It is also very useful since being clearly written and presenting several ways of examples of the application of biomechanics to help teach and apply biomechanical variables and concepts, including sport-related ones

  6. Construction and biomechanical properties of polyaxial self-locking anatomical plate based on the geometry of distal tibia.

    Liang, Weiguo; Ye, Weixiong; Ye, Dongping; Zhou, Ziqiang; Chen, Zhiguang; Li, Aiguo; Xie, Zong-Han; Zhang, Lihai; Xu, Jiake

    2014-01-01

    In order to provide scientific and empirical evidence for the clinical application of the polyaxial self-locking anatomical plate, 80 human tibias from healthy adults were scanned by spiral CT and their three-dimensional images were reconstructed using the surface shaded display (SSD) method. Firstly, based on the geometric data of distal tibia, a polyaxial self-locking anatomical plate for distal tibia was designed and constructed. Biomechanical tests were then performed by applying axial loading, 4-point bending, and axial torsion loading on the fracture fixation models of fresh cadaver tibias. Our results showed that variation in twisting angles of lateral tibia surface was found in various segments of the distal tibia. The polyaxial self-locking anatomical plate was constructed based on the geometry of the distal tibia. Compared to the conventional anatomical locking plate, the polyaxial self-locking anatomical plate of the distal tibia provides a better fit to the geometry of the distal tibia of the domestic population, and the insertion angle of locking screws can be regulated up to 30°. Collectively, this study assesses the geometry of the distal tibia and provides variable locking screw trajectory to improve screw-plate stability through the design of a polyaxial self-locking anatomical plate.

  7. Biomechanics principles and practices

    Peterson, Donald R

    2014-01-01

    Presents Current Principles and ApplicationsBiomedical engineering is considered to be the most expansive of all the engineering sciences. Its function involves the direct combination of core engineering sciences as well as knowledge of nonengineering disciplines such as biology and medicine. Drawing on material from the biomechanics section of The Biomedical Engineering Handbook, Fourth Edition and utilizing the expert knowledge of respected published scientists in the application and research of biomechanics, Biomechanics: Principles and Practices discusses the latest principles and applicat

  8. Implications of combined ovariectomy and glucocorticoid (dexamethasone) treatment on mineral, microarchitectural, biomechanical and matrix properties of rat bone.

    Govindarajan, Parameswari; Khassawna, Thaqif; Kampschulte, Marian; Böcker, Wolfgang; Huerter, Britta; Dürselen, Lutz; Faulenbach, Miriam; Heiss, Christian

    2013-12-01

    Osteoporosis is one of the deleterious side effects of long-term glucocorticoid therapy. Since the condition is particularly aggressive in postmenopausal women who are on steroid therapy, in this study we have attempted to analyse the combined effect of glucocorticoid (dexamethasone) treatment and cessation of oestrogen on rat bone. The dual aim was to generate osteoporotic bone status in a short time scale and to characterise the combination of glucocorticoid-postmenopausal osteoporotic conditions. Sprague Dawley rats (N = 42) were grouped randomly into three groups: untreated control, sham-operated and ovariectomized-steroid (OVX-Steroid) rats. Control animals were euthanized with no treatment [Month 0 (M0)], while sham and OVX-Steroid rats were monitored up to 1 month (M1) and 3 months (M3) post laparotomy/post OVX-Steroid treatment. Histology, dual-energy X-ray absorptiometry (DXA), micro-computed tomography (micro-CT), and biomechanical and mRNA expression analysis of collagenous, non-collagenous matrix proteins and osteoclast markers were examined. The study indicated enhanced osteoclastogenesis and significantly lower bone mineral density (BMD) in the OVX-Steroid rats with Z-scores below -2.5, reduced torsional strength, reduced bone volume (BV/TV%), significantly enhanced trabecular separation (Tb.S), and less trabecular number (Tb.N) compared with sham rats. Osteoclast markers, cathepsin K and MMP 9 were upregulated along with Col1α1 and biglycan with no significant expression variation in fibronectin, MMP 14, LRP-5, Car II and TNC. These results show higher bone turnover with enhanced bone resorption accompanied with reduced torsional strength in OVX-Steroid rats; and these changes were attained within a short timeframe. This could be a useful model which mimics human postmenopausal osteoporosis that is associated with steroid therapy and could prove of value both in disease diagnosis and for testing generating and testing biological agents which could

  9. Biomechanics of subcellular structures by non-invasive Brillouin microscopy

    Antonacci, Giuseppe; Braakman, Sietse

    2016-11-01

    Cellular biomechanics play a pivotal role in the pathophysiology of several diseases. Unfortunately, current methods to measure biomechanical properties are invasive and mostly limited to the surface of a cell. As a result, the mechanical behaviour of subcellular structures and organelles remains poorly characterised. Here, we show three-dimensional biomechanical images of single cells obtained with non-invasive, non-destructive Brillouin microscopy with an unprecedented spatial resolution. Our results quantify the longitudinal elastic modulus of subcellular structures. In particular, we found the nucleoli to be stiffer than both the nuclear envelope (p biomechanics and its role in pathophysiology.

  10. Changes in the histomorphometric and biomechanical properties of the proximal femur of ovariectomized rat after treatment with the phytoestrogens genistein and equol.

    Tezval, Mohammad; Sehmisch, Stephan; Seidlová-Wuttke, Dana; Rack, Thomas; Kolios, Leila; Wuttke, Wolfgang; Stuermer, Klaus Michael; Stuermer, Ewa Klara

    2010-02-01

    The isoflavonoids found in soy have attracted great interest as dietary phytoestrogens that might be effective for postmenopausal hormone replacement therapy. Special attention has been devoted to the hormonal effects of various isoflavonoids, like genistein (GEN) and daidzein's (DAID) potent metabolite, equol (EQ). Here we aimed to investigate the short-term effects of genistein and equol on the proximal femur of ovariectomized (OVX) rats. Forty-eight, 3-month-old female Sprague-Dawley rats were ovarectomized; after eight weeks the bilateral osteotomy and osteosynthesis (OS) of their tibiae was performed and the rats were randomly divided into the following four groups: OVX control group (C), treated with estradiol-17beta (E2) -benzoate (E; daily intake 0.086 mg/d per animal), genistein (GEN; daily intake 12.7 mg/d per animal) and equol (EQ; daily intake 4.65 mg/d per animal). At 5 weeks postoperatively (OS), the breaking test was performed on the trochanteric region of femur. Additionally, histomorphometric assessment, and trabecular and cortical bone microstructure analyses were performed. The relative gain of body weight (BW) in the EQ (24 %) group was significantly (p max)) and yield load (yL) were higher (p Wi) among the four groups. The treatment with EQ resulted in improved biomechanical and histomorphometric properties as compared to the treatment with GEN. Thus, of the studied substances, EQ seems to be a possible alternative to hormone replacement therapy, but further studies are needed.

  11. Effect of Extension and Type of Composite-Restored Class II Cavities on Biomechanical Properties of Teeth: A Three Dimensional Finite Element Analysis.

    Azam Valian

    2015-04-01

    Full Text Available Controversy exists regarding cavity preparation for restoration of interproximal caries in posterior teeth in terms of preserving the tooth structure and suitable stress distribution. This study aimed to assess the effect of extension and type of class II cavities and the remaining tooth structure in maxillary premolars restored with composite resin on the biomechanical properties of teeth using finite element method (FEM.Using FEM, eight three-dimensional (3D models of class II cavities in maxillary premolars with variable mesiodistal (MD dimensions, variable thickness of the residual wall in-between the mesial and distal cavities and different locations of the wall were designed. Other dimensions were the same in all models. Cavities were restored with composite resin. A load equal to the masticatory force (200N was applied to the teeth. Finite element analysis (FEA was used to calculate the von Mises stress.Stress in the enamel margin increased by increasing the MD dimensions of the cavities. Deviation of the residual wall between the mesial and distal cavities from the tooth center was found to be an important factor in increasing stress concentration in the enamel. Increasing the MD dimensions of the cavity did not cause any increase in stress concentration in dentin.Increasing the MD dimensions of the cavities, decreasing the thickness of the residual wall between the mesial and distal cavities and its deviation from the tooth center can increase stress concentration in the enamel but not in dentin.

  12. 部分腕关节韧带的生物力学特性%Biomechanical properties of partial carpal ligaments

    徐永清; 钟世镇; 赵卫东; 徐达传

    2005-01-01

    背景:以腕关节不稳定为主的腕部疾病正受到手外科医生的重视,但是中国人腕韧带的相关生物力学特性尚待研究.目的:了解部分腕关节韧带生物力学特性,为临床手外科发展提供实验依据.设计:单一样本研究.单位:解放军成都军区昆明总医院骨科,解放军第一军医大学临床解剖学研究所.对象:中国成人新鲜腕关节标本16侧,由第一军医大学解剖教研室提供,在生物力学实验室完成测试.干预:在SWD-10型材料试验机上以5 mm/min的定速率拉伸部分腕关节韧带至韧带断裂,测定腕关节部分韧带生物力学特性.主要观察指标:桡舟韧带、桡舟头韧带、桡月韧带、尺月韧带、尺三角韧带、尺侧囊结构、舟月骨间韧带、月三角骨间韧带断裂时承受的最大拉伸力和刚度.结果:在桡尺骨远端与腕骨连接的韧带中,尺月韧带的最大拉伸力和刚度最大为(219.2±55.4)N和(65.5±19.6)N/mm2,尺三角韧带和尺侧囊结构的最大拉伸力和刚度最小分别为(54.0±25.5)N,(17.8±6.0)N/mm2和(58.7±17.6)N,(13 4±4.7)N/mm2.舟月骨间韧带的最大拉伸力和刚度较大为(286.1±90.8)N,(95.5±40.0)N/mm2,但月三角骨间韧带更大为(375.3±52.6)N,(179.0±39.0)N/mm2.结论:腕关节韧带中近排腕骨间韧带的最大拉伸力和刚度较桡尺骨远端与腕骨连接的韧带大,近排腕骨间韧带中月三角骨间韧带的最大拉伸力和刚度较舟月骨间韧带大,在桡尺骨远端与腕骨连接的韧带中,尺月韧带的最大拉伸力和刚度最大.%BACKGROUND: Although hand urgical doctors have drawn the attentions to carpal diseases mainly manifesting as carpalinstability, it is still expected to carry on the researches on biomechanical properties of Chinese carpal ligaments. OBJECTIVE: To understand the biomechanical properties of partial carpal ligaments so as to provide experimental evidence for the development ofclinical hand surgery. DESIGN: A

  13. Microstructure, mechanical properties and wetting behavior of F: Si–C–N films as bio-mechanical coating grown by DC unbalanced magnetron sputtering

    Shi, Zhifeng, E-mail: scut0533@126.com [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Wang, Yingjun, E-mail: imwangyj@163.com [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Huang, Nan [Key Lab. for Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, 610031 Chengdu (China); Ning, Chengyun; Wang, Lin [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China)

    2013-03-05

    Highlights: ► The F: Si–C–N film coating on Co–Cr alloy as bio-mechanical coating was put forward. ► Significant role of F and C doped on structure and properties in the film was observed. ► The as-deposited F: Si–C–N films are amphipathic nature. ► F: Si–C–N coatings show improvement in the tribological behavior over the uncoated Co–Cr–Mo. ► Compared with Co–Cr alloy, F: Si–C–N films could improve hardness enhances 1.7 times. -- Abstract: A systematic structure and properties investigation on the deposition of fluorinated silicon–carbon–nitride (Si–C–N) films under varying CF{sub 4} flows was carried out by direct current unbalanced magnetron sputtering techniques. Significant role of fluorine and carbon-doped on growth characteristics and mechanical properties in the film was observed. The chemical bonding configurations, surface topography and mechanical properties were characterized by means of X-ray photoelectron spectroscopy (XPS), Raman and infrared spectroscopies, atomic force microscopy (AFM) and nano-indentation technique and CSM pin-on-disk tribometer. It was found that the as-deposited F: Si–C–N films are amphipathic nature, and large variations took place these films’ deposition rate, composition, microstructure and mechanical properties when CF{sub 4} flows varied from 0 to 9 sccm. At CF{sub 4} gas flow rate 9 sccm, the F: Si–C–N coatings demonstrated a fluorine content of 5.95 at.% and a moderate friction coefficient of 0.03. It is obvious from the hardness results that the F: Si–C–N coating enhances the hardness of the Co–Cr–Mo alloy to approximately 16.3 GPa on a smoother surface. The tribological characterization of Co–Cr–Mo alloy with F: Si–C–N coating sliding against ultrahigh molecular weight polyethylene (UHMWPE) counter-surface in fetal bovine serum, shows that the wear resistance of the F: Si–C–N coated Co–Cr–Mo alloy/UHMWPE sliding pair show much obviously

  14. Impact of oral contraceptive use and menstrual phases on patellar tendon morphology, biochemical composition and biomechanical properties in female athletes

    Hansen, Mette; Couppe, Christian; Hansen, Christina S

    2013-01-01

    isometric knee extensor MVC to estimate mechanical tendon properties. Further, tendon cross-sectional area and length were measured from MRI images, and tendon biopsies were obtained for analysis of tendon fibril characteristics and collagen cross-linking. Results: Overall, no difference in tendon...

  15. Keratoconus and Normal-Tension Glaucoma: A Study of the Possible Association with Abnormal Biomechanical Properties as Measured by Corneal Hysteresis (An AOS Thesis)

    Cohen, Elisabeth J.

    2009-01-01

    Purpose: To test the hypothesis that keratoconus and pellucid patients who have glaucoma or are suspected of having glaucoma have lower corneal hysteresis (CH) and/or corneal resistance factor (CRF) measurements compared to controls. Methods: A prospective study at a tertiary eye center of keratoconus and pellucid patients with glaucoma or suspected of having glaucoma, and age-matched keratoconus and pellucid controls, was performed. After informed consent was obtained, corneal topography, ocular response analyzer measurements, pachymetry, intraocular pressure, A-scan measurements, Humphrey visual fields (VFs), and disc photos were done. Analyses compared cases to controls on primary (CH and CRF) and secondary variables. Disc photos and VFs were rated in a masked fashion. Results: The mean CH (8.2, SD=1.6, vs 8.3, SD=1.5) and CRF (7.3, SD=2.0, vs 6.9, SD=2.1) were low and did not differ significantly between 20 study patients (29 eyes) and 40 control patients (61 eyes), respectively. CH had a negative, significant correlation with maximum corneal curvature by topography (P < .002) and positive, significant correlation with central corneal thickness (P < .003). The mean cup-disc ratio was larger among cases than controls (0.54, SD=0.20, vs 0.38, SD=0.20; P = .003). VFs were suggestive of glaucoma more often among the study eyes than controls (11 of 29, 37.9%, vs 8 of 60, 13.3%; P =.019). Conclusions: CH was low in study and control patients and was correlated with severity of keratoconus/pellucid, but not with glaucoma/suspected glaucoma or control status. Evidence of glaucoma was more common in study eyes than controls, but was present in both. PMID:20126503

  16. Biomechanics of the brain

    Miller, Karol

    2011-01-01

    With contributions from scientists at major institutions, this book presents an introduction to brain anatomy for engineers and scientists. It provides, for the first time, a comprehensive resource in the field of brain biomechanics.

  17. Computational modeling in biomechanics

    Mofrad, Mohammad

    2010-01-01

    This book provides a glimpse of the diverse and important roles that modern computational technology is playing in various areas of biomechanics. It includes unique chapters on ab initio quantum mechanical, molecular dynamic and scale coupling methods..

  18. Biomechanically Engineered Athletes.

    Perry, Tekla S.

    1991-01-01

    The real-world meeting of electronics, computer monitoring, control systems, and mathematics, introduced in the context of sports, is described. Recent advances in the field of biomechanics and its use in improving athletic performance are discussed. (KR)

  19. Muscle-skeletal model of the thigh: a tool for understanding the biomechanics of gait in patients with cerebral palsy

    Ravera, Emiliano Pablo; Catalfamo Formento, Paola Andrea; José Crespo, Marcos; Andrés Braidot, Ariel

    2011-12-01

    Cerebral Palsy represents the most common cause of physical disability in modern world and within the pediatrics orthopedics units. The gait analysis provides great contributions to the understanding of gait disorders in CP. Giving a more comprehensive treatment plan, including or excluding surgical procedures that can potentially decrease the number of surgical interventions in the life of these patients. Recommendations for orthopedic surgery may be based on a quantitative description of how to alter the properties probably muscle force generation, and how this affects the action of the muscle to determine how these muscles, impaired by disease or surgery, contributing to the movement of the segments of the limb during crouch gait. So the causes and appropriate treatment of gait abnormalities are difficult to determine because the movements generated by the muscular forces of these patients are not clearly understood. A correct determination of the etiology of abnormal patterns of the knee is the key to select the appropriate therapy, presenting a major challenge at present since there is no theoretical basis to determine the biomechanical causes of abnormal gait of these patients. The potential and necessity of using correct biomechanical models that consistently study the abnormalities becomes clear. Reinforcing and correcting a simple gait analysis and eliminating the unknowns when selecting the appropriate treatment is crucial in clinical settings. In this paper a computer muscle-skeletal model is proposed. The model represents a person's thigh simulating the six most representative muscles and joints of the hip and knee. In this way you can have a better understanding of gait abnormalities present in these patients. So the quality of these estimates of individual muscle dynamics facilitate better understanding of the biomechanics of gait pathologies helping to reach better diagnosis prior to surgery and rehabilitation treatments.

  20. Fundamentals of Biomechanics

    Duane Knudson

    2007-01-01

    DESCRIPTION This book provides a broad and in-depth theoretical and practical description of the fundamental concepts in understanding biomechanics in the qualitative analysis of human movement. PURPOSE The aim is to bring together up-to-date biomechanical knowledge with expert application knowledge. Extensive referencing for students is also provided. FEATURES This textbook is divided into 12 chapters within four parts, including a lab activities section at the end. The division is as follow...

  1. 牛肌腱冻干脱细胞支架的生物力学特性%Biomechanical properties of a decellularized scaffold of lyophilized bovine tendon

    钱闯; 陈雄生; 周盛源; 朱巍

    2015-01-01

    背景:目前的脱细胞方法在去除细胞的同时对细胞外基质存在一定的损伤,降低了脱细胞支架的生物力学性能.目的:分析冻干牛肌腱脱细胞支架的生物力学特性.方法:取新鲜小牛趾伸屈肌腱,去除小牛肌腱表面的滑膜、腱膜及软组织,双蒸水冲洗干净后低压冻干,通过物理方法制备肌腱纤维束60个,随机均分为两组,实验组于无菌操作下置入丝氨酸蛋白酶抑制剂,室温下持续24 h,无菌PBS冲洗后,再移入低浓度胰酶+乙醇混合溶液中,在不破坏细胞外基质的情况下去除细胞壁,室温下持续5 h,再将纤维束移入脱氧核糖核酸酶溶液中持续5 h,最后将已完成脱细胞步骤的支架使用PBS冲洗48 h,无菌室内室温下干燥;对照组不做处置.检测两组材料的弹性模量、耐久性及最大应力.结果与结论:两组耐久性相似,但实验组在相同位移处的应力小于对照组;两组弹性模量比较差异无显著性意义,但实验组最大应力低于对照组(P < 0.01).说明冻干脱细胞支架能够在一定程度上模仿牛肌腱的生物力学功能.%BACKGROUND:Current decelularized methods have the certain damage to the extracelular matrix and reduce the biomechanical properties of acelular scaffolds. OBJECTIVE:To explore the biomechanical properties of decelularized scaffold of lyophilized bovine tendon. METHODS:Sixty lyophilized fiber bundles from fresh flexion tendon of calf toes were randomly divided into two groups: control group and experimental group. In the experimental group, serine protease inhibitors were placed asepticaly for 24 hours at room temperature, then the samples were rinsed with PBS and transferred to the low concentration of trypsin+ethanol mixed solution to remove the cel wal without destruction of the extracelular matrix at room temperature for 5 hours; after that, the fiber bundles were cultured in DNA enzyme solution for 5 hours, finaly the acelular scaffold was

  2. Differential effects of IGF-1 deficiency during the life span on structural and biomechanical properties in the tibia of aged mice.

    Ashpole, Nicole M; Herron, Jacquelyn C; Estep, Patrick N; Logan, Sreemathi; Hodges, Erik L; Yabluchanskiy, Andriy; Humphrey, Mary Beth; Sonntag, William E

    2016-04-01

    Advanced aging is associated with the loss of structural and biomechanical properties in bones, which increases the risk for bone fracture. Aging is also associated with reductions in circulating levels of the anabolic signaling hormone, insulin-like growth factor (IGF)-1. While the role of IGF-1 in bone development has been well characterized, the impact of the age-related loss of IGF-1 on bone aging remains controversial. Here, we describe the effects of reducing IGF-1 at multiple time points in the mouse life span--early in postnatal development, early adulthood, or late adulthood on tibia bone aging in both male and female igf (f/f) mice. Bone structure was analyzed at 27 months of age using microCT. We find that age-related reductions in cortical bone fraction, cortical thickness, and tissue mineral density were more pronounced when IGF-1 was reduced early in life and not in late adulthood. Three-point bone bending assays revealed that IGF-1 deficiency early in life resulted in reduced maximum force, maximum bending moment, and bone stiffness in aged males and females. The effects of IGF-1 on bone aging are microenvironment specific, as early-life loss of IGF-1 resulted in decreased cortical bone structure and strength along the diaphysis while significantly increasing trabecular bone fraction and trabecular number at the proximal metaphysis. The increases in trabecular bone were limited to males, as early-life loss of IGF-1 did not alter bone fraction or number in females. Together, our data suggest that the age-related loss of IGF-1 influences tibia bone aging in a sex-specific, microenvironment-specific, and time-dependent manner.

  3. The impact of chronic use of prostaglandin analogues on the biomechanical properties of the cornea in patients with primary open-angle glaucoma

    Meda, Roman; Wang, Qianqian; Paoloni, David; Harasymowycz, Paul; Brunette, Isabelle

    2017-01-01

    Aims To determine the influence of prostaglandin analogues (PGAs) on corneal biomechanical properties in patients undergoing chronic treatment for primary open-angle glaucoma (POAG). Methods Prospective, interventional case–control study. 70 eyes from 35 patients with POAG on chronic PGA therapy were recruited. One eye per patient underwent PGA cessation for 6 weeks while the contralateral eye continued to receive the treatment. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOP) (IOPcc), central corneal thickness (CCT) and Goldmann tonometry (Haag-Streit AG, Koeniz, Switzerland) IOP (IOPGAT) were measured at baseline (visit 1), 6 weeks after PGA cessation (visit 2) and 6 weeks after PGAs reinitiation (visit 3) and were analysed using a linear mixed-effect model. The discrepancy between IOPcc and IOPGAT was defined as IOP bias (IOPcc—IOPGAT). Results Baseline characteristics were comparable between the two groups. In the study eyes, significant increases (p<0.0001) were detected at visit 2 in CH (9.0±1.8 vs 10.3±1.7 mm Hg), CRF (10.5±2.1 vs 11.7±2.1 mm Hg), CCT (541.8±43.2 vs 551.9±41.9 μm) and IOPGAT (15.4±3.0 vs 18.4±3.8 mm Hg). IOP bias in this group was significantly lowered at visit 2 (p<0.0001). These effects were reversed at visit 3. The control eyes did not demonstrate any significant changes over the study period. Conclusion Topical PGAs induce reversible reduction in CH, CRF and CCT in patients with POAG. These changes contribute to underestimation of the IOP measured by Goldmann applanation tonometry and warrant caution when assessing response to treatment. Trial registration number NCT02388360, Results. PMID:27162226

  4. Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

    Esteban Pérez-Pevida; Aritza Brizuela-Velasco; David Chávarri-Prado; Antonio Jiménez-Garrudo; Fernando Sánchez-Lasheras; Eneko Solaberrieta-Méndez; Markel Diéguez-Pereira; Fernández-González, Felipe J.; Borja Dehesa-Ibarra; Francesca Monticelli

    2016-01-01

    The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conv...

  5. Plant Fibre: Molecular Structure and Biomechanical Properties, of a Complex Living Material, Influencing Its Deconstruction towards a Biobased Composite

    Mathias Sorieul

    2016-07-01

    Full Text Available Plant cell walls form an organic complex composite material that fulfils various functions. The hierarchical structure of this material is generated from the integration of its elementary components. This review provides an overview of wood as a composite material followed by its deconstruction into fibres that can then be incorporated into biobased composites. Firstly, the fibres are defined, and their various origins are discussed. Then, the organisation of cell walls and their components are described. The emphasis is on the molecular interactions of the cellulose microfibrils, lignin and hemicelluloses in planta. Hemicelluloses of diverse species and cell walls are described. Details of their organisation in the primary cell wall are provided, as understanding of the role of hemicellulose has recently evolved and is likely to affect our perception and future study of their secondary cell wall homologs. The importance of the presence of water on wood mechanical properties is also discussed. These sections provide the basis for understanding the molecular arrangements and interactions of the components and how they influence changes in fibre properties once isolated. A range of pulping processes can be used to individualise wood fibres, but these can cause damage to the fibres. Therefore, issues relating to fibre production are discussed along with the dispersion of wood fibres during extrusion. The final section explores various ways to improve fibres obtained from wood.

  6. Exploring the biomechanical properties of brain malignancies and their pathologic determinants in vivo with magnetic resonance elastography.

    Jamin, Yann; Boult, Jessica K R; Li, Jin; Popov, Sergey; Garteiser, Philippe; Ulloa, Jose L; Cummings, Craig; Box, Gary; Eccles, Suzanne A; Jones, Chris; Waterton, John C; Bamber, Jeffrey C; Sinkus, Ralph; Robinson, Simon P

    2015-04-01

    Malignant tumors are typically associated with altered rigidity relative to normal host tissue. Magnetic resonance elastography (MRE) enables the noninvasive quantitation of the mechanical properties of deep-seated tissue following application of an external vibrational mechanical stress to that tissue. In this preclinical study, we used MRE to quantify (kPa) the elasticity modulus Gd and viscosity modulus Gl of three intracranially implanted glioma and breast metastatic tumor models. In all these brain tumors, we found a notable softness characterized by lower elasticity and viscosity than normal brain parenchyma, enabling their detection on Gd and Gl parametric maps. The most circumscribed tumor (U-87 MG glioma) was the stiffest, whereas the most infiltrative tumor (MDA-MB-231 metastatic breast carcinoma) was the softest. Tumor cell density and microvessel density correlated significantly and positively with elasticity and viscosity, whereas there was no association with the extent of collagen deposition or myelin fiber entrapment. In conclusion, although malignant tumors tend to exhibit increased rigidity, intracranial tumors presented as remarkably softer than normal brain parenchyma. Our findings reinforce the case for MRE use in diagnosing and staging brain malignancies, based on the association of different tumor phenotypes with different mechanical properties.

  7. Carrier trapping induced abnormal temperature dependent photoluminescence properties of novel sandwiched structure InGaN quantum wells

    He, Juan; Li, Ding; Rajabi, K.; Yang, Wei; Hu, Xiaodong [State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Liu, Lei [Suzhou Institute of Nano-tech and Nano-bionics, CAS, Suzhou 215125 (China)

    2014-04-15

    A dual-wavelength LED sample with novel sandwiched structure in high-In-content MQWs is studied by temperature dependent photoluminescence (TDPL) and the abnormal temperature dependence of emission intensity is obtained. The novel MQWs structure which contains staggered quantum wells and an ultra-thin InN interlayer in the wells shows better luminescence property than the reference sample which has conventional quantum wells. Under 325 nm continuous wave laser excitation the LED sample of novel structure exhibits unexpected increasing luminescence intensity as temperature goes up from 140 K to 220 K and reaches its maximum at 220 K. This could be attributed to (1) the carrier redistribution and the novel sandwiched MQWs' high carrier trapping capability; (2) the intrinsic emission property of the MQWs enhanced by improvement of electron-hole overlap and reduction of quantum confined Stark effect (QCSE) and compositional fluctuation. TDPL under 405 nm laser excitation is also measured to support this view. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis.

    Pérez-Pevida, Esteban; Brizuela-Velasco, Aritza; Chávarri-Prado, David; Jiménez-Garrudo, Antonio; Sánchez-Lasheras, Fernando; Solaberrieta-Méndez, Eneko; Diéguez-Pereira, Markel; Fernández-González, Felipe J; Dehesa-Ibarra, Borja; Monticelli, Francesca

    2016-01-01

    The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone.

  9. Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

    Esteban Pérez-Pevida

    2016-01-01

    Full Text Available The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP, conventional (Ti-6Al-4V, and hyperelastic (Ti-Nb-Zr. A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone.

  10. Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

    Chávarri-Prado, David; Jiménez-Garrudo, Antonio; Solaberrieta-Méndez, Eneko; Diéguez-Pereira, Markel; Fernández-González, Felipe J.; Dehesa-Ibarra, Borja; Monticelli, Francesca

    2016-01-01

    The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone. PMID:27995137

  11. Corneal biomechanics: a review.

    Piñero, David P; Alcón, Natividad

    2015-03-01

    Biomechanics is often defined as 'mechanics applied to biology'. Due to the variety and complexity of the behaviour of biological structures and materials, biomechanics is better defined as the development, extension and application of mechanics for a better understanding of physiology and physiopathology and consequently for a better diagnosis and treatment of disease and injury. Different methods for the characterisation of corneal biomechanics are reviewed in detail, including those that are currently commercially available (Ocular Response Analyzer and CorVis ST). The clinical applicability of the parameters provided by these devices are discussed, especially in the fields of glaucoma, detection of ectatic disorders and orthokeratology. Likewise, other methods are also reviewed, such as Brillouin microscopy or dynamic optical coherence tomography and others with potential application to clinical practice but not validated for in vivo measurements, such as ultrasonic elastography. Advantages and disadvantages of all these techniques are described. Finally, the concept of biomechanical modelling is revised as well as the requirements for developing biomechanical models, with special emphasis on finite element modelling.

  12. Gingival Recessions and Biomechanics

    Laursen, Morten Godtfredsen

    Gingival recessions and biomechanics “Tissue is the issue, but bone sets the tone.“ A tooth outside the cortical plate can result in loss of bone and development of a gingival recession. The presentation aims to show biomechanical considerations in relation to movement of teeth with gingival...... recessions. Gingival recession is a problem often in the region of the lower incisors. A micro-CT study on human autopsy material, performed at the University of Aarhus, confirmed that the anterior mandibular alveolar envelope is indeed very thin. The prognosis of a gingival recession can be improved...

  13. Meiotic abnormalities

    NONE

    1993-12-31

    Chapter 19, describes meiotic abnormalities. These include nondisjunction of autosomes and sex chromosomes, genetic and environmental causes of nondisjunction, misdivision of the centromere, chromosomally abnormal human sperm, male infertility, parental age, and origin of diploid gametes. 57 refs., 2 figs., 1 tab.

  14. Waves and high nutrient loads jointly decrease survival and separately affect morphological and biomechanical properties in the seagrass Zostera noltii

    La Nafie, Y.A.; de los Santos, C.B.; Brun, F.G.; van Katwijk, M.M.; Bouma, T.J.

    2012-01-01

    In an 8-week aquarium experiment, we investigated the interactive effects of waves (present vs. absent) and water-column nutrient level (high vs. low) on the survival, growth, morphology, and biomechanics of the seagrass, Zostera noltii. Survival was reduced when plants were exposed to both waves and high nutrient levels. Wave and nutrient interaction significantly reduced aboveground biomass and leaf lengths, whereas waves independently reduced growth rate, internode abundance, elongation, a...

  15. Mathematical foundations of biomechanics.

    Niederer, Peter F

    2010-01-01

    The aim of biomechanics is the analysis of the structure and function of humans, animals, and plants by means of the methods of mechanics. Its foundations are in particular embedded in mathematics, physics, and informatics. Due to the inherent multidisciplinary character deriving from its aim, biomechanics has numerous connections and overlapping areas with biology, biochemistry, physiology, and pathophysiology, along with clinical medicine, so its range is enormously wide. This treatise is mainly meant to serve as an introduction and overview for readers and students who intend to acquire a basic understanding of the mathematical principles and mechanics that constitute the foundation of biomechanics; accordingly, its contents are limited to basic theoretical principles of general validity and long-range significance. Selected examples are included that are representative for the problems treated in biomechanics. Although ultimate mathematical generality is not in the foreground, an attempt is made to derive the theory from basic principles. A concise and systematic formulation is thereby intended with the aim that the reader is provided with a working knowledge. It is assumed that he or she is familiar with the principles of calculus, vector analysis, and linear algebra.

  16. ANALISIS ABNORMAL RETURN SAHAMSEBELUM DAN SESUDAH PENGUMUMAN PERATURAN LOAN TO VALUE KPR(Studi Pada Perusahaan Properti Di Bursa Efek Indonesia

    Dwi Suharyanto

    2016-04-01

    Full Text Available This study aims to analyze the abnormal stock return of property companies in Indonesia Stock Exchange as a result of the announcement of Bank Indonesia on  the  restriction  of  the  maximum  Loan  to  Value  (LTV  of  the  mortgage loans.  This  study  uses  event  study,  which  observed  the  average  abnormal return over the 10 days prior to the announcement up to 10 days thereafter. The  results  showed  that  there  was  no  signifi cant  difference  between  the abnormal  returns  before  and  after  the  announcement.  However,  there  is  an increase  in  the  number  of  days  that  experienced  abnormal  returns,  ie  2 (two  days  in  the  period before the announcement of a 5 (fi ve days in the period thereafter. While at the moment of announcement there is no abnormal return. This suggests that the effect of the  announcement  was  not  immediately responded by the market, but there is a lag time for the market to react. These conditions may be caused investors do not have the experience to identify and measure the impact of LTV mortgage regulation. Signifi cant  abnormal  return occurs also varies, which is experiencing abnormal gain 3 days and 4 days of having abnormal loss, which shows the confusion in the market so it happened a few times stock price correction. Another possibility for the market considers these policies also have a positive side. Properties company performance may be declining, but the industry would likely have a positive impact in the long run because it will reduce the risk of price bubbles. Keyword : Abnormal Return, Event Study, Mortgage Loan, Loan to Value.

  17. Evaluation of a minimally invasive procedure for sacroiliac joint fusion – an in vitro biomechanical analysis of initial and cycled properties

    Lindsey DP

    2014-05-01

    Full Text Available Derek P Lindsey,1 Luis Perez-Orribo,2 Nestor Rodriguez-Martinez,2 Phillip M Reyes,2 Anna Newcomb,2 Alexandria Cable,2 Grace Hickam,2 Scott A Yerby,1 Neil R Crawford21SI-BONE, Inc., San Jose, CA, USA; 2Spinal Biomechanics Research Laboratory, Barrow Neurological Institute, St Joseph's Hospital and Medical Center, Phoenix, AZ, USAIntroduction: Sacroiliac (SI joint pain has become a recognized factor in low back pain. The purpose of this study was to investigate the effect of a minimally invasive surgical SI joint fusion procedure on the in vitro biomechanics of the SI joint before and after cyclic loading.Methods: Seven cadaveric specimens were tested under the following conditions: intact, posterior ligaments (PL and pubic symphysis (PS cut, treated (three implants placed, and after 5,000 cycles of flexion–extension. The range of motion (ROM in flexion–extension, lateral bending, and axial rotation was determined with an applied 7.5 N • m moment using an optoelectronic system. Results for each ROM were compared using a repeated measures analysis of variance (ANOVA with a Holm–Šidák post-hoc test.Results: Placement of three fusion devices decreased the flexion–extension ROM. Lateral bending and axial rotation were not significantly altered. All PL/PS cut and post-cyclic ROMs were larger than in the intact condition. The 5,000 cycles of flexion–extension did not lead to a significant increase in any ROMs.Discussion: In the current model, placement of three 7.0 mm iFuse Implants significantly decreased the flexion–extension ROM. Joint ROM was not increased by 5,000 flexion–extension cycles.Keywords: biomechanics, iliosacral, arthrodesis, cadaver

  18. Biomechanics of Rowing

    Hase, Kazunori; Kaya, Motoshi; Yamazaki, Nobutoshi; Andrews, Brian J.; Zavatsky, Amy B.; Halliday, Suzanne E.

    Compared with the other exercise, such as walking and cycling, rowing was expected to have some fitness advantage, while there were some misgivings about the risk of injury. The objectives of this study were to quantify biomechanical characteristics of rowing for fitness and rehabilitation and to offer normative data for the prevention of injury and for determining effective exercise. An experiment was performed to collect the kinematic and kinetic data during rowing by experienced and non-experienced subjects. A three-dimensional whole-body musculo-skeletal model was used to calculate the biomechanical loads, such as the joint moments, the muscular tensions, the joint contact forces and the energy consumption. The results of this study indicate that rowing is an effective exercise for rehabilitation and fitness. However, the non-experienced rower should acquire considerable skill to obtain sufficient exercise. The rowing cadence should be decided according to the purpose of the exercise.

  19. Abnormal sodium current properties contribute to cardiac electrical and contractile dysfunction in a mouse model of myotonic dystrophy type 1.

    Algalarrondo, Vincent; Wahbi, Karim; Sebag, Frédéric; Gourdon, Geneviève; Beldjord, Chérif; Azibi, Kamel; Balse, Elise; Coulombe, Alain; Fischmeister, Rodolphe; Eymard, Bruno; Duboc, Denis; Hatem, Stéphane N

    2015-04-01

    Myotonic dystrophy type 1 (DM1) is the most common neuromuscular disorder and is associated with cardiac conduction defects. However, the mechanisms of cardiac arrhythmias in DM1 are unknown. We tested the hypothesis that abnormalities in the cardiac sodium current (INa) are involved, and used a transgenic mouse model reproducing the expression of triplet expansion observed in DM1 (DMSXL mouse). The injection of the class-I antiarrhythmic agent flecainide induced prominent conduction abnormalities and significantly lowered the radial tissular velocities and strain rate in DMSXL mice compared to WT. These abnormalities were more pronounced in 8-month-old mice than in 3-month-old mice. Ventricular action potentials recorded by standard glass microelectrode technique exhibited a lower maximum upstroke velocity [dV/dt](max) in DMSXL. This decreased [dV/dt](max) was associated with a 1.7 fold faster inactivation of INa in DMSXL myocytes measured by the whole-cell patch-clamp technique. Finally in the DMSXL mouse, no mutation in the Scn5a gene was detected and neither cardiac fibrosis nor abnormalities of expression of the sodium channel protein were observed. Therefore, alterations in the sodium current markedly contributed to electrical conduction block in DM1. This result should guide pharmaceutical and clinical research toward better therapy for the cardiac arrhythmias associated with DM1.

  20. Morphology and biomechanics of human heart

    Chelnokova, Natalia O.; Golyadkina, Anastasiya A.; Kirillova, Irina V.; Polienko, Asel V.; Ivanov, Dmitry V.

    2016-03-01

    Object of study: A study of the biomechanical characteristics of the human heart ventricles was performed. 80 hearts were extracted during autopsy of 80 corpses of adults (40 women and 40 men) aged 31-70 years. The samples were investigated in compliance with the recommendations of the ethics committee. Methods: Tension and compression tests were performed with help of the uniaxial testing machine Instron 5944. Cardiometry was also performed. Results: In this work, techniques for human heart ventricle wall biomechanical properties estimation were developed. Regularities of age and gender variability in deformative and strength properties of the right and left ventricle walls were found. These properties were characterized by a smooth growth of myocardial tissue stiffness and resistivity at a relatively low strain against reduction in their strength and elasticity from 31-40 to 61-70 years. It was found that tissue of the left ventricle at 61-70 years had a lower stretchability and strength compared with tissues of the right ventricle and septum. These data expands understanding of the morphological organization of the heart ventricles, which is very important for the development of personalized medicine. Taking into account individual, age and gender differences of the heart ventricle tissue biomechanical characteristics allows to rationally choosing the type of patching materials during reconstructive operations on heart.

  1. Effect of knee physiological anatomy environment on knee biomechanical properties%膝关节生理解剖环境对膝关节生物力学特性的影响

    张美娟

    2012-01-01

    背景:了解膝关节的生物力学特点对理解人工膝关节假体的设计原理和手术操作原则是至关重要的.目的:分析膝关节周围的力学环境及与膝关节生物力学的关系,进一步探索膝关节的稳定性及损伤机制.方法:应用计算机检索CNKI和PubMed数据库中1998-01/2011-08关于膝关节生物力学方面的文章,在标题和摘要中以"膝关节,韧带,半月板,关节软骨,生物力学"或"knee joints,ligament,meniscus,cartilage,biomechanical"为检索词进行检索.选择文章内容与膝关节生物力学有关者,同一领域文献则选择近期发表或发表在权威杂志文章.初检得到163篇文献,根据纳入标准选择关于膝关节损伤生物力学特性方面的25篇文献进行综述.结果与结论:膝关节的稳定除了依赖膝关节骨以外,还以依赖前后交叉韧带的制约、内外副韧带的平衡、以及伸膝装置与股四头肌及腘绳肌的力量均衡,尤其是内外侧副韧带的平衡和稳定作用.说明膝关节的解剖环境决定了膝关节在负荷、运动及稳定等生物力学特性上的复杂性,因此,了解膝关节生理结构和解剖特点有利于掌握膝关节的生物力学特点,因此此方面的研究对膝关节疼痛、损伤及组织工程研究至关重要.%BACKGROUND: The understanding of the knee biomechanical properties is critical to understand the design and operative principles of the knee prosthesis.OBJECTIVE: To summarize the relationship between peripheral mechanics environment and biomechanics of the knee joint, and to investigate the stability and injury mechanism of the knee joint.METHODS: The CNKI database and PubMed database (1998-01/2011-08) were used to search the related articles about biomechanics of the knee joint. The keywords of “knee joints, ligament, meniscus, cartilage, biomechanical” in English and Chinese were put into the title and the abstract to search the articles. The articles that related to

  2. Leukocyte abnormalities.

    Gabig, T G

    1980-07-01

    Certain qualitative abnormalities in neutrophils and blood monocytes are associated with frequent, severe, and recurrent bacterial infections leading to fatal sepsis, while other qualitative defects demonstrated in vitro may have few or no clinical sequelae. These qualitative defects are discussed in terms of the specific functions of locomotion, phagocytosis, degranulation, and bacterial killing.

  3. Changes in bone micro-architecture and biomechanical properties in the th3 thalassemia mouse are associated with decreased bone turnover and occur during the period of bone accrual

    Vogiatzi, Maria G.; Tsay, Jaime; Verdelis, Kostas; Rivella, Stefano; Grady, Robert W; Doty, Stephen; Giardina, Patricia J; Boskey, Adele L

    2010-01-01

    Osteoporosis and fractures occur frequently in patients with beta thalassemias, a group of congenital hemolytic anemias characterized by decreased synthesis of the beta chain of hemoglobin. In this study, we determined the bone abnormalities of the th3 thalassemia mouse, generated by deletion of the mouse beta chain genes. The heterozygote th3/+ mouse has moderate anemia, and serves as a model of beta thalassemia intermedia (TI), which represents the mild thalassemia phenotype. The th3/th3 mouse has lethal anemia and is a model of beta thalassemia major (TM), which is characterized by life-threatening anemia requiring regular transfusions to sustain life. Compared to controls: i) Micro-CT of trabecular bone showed decreased bone volume fraction, number of trabeculae and trabecular thickness in both th3/+ and th3/th3 (p<0.05). ii) Cortical bone analysis showed thinner cortices and increased marrow area in th3/+ animals (p<0.05). iii) Micro-CT abnormalities in th3/+ mice were present by 2 months and did not worsen with age. iv) Histomorphometry was significant for decreased bone formation and resorption in both th3/+ and th3/th3. Similarly, cathepsin K and osteocalcin expression from bone of both th3/+and th3/th3 animals was reduced (p<0.05). vi) Biomechanics showed reduced maximum load, maximum moment and structural stiffness in both th3/+and th3/th3 (p<0.01). In conclusion, the th3 mouse model of thalassemia manifests bone changes reminiscent of those in humans, and can be used for further bone studies in thalassemia. Bone changes are associated with decreased bone turnover, and develop early on during the period of bone accrual. PMID:20449578

  4. Research on the biomechanical properties of spine based on the 3D finite demem model%基于三维有限元模型的脊柱生物力学特性研究进展

    李芳燕; 黄永锋

    2008-01-01

    脊柱相关疾病研究是一门新兴的边缘学科,其研究重点即为脊柱的生物力学特性.综合分析了基于三维有限元模型的腰椎和颈椎生物力学特性研究方法;总结出有限元建模的三种方法,即几何建模法、三维坐标仪建模法以及图像建模法;提炼出图像建模法的关键步骤,即几何模型的建立、椎骨和软组织的材料特性定义、边界条件定义以及模型验证分析;最后提出有限元建模的两个主要改进方面及其研究趋势.%The research of spine related disease is an emerging interdisciplinary subject and the key point is the spinal biomechanical properties.In this paper,the method of studying biomechanical properties of lumhar and cervical vertebra based on 3D finite element model is analyzed.Three kinds of method in building finite element model are specified:geometric modeling method,3D coordinatngraphic modeling method and image modeling method.The three key steps of image modeling method for building of basic geometric model are extracted as defining material behavior of vertebra and soft tissue,defining boundary condition,and confirming of the model.Then two principal improving aspects of building finite element model and the foreground of the research are discussed.

  5. [Biomechanical properties of the cribriform lamina in glaucoma-induced atrophy of the optic nerve and after decompression operations on the scleral canal].

    Mostovoĭ, E N; Shmyreva, V F; Kaĭdalov, A B

    2008-01-01

    The authors made a mathematical and clinical analysis of the cribriform lamina (CL) of the optic nerve and nerve fiber bundles passing through its foramens in glaucoma-induced optic neuropathy. It was shown that in elevated intraocular pressure, there was a significant CL deformity leading to the compression and deformity of nerve fibers. The important biomechanical characteristic of CL deformity is the tangent of the angle between the longitudinal axis of the scleral canal and the perpendicular to the CL surface. An increase in the inner radius of the scleral canal of the optic nerve due to its dissection at decompression surgery is one of the ways of diminishing CL flexure and nerve fiber deformity. A small increase in the scleral canal radius (by approximately 10%) was demonstrated to eliminate significant CL flexure.

  6. Biomedical Imaging and Computational Modeling in Biomechanics

    Iacoviello, Daniela

    2013-01-01

    This book collects the state-of-art and new trends in image analysis and biomechanics. It covers a wide field of scientific and cultural topics, ranging from remodeling of bone tissue under the mechanical stimulus up to optimizing the performance of sports equipment, through the patient-specific modeling in orthopedics, microtomography and its application in oral and implant research, computational modeling in the field of hip prostheses, image based model development and analysis of the human knee joint, kinematics of the hip joint, micro-scale analysis of compositional and mechanical properties of dentin, automated techniques for cervical cell image analysis, and iomedical imaging and computational modeling in cardiovascular disease.   The book will be of interest to researchers, Ph.D students, and graduate students with multidisciplinary interests related to image analysis and understanding, medical imaging, biomechanics, simulation and modeling, experimental analysis.

  7. Biomechanics of the Gastrointestinal Tract in Health and Disease

    Zhao, Jingbo; Liao, Donghua; Gregersen, Hans

    2010-01-01

    . The biomechanical properties are crucial for GI motor function because peristaltic motion that propels the food through the GI tract is a result of interaction of the passive and active tissue forces and the hydrodynamic forces in the food bolus and remodeling of the mechanical properties reflects the changes...

  8. Formation of abnormal high pressure and its application in the study of oil-bearing property of lithologic hydrocarbon reservoirs in the Dongying Sag

    ZHANG ShanWen; ZHANG LinYe; ZHANG ShouChun; LIU Qing; ZHU RiFang; BAO YouShu

    2009-01-01

    The mechanisms of abnormal high pressures are studied in this paper, and it is concluded that the undercompaction, hydrocarbon generation and stratum denudation are obviously effective to fluid pressure buildup. Because of the episodic difference, the hydrocarbon generation and stratum denu-dation are the main factors influencing oil-gas migration. On the basis of basin evolutionary analysis in the Dongying Sag, it is considered that the undercompaction mainly caused the abnormal pressure before the first denudation by the uplift in Late Paleogene, while hydrocarbon generation was the main factor of abnormal pressure after the denudation. The second denudation occurred in Late Neogene, which changed the pressure field and induced the fluid migration. The development of overpressures is the necessary condition to the formation of lithologic hydrocarbon reservoirs, which have positive correlations to overpressures. According to the fullness of the present reservoirs, the quantitative re-lations between oil-bearing property and driving forces of reservoir formation were determined, the latter were decided by dynamic source, reservoir capillary pressure, fluid pressure of surrounding rocks and the dynamic attenuation in different conducting systems.

  9. Minicomputer For Biomechanical Research

    Shierman, Gail; Rhymes, Tom

    1982-02-01

    The increased capabilities of minicomputers today allows a biomechanics laboratory to establish a self-contained computer system for a reasonable price. The system includes a microprocessor, a printer and a CRT. Analog to digital conversion is an important feature to consider as well as the ability to interface with a mainframe computer. A minicomputer adapted for film analysis should be a consideration for data analysis when developing a cinematography laboratory. For the past 10-15 years the area of biomechanics has enjoyed the advances in technology. Equipment and instrumentation once used exclusively by engineers and physicists have become readily available to those involved with snorts analyses. Among the various pieces of equipment accessible to biomechanists today, probably the most important one is the computer. At this time several biomechanics laboratories are using the computer to analyze kinematic and kinetic data obtained from film. The computer in use at each school is generally the main University or College computer with a remote terminal set-up in the biomechanics laboratory. This system functions well if there is adequate response from the time-sharing system of the main computer, and if there is at least one knowledgeable technician available. With the trend toward minicomputers today, their increased capabilities, and their ease of use, a self-contained minicomputer system in the biomechanics laboratory appears to be a viable alternative. The computer system in use in the ,Biomechanics Laboratory at the University of Oklahoma is based around the Cromemco Z2D computer connected to a PCD motion analyzer (Figure 1). The data acquisition system consists of the eight-bit microprocessor-based minicomputer connected to an analog to digital converter (ADC). As a terminal for the computer, we have either a video display unit or a Model 43 Teletype. The Model 43 provides a hard copy out-put while the video terminal provides much faster I/O, useful for

  10. The Contributions of the Amino and Carboxy Terminal Domains of Flightin to the Biomechanical Properties of Drosophila Flight Muscle Thick Filaments.

    Gasek, Nathan S; Nyland, Lori R; Vigoreaux, Jim O

    2016-01-01

    Flightin is a myosin binding protein present in Pancrustacea. In Drosophila, flightin is expressed in the indirect flight muscles (IFM), where it is required for the flexural rigidity, structural integrity, and length determination of thick filaments. Comparison of flightin sequences from multiple Drosophila species revealed a tripartite organization indicative of three functional domains subject to different evolutionary constraints. We use atomic force microscopy to investigate the functional roles of the N-terminal domain and the C-terminal domain that show different patterns of sequence conservation. Thick filaments containing a C-terminal domain truncated flightin (fln(ΔC44)) are significantly shorter (2.68 ± 0.06 μm; p thick filaments containing a full length flightin (fln⁺; 3.21 ± 0.05 μm) and thick filaments containing an N-terminal domain truncated flightin (fln(ΔN62); 3.21 ± 0.06 μm). Persistence length was significantly reduced in fln(ΔN62) (418 ± 72 μm; p thick filament bending propensity. Our results indicate that the flightin amino and carboxy terminal domains make distinct contributions to thick filament biomechanics. We propose these distinct roles arise from the interplay between natural selection and sexual selection given IFM's dual role in flight and courtship behaviors.

  11. Biomechanical conditions of walking

    Fan, Y F; Luo, L P; Li, Z Y; Han, S Y; Lv, C S; Zhang, B

    2015-01-01

    The development of rehabilitation training program for lower limb injury does not usually include gait pattern design. This paper introduced a gait pattern design by using equations (conditions of walking). Following the requirements of reducing force to the injured side to avoid further injury, we developed a lower limb gait pattern to shorten the stride length so as to reduce walking speed, to delay the stance phase of the uninjured side and to reduce step length of the uninjured side. This gait pattern was then verified by the practice of a rehabilitation training of an Achilles tendon rupture patient, whose two-year rehabilitation training (with 24 tests) has proven that this pattern worked as intended. This indicates that rehabilitation training program for lower limb injury can rest on biomechanical conditions of walking based on experimental evidence.

  12. Expression of the Hutchinson-Gilford Progeria Mutation during Osteoblast Development Results in Loss of Osteocytes, Irregular Mineralization, and Poor Biomechanical Properties*

    Schmidt, Eva; Nilsson, Ola; Koskela, Antti; Tuukkanen, Juha; Ohlsson, Claes; Rozell, Björn; Eriksson, Maria

    2012-01-01

    Hutchinson-Gilford progeria syndrome (HGPS) is a very rare genetic disorder that is characterized by multiple features of premature aging and largely affects tissues of mesenchymal origin. In this study, we describe the development of a tissue-specific mouse model that overexpresses the most common HGPS mutation (LMNA, c.1824C>T, p.G608G) in osteoblasts. Already at the age of 5 weeks, HGPS mutant mice show growth retardation, imbalanced gait and spontaneous fractures. Histopathological examination revealed an irregular bone structure, characterized by widespread loss of osteocytes, defects in mineralization, and a hypocellular red bone marrow. Computerized tomography analysis demonstrated impaired skeletal geometry and altered bone structure. The skeletal defects, which resemble the clinical features reported for bone disease in HGPS patients, was associated with an abnormal osteoblast differentiation. The osteoblast-specific expression of the HGPS mutation increased DNA damage and affected Wnt signaling. In the teeth, irregular dentin formation, as was previously demonstrated in human progeria cases, caused severe dental abnormalities affecting the incisors. The observed phenotype also shows similarities to reported bone abnormalities in aging mice and may therefore help to uncover general principles of the aging process. PMID:22893709

  13. Expression of the Hutchinson-Gilford progeria mutation during osteoblast development results in loss of osteocytes, irregular mineralization, and poor biomechanical properties.

    Schmidt, Eva; Nilsson, Ola; Koskela, Antti; Tuukkanen, Juha; Ohlsson, Claes; Rozell, Björn; Eriksson, Maria

    2012-09-28

    Hutchinson-Gilford progeria syndrome (HGPS) is a very rare genetic disorder that is characterized by multiple features of premature aging and largely affects tissues of mesenchymal origin. In this study, we describe the development of a tissue-specific mouse model that overexpresses the most common HGPS mutation (LMNA, c.1824C>T, p.G608G) in osteoblasts. Already at the age of 5 weeks, HGPS mutant mice show growth retardation, imbalanced gait and spontaneous fractures. Histopathological examination revealed an irregular bone structure, characterized by widespread loss of osteocytes, defects in mineralization, and a hypocellular red bone marrow. Computerized tomography analysis demonstrated impaired skeletal geometry and altered bone structure. The skeletal defects, which resemble the clinical features reported for bone disease in HGPS patients, was associated with an abnormal osteoblast differentiation. The osteoblast-specific expression of the HGPS mutation increased DNA damage and affected Wnt signaling. In the teeth, irregular dentin formation, as was previously demonstrated in human progeria cases, caused severe dental abnormalities affecting the incisors. The observed phenotype also shows similarities to reported bone abnormalities in aging mice and may therefore help to uncover general principles of the aging process.

  14. Time-Dependent Lagrangian Biomechanics

    Ivancevic, Tijana T

    2009-01-01

    In this paper we present the time-dependent generalization of an 'ordinary' autonomous human musculo-skeletal biomechanics. We start with the configuration manifold of human body, given as a set of its all active degrees of freedom (DOF). This is a Riemannian manifold with a material metric tensor given by the total mass-inertia matrix of the human body segments. This is the base manifold for standard autonomous biomechanics. To make its time-dependent generalization, we need to extend it with a real time axis. On this extended configuration space we develop time-dependent biomechanical Lagrangian dynamics, using derived jet spaces of velocities and accelerations, as well as the underlying geometric evolution of the mass-inertia matrix. Keywords: Human time-dependent biomechanics, configuration manifold, jet spaces, geometric evolution

  15. Systems biomechanics of the cell

    Maly, Ivan V

    2013-01-01

    Systems Biomechanics of the Cell attempts to outline systems biomechanics of the cell as an emergent and promising discipline. The new field owes conceptually to cell mechanics, organism-level systems biomechanics, and biology of biochemical systems. Its distinct methodology is to elucidate the structure and behavior of the cell by analyzing the unintuitive collective effects of elementary physical forces that interact within the heritable cellular framework. The problematics amenable to this approach includes the variety of cellular activities that involve the form and movement of the cell body and boundary (nucleus, centrosome, microtubules, cortex, and membrane). Among the elementary system effects in the biomechanics of the cell, instability of symmetry, emergent irreversibility, and multiperiodic dissipative motion can be noted. Research results from recent journal articles are placed in this unifying framework. It is suggested that the emergent discipline has the potential to expand the spectrum of ques...

  16. 去势手术联合激素注射对绵羊腰椎生物力学性能的作用%The effect of ovariectomy combined with methylprednisolone injection on biomechanical properties of sheep lumbar vertebrae

    刘达; 张译; 潘显明; 龚凯; 谢庆云; 屈波; 蒋凯

    2012-01-01

    Objective To evaluate the effect of ovariectomy combined with methylprednisolone injection on biomechanical properties of sheep lumbar vertebrae. Methods Ten adult sheep were divided into sham group (re = 5) and experiment group (re = 5) randomly. Both ovaries were just exposed in sham group. In experiment group, bilateral ovariectomy ( OVX) was performed, and 1 month later methylprednisolone (0.45 mg/Kg/d) were injected intramuscularly for 10 months. Bone mineral density (BMD) of all sheep lumbar vertebrae was examined before and 1 year after surgery. Compression test and axial pullout test were performed to evaluate biomechanical properties of sheep lumbar vertebrae 1 year after surgery. Results BMD in experiment group had a mean decrease by 25. 7% after 1 year of the surgery, which was significant (P < 0. 05 ) . The ultimate compression load and energy to failure in experiment group were significantly lower than those in sham group ( P < 0. 05 ). The maximum pullout strength and energy to failure in experiment group were significantly lower than those in sham group (P <0. 05) . Conclusion The method of ovariectomy combined with methylprednisolone injection can significantly decrease BMD and biomechanical properties of sheep lumbar vertebrae. This method can be used to establish osteoporotic spine model for studies on stability and inter fixation of the spine.%目的 评价去势手术联合激素注射对绵羊腰椎生物力学性能的作用.方法 健康成年绵羊10只,随机分为假手术组(n=5)和实验组(n=5).假手术组仅显露双侧卵巢;实验组行双侧卵巢切除术(ovariectomy,OVX),且术后1月开始肌肉注射甲基强的松龙(0.45 mg/kg/d)10月.测量术前和术后1年绵羊腰椎的骨密度(BMD),通过压缩实验和轴向拔出实验来评价术后1年椎体的生物力学性能.结果 术后1年实验组绵羊腰椎的BMD显著下降(P<0.05),平均下降25.7%.实验组的最大压缩应力和能量吸收值均显著低于假手

  17. 交联剂对脱细胞膀胱基质生物力学性能的影响%Effects of different crosslinking agents on biomechanical properties of acellular bladder matrix

    范雪梅; 李胜平; 徐惠成

    2013-01-01

    目的 研究不同交联剂对猪脱细胞膀胱基质的组织结构影响,并比较其生物力学性能,为盆底修复替代材料的选择提供依据.方法 采用表面活性剂+酶消化法去除新鲜猪膀胱的细胞成分,将脱细胞膀胱基质随机分为3组,A组经0.25%戊二醛交联,B组经0.625%京尼平交联,C组未交联.对各组材料进行HE染色,观察纤维的变化情况.使用生物力学性能测试系统检测抗拉强度、断裂伸长率、弹性模量,并进行统计学分析.结果 京尼平交联脱细胞膀胱基质后呈深蓝色,保持了天然组织构架的完整,纤维更加致密.戊二醛交联脱细胞膀胱基质后呈浅黄色,纤维排列紊乱且有断裂.新鲜猪膀胱经上述三种方法处理后,其弹性模量增大、断裂伸长率减小,而其中京尼平交联处理的脱细胞膀胱基质力学性能与新鲜膀胱组织更为相近.结论 京尼平交联的脱细胞膀胱基质组织结构的形态佳,同时较大限度地保留膀胱组织的力学性能,可能是较理想的盆底重建材料.%Objective To compare the effects of different crosslinking agents on structures and biomechanical properties of porcine acellular bladder matrix.This could provide the basic selection of ideal biomaterials for the reconstruction of female pelvis.Methods Cellular components of fresh porcine bladder were removed by detergent-enzymatic method.They were randomly divided into three groups,and group A was crosslinked with 0.25%glutaraldehyde,group B was crosslinked with 0.625% genipin,group C wasn't crosslinked.Then all samples were examined the morphology with hematoxylin and eosin staining,and biomechanical tests were also performed and evaluated the biomechanical properties by statistical analysis.Results The genipin-crosslinked acellular bladder matrix was dark blue,with very well preserved collagen fiber.The glutaraldehyde-crosslinked acellular bladder matrix was light yellow,with disordered and fracture

  18. Biomechanics of whiplash injury

    CHEN Hai-bin; King H YANG; WANG Zheng-guo

    2009-01-01

    Despite a large number of rear-end collisions on the road and a high frequency of whiplash injuries reported, the mechanism of whiplash injuries is not completely understood. One of the reasons is that the injury is not necessarily accompanied by obvious tissue damage detectable by X-ray or MRI. An extensive series of biomechanics studies, including injury epidemiology, neck kinematics,facet capsule ligament mechanics, injury mechanisms and injury criteria, were undertaken to help elucidate these whiplash injury mechanisms and gain a better understanding of cervical facet pain. These studies provide the following evidences to help explain the mechanisms of the whiplash injury: (1) Whiplash injuries are generally considered to be a soft tissue injury of the neck with symptoms such as neck pain and stiffness, shoulder weakness, dizziness, headache and memory loss, etc. (2) Based on kinematical studies on the cadaver and volunteers, there are three distinct periods that have the potential to cause injury to the neck. In the first stage, flexural deformation of the neck is observed along with a loss of cervical lordosis; in the second stage, the cervical spine assumes an S-shaped curve as the lower vertebrae begin to extend and gradually cause the upper vertebrae to extend; during the final stage, the entire neck is extended due to the extension moments at both ends. (3)The in vivo environment afforded by rodent models of injury offers particular utility for linking mechanics, nociception and behavioral outcomes. Experimental findings have examined strains across the facet joint as a mechanism of whiplash injury, and suggested a capsular strain threshold or a vertebral distraction threshold for whiplash-related injury,potentially producing neck pain. (4) Injuries to the facet capsule region of the neck are a major source of post-crash pain. There are several hypotheses on how whiplash-associated injury may occur and three of these injuries are related to strains within

  19. Biomechanics of whiplash injury.

    Chen, Hai-bin; Yang, King H; Wang, Zheng-guo

    2009-10-01

    Despite a large number of rear-end collisions on the road and a high frequency of whiplash injuries reported, the mechanism of whiplash injuries is not completely understood. One of the reasons is that the injury is not necessarily accompanied by obvious tissue damage detectable by X-ray or MRI. An extensive series of biomechanics studies, including injury epidemiology, neck kinematics, facet capsule ligament mechanics, injury mechanisms and injury criteria, were undertaken to help elucidate these whiplash injury mechanisms and gain a better understanding of cervical facet pain. These studies provide the following evidences to help explain the mechanisms of the whiplash injury: (1) Whiplash injuries are generally considered to be a soft tissue injury of the neck with symptoms such as neck pain and stiffness, shoulder weakness, dizziness, headache and memory loss, etc. (2) Based on kinematical studies on the cadaver and volunteers, there are three distinct periods that have the potential to cause injury to the neck. In the first stage, flexural deformation of the neck is observed along with a loss of cervical lordosis; in the second stage, the cervical spine assumes an S-shaped curve as the lower vertebrae begin to extend and gradually cause the upper vertebrae to extend; during the final stage, the entire neck is extended due to the extension moments at both ends. (3) The in vivo environment afforded by rodent models of injury offers particular utility for linking mechanics, nociception and behavioral outcomes. Experimental findings have examined strains across the facet joint as a mechanism of whiplash injury, and suggested a capsular strain threshold or a vertebral distraction threshold for whiplash-related injury, potentially producing neck pain. (4) Injuries to the facet capsule region of the neck are a major source of post-crash pain. There are several hypotheses on how whiplash-associated injury may occur and three of these injuries are related to strains

  20. The effect of secondary abnormal grain growth on the dielectric properties of La/Mn co-doped BaTiO3 ceramics

    Živković Lj.M.

    2006-01-01

    Full Text Available La/Mn-codoped BaTiO3 systems, obtained by solid state reactions, were investigated regarding their microstructure characteristics and ferroelectric properties. Different concentrations of La2O3 were used for doping, ranging from 0.1 to 5.0 at% La, while a content of Mn was constant at 0.05 at%. For all samples sintered below the eutectic temperature (1332°C, a uniform microstructure was formed with average grain size from 1-3 μm. The appearance of secondary abnormal grains with (111 double twins grains with curved or faceted grain boundaries were observed in La/Mn BaTiO3 ceramics after sintering at temperatures above the eutectic temperature. All sintered samples exhibited a high electrical resistivity. Better dielectric performances were obtained for low doped samples (0.1 at% La sintered at 1350°C. For samples with La content above 1.0 at% a lower value in dielectric permittivity at higher sintering temperature is due to secondary abnormal grain growth, and to the presence of a non-ferroelectric phase rich in La. The Curie constant together with other dielectric parameters were also calculated.

  1. The characteristics of keratoconus biomechanical properties measuring by Corvis ST and ORA%圆锥角膜生物力学在Corvis ST与ORA下的变化特点

    李勇; 魏升升; 李晶; 刘建国; 叶璐; 万雅群; 李娟; 杜婧

    2015-01-01

    数均有改变.可视化角膜生物力学分析仪(Corvis ST)和眼反应分析仪(ORA)均能较好反映圆锥角膜生物力学改变特点,多项参数具有明显的相关性.%Objective To investigate the characteristics of keratoconus biomechanical properties by comparing normal eyes.Methods In this case control study,patients from March 2009 to June 2014 were included.The corneal biomechanical properties of 34 keratoconus patients (42 eyes) and 61 normal patients (61 eyes) were measured with Corneal Visualization Scheimpflug Technology (Corvis ST) and Ocular Response Analyze (ORA).The Length of Appl 1 (lst A length),Velocity of Appl 1 (Vin),Length of Appl 2 (2nd A length),Velocity of Appl 2 (Vout),Deformation Amplitude (DA),P.Dist and Radius were measured with Corvis ST.CH and CRF were measured with ORA.Comparison of keratoconic and normal eye's measurement values from ORA and Corvis ST were performed using Paired t test or Two independent tests.Pearson or Spearman correlations were used to evaluate the relationship between Corvis ST and ORA in measurement of keratoconus biomechanical.Results Comparing normal eye's biomechanical properties measurement values,the l stA length and Radius significantly decreased in keratoconus eyes,and there were significantly statistical difference (t =-0.51,-6.54;P =0.01,0.00),however,the Vout absolute value and Def.Ampl increased in keratoconus eyes,and there were significantly statistical difference (Z =-2.25,t =4.27;P =0.03,0.00).The CH and CRF of ORA also decreased in keratoconus eyes,and there were significantly statistical difference (t =-5.20,-7.06;P =0.00,0.00).There were significant correlations between CH of ORA and 1stA length,Vout,Def.Ampl and Radius of Corvis ST (P =0.00,0.04,0.03,0.00).There were significant correlations between CRF of ORA and lstA length,Vout,Def.Ampl and Radius of Corvis ST (P =0.02,0.03,0.00,0.00).Conclusions Comparing normal eyes,the biomechanical properties parameters changed obviously in

  2. Biomechanics and functionality of hepatocytes in liver cirrhosis.

    Sun, Shan; Song, Zhenyuan; Cotler, Scott J; Cho, Michael

    2014-06-27

    Cirrhosis is a life-threatening condition that is generally attributed to overproduction of collagen fibers in the extracellular matrix that mechanically stiffens the liver. Chronic liver injury due to causes including viral hepatitis, inherited and metabolic liver diseases and external factors such as alcohol abuse can result in the development of cirrhosis. Progression of cirrhosis leads to hepatocellular dysfunction. While extensive studies to understand the complexity underlying liver fibrosis have led to potential application of anti-fibrotic drugs, no such FDA-approved drugs are currently available. Additional studies of hepatic fibrogenesis and cirrhosis primarily have focused on the extracellular matrix, while hepatocyte biomechanics has received limited attention. The role of hepatocyte biomechanics in liver cirrhosis remains elusive, and how the cell stiffness is correlated with biological functions of hepatocytes is also unknown. In this study, we demonstrate that the biomechanical properties of hepatocytes are correlated with their functions (e.g., glucose metabolism), and that hepatic dysfunction can be restored through modulation of the cellular biomechanics. Furthermore, our results indicate the hepatocyte functionality appears to be regulated through a crosstalk between the Rho and Akt signaling. These novel findings may lead to biomechanical intervention of hepatocytes and the development of innovative tissue engineering for clinical treatment to target liver cells rather than exclusively focusing on the extracellular matrix alone in liver cirrhosis.

  3. Judo Biomechanical Optimization

    Sacripanti, Attilio

    2016-01-01

    In this paper, for the first time, there is comprehensively tackling the problem of biomechanical optimization of a sport of situation such as judo. Starting from the optimization of more simple sports, optimization of this kind of complex sports is grounded on a general physics tool such as the analysis of variation. The objective function is divided for static and dynamic situation of Athletes couple, and it is proposed also a sort of dynamic programming problem Strategic Optimization. A dynamic programming problem is an optimization problem in which decisions have to be taken sequentially over several time periods linked in some fashion. A strategy for a dynamic programming problem is just a contingency plan, a plan that specifies what is to be done at each stage as a function of all that has transpired up to that point. It is possible to demonstrate, under some conditions, that a Markovian optimal strategy is an optimal strategy for the dynamic programming problem under examination. At last we try to appr...

  4. Biomechanics of Wheat/Barley Straw and Corn Stover

    Christopher T. Wright; Peter A. Pryfogle; Nathan A. Stevens; Eric D. Steffler; J. Richard Hess; Thomas H. Ulrich

    2005-03-01

    The lack of understanding of the mechanical characteristics of cellulosic feedstocks is a limiting factor in economically collecting and processing crop residues, primarily wheat and barley stems and corn stover. Several testing methods, including compression, tension, and bend have been investigated to increase our understanding of the biomechanical behavior of cellulosic feedstocks. Biomechanical data from these tests can provide required input to numerical models and help advance harvesting, handling, and processing techniques. In addition, integrating the models with the complete data set from this study can identify potential tools for manipulating the biomechanical properties of plant varieties in such a manner as to optimize their physical characteristics to produce higher value biomass and more energy efficient harvesting practices.

  5. A study on the effect of the corneal biomechanical properties undergoing overnight orthokeratology%角膜塑形术治疗近视眼安全性的探讨

    毛欣杰; 黄橙赤; 陈琳; 吕帆

    2010-01-01

    Objective To evaluate the changes of corneal biomechanical properties and corneal topography undergoing overnight orthokeratology treatment. Methods Thirty teenagers with low andmoderate myopia with age of 11.67±1.63,myopia(-2.56±0.86)D,were included and were fitted with Ortho-K CL. The corneal biomechanical properties,including corneal hysteresis (CH),corneal resistance factor(CRF),goldmann-correlated lOP(IOPg) and corneal-compensated intraocular pressure(IOPcc) were measured with ocular response analyzer(ORA).Corneal topography,central corneal thickness(CCT) and corneal endothelium density were measured with computerized corneal topography,optical coherence tomography(OCT) and non contact specular microscope respectively.The measurements were taken at pre-wear,1 day and 7,30,90,180 days after orthokeratology.Only data from the right eyes were analysed.Results All subjects were significantly reduced the myopia amount after 1 day of lens Wear.The corneal curvature flattening(F=38.837,P<0.01)became slightly down to stable after the first week.There were significant decrease in CH and CRF after the orthokeratology treatment within the first week,and CH and CRF reversed and thereafeter into the original level at 3-month and 6-month follow up.IOPg and IOPcc decreased and reached the lowwest level at 1-week visit and after then became down to stable.There were significant reduction in CCT after 1 week(F=4.739,P<0.05).There were no significant changes in corneal endothelium density during orthokeratology treatment for 6 months.Conclusions The amount of myopia reduction with orthokeratology occurred mostly within 1 week while the corneal biomechanical properties such as CH and CRF were decreased. However the corneal biomechanical properties are reversal to the original level thereafter and remain unchanged within the 6 months follow up visits.It proves that orthokeratology does not demage corneal microsturcture.The early sign of reduction may due to the temporal

  6. Corneal biomechanical properties changes in keratoconus eyes induced by rigid gas-permeable contact lenses%圆锥角膜配戴RGPCL后角膜生物力学性能改变

    郭曦; 杨丽娜; 谢培英; 周建兰; 王丹

    2015-01-01

    Objective To observe the changes in corneal shape,corneal thickness and corneal biomechanics in keratoconus patients who wore RGPCL for more than 1 year.Methods In this retrospective case series study,15 patients (30 eyes) with moderate or worse keratoconus were recruited.Average spherical and astigmatic powers were-9.53±3.60 D and-3.42±2.13 D,respectively.The RGPCL were fitted for diagnosed keratoconus eyes,and a paired t-test was used to compare corneal parameters between before and after 1 year of lens wear.Measured parameters included spherical and astigmatism power,corneal fiat and steep K values,corneal thickness,corneal hysteresis (CH) and the corneal resistance factor (CRF).Results Some changes occurred to keratoconus eyes after 1 year of wear:corneal steep K values decreased from 49.21±4.06 D to 47.95±3.16 D (t=3.156,P<0.05); the corneal surface regularity index (SRI) and surface asymmetry index (SAI) decreased from 0.47±0.15 and 0.49±0.16 to 0.36±0.14 and 0.38±0.19 (t=2.314,2.253,P<0.05); corneal astigmatism decreased from-3.42±2.13 D to-2.63±1.57 D (t=-5.270,P<0.01); corneal thickness had no significant change; corneal biomechanical CH increased from 8.26±0.39 mmHg to 10.23±0.49 mmHg (t=-5.954,P<0.01); and corneal biomechanical CRF increased from 7.53±0.56 mmHg to 9.05±0.58 mmHg (t=-5.340,P<0.01).Conclusion By following the change in corneal shape after 1 year of RGPCL wear,corneal biomechanical properties have significant increases in eyes with moderate or worse keratoconus.The patient's condition and corneal biomechanics can be the key indicators for the efficacy of treating keratoconus patients with RGPCLs.%目的 观察圆锥角膜患者配戴1年以上RGPCL后的角膜形态、角膜厚度和角膜生物力学性能变化.方法 回顾性系列病例研究.选择诊断为中、重度圆锥角膜患者15例(30眼),平均球镜度为(-9.53±3.60)D,平均散光度为(-3.42±2.13)D.为患眼验配RGPCL,采用配

  7. 脊柱腰骶段生物力学特性及内固定材料的应用%Biomechanical properties of the lumbosacral spine and application of internal fixation materials

    孙弘昊; 郭庆升; 朱志勇

    2016-01-01

    steel, titanium and titanium aloys have been widely used in rigid internal fixation, but metal sedimentation, non-transparency, stress shielding and osteoporosis after internal fixation impact the fusion effects and imaging observation. Absorbable materials as newly-developing materials have good biocompatibility and biodegradability in orthopedic internal fixation. To select the appropriate material for internal fixation, the biomechanical properties of internal fixation materials wil be investigated according to the degree of vertebral damage and lumbosacral stability.

  8. Pharmacological Effect of EPF on Biomechanical Properties among Ovariectomized Rats%淫羊藿黄酮对去势大鼠骨生物力学性能的影响

    陈鹏; 刘文和; 颜林淋; 陈家玉; 胡伟文; 曹锡文; 李杨

    2014-01-01

    物力学性能的降低,使其维持在较高水平。%This study was aimed to explore pharmacological effects of epimedium pubescen flavonoid (EPF) on biomechanical properties among ovariectomized rats. Sixty female Sprague-Dawley (SD) rats (aged 2-month-old) were randomly divided into six groups (n = 10), which were the sham control group (Group A), the model group (GroupB), the standard group (Group C), the treated 1 group (Group D), the treated 2 group (Group E), and the treated 3 group (Group F). Except the sham control group (Group A), rats in other groups had been ovariectomized. All rats were given the same feedstuff. Meanwhile, Group C was given calcium 75 mg·kg-1 combined with VitD3 21 IU·kg-1 by gastrogavage every day for 4 months; Group D was given EPF 75 mg·kg-1; Group E was given EPF 150 mg·kg-1;Group F was given EPF 300 mg·kg-1. At the end of the 4th month, all rats were sacrificed. Bones, which included tibia, femur and humerus of both sides and all lumbar vertebra bodies, had been taken out. Measurement was made on the elastic modulus, maximum loading capability, maximum stress, potential energy of deformation, and structural rigidity of biomechanical properties of the fourth lumbar vertebra body (LV4); the maximum loading capability, bone break load, potential energy of deformation, structural rigidity of the structural dynamics properties of the femur com-pact bone; the elastic modulus, maximum stress, maximum inherent strain, bone break stress, and bone break strain of the mechanical properties of a material of the femur compact bone in the experimental rats. The results showed that compared with Group B, the elastic modulus, maximum loading capability, maximum stress, potential energy of deformation, and structural rigidity of LV4; the maximum loading capability, bone break load, potential energy of de-formation, structural rigidity of the structural dynamics properties of the femur compact bone; the elastic modulus, maximum stress

  9. Kinesiology/Biomechanics: Perspectives and Trends.

    Atwater, Anne E.

    1980-01-01

    Past and recent developments and future directions in kinesiology and biomechanics are reviewed. Similarities and differences between these two areas are clarified. The areas of kinesiology and biomechanics have distinct unique qualities and should be treated as separate disciplines. (CJ)

  10. Abnormal physiological properties and altered cell wall composition in Streptococcus pneumoniae grown in the presence of clavulanic acid.

    Severin, A; Severina, E; Tomasz, A

    1997-01-01

    Subinhibitory concentrations of clavulanate caused premature induction of stationary-phase autolysis, sensitization to lysozyme, and reductions in the MICs of deoxycholate and penicillin for Streptococcus pneumoniae. In the range of clavulanate concentrations producing these effects, this beta-lactam compound was selectively bound to PBP 3. Cell walls isolated from pneumococci grown in the presence of clavulanate showed increased sensitivity to the hydrolytic action of purified pneumococcal autolysin in vitro. High-performance liquid chromatography analysis of the peptidoglycan isolated from the clavulanate-grown cells showed major qualitative and quantitative changes in stem peptide composition, the most striking feature of which was the accumulation of peptide species carrying intact D-alanyl-D-alanine residues at the carboxy termini. The altered biological and biochemical properties of the clavulanate-grown pneumococci appear to be the consequences of suppressed D,D-carboxypeptidase activity. PMID:9055983

  11. Biomechanics and the wheelchair.

    McLaurin, C A; Brubaker, C E

    1991-04-01

    Wheelchair biomechanics involves the study of how a wheelchair user imparts power to the wheels to achieve mobility. Because a wheelchair can coast, power input need not be continuous, but each power strike can be followed by a period of recovery, with the stroking frequency depending on user preferences and the coasting characteristics of the wheelchair. The latter is described in terms of rolling resistance, wind resistance and the slope of the surface. From these three factors the power required to propel the wheelchair is determined, and must be matched by the power output of the user. The efficiency of propulsion is the ratio of this power output to the metabolic cost and is typically in the order of 5% in normal use. The features required in a wheelchair depend upon user characteristics and intended activities. The ideal wheelchair for an individual will have the features that closely match these characteristics and activities. Thus prescription is not just choosing a wheelchair, but choosing the components of the wheelchair that best serve the intended purpose. In this paper, each component is examined for available options and how these options effect the performance of the wheelchair for the individual. The components include wheels, tyres, castors, frames, bearings, materials, construction details, seats, backrests, armrests, foot and legrests, headrests, wheel locks, running brakes, handrims, levers, accessories, adjustments and detachable parts. Each component is considered in relation to performance characteristics including rolling resistance, versatility, weight, comfort, stability, maneouvrability, transfer, stowage, durability and maintenance. Where they exist, wheelchair standards are referred to as a source of information regarding these characteristics.

  12. 局部注射肝素钠免跟腱系统生物力学性质的变化%Effects of heparin with local injection on the biomechanical properties of Achilles tendon system in rabbits

    刘波

    2008-01-01

    背景: 跟腱腱围炎会导致跟腱生物力学特件的改变,日前以局部注射肝素钠治疗较为普遍,但其对跟腱生物力学特性影响的报道甚少.目的: 观察跟腱劳损后生物力学性质及黏弹性的变化,同时验证肝素钠对跟腱生物力学特性及黏弹性的影响.设计、时间及地点: 于2005-03/12存四川省骨科医院生物力学实验室完成随机对照动物实验.材料: 50只成年日本大耳白兔,体质量(4.10±0.23)kg,用于制备跟腱劳损动物模型.方法: 50只动物随机分为对照组(n=20)、训练组(n=12)和肝素钠组(n=18).动物3周运动训练后继续训练,同时开始跟腱腱围及跟腱止点的肝素局部注射,2次/周.6周后进行跟腱的循环蠕变和应力松弛测定,最后进行跟腱的断裂实验.主要观察指标: 测定不同运动后跟腱的生物力学特性及黏弹性的变化,包括跟腱的横截面积、循环蠕变、滞后环、应力松弛、强度特性和应力-应变.结果: 训练组和肝素钠组动物的滞后环明显减小,应力松弛加快.训练后跟腱的屈服载荷及能量、断裂能量、屈服应力、应变能力明显高于对照组.肝素钠组所有生物力学指标都得到改善.结论: 大强度运动可使跟腱的黏弹性下降,局部注射肝素钠可改善跟腱的强度特性和黏弹性.劳损后跟腱腱围和跟腱止点局部注射肝素钠对改善跟腱系统的强度特性和黏弹性有益.%BACKGROUND: Achilles peritendinitis can change characteristics of mechanical and viscoelastic properties in Achilles tendon, especially the biomechanical properties of Achilles tendon after heparin local injection. OBJECTIVE: To examine the changes of mechanical and viscoelastic properties in Achilles tendon of overuse injuries and the effects of heparin on the mechanical and viscoelastic properties in Achilles tendon. DESIGN, TIME AND SETTIMG: Control animal specimen study was performed at the Biomechanical Laboratory of

  13. Biomechanical analysis of rollator walking

    Alkjaer, T; Larsen, Peter K; Pedersen, Gitte

    2006-01-01

    The rollator is a very popular walking aid. However, knowledge about how a rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate the biomechanical effects of walking with and without a rollator on the walking pattern in healthy subjects.......The rollator is a very popular walking aid. However, knowledge about how a rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate the biomechanical effects of walking with and without a rollator on the walking pattern in healthy subjects....

  14. Fibrillin: from microfibril assembly to biomechanical function.

    Kielty, Cay M; Baldock, Clair; Lee, David; Rock, Matthew J; Ashworth, Jane L; Shuttleworth, C Adrian

    2002-02-28

    Fibrillins form the structural framework of a unique and essential class of extracellular microfibrils that endow dynamic connective tissues with long-range elasticity. Their biological importance is emphasized by the linkage of fibrillin mutations to Marfan syndrome and related connective tissue disorders, which are associated with severe cardiovascular, ocular and skeletal defects. These microfibrils have a complex ultrastructure and it has proved a major challenge both to define their structural organization and to relate it to their biological function. However, new approaches have at last begun to reveal important insights into their molecular assembly, structural organization and biomechanical properties. This paper describes the current understanding of the molecular assembly of fibrillin molecules, the alignment of fibrillin molecules within microfibrils and the unique elastomeric properties of microfibrils.

  15. Acute and Stress-related Injuries of Bone and Cartilage: Pertinent Anatomy, Basic Biomechanics, and Imaging Perspective.

    Pathria, Mini N; Chung, Christine B; Resnick, Donald L

    2016-07-01

    Bone or cartilage, or both, are frequently injured related to either a single episode of trauma or repetitive overuse. The resulting structural damage is varied, governed by the complex macroscopic and microscopic composition of these tissues. Furthermore, the biomechanical properties of both cartilage and bone are not uniform, influenced by the precise age and activity level of the person and the specific anatomic location within the skeleton. Of the various histologic components that are found in cartilage and bone, the collagen fibers and bundles are most influential in transmitting the forces that are applied to them, explaining in large part the location and direction of the resulting internal stresses that develop within these tissues. Therefore, thorough knowledge of the anatomy, physiology, and biomechanics of normal bone and cartilage serves as a prerequisite to a full understanding of both the manner in which these tissues adapt to physiologic stresses and the patterns of tissue failure that develop under abnormal conditions. Such knowledge forms the basis for more accurate assessment of the diverse imaging features that are encountered following acute traumatic and stress-related injuries to the skeleton. (©) RSNA, 2016.

  16. Clinical applications of biomechanics cinematography.

    Woodle, A S

    1986-10-01

    Biomechanics cinematography is the analysis of movement of living organisms through the use of cameras, image projection systems, electronic digitizers, and computers. This article is a comparison of cinematographic systems and details practical uses of the modality in research and education.

  17. Biomechanical properties of plum interlocking intramedullary nail in fixed subtrochanteric femoral fracture%改良梅花型交锁髓内钉固定股骨粗隆下骨折的生物力学研究

    王新家; 李晶

    2013-01-01

    Objective To evaluate the biomechanical properties of plum interlocking intramedullary nail in fixed subtrochanteric femoral fracture,compare with the Gamma nail,and analyze the feasibility of plum interlocking intramedullary nail in the treatment of subtrochanteric femoral fracture.Methods Eight male adult femur specimens according to the left and right side were divided into experimental group and control group.Subtrochanteric transverse femoral fracture models were built plum interlocking intramedullary nails(length 350 mm) were used for the experimental group.Gamma nails(length 350 mm) were used for the control group.Then the axially vertical compression,three-point bending and torsion test resistance to axial compression of subtrochanteric fracture model in the different internal fixation methods were compared in experimental group with control group with statistical analysis.Results I n the control group,1 000 N axial load under the pressure of the compressive stiffness,anti-1 000 N pressure bending stiffness and torsional rigidity 3 N/m were (2 359.4±200.8)N/mm,(0.64±0.16)N/m,(614.7±60.2)Nm/°; In the experimental group,three indicators were (2 178.1±129.5)N/mm,(0.48±0.13)N/m,(439.1±48.2)Nm/°.There were no significant differences between the experimental group and the control group (P >0.05).Conclusion The plum interlocking inttrmedullary nail has a good biomechanical properties,and can be used to fix subtrochanteric transverse femoral fracture.%目的 比较自行设计的改良梅花型交锁髓内钉与国产Gamma钉固定股骨粗隆下骨折的即刻生物力学特性,探讨改良梅花型交锁髓内钉固定股骨粗隆下骨折的可行性.方法 8具成年健康男性股骨标本,按左右侧分为实验组和对照组,分别制作股骨粗隆下横形骨折模型.实验组采用长度350 mm的改良梅花型交锁髓内钉固定骨折,对照组采用长度350 mm国产Gamma钉固定骨折.分别检测抗轴向压缩、抗侧弯及抗扭转

  18. Contribution of biomechanics to clinical practice in orthopaedics.

    Woo, Savio L-Y

    2004-01-01

    Biomechanics is a field that has a very long history. It was described in ancient Chinese and Greek literature as early as 400-500 BC. The foundation of biomechanics, however, was laid during a period between the 1500's to 1700's by renowned personalities, da Vinci, Galileo, Borelli, Hooke, Newton, and so (Fung, Y.C., Biomechanics: Mechanical Properties of Living Tissues, 2nd Ed. Springer Verlag, Chapter 1, 1993). Beginning in the 1950's, Muybridge, Steindler, Inman, Lissner, and Hirsch performed the pioneering work on musculoskeletal biomechanics and the foundation of orthopaedic biomechanics was formed. For the following two decades, the field has blossomed and significant contributions in the biomechanics of bone, articular cartilage, soft tissues, upper and lower extremities, spine and so on has been made. More sophisticated equipment, coupled with mathematical modeling and better engineering design, has enabled us to make great strides. Bioengineers, in collaboration with orthopaedic surgeons, have translated many laboratory discoveries into clinical practice, leading to improved patient treatment and outcome. In the past 30 years, my colleagues and I have focused our research on the biomechanics of musculoskeletal soft tissues, ligaments and tendons, in particular. Therefore, in this lecture, the function of knee ligaments, the associated homeostatic responses secondary to immobilization and exercise, and healing of the ligaments will be reviewed. Examples of scientific findings that help to guide the surgical management of injury to ligaments will be given. New ideas on functional tissue engineering to improve the healing of knee ligaments and tendons will be presented. We have learned that tendons and ligaments are indeed complex biological tissues. To fully understand their behavior, healing and remodelling processes, this author advocates major efforts be made to bring molecular biologists, morphologists, biochemists, bioengineers, physical therapists and

  19. Biomechanical Properties of Hemlocks: A Novel Approach to Evaluating Physical Barriers of the Plant–Insect Interface and Resistance to a Phloem-Feeding Herbivore

    Paul Ayayee

    2014-06-01

    Full Text Available Micromechanical properties that help mediate herbivore access may be particularly important when considering herbivorous insects that feed with piercing-sucking stylets. We used microindentation to quantify the micromechanical properties of hemlock, Tsuga spp., to quantify the hardness of the feeding site of the invasive hemlock woolly adelgid, Adelges tsugae. We measured hardness of the hemlock leaf cushion, the stylet insertion point of the adelgid, across four seasons in a 1 y period for four hemlock species growing in a common garden, including eastern, western, mountain, and northern Japanese hemlocks. Leaf cushion hardness was highest in the fall and winter and lowest in summer for all species. Northern Japanese hemlock had relatively greater hardness than the remaining species. Our data contributes an additional perspective to the existing framework within which greater susceptibility and subsequent mortality of eastern hemlocks is observed. The potential application of microindentation to understanding the nature and relevance of plant mechanical defenses in plant–herbivore interactions is also demonstrated and highlighted.

  20. Biomechanical properties of the tomato (Solanum lycopersicum) fruit cuticle during development are modulated by changes in the relative amounts of its components.

    España, Laura; Heredia-Guerrero, José A; Segado, Patricia; Benítez, José J; Heredia, Antonio; Domínguez, Eva

    2014-05-01

    In this study, growth-dependent changes in the mechanical properties of the tomato (Solanum lycopersicum) cuticle during fruit development were investigated in two cultivars with different patterns of cuticle growth and accumulation. The mechanical properties were determined in uniaxial tensile tests using strips of isolated cuticles. Changes in the functional groups of the cuticle chemical components were analysed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR). The early stages of fruit growth are characterized by an elastic cuticle, and viscoelastic behaviour only appeared at the beginning of cell enlargement. Changes in the cutin:polysaccharide ratio during development affected the strength required to achieve viscoelastic deformation. The increase in stiffness and decrease in extensibility during ripening, related to flavonoid accumulation, were accompanied by an increase in cutin depolymerization as a result of a reduction in the overall number of ester bonds. Quantitative changes in cuticle components influence the elastic/viscoelastic behaviour of the cuticle. The cutin:polysaccharide ratio modulates the stress required to permanently deform the cuticle and allow cell enlargement. Flavonoids stiffen the elastic phase and reduce permanent viscoelastic deformation. Ripening is accompanied by a chemical cleavage of cutin ester bonds. An infrared (IR) band related to phenolic accumulation can be used to monitor changes in the cutin esterification index.

  1. Anatomical and biomechanical traits of broiler chickens across ontogeny. Part II. Body segment inertial properties and muscle architecture of the pelvic limb

    Heather Paxton

    2014-07-01

    Full Text Available In broiler chickens, genetic success for desired production traits is often shadowed by welfare concerns related to musculoskeletal health. Whilst these concerns are clear, a viable solution is still elusive. Part of the solution lies in knowing how anatomical changes in afflicted body systems that occur across ontogeny influence standing and moving. Here, to demonstrate these changes we quantify the segment inertial properties of the whole body, trunk (legs removed and the right pelvic limb segments of five broilers at three different age groups across development. We also consider how muscle architecture (mass, fascicle length and other properties related to mechanics changes for selected muscles of the pelvic limb. All broilers used had no observed lameness, but we document the limb pathologies identified post mortem, since these two factors do not always correlate, as shown here. The most common leg disorders, including bacterial chondronecrosis with osteomyelitis and rotational and angular deformities of the lower limb, were observed in chickens at all developmental stages. Whole limb morphology is not uniform relative to body size, with broilers obtaining large thighs and feet between four and six weeks of age. This implies that the energetic cost of swinging the limbs is markedly increased across this growth period, perhaps contributing to reduced activity levels. Hindlimb bone length does not change during this period, which may be advantageous for increased stability despite the increased energetic costs. Increased pectoral muscle growth appears to move the centre of mass cranio-dorsally in the last two weeks of growth. This has direct consequences for locomotion (potentially greater limb muscle stresses during standing and moving. Our study is the first to measure these changes in the musculoskeletal system across growth in chickens, and reveals how artificially selected changes of the morphology of the pectoral apparatus may cause

  2. 有氧运动配合雷洛昔芬对骨生物力学性能影响的研究%Aerobic Exercise Combined with Effects of Raloxifene on Bone Biomechanical Properties

    谢江涛; 罗珊

    2014-01-01

    目的:通过对去势大鼠骨生物力学指标的检测,探讨有氧运动与雷洛昔芬联合作用对去势大鼠骨生物力学性能的影响。方法:将50只雌性SD大鼠随机分为5组:假手术组、模型组、有氧运动组、雷洛昔芬组、有氧运动+雷洛昔芬组。假手术组不去卵巢,其余各组去卵巢造模;有氧运动组、雷洛昔芬组、有氧运动+雷洛昔芬组分别在去卵巢的基础上进行有氧运动训练和(或)灌胃选择性雌激素受体调节剂雷洛昔芬。8周后比较各组大鼠股骨结构力学和材料力学指标的变化。结果:(1)与模型组相比,有氧运动组、雷洛昔芬组、有氧运动+雷洛昔芬组大鼠的各项指标都显著优于模型组(P<0.05),部分指标出现显著性差异(P<0.01)。(2)模型组各项指标都与假手术组有显著性差别(P<0.05)。结论:有氧运动配合雷洛昔芬治疗联合应用预防废用性骨质疏松比单独应用能获得更好的效果;并且更加安全易行。%Objective: ovariectomized rats bone biomechanical indicators detect, investigate the combined effects of aerobic exercise and raloxifene on ovariectomized rats bone biomechanical properties. Methods: 50 female SD rats were randomly divided into five groups: sham operation group, model group, aerobic exercise group, the raloxifene group, aerobic exercise + raloxifene group. Sham group only surgery but not ovariectomy, the rest of the group of ovariectomized modeling; aerobic exercise group, the raloxifene group aerobic exercise + raloxifene groups, respectively, based on ovariectomized aerobic exercise training and (or) orally selective estrogen receptor modulator raloxifene. After eight weeks, comparing changes in the rat femur structural mechanics and material mechanics index. Results: (1) Compared with model group, the aerobic exercise group, raloxifene group, the indicators of aerobic exercise + raloxifene rats

  3. Biomechanical design considerations for transradial prosthetic interface: A review.

    Sang, Yuanjun; Li, Xiang; Luo, Yun

    2016-03-01

    Traditional function and comfort assessment of transradial prostheses pay scant attention to prosthetic interface. With better understanding of the biomechanics of prosthetic interface comes better efficiency and safety for interface design; in this way, amputees are more likely to accept prosthetic usage. This review attempts to provide design and selection criteria of transradial interface for prosthetists and clinicians. Various transradial socket types in the literature were chronologically reviewed. Biomechanical discussion of transradial prosthetic interface design from an engineering point of view was also done. Suspension control, range of motion, stability, as well as comfort and safety of socket designs have been considered in varying degrees in the literature. The human-machine interface design should change from traditional "socket design" to new "interface design." From anatomy and physiology to biomechanics of the transradial residual limb, the force and motion transfer, together with comfort and safety, are the two main aspects in prosthetic interface design. Load distribution and transmission should mainly rely on achieving additional skeletal control through targeted soft tissue relief. Biomechanics of the residual limb soft tissues should be studied to find the relationship between mechanical properties and the comfort and safety of soft tissues.

  4. Challenging the in-vivo assessment of biomechanical properties of the uterine cervix: A critical analysis of ultrasound based quasi-static procedures.

    Maurer, M M; Badir, S; Pensalfini, M; Bajka, M; Abitabile, P; Zimmermann, R; Mazza, E

    2015-06-25

    Measuring the stiffness of the uterine cervix might be useful in the prediction of preterm delivery, a still unsolved health issue of global dimensions. Recently, a number of clinical studies have addressed this topic, proposing quantitative methods for the assessment of the mechanical properties of the cervix. Quasi-static elastography, maximum compressibility using ultrasound and aspiration tests have been applied for this purpose. The results obtained with the different methods seem to provide contradictory information about the physiologic development of cervical stiffness during pregnancy. Simulations and experiments were performed in order to rationalize the findings obtained with ultrasound based, quasi-static procedures. The experimental and computational results clearly illustrate that standardization of quasi-static elastography leads to repeatable strain values, but for different loading forces. Since force cannot be controlled, this current approach does not allow the distinction between a globally soft and stiff cervix. It is further shown that introducing a reference elastomer into the elastography measurement might overcome the problem of force standardization, but a careful mechanical analysis is required to obtain reliable stiffness values for cervical tissue. In contrast, the maximum compressibility procedure leads to a repeatable, semi-quantitative assessment of cervical consistency, due to the nonlinear nature of the mechanical behavior of cervical tissue. The evolution of cervical stiffness in pregnancy obtained with this procedure is in line with data from aspiration tests.

  5. The Biomechanics of Cervical Spondylosis

    Lisa A. Ferrara

    2012-01-01

    Full Text Available Aging is the major risk factor that contributes to the onset of cervical spondylosis. Several acute and chronic symptoms can occur that start with neck pain and may progress into cervical radiculopathy. Eventually, the degenerative cascade causes desiccation of the intervertebral disc resulting in height loss along the ventral margin of the cervical spine. This causes ventral angulation and eventual loss of lordosis, with compression of the neural and vascular structures. The altered posture of the cervical spine will progress into kyphosis and continue if the load balance and lordosis is not restored. The content of this paper will address the physiological and biomechanical pathways leading to cervical spondylosis and the biomechanical principles related to the surgical correction and treatment of kyphotic progression.

  6. The biomechanics of cervical spondylosis.

    Ferrara, Lisa A

    2012-01-01

    Aging is the major risk factor that contributes to the onset of cervical spondylosis. Several acute and chronic symptoms can occur that start with neck pain and may progress into cervical radiculopathy. Eventually, the degenerative cascade causes desiccation of the intervertebral disc resulting in height loss along the ventral margin of the cervical spine. This causes ventral angulation and eventual loss of lordosis, with compression of the neural and vascular structures. The altered posture of the cervical spine will progress into kyphosis and continue if the load balance and lordosis is not restored. The content of this paper will address the physiological and biomechanical pathways leading to cervical spondylosis and the biomechanical principles related to the surgical correction and treatment of kyphotic progression.

  7. Structural and biomechanical aspects of equine sacroiliac joint function and their relationship to clinical disease.

    Goff, L M; Jeffcott, L B; Jasiewicz, J; McGowan, C M

    2008-06-01

    Pain originating from the sacroiliac joint (SIJ) in horses has long been associated with poor performance, yet specific diagnosis of sacroiliac dysfunction (SID) has been difficult to achieve. Clinical presentation of SID appears to fall into two categories. The first, presenting as pain and poor performance, is responsive to local analgesia of periarticular structures with poorly defined pathology. The second presents primarily as poor performance with bony pathological changes as a result of chronic instability. Diagnostic tests based on biomechanics as well as manual provocation for SIJ pain have formed the basis of tests currently used to diagnose SIJ dysfunction in humans. This review summarises the anatomy and biomechanics of the equine SIJ and current biomechanical, innervation and motor control concepts in human SID. The relationship between abnormal SIJ motion and altered neuromotor control with clinical disease of the equine SIJ are discussed. Future utilisation of these principles to develop new diagnostic and management tools for the equine SID is promising.

  8. Biomechanics of Gait during Pregnancy

    2014-01-01

    Introduction. During pregnancy women experience several changes in the body’s physiology, morphology, and hormonal system. These changes may affect the balance and body stability and can cause discomfort and pain. The adaptations of the musculoskeletal system due to morphological changes during pregnancy are not fully understood. Few studies clarify the biomechanical changes of gait that occur during pregnancy and in postpartum period. Purposes. The purpose of this re...

  9. Probabilistic Modeling of Intracranial Pressure Effects on Optic Nerve Biomechanics

    Ethier, C. R.; Feola, Andrew J.; Raykin, Julia; Myers, Jerry G.; Nelson, Emily S.; Samuels, Brian C.

    2016-01-01

    Altered intracranial pressure (ICP) is involved/implicated in several ocular conditions: papilledema, glaucoma and Visual Impairment and Intracranial Pressure (VIIP) syndrome. The biomechanical effects of altered ICP on optic nerve head (ONH) tissues in these conditions are uncertain but likely important. We have quantified ICP-induced deformations of ONH tissues, using finite element (FE) and probabilistic modeling (Latin Hypercube Simulations (LHS)) to consider a range of tissue properties and relevant pressures.

  10. Biomechanics of Pediatric Manual Wheelchair Mobility

    2015-01-01

    Currently, there is limited research of the biomechanics of pediatric manual wheelchair mobility. Specifically, the biomechanics of functional tasks and their relationship to joint pain and health is not well understood. To contribute to this knowledge gap, a quantitative rehabilitation approach was applied for characterizing upper extremity biomechanics of manual wheelchair mobility in children and adolescents during propulsion, starting and stopping tasks. A Vicon motion analysis system ...

  11. Sport and Exercise Biomechanics (Bios Instant Notes)

    Paul Grimshaw; Adrian Lees; Neil Fowler; Adrian Burden

    2007-01-01

    DESCRIPTION Instant Notes on Sport and Exercise Biomechanics provides a broad overview of the fundamental concepts in exercise and sport biomechanics. PURPOSE The book aims to provide instant notes on essential information about biomechanics, and is designed to help undergraduate students to grasp the corresponding subjects in physical effort rapidly and easily. AUDIENCE The book provides a useful resource for undergraduate and graduate students as a fundamental reference book. For the resear...

  12. High-performance spider webs: integrating biomechanics, ecology and behaviour.

    Harmer, Aaron M T; Blackledge, Todd A; Madin, Joshua S; Herberstein, Marie E

    2011-04-06

    Spider silks exhibit remarkable properties, surpassing most natural and synthetic materials in both strength and toughness. Orb-web spider dragline silk is the focus of intense research by material scientists attempting to mimic these naturally produced fibres. However, biomechanical research on spider silks is often removed from the context of web ecology and spider foraging behaviour. Similarly, evolutionary and ecological research on spiders rarely considers the significance of silk properties. Here, we highlight the critical need to integrate biomechanical and ecological perspectives on spider silks to generate a better understanding of (i) how silk biomechanics and web architectures interacted to influence spider web evolution along different structural pathways, and (ii) how silks function in an ecological context, which may identify novel silk applications. An integrative, mechanistic approach to understanding silk and web function, as well as the selective pressures driving their evolution, will help uncover the potential impacts of environmental change and species invasions (of both spiders and prey) on spider success. Integrating these fields will also allow us to take advantage of the remarkable properties of spider silks, expanding the range of possible silk applications from single threads to two- and three-dimensional thread networks.

  13. 新生小牛皮肤的形态学和生物力学特点及脱细胞方法探索%Study on morphologic and biomechanical properties of newborn bovine skin and method for decellularization

    陈博; 彭代智; 左海斌; 郑必祥; 周灵

    2012-01-01

    组合可制备出空间结构和脱细胞效果较为理想的新生牛脱细胞真皮基质,为修复人体软组织缺损提供有应用前景的生物材料.%Objective To compare the dermal tissue structure ,content of difference types of collagen and biomechanical properties between human and newborn bovine skin ,and to find the evidence of bovine dermal matrix used in clinic ,in order to explore the decellularization of newborn bovine skin .Methods The dorsal full-thickness of samples were stained by hematoxylin and eosin (HE) staining ,Masson's trichrome staining ,sirius red staining ,and Gomori staining,and were examined under light microscopy . These samples were also observed by scanning electron microscopy (SEM ) and transmission electron microscopy (TEM ) .The relevant data of histological images were measured with image analysis software.The biomechanical properties of those samples were detected by material testing machine .And the dermal matrix was decellularized using trypsin combined detergent .Results Compared with human skin ,the thickness of the dermis and epidermis were significantly thinner ,and the ratio between the dermis and epidermis was significantly reduced in the newborn bovine skin.The gap rate between bundles [(41 .72+1.81) vs (40 .66+1.40)] and the caliber of the bundles [(11.28+0 .18)μm vs (10 .88+0 .66)μm] were not significant in statistics (P=0 .467 ,P=0 .368) . From the observation of scanning electron microscopy (SEM) examination,the dermal collagen bundles of newborn bovine were thinner and rarefaction arranged .Compared with human dermis ,the newborn bovine had longer cyclical transverse striation ,and the collagenous fibrils had no significant difference by transmission electron microscope (TEM ) .The maximum stress of newborn bo-vine[(21.08+0 .91) Mpa] was stronger than that of human dermis [(12 .76+1 .60) Mpa,P=0 .001],and the elastic modulus were also stronger than that of human [(82 .12+1.23) Mpa vs (48 .63+5 .50) Mpa,P=0 .001].The exploration of

  14. Modeling spinal cord biomechanics

    Luna, Carlos; Shah, Sameer; Cohen, Avis; Aranda-Espinoza, Helim

    2012-02-01

    Regeneration after spinal cord injury is a serious health issue and there is no treatment for ailing patients. To understand regeneration of the spinal cord we used a system where regeneration occurs naturally, such as the lamprey. In this work, we analyzed the stress response of the spinal cord to tensile loading and obtained the mechanical properties of the cord both in vitro and in vivo. Physiological measurements showed that the spinal cord is pre-stressed to a strain of 10%, and during sinusoidal swimming, there is a local strain of 5% concentrated evenly at the mid-body and caudal sections. We found that the mechanical properties are homogeneous along the body and independent of the meninges. The mechanical behavior of the spinal cord can be characterized by a non-linear viscoelastic model, described by a modulus of 20 KPa for strains up to 15% and a modulus of 0.5 MPa for strains above 15%, in agreement with experimental data. However, this model does not offer a full understanding of the behavior of the spinal cord fibers. Using polymer physics we developed a model that relates the stress response as a function of the number of fibers.

  15. High-resolution peripheral quantitative computed tomography (HR-pQCT) can assess microstructural and biomechanical properties of both human distal radius and tibia: Ex vivo computational and experimental validations.

    Zhou, Bin; Wang, Ji; Yu, Y Eric; Zhang, Zhendong; Nawathe, Shashank; Nishiyama, Kyle K; Rosete, Fernando Rey; Keaveny, Tony M; Shane, Elizabeth; Guo, X Edward

    2016-05-01

    High-resolution peripheral quantitative computed tomography (HR-pQCT) provides in vivo three-dimensional (3D) imaging at the distal radius and tibia and has been increasingly used to characterize cortical and trabecular bone morphology in clinical studies. In this study, we comprehensively examined the accuracy of HR-pQCT and HR-pQCT based micro finite element (μFE) analysis predicted bone elastic stiffness and strength through comparisons with gold-standard micro computed tomography (μCT) based morphological/μFE measures and direct mechanical testing results. Twenty-six sets of human cadaveric distal radius and tibia segments were imaged by HR-pQCT and μCT. Microstructural analyses were performed for the registered HR-pQCT and μCT images. Bone stiffness and yield strength were determined by both HR-pQCT and μCT based linear and nonlinear μFE predictions and mechanical testing. Our results suggested that strong and significant correlations existed between the HR-pQCT standard, model-independent and corresponding μCT measurements. HR-pQCT based nonlinear μFE overestimated stiffness and yield strength while the linear μFE underestimated yield strength, but both were strongly correlated with those predicted by μCT μFE and measured by mechanical testing at both radius and tibia (R(2)>0.9). The microstructural differences between HR-pQCT and μCT were also examined by the Bland-Altman plots. Our results showed HR-pQCT morphological measurements of BV/TV(d), Tb.Th, and Tb.Sp, can be adjusted by correction values to approach true values measured by gold-standard μCT. In addition, we observed moderate correlations of HR-pQCT biomechanical and microstructural parameters between the distal radius and tibia. We concluded that morphological and mechanical properties of human radius and tibia bone can be assessed by HR-pQCT based measures.

  16. Propiedades biomecánicas y proceso de esterilización de las matrices alodérmicas usadas en periodoncia Biomechanical properties and sterilization process of allodermics matrix used on periodontic

    C.M. Ardila Medina

    2011-12-01

    . Due to the increased use of allografts on periodontics and other areas of health sciences, has brought more focus to the safety of allogenic tissue and the efficacy of various sterilization techniques. Unfortunately, these sterilization techniques could produce deleterious effects on the biomechanical properties of allogenic tissues, causing undesirable results on the interventions. Moreover, it has been suggested that despite the thoroughness of the evaluation processes and tissue donors, in addition to the processing of the matrices, there is possibility of retention of genetic material on allografts commercially available

  17. Biomechanical properties of the biceps-labral complex submitted to mechanical stress Propriedades biomecânicas do complexo labrum-glenóide bicipital superior submetido ao estresse mecânico

    Adson do Socorro Sá Costa

    2006-08-01

    Full Text Available PURPOSE: To determine biomechanical properties of the superior labrum-biceps tendon complex submitted to continuous and sudden mechanical strain. METHODS: Eighteen shoulder specimens from 15 unclaimed corpses, ages ranging from 20 to 40 years, were submitted to continuous or sudden tensile tests using 3 different traction machines. Shoulders presenting signs of degenerative diseases or preexisting traumatic lesions were excluded. RESULTS: Rupture of the distal portion of the long hand of the biceps occurred when stretching forces reached 290N in continuous traction and 384N in sudden traction. No labral-complex lesions were observed. CONCLUSION: Either a simple continuous or a sudden uniaxial traction of the arm do not play a role in the genesis of superior labrum anterior-posterior (SLAP lesions in the shoulder joint. produceOBJETIVO: Determinar as propriedades biomecânicas do complexo labrum-glenóide bicipital superior submetido ao estresse mecânico contínuo ou repetitivo (repentino. MÉTODOS: Dezoito ombros provenientes de 15 cadáveres não reclamados, idades na faixa de 20 a 40 anos, foram submetidos aos testes de tração contínua ou repentina usando três diferentes máquinas de tração. Foram excluídos do estudo os ombros que apresentavam lesões degenerativas ou evidências de lesões traumáticas pré-existentes. RESULTADOS: Ocorreu ruptura da porção distal do tendão do bíceps sob a tensão contínua de 290 N e de 348N na tração repentina. Não foram observadas lesões no complexo labrum-bicipital. CONCLUSÃO: A simples tração contínua ou súbita do braço não produz lesões do complexo Labrum Glenóide Bicipital Superior (SLAP na articulação do ombro.

  18. Graft Biomechanics Following Three Corneal Transplantation Techniques

    Feizi, Sepehr; Montahai, Talieh; Moein, Hamidreza

    2015-01-01

    Purpose: To compare corneal biomechanical properties following three different transplantation techniques, including Descemet stripping automated endothelial keratoplasty (DSAEK), deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in comparison to normal eyes. Methods: This cross-sectional comparative study included 118 eyes: 17 eyes of 17 patients received DSAEK, 23 eyes of 21 patients underwent DALK using Anwar's big bubble technique, and 45 eyes of 36 patients had PK; 33 right eyes of 33 normal subjects served as the control group. Using the ocular response analyzer (ORA, Reichert Ophthalmic Instruments, Buffalo, New York, USA), corneal hysteresis (CH) and corneal resistance factor (CRF) were measured and compared among the study groups at least 3 months after all sutures were removed. Results: Mean patient age was 26.9 ± 5.0 years in the control group, 28.8 ± 4.2 in the PK group, 27.2 ± 6.5 in the DALK group, and 62.5 ± 16.8 in the DSAEK group (P < 0.001). Central corneal thickness (CCT) was 539.0 ± 24.8, 567.5 ± 38.8, 547.0 ± 42.6 and 631.1 ± 84.8 μm, respectively (P < 0.001). CH and CRF were significantly lower in the DSAEK group (7.79 ± 2.0 and 7.88 ± 1.74 mmHg, respectively) as compared to the PK (10.23 ± 2.07 and 10.13 ± 2.22 mmHg, respectively) and DALK (9.64 ± 2.07 and 9.36 ± 2.09 mmHg, respectively) groups. The two latter groups demonstrated biomechanical parameters comparable to normal subjects (9.84 ± 1.59 and 9.89 ± 1.73 mmHg, respectively). Conclusion: Graft biomechanical parameters after DSAEK are lower than those following PK and DALK. After PK and DALK in keratoconic eyes, these metrics are increased to normal values. These differences may have implications for interpreting intraocular pressure or planning graft refractive surgery after keratoplasty. PMID:26730307

  19. Tibiofemoral cartilage contact biomechanics in patients after reconstruction of a ruptured anterior cruciate ligament.

    Hosseini, Ali; Van de Velde, Samuel; Gill, Thomas J; Li, Guoan

    2012-11-01

    We investigated the in vivo cartilage contact biomechanics of the tibiofemoral joint in patients after reconstruction of a ruptured anterior cruciate ligament (ACL). A dual fluoroscopic and MR imaging technique was used to investigate the cartilage contact biomechanics of the tibiofemoral joint during in vivo weight-bearing flexion of the knee in eight patients 6 months following clinically successful reconstruction of an acute isolated ACL rupture. The location of tibiofemoral cartilage contact, size of the contact area, cartilage thickness at the contact area, and magnitude of the cartilage contact deformation of the ACL-reconstructed knees were compared with those previously measured in intact (contralateral) knees and ACL-deficient knees of the same subjects. Contact biomechanics of the tibiofemoral cartilage after ACL reconstruction were similar to those measured in intact knees. However, at lower flexion, the abnormal posterior and lateral shift of cartilage contact location to smaller regions of thinner tibial cartilage that has been described in ACL-deficient knees persisted in ACL-reconstructed knees, resulting in an increase of the magnitude of cartilage contact deformation at those flexion angles. Reconstruction of the ACL restored some of the in vivo cartilage contact biomechanics of the tibiofemoral joint to normal. Clinically, recovering anterior knee stability might be insufficient to prevent post-operative cartilage degeneration due to lack of restoration of in vivo cartilage contact biomechanics.

  20. Urine - abnormal color

    ... medlineplus.gov/ency/article/003139.htm Urine - abnormal color To use the sharing features on this page, please enable JavaScript. The usual color of urine is straw-yellow. Abnormally colored urine ...

  1. Aortic biomechanics in hypertrophic cardiomyopathy

    Badran, Hala Mahfouz; Soltan, Ghada; Faheem, Nagla; Elnoamany, Mohamed Fahmy; Tawfik, Mohamed; Yacoub, Magdi

    2015-01-01

    Background: Ventricular-vascular coupling is an important phenomenon in many cardiovascular diseases. The association between aortic mechanical dysfunction and left ventricular (LV) dysfunction is well characterized in many disease entities, but no data are available on how these changes are related in hypertrophic cardiomyopathy (HCM). Aim of the work: This study examined whether HCM alone is associated with an impaired aortic mechanical function in patients without cardiovascular risk factors and the relation of these changes, if any, to LV deformation and cardiac phenotype. Methods: 141 patients with HCM were recruited and compared to 66 age- and sex-matched healthy subjects as control group. Pulse pressure, aortic strain, stiffness and distensibility were calculated from the aortic diameters measured by M-mode echocardiography and blood pressure obtained by sphygmomanometer. Aortic wall systolic and diastolic velocities were measured using pulsed wave Doppler tissue imaging (DTI). Cardiac assessment included geometric parameters and myocardial deformation (strain and strain rate) and mechanical dyssynchrony. Results: The pulsatile change in the aortic diameter, distensibility and aortic wall systolic velocity (AWS') were significantly decreased and aortic stiffness index was increased in HCM compared to control (P < .001) In HCM AWS' was inversely correlated to age(r = − .32, P < .0001), MWT (r = − .22, P < .008), LVMI (r = − .20, P < .02), E/Ea (r = − .16, P < .03) LVOT gradient (r = − 19, P < .02) and severity of mitral regurg (r = − .18, P < .03) but not to the concealed LV deformation abnormalities or mechanical dyssynchrony. On multivariate analysis, the key determinant of aortic stiffness was LV mass index and LVOT obstruction while the role LV dysfunction in aortic stiffness is not evident in this population. Conclusion: HCM is associated with abnormal aortic mechanical properties. The severity of cardiac

  2. Corneal Biomechanical Findings in Contact Lens Induced Corneal Warpage

    Letafatnejad, Mojgan; Beheshtnejad, Amir Hooshang; Ghaffary, Seyed Reza; Hassanpoor, Narges; Yaseri, Mehdi

    2016-01-01

    Purpose. To evaluate the difference in biomechanical properties between contact lens induced corneal warpage and normal and keratoconic eyes. Method. Prospective observational case control study, where 94 eyes of 47 warpage suspicious and 46 eyes of 23 keratoconic patients were included. Warpage suspected cases were followed until a definite diagnosis was made (warpage, normal, or keratoconus). Results. 44 eyes of 22 patients had contact lens related corneal warpage. 46 eyes of 23 people were diagnosed as nonwarpage normal eyes. 46 eyes of 23 known keratoconus patients were included for comparison. The mean age of the participants was 23.8 ± 3.8 years, and 66.2% of the subjects were female. The demographic and refractive data were not different between warpage and normal groups but were different in the keratoconus group. The biomechanical properties (corneal hysteresis or CH and corneal resistance factor or CRF) were different with the highest value in the warpage group followed by normal and keratoconus groups. CRF was 10.08 ± 1.75, 9.23 ± 1.22, and 7.38 ± 2.14 and CH was 10.21 ± 1.57, 9.59 ± 1.21, and 8.69 ± 2.34 in the warpage, normal, and keratoconus groups, respectively. Conclusion. Corneal biomechanics may be different in people who develop contact lens induced warpage. PMID:27688908

  3. Multiscale modeling methods in biomechanics.

    Bhattacharya, Pinaki; Viceconti, Marco

    2017-01-19

    More and more frequently, computational biomechanics deals with problems where the portion of physical reality to be modeled spans over such a large range of spatial and temporal dimensions, that it is impossible to represent it as a single space-time continuum. We are forced to consider multiple space-time continua, each representing the phenomenon of interest at a characteristic space-time scale. Multiscale models describe a complex process across multiple scales, and account for how quantities transform as we move from one scale to another. This review offers a set of definitions for this emerging field, and provides a brief summary of the most recent developments on multiscale modeling in biomechanics. Of all possible perspectives, we chose that of the modeling intent, which vastly affect the nature and the structure of each research activity. To the purpose we organized all papers reviewed in three categories: 'causal confirmation,' where multiscale models are used as materializations of the causation theories; 'predictive accuracy,' where multiscale modeling is aimed to improve the predictive accuracy; and 'determination of effect,' where multiscale modeling is used to model how a change at one scale manifests in an effect at another radically different space-time scale. Consistent with how the volume of computational biomechanics research is distributed across application targets, we extensively reviewed papers targeting the musculoskeletal and the cardiovascular systems, and covered only a few exemplary papers targeting other organ systems. The review shows a research subdomain still in its infancy, where causal confirmation papers remain the most common. For further resources related to this article, please visit the WIREs website.

  4. Exploring the biomechanics of taurodontism

    Benazzi, Stefano; Nguyen, Huynh N; Kullmer, Ottmar; Hublin, Jean-Jacques

    2015-01-01

    Taurodontism (i.e. enlarged pulp chamber with concomitant apical displacement of the root bi/trifurcation) is considered a dental anomaly with relatively low incidence in contemporary societies, but it represents a typical trait frequently found in Neandertal teeth. Four hypotheses can be envisioned to explain the high frequency in Neandertals: adaptation to a specific occlusal loading regime (biomechanical advantage), adaptation to a high attrition diet, pleiotropic or genetic drift effects. In this contribution we used finite element analysis (FEA) and advanced loading concepts based on macrowear information to evaluate whether taurodontism supplies some dental biomechanical advantages. Loads were applied to the digital model of the lower right first molar (RM1) of the Neandertal specimen Le Moustier 1, as well as to the digital models of both a shortened and a hyper-taurodontic version of Le Moustier RM1. Moreover, we simulated a scenario where an object is held between teeth and pulled in different directions to investigate whether taurodontism might be useful for para-masticatory activities. Our results do not show any meaningful difference among all the simulations, pointing out that taurodontism does not improve the functional biomechanics of the tooth and does not favour para-masticatory pulling activities. Therefore, taurodontism should be considered either an adaptation to a high attrition diet or most likely the result of pleiotropic or genetic drift effects. Finally, our results have important implications for modern dentistry during endodontic treatments, as we observed that filling the pulp chamber with dentine-like material increases tooth stiffness, and ultimately tensile stresses in the crown, thus favouring tooth failure. PMID:25407030

  5. Applied Biomechanics in an Instructional Setting

    Hudson, Jackie L.

    2006-01-01

    Biomechanics is the science of how people move better, meaning more skillfully and more safely. This article places more emphasis on skill rather than safety, though there are many parallels between them. It shares a few features of the author's paradigm of applied biomechanics and discusses an integrated approach toward a middle school football…

  6. Changes of Biomechanical Properties of Soft Tissues in Underwater Corpse for Postmortem Interval Estimation%水中尸体软组织生物力学性状时序性变化用于死亡时间推断

    唐谷; 周晖; 汪家文; 钱红; 赖跃; 于晓军

    2012-01-01

    目的 探讨水中浸泡尸体软组织生物力学性状的时序性变化规律及其用于PMI推断的价值. 方法 SD大鼠颈椎脱臼处死后恒温下置于自来水中浸泡,按死后0、6、12、18、24、30、36、42、48、60、72、96、120、144、168、192h时间点分组,分别取血管壁、皮肤、肌肉、小肠和结肠组织,应用万能材料试验机检测各组织的极限载荷、应变、最大应力等生物力学参数. 结果 除血管壁外,皮肤、肌肉、小肠和结肠等软组织的生物力学性状均随死亡时间呈逐渐下降时序性变化,存在各自不同的与PMI明显线性关系的“窗口期”. 结论 水中尸体软组织的生物力学性状的时序性变化与PMI之间存在一定规律性相关,可作为推断PMI的一种简便和量化的新技术手段.尸体周围散热介质的比热容可能是影响尸温、组织自溶腐败及其生物力学性状的物理学因素之一.%Objective To explore the postmortem changes of biomechanical properties of underwater corpses and value for estimating postmortem interval. Methods SD rats were sacrificed by cervical vertebra dislocation and stored in the water at constant temperature. The vessel wall, skin, muscle, small intestine and colon were sampled at different postmortem time points (0 h, 6 h, 12 h, 18 h, 24 h, 30 h, 36 h, 42 h, 48 h, 60h, 72h, 96h, 120h, 144h, 168h, 192h). The biomechanics properties of different soft tissues including ultimate load, strain, maximum stress were measured by electronic universal material testing machine. Results Except for the vessel wall, the biomechanics properties of skin, muscle, small intestine and colon showed linear decrease gradually after death. Each tissue displayed its obvious "window period" for PMI estimation. Conclusion The time-sequential changes of biomechanical property parameters of soft tissue in underwater corpses are significantly correlated with PMI and it could be a simple and quantitive new

  7. Effects of lovastatin on bone mass and biomechanical property in tail-suspended rats%洛伐他汀对尾悬吊大鼠骨量及生物力学性能的影响

    何余庆; 郑杰; 赵嘉懿

    2012-01-01

    目的 通过尾悬吊法制作拟失重大鼠骨质疏松动物模型,观察洛伐他汀体内给药对尾悬吊大鼠骨量、微观结构、生物力学性能的作用潜能.方法 将24只10周龄雄性SD大鼠随机分成3组,每组各8只:正常对照组(G1组,8只,每日予蒸馏水灌胃)、尾悬吊组(G2组,将大鼠在悬吊笼中尾部悬吊,后肢离地,使躯干与地面成40°角,同时每日予每天蒸馏水灌胃)、尾悬吊加洛伐他汀组(G3组,在尾部悬吊基础上,每日予20mg/kg洛伐他汀灌胃);4周后处死所有大鼠,取大鼠右侧股骨用双能X线骨密度仪测量骨密度,并取胫骨近端进行骨组织形态计量学测定;同时取大鼠左侧股骨行生物力学检测.结果 G1组的右股骨各段骨密度和骨小梁相对体积、左股骨最大载荷量显著高于G2、G3组(均P<0.05),G1组的骨小梁分离度及骨吸收周长百分数、破骨细胞数、类骨质周长百分数显著低于G2、G3组(均P<0.05),且G2、G3组上述指标的差异均无统计学意义(均P >0.05).结论 尾悬吊4周可导致大鼠骨量丢失;洛伐他汀体内给药不能阻止尾悬吊大鼠股骨骨量丢失.%To investigate the effects of lovastatin on bone mass,microarchitecture and biomechanical property,and to observe the potential protective effect of lovastatin on unloading-induced osteoporosis.MethodsTwenty-four 10-week-old male Sprague-Dawley rats were randomized into three groups of eight animals each: G1, control group; G2, the tail-suspended group with vehicle; G3, the tail-suspended group and administered daily with 20 mg/kg of lovastatin by gavage. The experiment was lasted for four weeks, and all animals were sacrificed one day after the final lovastatin administration. The right femurs were harvested for the measurement of bone histomorphometry, and bone mineral density (BMD) measured by dual-energy X-ray absorptiometry.The left femurs were collected for biomechanical test.ResultsThe tBMD,pBMD and dBMD of

  8. Change of biomechanical properties in porcine sclera treated with genipin%京尼平诱导猪眼巩膜胶原交联后生物力学性能变化

    刘太祥; 吴君舒; 顾宇伟; 杨斌; 王铮

    2014-01-01

    Objective Investigate the change of biomechanical properties in porcine sclera treated with genipin and to explore a potential method to prevent the progerssion of myopia.Methods Experimental study.Forty-five porcine cadaver eyes were randomly divided into 9 groups and each group had 5 eyes.Eyes were treated with genipin at concentrations (by w/v) of 0.01%,0.10%,1.00% for 30 min.Riboflavin/ultraviolet-A (UVA) treated and untreated samples were used as controls.After treatment,scleral strips of 4.0 mm×10.0 mm were cut.At 24 h after treatment,the stress-strain parameters of the strips were measured using a INSTRON 3343 biomaterial microtester.Additionally,we also performed the stress-strain test at 1,6,12,24 and 36 h after treated with 1.00% genipin.Meanwhile the discoloration of sclera were observed and recorded with slit lamp camera system.The difference of the ultimate stress and modulus between treated and untreated groups were analyzed with One-Way ANOVA in SPSS 17.0.Results Compared with untreated groups,after treatment with genipin for 30 min,the ultimate stress and modulus were increased by 205% to 498% and 109% to 467% respectively.0.01% genipin for 30min had a similar stress-strain curve with those of eyes treated with riboflavin/UVA.Within 24 h after treating with 1.00% genipin,the sclera exhibited a bluish color which became deeper with time.And at 1,6,12,24 and 36 h after treatment,the ultimate stress were increased by 53%,146%,164%,223% and 175% respectively.The modulus at 8% strain also increased by 80%,151%,185%,352% and 296%.Conclusion Collagen crosslinking treated with genipin could increase the biomechanical strength in porcine sclera.The effect depends on the concentration of genipin.%目的 观察京尼平诱导胶原交联后猪眼巩膜生物力学的变化,为防治近视的发展探寻潜在的方法.方法 实验研究.离体猪眼45只,通过简单随机化方法分为9组,每组5眼.以0.01%、0

  9. Biomechanical performance of orthopedic gloves.

    Jackson, E M; Neal, J G; Williams, F M; Stern, C A; Suber, F; Thacker, J G; Edlich, R F

    1999-01-01

    The purpose of this study was to compare the biomechanical performance of commercially available orthopedic gloves to that of a single surgical glove, as well as a double glove system. The orthopedic gloves were found to be thicker than the single surgical glove. This increased thickness of the orthopedic glove was associated with a greater resistance to glove puncture. The thickest orthopedic gloves also had reduced tactile sensitivity when compared to the single surgical glove. In addition, the glove donning forces and glove hydration rates varied considerably. These latter biomechanical performance parameters were not significantly related to glove thickness. The double glove systems tested in this study had similar performance characteristics in regard to many of the orthopedic gloves. The glove donning forces for the double glove systems were the lowest of the gloves tested. In addition, the double glove systems displayed the greatest resistance to glove hydration of the gloves tested. Their performance in the glove hydration tests and the force required to don the double glove systems were much more desirable than any of the orthopedic gloves. The results of this study indicate that the double glove systems may provide a desirable alternative to the use of the single orthopedic gloves.

  10. Effects of exogenous IGF-1 on bone mineral density and biomechanical properties of ovariectomized rats%IGF-1对去卵巢大鼠骨密度及骨力学强度的影响

    赵荣兰; 刘新宇; 孙蓓; 梁东春; 郭刚; 张镜宇

    2008-01-01

    Objective To study the effects of exogenous IGF-1 on bone mineral density,bone turnover and bone biomechanical properties of ovariectomized (OVX) rats.Methods Sprague-Dawley rats were either ovariectomized (n=60) or sham operated (n=10).Three months after the operation,the existence of osteoporosis in OVX rats was confirmed by bone mineral densitometry.OVX rats were randomly separated into 5 groups,subjected to the treatment of PTH1-34,three different-dosage of IGF-1 or normal saline (NS) respectively.Sham rats,treated with NS,was established as sham control.Eight weeks alter the treatment,serum levels of Ca,P,steocalcin concentration and alkaline phosphatase (ALP) activity were assayed.The bone mineral density of lumbar spine and the mechanical strength of the femur were determined.The bone thick-ness of distal femur was determined by histological staining.Results IGF-1 did not improve the bone miner-81 density of lumbar spine in OVX rats,but significantly improved their mechanical strength.Serological test results showed that IGF-1 could lower serum calcium,phosphorus,calcium levels and ALP activity;histological staining showed that IGF-1 could significantly increase the femur bone thickness of OVX rats.Conclusion IGF-1 Can increase the mechanical strength of the femug in OVX rats through reconstructing bone architee-ture rather than increasing bone mineral density.%目的 研究外源性胰岛素样生长因子-1(IGF-1)对去卵巢(OVX)骨质疏松大鼠骨密度、骨转换率、骨力学强度等方面的影响.方法 对大鼠施行双侧卵巢摘除术,术后3个月以骨密度测定证实骨质疏松的存在后,随机分为5组,分别以生理盐水、甲状旁腺激素1-34及3种不同剂量IGF-1进行干预.同时设立生理盐水干预的假手术大鼠作为对照.8周后检测血清钙、磷、骨钙素水平及碱性磷酸酶活性;测定腰椎骨密度、股骨力学强度;组织学染色测定股骨远端骨皮质厚度.结果 IGF-1虽未提

  11. Graphic-based musculoskeletal model for biomechanical analyses and animation.

    Chao, Edmund Y S

    2003-04-01

    The ability to combine physiology and engineering analyses with computer sciences has opened the door to the possibility of creating the 'Virtual Human' reality. This paper presents a broad foundation for a full-featured biomechanical simulator for the human musculoskeletal system physiology. This simulation technology unites the expertise in biomechanical analysis and graphic modeling to investigate joint and connective tissue mechanics at the structural level and to visualize the results in both static and animated forms together with the model. Adaptable anatomical models including prosthetic implants and fracture fixation devices and a robust computational infrastructure for static, kinematic, kinetic, and stress analyses under varying boundary and loading conditions are incorporated on a common platform, the VIMS (Virtual Interactive Musculoskeletal System). Within this software system, a manageable database containing long bone dimensions, connective tissue material properties and a library of skeletal joint system functional activities and loading conditions are also available and they can easily be modified, updated and expanded. Application software is also available to allow end-users to perform biomechanical analyses interactively. This paper details the design, capabilities, and features of the VIMS development at Johns Hopkins University, an effort possible only through academic and commercial collaborations. Examples using these models and the computational algorithms in a virtual laboratory environment are used to demonstrate the utility of this unique database and simulation technology. This integrated system will impact on medical education, basic research, device development and application, and clinical patient care related to musculoskeletal diseases, trauma, and rehabilitation.

  12. Biomechanics and analysis of running gait.

    Dugan, Sheila A; Bhat, Krishna P

    2005-08-01

    Physical activity, including running, is important to general health by way of prevention of chronic illnesses and their precursors. To keep runners healthy, it is paramount that one has sound knowledge of the biomechanics of running and assessment of running gait. More so, improving performance in competitive runners is based in sound training and rehabilitation practices that are rooted firmly in biomechanical principles. This article summarized the biomechanics of running and the means with which one can evaluate running gait. The gait assessment techniques for collecting and analyzing kinetic and kinematic data can provide insights into injury prevention and treatment and performance enhancement.

  13. [Biomechanics of the ankle joint].

    Zwipp, H

    1989-03-01

    According to Fick, the tree-dimensional patterns of foot motion are best characterized as jawlike movement. Anatomically and biomechanically, this process represents conjoined, synchronous motion within the three mobile segments of the hindfoot: the ankle joint, the posterior subtalar joint, and the anterior subtalar joint. Foot kinematics can be described more completely if the anterior subtalar joint is defined not only as the talocalcaneal navicular joint, but as including the calcaneocuboid joint, thus representing the transverse joint of the tarsus, i.e., the Chopart joint. The axes of these three joints can be defined precisely. In some parts they represent a screwlike motion, clockwise or counter-clockwise, around the central ligamentous structures (fibulotibial ligament, talocalcaneal interosseous ligament, bifurcate ligament). The individual anatomy and structure of these ligaments provide variations in the degree and direction of foot motion. A precise knowledge of foot kinematics is important in surgical ligament and joint reconstruction and in selective foot arthrodeses.

  14. Biomechanics of knife stab attacks.

    Chadwick, E K; Nicol, A C; Lane, J V; Gray, T G

    1999-10-25

    Equipment, materials and methods for the measurement of the biomechanical parameters governing knife stab attacks have been developed and data have been presented that are relevant to the improvement of standards for the testing of stab-resistant materials. A six-camera Vicon motion analysis system was used to measure velocity, and derive energy and momentum during the approach phase of the attack and a specially developed force-measuring knife was used to measure three-dimensional forces and torque during the impact phase. The body segments associated with the knife were modelled as a series of rigid segments: trunk, upper arm, forearm and hand. The velocities of these segments, together with knowledge of the mass distribution from biomechanical tables, allowed the calculation of the individual segment energy and momentum values. The instrumented knife measured four components of load: axial force (along the length of the blade), cutting force (parallel to the breadth of the blade), lateral force (across the blade) and torque (twisting action) using foil strain gauges. Twenty volunteers were asked to stab a target with near maximal effort. Three styles of stab were used: a short thrust forward, a horizontal style sweep around the body and an overhand stab. These styles were chosen based on reported incidents, providing more realistic data than had previously existed. The 95th percentile values for axial force and energy were 1885 N and 69 J, respectively. The ability of current test methods to reproduce the mechanical parameters measured in human stab attacks has been assessed. It was found that current test methods could reproduce the range of energy and force values measured in the human stab attacks, although the simulation was not accurate in some respects. Non-axial force and torque values were also found to be significant in the human tests, but these are not reproduced in the standard mechanical tests.

  15. Patient-specific biomechanical model as whole-body CT image registration tool.

    Li, Mao; Miller, Karol; Joldes, Grand Roman; Doyle, Barry; Garlapati, Revanth Reddy; Kikinis, Ron; Wittek, Adam

    2015-05-01

    Whole-body computed tomography (CT) image registration is important for cancer diagnosis, therapy planning and treatment. Such registration requires accounting for large differences between source and target images caused by deformations of soft organs/tissues and articulated motion of skeletal structures. The registration algorithms relying solely on image processing methods exhibit deficiencies in accounting for such deformations and motion. We propose to predict the deformations and movements of body organs/tissues and skeletal structures for whole-body CT image registration using patient-specific non-linear biomechanical modelling. Unlike the conventional biomechanical modelling, our approach for building the biomechanical models does not require time-consuming segmentation of CT scans to divide the whole body into non-overlapping constituents with different material properties. Instead, a Fuzzy C-Means (FCM) algorithm is used for tissue classification to assign the constitutive properties automatically at integration points of the computation grid. We use only very simple segmentation of the spine when determining vertebrae displacements to define loading for biomechanical models. We demonstrate the feasibility and accuracy of our approach on CT images of seven patients suffering from cancer and aortic disease. The results confirm that accurate whole-body CT image registration can be achieved using a patient-specific non-linear biomechanical model constructed without time-consuming segmentation of the whole-body images.

  16. THE CENTER FOR MILITARY BIOMECHANICS RESEARCH

    Federal Laboratory Consortium — The Center for Military Biomechanics Research is a 7,500 ft2 dedicated laboratory outfitted with state-of-the-art equipment for 3-D analysis of movement, measurement...

  17. Biomechanical patterns of text-message distraction.

    Le, Peter; Hwang, Jaejin; Grawe, Sarah; Li, Jing; Snyder, Alison; Lee, Christina; Marras, William S

    2015-01-01

    The objective of this study was to identify biomechanical measures that can distinguish texting distraction in a laboratory-simulated driving environment. The goal would be to use this information to provide an intervention for risky driving behaviour. Sixteen subjects participated in this study. Three independent variables were tested: task (texting, visual targeting, weighted and non-weighted movements), task direction (front and side) and task distance (close and far). Dependent variables consisted of biomechanical moments, head displacement and the length of time to complete each task. Results revealed that the time to complete each task was higher for texting compared to other tasks. Peak moments during texting were only distinguishable from visual targeting. Peak head displacement and cumulative biomechanical exposure measures indicated that texting can be distinguished from other tasks. Therefore, it may be useful to take into account both temporal and biomechanical measures when considering warning systems to detect texting distraction.

  18. Hereditary urea cycle abnormality

    ... vitro so the specific genetic cause is known. Teamwork between parents, the affected child, and doctors can help prevent severe illness. Alternative Names Abnormality of the urea cycle - hereditary; Urea cycle - hereditary abnormality Images Male urinary system Urea cycle References Lichter-Konecki ...

  19. Biomechanical study of intervertebral disc degeneration

    González Guitiérrez, Ramiro Arturo

    2012-01-01

    Degeneration and age affect the biomechanics of the intervertebral disc, by reducing its stiffness, flexibility and shock absorption capacities against daily movement and spinal load. The biomechanical characterization of intervertebral discs is achieved by conducting mechanical testing to vertebra-disc-vertebra segments and applying axial, shear, bend and torsion loads, statically or dynamically, with load magnitudes corresponding to the physiological range. However, traditional testing does...

  20. Harnessing Biomechanics to Develop Cartilage Regeneration Strategies

    Athanasiou, KA; Responte, DJ; Brown, WE; Hu, JC

    2015-01-01

    Copyright © 2015 by ASME. As this review was prepared specifically for the American Society of Mechanical Engineers H.R. Lissner Medal, it primarily discusses work toward cartilage regeneration performed in Dr. Kyriacos A. Athanasiou's laboratory over the past 25 years. The prevalence and severity of degeneration of articular cartilage, a tissue whose main function is largely biomechanical, have motivated the development of cartilage tissue engineering approaches informed by biomechanics. Thi...

  1. Mechanics without muscle: biomechanical inspiration from the plant world.

    Martone, Patrick T; Boller, Michael; Burgert, Ingo; Dumais, Jacques; Edwards, Joan; Mach, Katharine; Rowe, Nick; Rueggeberg, Markus; Seidel, Robin; Speck, Thomas

    2010-11-01

    Plant and animal biomechanists have much in common. Although their frame of reference differs, they think about the natural world in similar ways. While researchers studying animals might explore airflow around flapping wings, the actuation of muscles in arms and legs, or the material properties of spider silk, researchers studying plants might explore the flow of water around fluttering seaweeds, the grasping ability of climbing vines, or the material properties of wood. Here we summarize recent studies of plant biomechanics highlighting several current research themes in the field: expulsion of high-speed reproductive projectiles, generation of slow movements by shrinking and swelling cell walls, effects of ontogenetic shifts in mechanical properties of stems, flexible reconfiguration and material properties of seaweeds under crashing waves, and the development of botanically-inspired commercial products. Our hope is that this synopsis will resonate with both plant and animal biologists, encourage cross-pollination across disciplines, and promote fruitful interdisciplinary collaborations in the future.

  2. Biomechanical properties of relevant blood vessels in the heterogeneic heart transplantation from swine to human%猪→人异种心脏移植中相关血管的生物力学特性

    张一飞; 余明华; 唐杰; 黄铁柱

    2006-01-01

    BACKGROUND: The source of conspecific heart transplantation organ is very limited and deficiency becomes more and more obvious.OBJECTIVE: To observe the mechanical properties of ascending aorta at one-dimensional loading between healthy persons and swine of different months, so as to provide necessary biomechanical experimental basis for anastomosing blood vessel in heterogeneic heart transplantation from swine to human.DESIGN: Open design SETTING: Staff Room of Anatomy, Yunyang Medical College MATERIALS: This experiment was carried out at the Laboratory of Biomechanics, Yunyang Medical College from April 2002 to July 2003.Ascending aortas of human were obtained from the 6 adult male corpses without cardiovascular diseases, aged 18 to 30 years, who died for accident and donated by Yunyang Medical College. Totally 42 conspecific swine of 1 month old, with certification number of QN0202, were provided by Animal Experimental Center of Yunyang Medical College. They were raised with common foodstuff. The 42 swine were butchered respectively at 1,2,3,4,5,6 and 7 months, 6 swine once. After anatomical isolation and in situ measurement of respective in vivo length, ascending aorta from aorta valve ring base plane to initiation part of innominate artery was taken out (Artherosclerosis was not presented in all the samples) and divided into five equal segments, and the second and fourth segments were used for mechanical test of one-dimensional loading.METHODS: Six adult male corpses and ascending aorta of 42 swine of 1 to 7 months were performed mechanical test of one-dimensional loading.All the blood segments were pre-treated ten times with the same strain rate at room temperature 32 ℃(loading range from 0 to 0.5 N). Hysteresis disappeared after blood vessel was given periodic permanent loading and unloading, and repeated force-deformed data were obtained. Blood vessel was given loading and unloading once with the same loading range and strain rate. The recorded force

  3. Biomechanical and nonfunctional assessment of physical capacity in male ICU survivors

    Poulsen, Jesper Brøndum; Rose, Martin Høyer; Jensen, Bente Rona

    2013-01-01

    : ICU admission is associated with decreased physical function for years after discharge. The underlying mechanisms responsible for this muscle function impairment are undescribed. The aim of this study was to describe the biomechanical properties of the quadriceps muscle in ICU survivors 12 mont...

  4. "Jeopardy" in Abnormal Psychology.

    Keutzer, Carolin S.

    1993-01-01

    Describes the use of the board game, Jeopardy, in a college level abnormal psychology course. Finds increased student interaction and improved application of information. Reports generally favorable student evaluation of the technique. (CFR)

  5. Chromosomal Abnormalities in ADHD

    J Gordon Millichap

    2002-07-01

    Full Text Available The prevalence of fragile X syndrome, velocardiofacial syndrome (VCFS, and other cytogenetic abnormalities among 100 children (64 boys with combined type ADHD and normal intelligence was assessed at the NIMH and Georgetown University Medical Center.

  6. Abnormal menstrual periods (image)

    ... may have a variety of causes, such as endometrial hyperplasia, endometrial polyps, uterine fibroids, and abnormal thyroid or ... the endometrium becomes unusually thick it is called endometrial ... Hyperplasia may cause profuse or extended menstrual bleeding.

  7. Chromosomal abnormalities and autism

    Farida El-Baz

    2016-01-01

    Conclusion: Chromosomal abnormalities were not detected in the studied autistic children, and so the relation between the genetics and autism still needs further work up with different study methods and techniques.

  8. Pilot biomechanical design of biomaterials for artificial nucleus prosthesis using 3D finite-element modeling

    Qijin Huang; Guoquan Liu; Yong Li; Jin Gao; Zhengqiu Gu; Yuanzheng Ma; Haibin Xue

    2004-01-01

    Pilot biomechanical design of biomaterials for artificial nucleus prosthesis was carried out based on the 3D finite-element method. Two 3D models of lumbar intervertebral disc respectively with a real human nucleus and with the nucleus removed were developed and validated using published experimental and clinical data. Then the models with a stainless steel nucleus prosthesis implanted and with polymer nucleus prostheses of various properties implanted were used for the 3D finite-element biomechanical analysis. All the above simulation and analysis were carried out for the L4/L5 disc under a human worst-daily compression load of 2000 N. The results show that the polymer materials with Young's modulus of elasticity E = 0.1-100 MPa and Poisson's ratio v=0.35-0.5 are suitable to produce artificial nucleus prosthesis in view of biomechanical consideration.

  9. Biomechanical evaluation of wrist-driven flexor hinge orthosis in persons with spinal cord injury.

    Kang, Yeoun-Seung; Park, Yoon-Ghil; Lee, Bum-Suk; Park, Hyung-Soon

    2013-01-01

    The wrist-driven flexor hinge orthosis (WDFHO) is a device used to restore hand function in persons with tetraplegic spinal cord injury by furnishing three-point prehension. We assessed the effectiveness and biomechanical properties of the WDFHO in 24 persons with cervical 6 or 7 tetraplegia who have severely impaired hand function. This study introduces a mechanical operating model to assess the efficiency of the WDFHO. Experimental results showed that pinch force increased significantly (p < 0.001) after using the WDFHO and was found to positively correlate with the strength of wrist extensor muscles (r = 0.41, p < 0.001). However, when the strength of the wrist extensors acting on the WDFHO was greater, the reciprocal wrist and finger motion that generates three-point prehension was less effective (r = 0.79, p < 0.001). Reliable and valid biomechanical evaluation of the WDFHO could improve our understanding of its biomechanics.

  10. Biomechanical evaluation of wrist-driven flexor hinge orthosis in persons with spinal cord injury

    Yeoun-Seung Kang, MD, PhD, CPO

    2013-11-01

    Full Text Available The wrist-driven flexor hinge orthosis (WDFHO is a device used to restore hand function in persons with tetraplegic spinal cord injury by furnishing three-point prehension. We assessed the effectiveness and biomechanical properties of the WDFHO in 24 persons with cervical 6 or 7 tetraplegia who have severely impaired hand function. This study introduces a mechanical operating model to assess the efficiency of the WDFHO. Experimental results showed that pinch force increased significantly (p < 0.001 after using the WDFHO and was found to positively correlate with the strength of wrist extensor muscles (r = 0.41, p < 0.001. However, when the strength of the wrist extensors acting on the WDFHO was greater, the reciprocal wrist and finger motion that generates three-point prehension was less effective (r = 0.79, p < 0.001. Reliable and valid biomechanical evaluation of the WDFHO could improve our understanding of its biomechanics.

  11. Abnormal protein aggregationand neurodegenerativediseases

    2001-01-01

    Abnormal protein aggregation or amyloid is the major cause ofmany neurodegenerative disorders. The present review focuses on the correlation between sequence and structure features of proteins related to the diseases and abnormal protein aggregation. Recent progress has improved our knowledge on understand-ing the mechanism of amyloid formation. We suggest a nucleation model for ordered protein aggregation, which can also explain pathogenesis mechanisms of these neurodegenerative diseases in vivo.

  12. Lower limb biomechanics during running in individuals with achilles tendinopathy: a systematic review

    Munteanu Shannon E

    2011-05-01

    Full Text Available Abstract Background Abnormal lower limb biomechanics is speculated to be a risk factor for Achilles tendinopathy. This study systematically reviewed the existing literature to identify, critique and summarise lower limb biomechanical factors associated with Achilles tendinopathy. Methods We searched electronic bibliographic databases (Medline, EMBASE, Current contents, CINAHL and SPORTDiscus in November 2010. All prospective cohort and case-control studies that evaluated biomechanical factors (temporospatial parameters, lower limb kinematics, dynamic plantar pressures, kinetics [ground reaction forces and joint moments] and muscle activity associated with mid-portion Achilles tendinopathy were included. Quality of included studies was evaluated using the Quality Index. The magnitude of differences (effect sizes between cases and controls was calculated using Cohen's d (with 95% CIs. Results Nine studies were identified; two were prospective and the remaining seven case-control study designs. The quality of 9 identified studies was varied, with Quality Index scores ranging from 4 to 15 out of 17. All studies analysed running biomechanics. Cases displayed increased eversion range of motion of the rearfoot (d = 0.92 and 0.67 in two studies, reduced maximum lower leg abduction (d = -1.16, reduced ankle joint dorsiflexion velocity (d = -0.62 and reduced knee flexion during gait (d = -0.90. Cases also demonstrated a number of differences in dynamic plantar pressures (primarily the distribution of the centre of force, ground reaction forces (large effects for timing variables and also showed reduced peak tibial external rotation moment (d = -1.29. Cases also displayed differences in the timing and amplitude of a number of lower limb muscles but many differences were equivocal. Conclusions There are differences in lower limb biomechanics between those with and without Achilles tendinopathy that may have implications for the prevention and management of

  13. Developmental biomechanics of the human cervical spine.

    Nuckley, David J; Linders, David R; Ching, Randal P

    2013-04-05

    Head and neck injuries, the leading cause of death for children in the U.S., are difficult to diagnose, treat, and prevent because of a critical void in our understanding of the biomechanical response of the immature cervical spine. The objective of this study was to investigate the functional and failure biomechanics of the cervical spine across multiple axes of loading throughout maturation. A correlational study design was used to examine the relationships governing spinal maturation and biomechanical flexibility curves and tolerance data using a cadaver human in vitro model. Eleven human cadaver cervical spines from across the developmental spectrum (2-28 years) were dissected into segments (C1-C2, C3-C5, and C6-C7) for biomechanical testing. Non-destructive flexibility tests were performed in tension, compression, flexion, extension, lateral bending, and axial rotation. After measuring their intact biomechanical responses, each segment group was failed in different modes to measure the tissue tolerance in tension (C1-C2), compression (C3-C5), and extension (C5-C6). Classical injury patterns were observed in all of the specimens tested. Both the functional (pcervical spine throughout maturation and elucidated age, spinal level, and mode of loading specificity. These data support our understanding of the child cervical spine from a developmental perspective and facilitate the generation of injury prevention or management schema for the mitigation of child spine injuries and their deleterious effects.

  14. SPORT AND EXERCISE BIOMECHANICS (BIOS INSTANT NOTES

    Paul Grimshaw

    2007-06-01

    Full Text Available DESCRIPTION Instant Notes on Sport and Exercise Biomechanics provides a broad overview of the fundamental concepts in exercise and sport biomechanics. PURPOSE The book aims to provide instant notes on essential information about biomechanics, and is designed to help undergraduate students to grasp the corresponding subjects in physical effort rapidly and easily. AUDIENCE The book provides a useful resource for undergraduate and graduate students as a fundamental reference book. For the researcher and lecturer it would be a starting point to plan and prepare more detailed experimental designs or lecture and/or laboratory classes in the field of exercise and sport biomechanics. It would also be interest to anyone who wonders the concepts like momentum possessed, whole body angular momentum, opposite parallel forces, superman position, parabolic flight path, joint/normal reaction force, etc. FEATURES This textbook is divided into following sections from A to F: kinematics of motion, kinetics of linear motion, kinetics of angular motion, special topics, applications and measurement techniques, respectively. In sub-sections the kinematics of motion are reviewed in detail, outlining the physics of motion. Furthermore, the discussions of mechanical characteristics of motion, the mechanisms of injury, and the analysis of the sport technique provide a source of valuable information for both students and lecturers in appropriate fields. ASSESSMENT This book is an important reading for biomechanics students, teachers and even researchers as well as anyone interested in understanding motion.

  15. Biomechanics and physiology in active manual wheelchair propulsion

    van der Woude, L H; Veeger, DirkJan (H. E. J.); Dallmeijer, A J; Janssen, T W; Rozendaal, L A

    2001-01-01

    Manual wheelchair propulsion in daily life and sports is increasingly being studied. Initially, an engineering and physiological perspective was taken. More recently a concomitant biomechanics interest is seen. Themes of biomechanical and physiological studies today are performance enhancing aspects

  16. Are cranial biomechanical simulation data linked to known diets in extant taxa? A method for applying diet-biomechanics linkage models to infer feeding capability of extinct species.

    Tseng, Zhijie Jack; Flynn, John J

    2015-01-01

    Performance of the masticatory system directly influences feeding and survival, so adaptive hypotheses often are proposed to explain craniodental evolution via functional morphology changes. However, the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages. Here we examine the link between cranial biomechanical properties for taxa with different dietary preferences in crown clade Carnivora, the most diverse clade of carnivorous mammals. We test whether hypercarnivores and generalists can be distinguished based on cranial mechanical simulation models, and how such diet-biomechanics linkages relate to morphology. Comparative finite element and geometric morphometrics analyses document that predicted bite force is positively allometric relative to skull strain energy; this is achieved in part by increased stiffness in larger skull models and shape changes that resist deformation and displacement. Size-standardized strain energy levels do not reflect feeding preferences; instead, caniform models have higher strain energy than feliform models. This caniform-feliform split is reinforced by a sensitivity analysis using published models for six additional taxa. Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders. These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects. Application of this diet-biomechanics linkage model to an analysis of an extinct stem carnivoramorphan and an outgroup creodont species provides biomechanical evidence for the evolution of taxa into distinct hypercarnivorous and generalist feeding styles prior to the appearance of crown carnivoran clades with similar feeding preferences.

  17. Are cranial biomechanical simulation data linked to known diets in extant taxa? A method for applying diet-biomechanics linkage models to infer feeding capability of extinct species.

    Zhijie Jack Tseng

    Full Text Available Performance of the masticatory system directly influences feeding and survival, so adaptive hypotheses often are proposed to explain craniodental evolution via functional morphology changes. However, the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages. Here we examine the link between cranial biomechanical properties for taxa with different dietary preferences in crown clade Carnivora, the most diverse clade of carnivorous mammals. We test whether hypercarnivores and generalists can be distinguished based on cranial mechanical simulation models, and how such diet-biomechanics linkages relate to morphology. Comparative finite element and geometric morphometrics analyses document that predicted bite force is positively allometric relative to skull strain energy; this is achieved in part by increased stiffness in larger skull models and shape changes that resist deformation and displacement. Size-standardized strain energy levels do not reflect feeding preferences; instead, caniform models have higher strain energy than feliform models. This caniform-feliform split is reinforced by a sensitivity analysis using published models for six additional taxa. Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders. These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects. Application of this diet-biomechanics linkage model to an analysis of an extinct stem carnivoramorphan and an outgroup creodont species provides biomechanical evidence for the evolution of taxa into distinct hypercarnivorous and generalist feeding styles prior to the appearance of crown carnivoran clades with similar feeding preferences.

  18. Biomechanics of Schlemm's canal endothelium and intraocular pressure reduction.

    Stamer, W Daniel; Braakman, Sietse T; Zhou, Enhua H; Ethier, C Ross; Fredberg, Jeffrey J; Overby, Darryl R; Johnson, Mark

    2015-01-01

    Ocular hypertension in glaucoma develops due to age-related cellular dysfunction in the conventional outflow tract, resulting in increased resistance to aqueous humor outflow. Two cell types, trabecular meshwork (TM) and Schlemm's canal (SC) endothelia, interact in the juxtacanalicular tissue (JCT) region of the conventional outflow tract to regulate outflow resistance. Unlike endothelial cells lining the systemic vasculature, endothelial cells lining the inner wall of SC support a transcellular pressure gradient in the basal to apical direction, thus acting to push the cells off their basal lamina. The resulting biomechanical strain in SC cells is quite large and is likely to be an important determinant of endothelial barrier function, outflow resistance and intraocular pressure. This review summarizes recent work demonstrating how biomechanical properties of SC cells impact glaucoma. SC cells are highly contractile, and such contraction greatly increases cell stiffness. Elevated cell stiffness in glaucoma may reduce the strain experienced by SC cells, decrease the propensity of SC cells to form pores, and thus impair the egress of aqueous humor from the eye. Furthermore, SC cells are sensitive to the stiffness of their local mechanical microenvironment, altering their own cell stiffness and modulating gene expression in response. Significantly, glaucomatous SC cells appear to be hyper-responsive to substrate stiffness. Thus, evidence suggests that targeting the material properties of SC cells will have therapeutic benefits for lowering intraocular pressure in glaucoma.

  19. Integrative biomechanics for tree ecology: beyond wood density and strength.

    Fournier, M; Dlouhá, J; Jaouen, G; Almeras, T

    2013-11-01

    Functional ecology has long considered the support function as important, but its biomechanical complexity is only just being elucidated. We show here that it can be described on the basis of four biomechanical traits, two safety traits against winds and self-buckling, and two motricity traits involved in sustaining an upright position, tropic motion velocity (MV) and posture control (PC). All these traits are integrated at the tree scale, combining tree size and shape together with wood properties. The assumption of trait constancy has been used to derive allometric scaling laws, but it was more recently found that observing their variations among environments and functional groups, or during ontogeny, provides more insights into adaptive syndromes of tree shape and wood properties. However, oversimplified expressions have often been used, possibly concealing key adaptive drivers. An extreme case of oversimplification is the use of wood basic density as a proxy for safety. Actually, as wood density is involved in stiffness, loads, and construction costs, the impact of its variations on safety is non-trivial. Moreover, other wood features, especially the microfibril angle (MFA), are also involved. Furthermore, wood is not only stiff and strong, but it also acts as a motor for MV and PC. The relevant wood trait for this is maturation strain asymmetry. Maturation strains vary with cell-wall characteristics such as MFA, rather than with wood density. Finally, the need for further studies about the ecological relevance of branching patterns, motricity traits, and growth responses to mechanical loads is discussed.

  20. 4th International Plant Biomechanics Conference Proceedings (Abstracts)

    Frank W. Telewski; Lothar H. Koehler; Frank W. Ewers

    2003-07-20

    The 4th International Plant Biomechanics Conference facilitated an interdisciplinary exchange between scientists, engineers, and educators addressing the major questions encountered in the field of Plant Biomechanics. Subjects covered by the conference include: Evolution; Ecology; Mechanoreception; Cell Walls; Genetic Modification; Applied Biomechanics of Whole Plants, Plant Products, Fibers & Composites; Fluid Dynamics; Wood & Trees; Fracture Mechanics; Xylem Pressure & Water Transport; Modeling; and Introducing Plant Biomechanics in Secondary School Education.

  1. Multiscale modeling in biomechanics and mechanobiology

    Hwang, Wonmuk; Kuhl, Ellen

    2015-01-01

    Presenting a state-of-the-art overview of theoretical and computational models that link characteristic biomechanical phenomena, this book provides guidelines and examples for creating multiscale models in representative systems and organisms. It develops the reader's understanding of and intuition for multiscale phenomena in biomechanics and mechanobiology, and introduces a mathematical framework and computational techniques paramount to creating predictive multiscale models.   Biomechanics involves the study of the interactions of physical forces with biological systems at all scales – including molecular, cellular, tissue and organ scales. The emerging field of mechanobiology focuses on the way that cells produce and respond to mechanical forces – bridging the science of mechanics with the disciplines of genetics and molecular biology. Linking disparate spatial and temporal scales using computational techniques is emerging as a key concept in investigating some of the complex problems underlying these...

  2. Sixth Computational Biomechanics for Medicine Workshop

    Nielsen, Poul MF; Miller, Karol; Computational Biomechanics for Medicine : Deformation and Flow

    2012-01-01

    One of the greatest challenges for mechanical engineers is to extend the success of computational mechanics to fields outside traditional engineering, in particular to biology, biomedical sciences, and medicine. This book is an opportunity for computational biomechanics specialists to present and exchange opinions on the opportunities of applying their techniques to computer-integrated medicine. Computational Biomechanics for Medicine: Deformation and Flow collects the papers from the Sixth Computational Biomechanics for Medicine Workshop held in Toronto in conjunction with the Medical Image Computing and Computer Assisted Intervention conference. The topics covered include: medical image analysis, image-guided surgery, surgical simulation, surgical intervention planning, disease prognosis and diagnostics, injury mechanism analysis, implant and prostheses design, and medical robotics.

  3. Biomechanical Analysis of a Filiform Mechanosensory Hair Socket of Crickets.

    Joshi, Kanishka; Mian, Ahsan; Miller, John

    2016-08-01

    Filiform mechanosensory hairs of crickets are of great interest to engineers because of the hairs' highly sensitive response to low-velocity air-currents. In this study, we analyze the biomechanical properties of filiform hairs of the cercal sensory system of a common house cricket. The cercal sensory system consists of two antennalike appendages called cerci that are situated at the rear of the cricket's abdomen. Each cercus is covered with 500-750 flow sensitive filiform mechanosensory hairs. Each hair is embedded in a complex viscoelastic socket that acts as a spring and dashpot system and guides the movement of the hair. When a hair deflects due to the drag force induced on its length by a moving air-current, the spiking activity of the neuron that innervates the hair changes and the combined spiking activity of all hairs is extracted by the cercal sensory system. Filiform hairs have been experimentally studied by researchers, though the basis for the hairs' biomechanical characteristics is not fully understood. The socket structure has not been analyzed experimentally or theoretically from a mechanical standpoint, and the characterization that exists is mathematical in nature and only provides a very rudimentary approximation of the socket's spring nature. This study aims to understand and physically characterize the socket's behavior and interaction with the filiform hair by examining hypotheses about the hair and socket biomechanics. A three-dimensional computer-aided design (CAD) model was first created using confocal microscopy images of the hair and socket structure of the cricket, and then finite-element analyses (FEAs) based on the physical conditions that the insect experiences were simulated. The results show that the socket can act like a spring; however, it has two-tier rotational spring constants during pre- and postcontacts of iris and hair bulge due to its constitutive nonstandard geometric shapes.

  4. Structural and biomechanical basis of mitochondrial movement in eukaryotic cells

    Wu M

    2013-10-01

    Full Text Available Min Wu,1 Aruna Kalyanasundaram,2 Jie Zhu1 1Laboratory of Biomechanics and Engineering, Institute of Biophysics, College of Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China; 2College of Pharmacology, University of Illinois at Chicago, Chicago, IL, USA Abstract: Mitochondria serve as energy-producing organelles in eukaryotic cells. In addition to providing the energy supply for cells, the mitochondria are also involved in other processes, such as proliferation, differentiation, information transfer, and apoptosis, and play an important role in regulation of cell growth and the cell cycle. In order to achieve these functions, the mitochondria need to move to the corresponding location. Therefore, mitochondrial movement has a crucial role in normal physiologic activity, and any mitochondrial movement disorder will cause irreparable damage to the organism. For example, recent studies have shown that abnormal movement of the mitochondria is likely to be the reason for Charcot–Marie–Tooth disease, amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease, Parkinson's disease, and schizophrenia. So, in the cell, especially in the particular polarized cell, the appropriate distribution of mitochondria is crucial to the function and survival of the cell. Mitochondrial movement is mainly associated with the cytoskeleton and related proteins. However, those components play different roles according to cell type. In this paper, we summarize the structural basis of mitochondrial movement, including microtubules, actin filaments, motor proteins, and adaptin, and review studies of the biomechanical mechanisms of mitochondrial movement in different types of cells. Keywords: mitochondrial movement, microtubules, actin filaments, motor proteins, adaptin

  5. Analysis of Biomechanical Factors in Bend Running

    Bing Zhang

    2013-03-01

    Full Text Available Sprint running is the demonstration of comprehensive abilities of technology and tactics, under various conditions. However, whether it is just to allocate the tracks for short-distance athletes from different racetracks has been the hot topic. This study analyzes its forces, differences in different tracks and winding influences, in the aspects of sport biomechanics. The results indicate, many disadvantages exist in inner tracks, middle tracks are the best and outer ones are inferior to middle ones. Thus it provides references for training of short-distance items in biomechanics and psychology, etc.

  6. Role of Aquaporin 0 in lens biomechanics.

    Sindhu Kumari, S; Gupta, Neha; Shiels, Alan; FitzGerald, Paul G; Menon, Anil G; Mathias, Richard T; Varadaraj, Kulandaiappan

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5(-/-)), AQP0 KO (heterozygous KO: AQP0(+/-); homozygous KO: AQP0(-/-); all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0(+/-) lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and together they help to confer

  7. Anatomy and biomechanics of the craniovertebral junction.

    Lopez, Alejandro J; Scheer, Justin K; Leibl, Kayla E; Smith, Zachary A; Dlouhy, Brian J; Dahdaleh, Nader S

    2015-04-01

    The craniovertebral junction (CVJ) has unique anatomical structures that separate it from the subaxial cervical spine. In addition to housing vital neural and vascular structures, the majority of cranial flexion, extension, and axial rotation is accomplished at the CVJ. A complex combination of osseous and ligamentous supports allow for stability despite a large degree of motion. An understanding of anatomy and biomechanics is essential to effectively evaluate and address the various pathological processes that may affect this region. Therefore, the authors present an up-to-date narrative review of CVJ anatomy, normal and pathological biomechanics, and fixation techniques.

  8. [Hair shaft abnormalities].

    Itin, P H; Düggelin, M

    2002-05-01

    Hair shaft disorders may lead to brittleness and uncombable hair. In general the hair feels dry and lusterless. Hair shaft abnormalities may occur as localized or generalized disorders. Genetic predisposition or exogenous factors are able to produce and maintain hair shaft abnormalities. In addition to an extensive history and physical examination the most important diagnostic examination to analyze a hair shaft problem is light microscopy. Therapy of hair shaft disorders should focus to the cause. In addition, minimizing traumatic influences to hair shafts, such as dry hair with an electric dryer, permanent waves and dyes is important. A short hair style is more suitable for such patients with hair shaft disorders.

  9. Study on the postmortem interval estimation by timedependent changes of biomechanical properties of the soft tissues in rats%利用尸体软组织生物力学性状时序性变化推断死亡时间

    杨含金; 马孟云; 于晓军; 于述伟; 赖跃; 徐小虎

    2011-01-01

    目的 探讨尸体软组织生物力学性状时序性变化规律及其推断死亡时间的可行性.方法 将实验大鼠用颈椎脱臼法处死,放置25℃恒温培养箱内即刻、6、12、18、24、30、36、42、48、60、72、96、120、144、168、192h,定时、定位、定向、定形切取大鼠胸部正中皮肤、腹壁肌肉、胸主动脉、结肠和小肠的生物力学试件,用电子万能材料试验机检测各试件的极限载荷、应变、应力生物力学参数.结果 除主动脉外,尸体皮肤、肌肉、小肠、结肠的各项软组织生物力学参数均呈明显的死后时序性下降趋势.各参数下降趋势具有显著性差异的“窗口期”分别为:极限载荷:死后18h内皮肤、小肠呈下降趋势;24h内肌肉、结肠呈下降趋势;96~168h肌肉呈下降趋势;72~192h结肠呈下降趋势.应变:各组织在24h内均呈下降趋势,其结肠72~192h缓慢下降趋势.应力:皮肤18h内呈下降趋势,肌肉、小肠24h内呈下降趋势,结肠36h内呈下降趋势.结论 大鼠尸体软组织各生物力学性状在不同的“窗口期”存在时序性变化规律,综合各指标可用于推断相应“窗口期”内的死亡时间.%Objective To observe the timedependent changes of biomechanical properties of soft tissues in rats at early postmortem interval. Methods After the rats were executed by cervical vertebra dislocation, the rats were kept in an artificial climate incubator (25℃). The skin of chest, abdominal wall muscle, aorta pectoral, colon and small intestine were taken at0,6, 12, 18, 24, 30, 36, 42, 48, 60, 72, 96, 120, 144, 168and 192h in set position, direction and shape for determination of their biomechanical properties of max load, tensile stress and strain with the electronic universal testing machine. Results Except for aorta pectoral, biomechanical properties of the soft tissues including max load, max tensile stress and strain were grealy reduced with the extension of

  10. Measurement system for an in-vitro characterization of the biomechanics and hemodynamics of arterial bifurcations

    Suárez-Bagnasco, D.; Balay, G.; Cymberknop, L.; Armentano, R. L.; Negreira, C. A.

    2013-03-01

    Arterial behaviour in-vivo is influenced, amongst other factors, by the interaction between blood flow and the arterial wall endothelium, and the biomechanical properties of the arterial wall. This interaction plays an important role in pathogenic mechanisms of cardiovascular diseases such as atherosclerosis and arteriosclerosis. To quantify these interactions both from biomechanical and hemodynamical standpoints, a complete characterization and modelling of the arterial wall, blood flow, shear wall and circumferential wall stresses are needed. The development of a new multi-parameter measurement system (distances, pressures, flows, velocity profiles, temperature, viscosity) for an in-vitro characterization of the biomechanics and hemodynamics in arterial bifurcations (specially in carotid bifurcations) is described. This set-up represents an improvement relative to previous set-ups developed by the group FCIEN-FMED and is presently under development. Main subsystems interactions and environment-system interactions were identified and compensated to improve system's performance. Several interesting problems related with signal acquisition using a variety of sensors and some experimental results are shown and briefly discussed. Experimental data allow construction of meshes and parameter estimation of the biomechanical properties of the arterial wall, as well as boundary conditions, all suitable to be employed in CFD and FSI numerical simulation.

  11. Biomechanical comparison of the human cadaveric pelvis with a fourth generation composite model.

    Girardi, Brandon L; Attia, Tarik; Backstein, David; Safir, Oleg; Willett, Thomas L; Kuzyk, Paul R T

    2016-02-29

    The use of cadavers for orthopaedic biomechanics research is well established, but presents difficulties to researchers in terms of cost, biosafety, availability, and ease of use. High fidelity composite models of human bone have been developed for use in biomechanical studies. While several studies have utilized composite models of the human pelvis for testing orthopaedic reconstruction techniques, few biomechanical comparisons of the properties of cadaveric and composite pelves exist. The aim of this study was to compare the mechanical properties of cadaveric pelves to those of the 4th generation composite model. An Instron ElectroPuls E10000 mechanical testing machine was used to load specimens with orientation, boundary conditions and degrees of freedom that approximated those occurring during the single legged phase of walking, including hip abductor force. Each specimen was instrumented with strain gauge rosettes. Overall specimen stiffness and principal strains were calculated from the test data. Composite specimens showed significantly higher overall stiffness and slightly less overall variability between specimens (composite K=1448±54N/m, cadaver K=832±62N/m; p<0.0001). Strains measured at specific sites in the composite models and cadavers were similar (but did differ) only when the applied load was scaled to overall construct stiffness. This finding regarding strain distribution and the difference in overall stiffness must be accounted for when using these composite models for biomechanics research. Altering the cortical wall thickness or tuning the elastic moduli of the composite material may improve future generations of the composite model.

  12. Stem biomechanics of three columnar cacti from the Sonoran Desert.

    Molina-Freaner, F; Tinoco-Ojanguren, C; Niklas, K

    1998-08-01

    The allometric relationship of stem length L with respect to mean stem diameter D was determined for 80 shoots of each of three columnar cactus species (Stenocereus thurberi, Lophocereus schottii, and S. gummosus) to determine whether this relationship accords with that predicted by each of three contending models purporting to describe the mechanical architecture of vertical shoots (i.e., geometric, stress, and elastic similitude, which predict L proportional to D(alpha), with alpha = 1/1, 1/2, and 2/3, respectively). In addition, anatomical, physical, and biomechanical stem properties were measured to determine how the stems of these three species maintain their elastic stability as they increase in size. Reduced major axis regression of L with respect to D showed that alpha = 2.82 ± 0.14 for S. thurberi, 2.32 ± 0.19 for L. schottii, and 4.21 ± 0.31 for S. gummosus. Thus, the scaling exponents for the allometry of L differed significantly from that predicted by each of the three biomechanical models. In contrast, these exponents were similar to that for the allometry previously reported for saguaro. Analyses of biomechanical data derived from bending tests performed on 30 stems selected from each of the three species indicated that the bulk stem tissue stiffness was roughly proportional to L2, while stem flexural rigidity (i.e., the ability to resist a bending force) scaled roughly as L3. Stem length was significantly and positively correlated with the volume fraction of wood, while regression analysis of the pooled data from the three species (i.e., 90 stems) indicated that bulk tissue stiffness scaled roughly as the 5/3-power of the volume fraction of wood in stems. These data were interpreted to indicate that wood served as the major stiffening agent in stems and that this tissue accumulates at a sufficient rate to afford unusually high scaling exponents tot stem length with respect to stem diameter (i.e., disproportionately large increments of stem length

  13. Abnormalities of gonadal differentiation.

    Berkovitz, G D; Seeherunvong, T

    1998-04-01

    Gonadal differentiation involves a complex interplay of developmental pathways. The sex determining region Y (SRY) gene plays a key role in testis determination, but its interaction with other genes is less well understood. Abnormalities of gonadal differentiation result in a range of clinical problems. 46,XY complete gonadal dysgenesis is defined by an absence of testis determination. Subjects have female external genitalia and come to clinical attention because of delayed puberty. Individuals with 46,XY partial gonadal dysgenesis usually present in the newborn period for the valuation of ambiguous genitalia. Gonadal histology always shows an abnormality of seminiferous tubule formation. A diagnosis of 46,XY true hermaphroditism is made if the gonads contain well-formed testicular and ovarian elements. Despite the pivotal role of the SRY gene in testis development, mutations of SRY are unusual in subjects with a 46,XY karyotype and abnormal gonadal development. 46,XX maleness is defined by testis determination in an individual with a 46,XX karyotype. Most affected individuals have a phenotype similar to that of Klinefelter syndrome. In contrast, subjects with 46,XX true hermaphroditism usually present with ambiguous genitalia. The majority of subjects with 46,XX maleness have Y sequences including SRY in genomic DNA. However, only rare subjects with 46,XX true hermaphroditism have translocated sequences encoding SRY. Mosaicism and chimaerism involving the Y chromosome can also be associated with abnormal gonadal development. However, the vast majority of subjects with 45,X/46,XY mosaicism have normal testes and normal male external genitalia.

  14. Cortical Abnormalities in ADHD

    J Gordon Millichap

    2003-12-01

    Full Text Available Grey-matter abnormalities at the cortical surface and regional brain size were mapped by high-resolution MRI and surface-based, computational image analytical techniques in a group of 27 children and adolescents with attention deficit hyperactivity disorder (ADHD and 46 controls, matched by age and sex, at the University of California at Los Angeles.

  15. Neurological abnormalities predict disability

    Poggesi, Anna; Gouw, Alida; van der Flier, Wiesje

    2014-01-01

    To investigate the role of neurological abnormalities and magnetic resonance imaging (MRI) lesions in predicting global functional decline in a cohort of initially independent-living elderly subjects. The Leukoaraiosis And DISability (LADIS) Study, involving 11 European centres, was primarily aimed...

  16. Lacrimal system abnormalities.

    Moore, B D

    1994-03-01

    This report outlines several of the more important abnormalities of the lacrimal system in infants and young children. Although rare, alacrima can be a very difficult clinical problem to treat. The most common cause of alacrima is the Riley-Day syndrome. Nasolacrimal duct obstruction is a very common anomaly in children. The clinical appearance and treatment of this disorder are discussed.

  17. Jet-Ricci Geometry of Time-Dependent Human Biomechanics

    Ivancevic, Tijana T

    2009-01-01

    We propose the time-dependent generalization of an `ordinary' autonomous human biomechanics, in which total mechanical + biochemical energy is not conserved. We introduce a general framework for time-dependent biomechanics in terms of jet manifolds derived from the extended musculo-skeletal configuration manifold. The corresponding Riemannian geometrical evolution follows the Ricci flow diffusion. In particular, we show that the exponential-like decay of total biomechanical energy (due to exhaustion of biochemical resources) is closely related to the Ricci flow on the biomechanical configuration manifold. Keywords: Time-dependent biomechanics, extended configuration manifold, configuration bundle, jet manifolds, Ricci flow diffusion

  18. Biomechanics in dermatology: Recent advances and future directions.

    Lewinson, Ryan T; Haber, Richard M

    2017-02-01

    Biomechanics is increasingly being recognized as an important research area in dermatology. To highlight only a few examples, biomechanics has contributed to the development of novel topical therapies for aesthetic and medical purposes, enhanced our understanding of the pathogenesis of plantar melanoma, and provided insight into the epidemiology of psoriatic disease. This article summarizes the findings from recent studies to demonstrate the important role that biomechanics may have in dermatologic disease and therapy and places these biomechanical findings in a clinical context for the practicing physician. In addition, areas for future biomechanics research and development in dermatology are discussed.

  19. Stents: Biomechanics, Biomaterials, and Insights from Computational Modeling.

    Karanasiou, Georgia S; Papafaklis, Michail I; Conway, Claire; Michalis, Lampros K; Tzafriri, Rami; Edelman, Elazer R; Fotiadis, Dimitrios I

    2017-04-01

    Coronary stents have revolutionized the treatment of coronary artery disease. Improvement in clinical outcomes requires detailed evaluation of the performance of stent biomechanics and the effectiveness as well as safety of biomaterials aiming at optimization of endovascular devices. Stents need to harmonize the hemodynamic environment and promote beneficial vessel healing processes with decreased thrombogenicity. Stent design variables and expansion properties are critical for vessel scaffolding. Drug-elution from stents, can help inhibit in-stent restenosis, but adds further complexity as drug release kinetics and coating formulations can dominate tissue responses. Biodegradable and bioabsorbable stents go one step further providing complete absorption over time governed by corrosion and erosion mechanisms. The advances in computing power and computational methods have enabled the application of numerical simulations and the in silico evaluation of the performance of stent devices made up of complex alloys and bioerodible materials in a range of dimensions and designs and with the capacity to retain and elute bioactive agents. This review presents the current knowledge on stent biomechanics, stent fatigue as well as drug release and mechanisms governing biodegradability focusing on the insights from computational modeling approaches.

  20. The biomechanical interaction between horse and rider

    Cocq, de P.

    2012-01-01

    The forces exerted by a rider on a horse have a direct influence on the mechanical load experienced by the horse and consequently on its motion pattern. The aim of this thesis is to explore the biomechanical interaction between rider, saddle and horse in order to get insight in the loading of the ho

  1. Biomechanics of Distance Running: A Longitudinal Study

    Nelson, Richard C.; Gregor, Robert J.

    1976-01-01

    Training for distance running over a long period produces meaningful changes in the running mechanics of experienced runners, as revealed in this longitudinal study of the biomechanical components of stride length, stride rate, stride time, and support and nonsupport time. (MB)

  2. Expose Mechanical Engineering Students to Biomechanics Topics

    Shen, Hui

    2011-01-01

    To adapt the focus of engineering education to emerging new industries and technologies nationwide and in the local area, a biomechanics module has been developed and incorporated into a mechanical engineering technical elective course to expose mechanical engineering students at ONU (Ohio Northern University) to the biomedical engineering topics.…

  3. Biomechanics of Pediatric Manual Wheelchair Mobility.

    Slavens, Brooke A; Schnorenberg, Alyssa J; Aurit, Christine M; Tarima, Sergey; Vogel, Lawrence C; Harris, Gerald F

    2015-01-01

    Currently, there is limited research of the biomechanics of pediatric manual wheelchair mobility. Specifically, the biomechanics of functional tasks and their relationship to joint pain and health is not well understood. To contribute to this knowledge gap, a quantitative rehabilitation approach was applied for characterizing upper extremity biomechanics of manual wheelchair mobility in children and adolescents during propulsion, starting, and stopping tasks. A Vicon motion analysis system captured movement, while a SmartWheel simultaneously collected three-dimensional forces and moments occurring at the handrim. A custom pediatric inverse dynamics model was used to evaluate three-dimensional upper extremity joint motions, forces, and moments of 14 children with spinal cord injury (SCI) during the functional tasks. Additionally, pain and health-related quality of life outcomes were assessed. This research found that joint demands are significantly different amongst functional tasks, with greatest demands placed on the shoulder during the starting task. Propulsion was significantly different from starting and stopping at all joints. We identified multiple stroke patterns used by the children, some of which are not standard in adults. One subject reported average daily pain, which was minimal. Lower than normal physical health and higher than normal mental health was found in this population. It can be concluded that functional tasks should be considered in addition to propulsion for rehabilitation and SCI treatment planning. This research provides wheelchair users and clinicians with a comprehensive, biomechanical, mobility assessment approach for wheelchair prescription, training, and long-term care of children with SCI.

  4. Interdisciplinary Vertical Integration: The Future of Biomechanics

    Gregor, Robert J.

    2008-01-01

    The field of biomechanics has grown rapidly in the past 30 years in both size and complexity. As a result, the term might mean different things to different people. This article addresses the issues facing the field in the form of challenges biomechanists face in the future. Because the field is so diverse, strength within the different areas of…

  5. Surface driven biomechanical breast image registration

    Eiben, Björn; Vavourakis, Vasileios; Hipwell, John H.; Kabus, Sven; Lorenz, Cristian; Buelow, Thomas; Williams, Norman R.; Keshtgar, M.; Hawkes, David J.

    2016-03-01

    Biomechanical modelling enables large deformation simulations of breast tissues under different loading conditions to be performed. Such simulations can be utilised to transform prone Magnetic Resonance (MR) images into a different patient position, such as upright or supine. We present a novel integration of biomechanical modelling with a surface registration algorithm which optimises the unknown material parameters of a biomechanical model and performs a subsequent regularised surface alignment. This allows deformations induced by effects other than gravity, such as those due to contact of the breast and MR coil, to be reversed. Correction displacements are applied to the biomechanical model enabling transformation of the original pre-surgical images to the corresponding target position. The algorithm is evaluated for the prone-to-supine case using prone MR images and the skin outline of supine Computed Tomography (CT) scans for three patients. A mean target registration error (TRE) of 10:9 mm for internal structures is achieved. For the prone-to-upright scenario, an optical 3D surface scan of one patient is used as a registration target and the nipple distances after alignment between the transformed MRI and the surface are 10:1 mm and 6:3 mm respectively.

  6. A Biomechanical Analysis of the Karate Chop.

    Cavanagh, Peter R.; Landa, Jean

    Although the sport of karate has been somewhat neglected by scientists, the following two isolated biomechanical studies exist in literature: (1) tracings of a karate chop in two planes were presented, but no data was given concerning the rates of movement of the limb segments, and (2) pre- and postimpact phenomena of five subjects were studied,…

  7. Ultrasonographic assessment of carpal tunnel biomechanics

    van Doesburg, M.H.M.

    2012-01-01

    In this thesis, we searched for a way to assess flexor tendon and median nerve biomechanics, as well as subsynovial connective tissue thickness (SSCT) in the carpal tunnel with ultrasound, and tried to see if these patterns would give a clue towards understanding the etiology of carpal tunnel syndro

  8. Biomechanics of Pediatric Manual Wheelchair Mobility

    Slavens, Brooke A.; Schnorenberg, Alyssa J.; Aurit, Christine M.; Tarima, Sergey; Vogel, Lawrence C.; Harris, Gerald F.

    2015-01-01

    Currently, there is limited research of the biomechanics of pediatric manual wheelchair mobility. Specifically, the biomechanics of functional tasks and their relationship to joint pain and health is not well understood. To contribute to this knowledge gap, a quantitative rehabilitation approach was applied for characterizing upper extremity biomechanics of manual wheelchair mobility in children and adolescents during propulsion, starting, and stopping tasks. A Vicon motion analysis system captured movement, while a SmartWheel simultaneously collected three-dimensional forces and moments occurring at the handrim. A custom pediatric inverse dynamics model was used to evaluate three-dimensional upper extremity joint motions, forces, and moments of 14 children with spinal cord injury (SCI) during the functional tasks. Additionally, pain and health-related quality of life outcomes were assessed. This research found that joint demands are significantly different amongst functional tasks, with greatest demands placed on the shoulder during the starting task. Propulsion was significantly different from starting and stopping at all joints. We identified multiple stroke patterns used by the children, some of which are not standard in adults. One subject reported average daily pain, which was minimal. Lower than normal physical health and higher than normal mental health was found in this population. It can be concluded that functional tasks should be considered in addition to propulsion for rehabilitation and SCI treatment planning. This research provides wheelchair users and clinicians with a comprehensive, biomechanical, mobility assessment approach for wheelchair prescription, training, and long-term care of children with SCI. PMID:26442251

  9. The Value of Biomechanical Research in Dance.

    Ranney, D. A.

    Simple observation of dance movement, while very useful, can lead to misconceptions, about the physical realities of dance movement, that make learning difficult. This gap between reality and understanding can be reduced by the application of biomechanical techniques such as cinematography, electromyography, and force-plate analysis. Biomechanical…

  10. Biomechanics of the pelvic floor musculature

    Janda, S.

    2006-01-01

    The present thesis was motivated by two main goals. The first research goal of the thesis was to understand the complex biomechanical behaviour of the pelvic floor muscles. The second goal was to study the mechanism of the pelvic organ prolapse (genital prolapse). The pelvic floor in humans is a ve

  11. Identifying nonlinear biomechanical models by multicriteria analysis

    Srdjevic, Zorica; Cveticanin, Livija

    2012-02-01

    In this study, the methodology developed by Srdjevic and Cveticanin (International Journal of Industrial Ergonomics 34 (2004) 307-318) for the nonbiased (objective) parameter identification of the linear biomechanical model exposed to vertical vibrations is extended to the identification of n-degree of freedom (DOF) nonlinear biomechanical models. The dynamic performance of the n-DOF nonlinear model is described in terms of response functions in the frequency domain, such as the driving-point mechanical impedance and seat-to-head transmissibility function. For randomly generated parameters of the model, nonlinear equations of motion are solved using the Runge-Kutta method. The appropriate data transformation from the time-to-frequency domain is performed by a discrete Fourier transformation. Squared deviations of the response functions from the target values are used as the model performance evaluation criteria, thus shifting the problem into the multicriteria framework. The objective weights of criteria are obtained by applying the Shannon entropy concept. The suggested methodology is programmed in Pascal and tested on a 4-DOF nonlinear lumped parameter biomechanical model. The identification process over the 2000 generated sets of parameters lasts less than 20 s. The model response obtained with the imbedded identified parameters correlates well with the target values, therefore, justifying the use of the underlying concept and the mathematical instruments and numerical tools applied. It should be noted that the identified nonlinear model has an improved accuracy of the biomechanical response compared to the accuracy of a linear model.

  12. 中等强度游泳训练对生长期大鼠股骨骨密度和生物力学性能的影响%The effect of middle intensity of swimming training to the growth period rats' bone mineral density of femur and biomechanical properties

    冯宁

    2012-01-01

    In order to study the effect of middle intensity of swimming training to the growth period rats' bone density of femur and biomechanical properties,This article comparatively divides 18 Wistar male rats into control group(n=10) and experimental group(n=8) with 60 min swimming,2% of body weight per day and total 10 weeks.At the end of training,the rats are put to death and the right femur is taken out.By using the method of DXA and CMT5504 to give three points bending experiment of the femur,then the computer automatically generate the index of bone structure and material mechanics.The results show that the effect of middle intensity of swimming training to trained nine weeks rats' bone density of femur is obviously lower than those of CON(P0.05).The change of rats' femoral biomechanical properties shows that the ability of rats' resist damage and deformation reduced.The article concludes that middle intensity of swimming trainingan leads the inhibitory effect of bone mineral density of femur,but there is little effect on biomechanical properties.%目的:探讨中等强度的游泳运动对生长期大鼠股骨骨密度(BMD)和生物力学性能的影响。方法:将4周龄Wistar雄性大鼠18只,分为对照组(n=10)、中等强度游泳组(n=8),中等强度游泳组负重2%自身体重游泳,每天运动60min,共训练9周(每周5d)。训练结束将大鼠处死后摘出右侧股骨,采用NORLAND公司生产的双能X线骨密度测定仪(DXA)测量股骨BMD;采用新三思集团生产的CMT5504微机控制电子万能试验机对股骨进行3点弯曲试验,电脑自动生成骨结构和材料力学指标。结果:大鼠经过9周训练后,中等强度游泳组股骨骨密度显著低于对照组(p〈0.05)。大鼠股骨生物力学性质变化结果表明,中等强度游泳组大鼠股骨抵抗破坏和变形的能力降低,但是没有显著性差异。结论:中等强度游泳训练对生长期大鼠股

  13. Effect of ultraviolet A (UVA) plus riboflavin induced collagen cross-linking on biomechanical properties of the sclera in guinea pigs%紫外光-核黄素交联法对豚鼠巩膜生物力学特性的影响

    吕雅平; 周浩; 夏文涛; 褚仁远; 周行涛; 戴锦晖

    2012-01-01

    目的 探索紫外光-核黄素交联法对巩膜织张力和强度的影响.方法 交联组和对照组皆选右眼为实验眼,交联组采用波长为(370±5)nm、辐射强度定为3.0 mW/cm2的紫外线和0.1%核黄素为光敏剂对豚鼠赤道部巩膜面进行胶原交联,对照组不进行交联处理.术后一个月取交联组交联区巩膜条带和对照组相应区域的巩膜条带,进行生物力学测试,并对眼球各组织进行HE染色光镜和透射电镜检测.结果 交联组巩膜的生物力学特性增强,赤道部交联组巩膜试件断裂时的极限应力增加了147%,弹性模量显著增加了193%,极限应变降低了21.9%;后极部交联组巩膜试件断裂时的极限应力增加了108%,弹性模量显著增加了191%,极限应变降低了40.42%.HE染色光镜检查结果显示形态学无病理改变,透射电镜结果显示交联组交联区的巩膜成纤维细胞增生活跃.结论 紫外光-核黄素交联法可以有效地提高巩膜的生物力学特性,增强巩膜组织的张力和强度,有望作为治疗高度病理性近视的一种方法.%Objective To study the effect of collagen cross-linking induced by riboflavin and ultraviolet A ( UVA ) on biomechanical properties of the sclera in guinea pigs. Methods The changes of biomechanical properties of the sclera induced by riboflavin and ultraviolet A ( UVA)-induced collagen crosslinking were examined in ten guinea pigs and compared with those of ten non-treated guinea pigs. Histological and ultrastructural changes of the sclera were examined to evaluate the side-effects. Results At one month after the UVA plus riboflavin treatment, the ultimate stress increased by 147% , elastic modulus increased by 193% , ultimate strain reduced by 21.9% in the equatorial sclera and significantly changed by 108% , 191% , 40.42% in the posterior sclera, respectively. Light microscopy showed no pathological alterations. Transmission electron microscopy showed active

  14. The biomechanics of solids and fluids: the physics of life

    Alexander, David E.

    2016-09-01

    Biomechanics borrows and extends engineering techniques to study the mechanical properties of organisms and their environments. Like physicists and engineers, biomechanics researchers tend to specialize on either fluids or solids (but some do both). For solid materials, the stress-strain curve reveals such useful information as various moduli, ultimate strength, extensibility, and work of fracture. Few biological materials are linearly elastic so modified elastic moduli are defined. Although biological materials tend to be less stiff than engineered materials, biomaterials tend to be tougher due to their anisotropy and high extensibility. Biological beams are usually hollow cylinders; particularly in plants, beams and columns tend to have high twist-to-bend ratios. Air and water are the dominant biological fluids. Fluids generate both viscous and pressure drag (normalized as drag coefficients) and the Reynolds number (Re) gives their relative importance. The no-slip conditions leads to velocity gradients (‘boundary layers’) on surfaces and parabolic flow profiles in tubes. Rather than rigidly resisting drag in external flows, many plants and sessile animals reconfigure to reduce drag as speed increases. Living in velocity gradients can be beneficial for attachment but challenging for capturing particulate food. Lift produced by airfoils and hydrofoils is used to produce thrust by all flying animals and many swimming ones, and is usually optimal at higher Re. At low Re, most swimmers use drag-based mechanisms. A few swimmers use jetting for rapid escape despite its energetic inefficiency. At low Re, suspension feeding depends on mechanisms other than direct sieving because thick boundary layers reduce effective porosity. Most biomaterials exhibit a combination of solid and fluid properties, i.e., viscoelasticity. Even rigid biomaterials exhibit creep over many days, whereas pliant biomaterials may exhibit creep over hours or minutes. Instead of rigid materials

  15. Nitrofurantoin and congenital abnormalities

    Czeizel, A.E.; Rockenbauer, M.; Sørensen, Henrik Toft;

    2001-01-01

    Objective: To study human teratogenic potential of oral nitrofurantoin treatment during pregnancy. Materials and Methods: Pair analysis of cases with congenital abnormalities and matched population controls in the population-based dataset of the Hungarian Case-Control Surveillance of Congenital...... or fetuses with Down’s syndrome (patient controls), 23 (2.8%) pregnant women were treated with nitrofurantoin. The above differences between population controls and cases may be connected with recall bias, because the case-control pair analysis did not indicate a teratogenic potential of nitrofurantoin use...... during the second and the third months of gestation, i.e. in the critical period for major congenital abnormalities. Conclusion: Treatment with nitrofurantoin during pregnancy does not present detectable teratogenic risk to the fetus....

  16. Mechanical Properties of Cells

    Bradley, Robert; Becerril, Joseph; Jeevarajan, Anthony

    2007-01-01

    Many physiologic and pathologic processes alter the biomechanical properties of the tissue they affect, and these changes may be manifest at the single cell level. The normal and abnormal mechanical properties of a given cell type can be established with the aid of an atomic force microscope (AFM), nonetheless, consistency in the area of the tip has been a mayor limitation of using the AFM for quantitative measurements of mechanical properties. This project attempts to overcome this limitation by using materials with a known elastic modulus, which resembles the one of the cell, to create force-deformation curves to calculate the area of indentation by means of Hooke s Law (sigma = E(epsilon)), which states that stress (sigma) is proportional to the strain (epsilon) where the constant of proportionality, E, is called the Young s modulus, also referred as the elastic modulus. Hook s Law can be rearranged to find the area of indentation (Area= Force/ E(epsilon)), where the indentation force is defined by the means of the added mass spring calibration method.

  17. Role of Aquaporin 0 in lens biomechanics

    Sindhu Kumari, S.; Gupta, Neha [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); Shiels, Alan [Washington University School of Medicine, St. Louis, MO (United States); FitzGerald, Paul G. [Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA (United States); Menon, Anil G. [University of Cincinnati College of Medicine, Cincinnati, OH (United States); Mathias, Richard T. [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States); Varadaraj, Kulandaiappan, E-mail: kulandaiappan.varadaraj@stonybrook.edu [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States)

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5{sup −/−}), AQP0 KO (heterozygous KO: AQP0{sup +/−}; homozygous KO: AQP0{sup −/−}; all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0{sup +/−} lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and

  18. The application of finite element analysis in the skull biomechanics and dentistry.

    Prado, Felippe Bevilacqua; Rossi, Ana Cláudia; Freire, Alexandre Rodrigues; Ferreira Caria, Paulo Henrique

    2014-01-01

    Empirical concepts describe the direction of the masticatory stress dissipation in the skull. The scientific evidence of the trajectories and the magnitude of stress dissipation can help in the diagnosis of the masticatory alterations and the planning of oral rehabilitation in the different areas of Dentistry. The Finite Element Analysis (FEA) is a tool that may reproduce complex structures with irregular geometries of natural and artificial tissues of the human body because it uses mathematical functions that enable the understanding of the craniofacial biomechanics. The aim of this study was to review the literature on the advantages and limitations of FEA in the skull biomechanics and Dentistry study. The keywords of the selected original research articles were: Finite element analysis, biomechanics, skull, Dentistry, teeth, and implant. The literature review was performed in the databases, PUBMED, MEDLINE and SCOPUS. The selected books and articles were between the years 1928 and 2010. The FEA is an assessment tool whose application in different areas of the Dentistry has gradually increased over the past 10 years, but its application in the analysis of the skull biomechanics is scarce. The main advantages of the FEA are the realistic mode of approach and the possibility of results being based on analysis of only one model. On the other hand, the main limitation of the FEA studies is the lack of anatomical details in the modeling phase of the craniofacial structures and the lack of information about the material properties.

  19. [Molecular abnormalities in lymphomas].

    Delsol, G

    2010-11-01

    Numerous molecular abnormalities have been described in lymphomas. They are of diagnostic and prognostic value and are taken into account for the WHO classification of these tumors. They also shed some light on the underlying molecular mechanisms involved in lymphomas. Overall, four types of molecular abnormalities are involved: mutations, translocations, amplifications and deletions of tumor suppressor genes. Several techniques are available to detect these molecular anomalies: conventional cytogenetic analysis, multicolor FISH, CGH array or gene expression profiling using DNA microarrays. In some lymphomas, genetic abnormalities are responsible for the expression of an abnormal protein (e.g. tyrosine-kinase, transcription factor) detectable by immunohistochemistry. In the present review, molecular abnormalities observed in the most frequent B, T or NK cell lymphomas are discussed. In the broad spectrum of diffuse large B-cell lymphomas microarray analysis shows mostly two subgroups of tumors, one with gene expression signature corresponding to germinal center B-cell-like (GCB: CD10+, BCL6 [B-Cell Lymphoma 6]+, centerine+, MUM1-) and a subgroup expressing an activated B-cell-like signature (ABC: CD10-, BCL6-, centerine-, MUM1+). Among other B-cell lymphomas with well characterized molecular abnormalies are follicular lymphoma (BCL2 deregulation), MALT lymphoma (Mucosa Associated Lymphoid Tissue) [API2-MALT1 (mucosa-associated-lymphoid-tissue-lymphoma-translocation-gene1) fusion protein or deregulation BCL10, MALT1, FOXP1. MALT1 transcription factors], mantle cell lymphoma (cycline D1 [CCND1] overexpression) and Burkitt lymphoma (c-Myc expression). Except for ALK (anaplastic lymphoma kinase)-positive anaplastic large cell lymphoma, well characterized molecular anomalies are rare in lymphomas developed from T or NK cells. Peripheral T cell lymphomas not otherwise specified are a heterogeneous group of tumors with frequent but not recurrent molecular abnormalities

  20. Feeling Abnormal: Simulation of Deviancy in Abnormal and Exceptionality Courses.

    Fernald, Charles D.

    1980-01-01

    Describes activity in which student in abnormal psychology and psychology of exceptional children classes personally experience being judged abnormal. The experience allows the students to remember relevant research, become sensitized to the feelings of individuals classified as deviant, and use caution in classifying individuals as abnormal.…

  1. 基于角膜生物力学性能的散光性角膜切开术有限元分析%Finite element analysis of astigmatic keratotomy based on corneal biomechanical properties

    李智冬; 包芳军; 王勤美; 黄锦海

    2016-01-01

    Objective To establish a finite-element biomechanical model of astigmatic keratotomy, and to investigate the impact of surgical parameters on corneal deformation, stress distribution and astigmatism correction. Methods With Rhinoceros modeling and Abaqus finite element analysis software, a three-dimensional finite-element model of astigmatic cornea was developed, and surgical parameters such as incision optical zone, incision depth and length were varied. Postoperative corneal stress, apical deformation and astigmatism correction were assessed. Results A significant increase of stress was noticed near corneal incisions, and maximum corneal stress decreased with the increase of incision depth. Both anterior and posterior corneal surface moved slightly forward postoperatively. Maximum corneal stress was 340 392, 361 022 and 214 187 Pa, and anterior and posterior apical deformation was 49.80, 51.64, 55.53 μm and 54.15, 55.91, 59.67μm, with 45°, 60° and 90° in arc length of the incision, respectively. The refractive power decreased in steep meridian and increased in flat meridian, resulting in a total decrease of corneal astigmatism. The magnitude of astigmatism correction was 0.85, 1.59, 2.23 and 3.06 D with 30°, 45°, 60° and 90° in arc length of the incision, respectively. Conclusions The finite-element biomechanical model of astigmatic keratotomy could be used to predict the optical outcomes after surgery. The magnitude of astigmatism correction is positively correlated with the surgical incision arc length.%目的:建立散光性角膜切开术的有限元生物力学模型,初步研究各项手术参数对术后角膜形态改变、应力分布及散光矫正量的影响。方法采用Rhinoceros软件建立定量的散光角膜三维模型,设置不同的切口半径、切割深度、切口弧长等手术参数,模拟散光性角膜切开术,于Abaqus软件中完成有限元分析,得到模拟散光性角膜切开术后的角膜形态、节

  2. Microgravity-Driven Optic Nerve/Sheath Biomechanics Simulations

    Ethier, C. R.; Feola, A.; Myers, J. G.; Nelson, E.; Raykin, J.; Samuels, B.

    2016-01-01

    Visual Impairment and Intracranial Pressure (VIIP) syndrome is a concern for long-duration space flight. Current thinking suggests that the ocular changes observed in VIIP syndrome are related to cephalad fluid shifts resulting in altered fluid pressures [1]. In particular, we hypothesize that increased intracranial pressure (ICP) drives connective tissue remodeling of the posterior eye and optic nerve sheath (ONS). We describe here finite element (FE) modeling designed to understand how altered pressures, particularly altered ICP, affect the tissues of the posterior eye and optic nerve sheath (ONS) in VIIP. METHODS: Additional description of the modeling methodology is provided in the companion IWS abstract by Feola et al. In brief, a geometric model of the posterior eye and optic nerve, including the ONS, was created and the effects of fluid pressures on tissue deformations were simulated. We considered three ICP scenarios: an elevated ICP assumed to occur in chronic microgravity, and ICP in the upright and supine positions on earth. Within each scenario we used Latin hypercube sampling (LHS) to consider a range of ICPs, ONH tissue mechanical properties, intraocular pressures (IOPs) and mean arterial pressures (MAPs). The outcome measures were biomechanical strains in the lamina cribrosa, optic nerve and retina; here we focus on peak values of these strains, since elevated strain alters cell phenotype and induce tissue remodeling. In 3D, the strain field can be decomposed into three orthogonal components, denoted as first, second and third principal strains. RESULTS AND CONCLUSIONS: For baseline material properties, increasing ICP from 0 to 20 mmHg significantly changed strains within the posterior eye and ONS (Fig. 1), indicating that elevated ICP affects ocular tissue biomechanics. Notably, strains in the lamina cribrosa and retina became less extreme as ICP increased; however, within the optic nerve, the occurrence of such extreme strains greatly increased as

  3. Hemorheological abnormalities in human arterial hypertension

    Lo Presti, Rosalia; Hopps, Eugenia; Caimi, Gregorio

    2014-05-01

    Blood rheology is impaired in hypertensive patients. The alteration involves blood and plasma viscosity, and the erythrocyte behaviour is often abnormal. The hemorheological pattern appears to be related to some pathophysiological mechanisms of hypertension and to organ damage, in particular left ventricular hypertrophy and myocardial ischemia. Abnormalities have been observed in erythrocyte membrane fluidity, explored by fluorescence spectroscopy and electron spin resonance. This may be relevant for red cell flow in microvessels and oxygen delivery to tissues. Although blood viscosity is not a direct target of antihypertensive therapy, the rheological properties of blood play a role in the pathophysiology of arterial hypertension and its vascular complications.

  4. Computer Models in Biomechanics From Nano to Macro

    Kuhl, Ellen

    2013-01-01

    This book contains a collection of papers that were presented at the IUTAM Symposium on “Computer Models in Biomechanics: From Nano to Macro” held at Stanford University, California, USA, from August 29 to September 2, 2011. It contains state-of-the-art papers on: - Protein and Cell Mechanics: coarse-grained model for unfolded proteins, collagen-proteoglycan structural interactions in the cornea, simulations of cell behavior on substrates - Muscle Mechanics: modeling approaches for Ca2+–regulated smooth muscle contraction, smooth muscle modeling using continuum thermodynamical frameworks, cross-bridge model describing the mechanoenergetics of actomyosin interaction, multiscale skeletal muscle modeling - Cardiovascular Mechanics: multiscale modeling of arterial adaptations by incorporating molecular mechanisms, cardiovascular tissue damage, dissection properties of aortic aneurysms, intracranial aneurysms, electromechanics of the heart, hemodynamic alterations associated with arterial remodeling followin...

  5. Advancements in identifying biomechanical determinants for abdominal aortic aneurysm rupture.

    Kontopodis, Nikolaos; Metaxa, Eleni; Papaharilaou, Yannis; Tavlas, Emmanouil; Tsetis, Dimitrios; Ioannou, Christos

    2015-02-01

    Abdominal aortic aneurysms are a common health problem and currently the need for surgical intervention is determined based on maximum diameter and growth rate criteria. Since these universal variables often fail to predict accurately every abdominal aortic aneurysms evolution, there is a considerable effort in the literature for other markers to be identified towards individualized rupture risk estimations and growth rate predictions. To this effort, biomechanical tools have been extensively used since abdominal aortic aneurysm rupture is in fact a material failure of the diseased arterial wall to compensate the stress acting on it. The peak wall stress, the role of the unique geometry of every individual abdominal aortic aneurysm as well as the mechanical properties and the local strength of the degenerated aneurysmal wall, all confer to rupture risk. In this review article, the assessment of these variables through mechanical testing, advanced imaging and computational modeling is reviewed and the clinical perspective is discussed.

  6. Degrees of freedom of tongue movements in speech may be constrained by biomechanics

    Perrier, Pascal; Payan, Yohan; Zandipour, Majid; Guenther, Franck; Khalighi, Ali

    2007-01-01

    A number of studies carried out on different languages have found that tongue movements in speech are made along two primary degrees of freedom (d.f.s): the high-front to low-back axis and the high-back to low-front axis. We explore the hypothesis that these two main d.f.s could find their origins in the physical properties of the vocal tract. A large set of tongue shapes was generated with a biomechanical tongue model using a Monte-Carlo method to thoroughly sample the muscle control space. The resulting shapes were analyzed with PCA. The first two factors explain 84% of the variance, and they are similar to the two experimentally observed d.f.s. This finding suggests that the d.f.s. are not speech-specific, and that speech takes advantage of biomechanically based tongue properties to form different sounds.

  7. Supplementing biomechanical modeling with EMG analysis

    Lewandowski, Beth; Jagodnik, Kathleen; Crentsil, Lawton; Humphreys, Bradley; Funk, Justin; Gallo, Christopher; Thompson, William; DeWitt, John; Perusek, Gail

    2016-01-01

    It is well established that astronauts experience musculoskeletal deconditioning when exposed to microgravity environments for long periods of time. Spaceflight exercise is used to counteract these effects, and the Advanced Resistive Exercise Device (ARED) on the International Space Station (ISS) has been effective in minimizing musculoskeletal losses. However, the exercise devices of the new exploration vehicles will have requirements of limited mass, power and volume. Because of these limitations, there is a concern that the exercise devices will not be as effective as ARED in maintaining astronaut performance. Therefore, biomechanical modeling is being performed to provide insight on whether the small Multi-Purpose Crew Vehicle (MPCV) device, which utilizes a single-strap design, will provide sufficient physiological loading to maintain musculoskeletal performance. Electromyography (EMG) data are used to supplement the biomechanical model results and to explore differences in muscle activation patterns during exercises using different loading configurations.

  8. Cervical spondylosis anatomy: pathophysiology and biomechanics.

    Shedid, Daniel; Benzel, Edward C

    2007-01-01

    Cervical spondylosis is the most common progressive disorder in the aging cervical spine. It results from the process of degeneration of the intervertebral discs and facet joints of the cervical spine. Biomechanically, the disc and the facets are the connecting structures between the vertebrae for the transmission of external forces. They also facilitate cervical spine mobility. Symptoms related to myelopathy and radiculopathy are caused by the formation of osteophytes, which compromise the diameter of the spinal canal. This compromise may also be partially developmental. The developmental process, together with the degenerative process, may cause mechanical pressure on the spinal cord at one or multiple levels. This pressure may produce direct neurological damage or ischemic changes and, thus, lead to spinal cord disturbances. A thorough understanding of the biomechanics, the pathology, the clinical presentation, the radiological evaluation, as well as the surgical indications of cervical spondylosis, is essential for the management of patients with cervical spondylosis.

  9. Anatomy and biomechanics of the elbow joint.

    Martin, Silvia; Sanchez, Eugenia

    2013-11-01

    Magnetic resonance (MR) imaging provides clinically useful information in assessing the elbow joint. Superior depiction of muscles, ligaments and tendons as well as the ability to directly visualize nerves, bone marrow and hyaline cartilage, are advantages of MR imaging relative to conventional imaging techniques. As the elbow is located superficially, clinical examination is easier for the orthopedic surgeon and only a few cases need a diagnosis for the radiologist, for this reason the elbow joint is little known for the radiologist. To better understand the injuries that occur in the elbow during the sport activities, we need a better understanding of the biomechanics of the joint. And for understanding the biomechanics, it is necessary to know the exact anatomy of the elbow joint and to be able to identify each anatomic structure in the different imaging planes and pulse sequences. This is especially important in MR as the imaging tool that shows a highest soft tissue resolution among other imaging techniques.

  10. Russia: An Abnormal Country

    Steven Rosefielde

    2005-06-01

    Full Text Available Andrei Shleifer and Daniel Treisman recently rendered a summary verdict on the post Soviet Russian transition experience finding that the Federation had become a normal country with the west's assistance, and predicting that it would liberalize and develop further like other successful nations of its type. This essay demonstrates that they are mistaken on the first count, and are likely to be wrong on the second too. It shows factually, and on the norms elaborated by Pareto, Arrow and Bergson that Russia is an abnormal political economy unlikely to democratize, westernize or embrace free enterprise any time soon

  11. Abnormal ionization in sonoluminescence

    Zhang, Wen-Juan; An, Yu

    2015-04-01

    Sonoluminescence is a complex phenomenon, the mechanism of which remains unclear. The present study reveals that an abnormal ionization process is likely to be present in the sonoluminescing bubble. To fit the experimental data of previous studies, we assume that the ionization energies of the molecules and atoms in the bubble decrease as the gas density increases and that the decrease of the ionization energy reaches about 60%-70% as the bubble flashes, which is difficult to explain by using previous models. Project supported by the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120002110031) and the National Natural Science Foundation of China (Grant No. 11334005).

  12. The anatomy and biomechanics of running.

    Nicola, Terry L; Jewison, David J

    2012-04-01

    To understand the normal series of biomechanical events of running, a comparative assessment to walking is helpful. Closed kinetic chain through the lower extremities, control of the lumbopelvic mechanism, and overall symmetry of movement has been described well enough that deviations from normal movement can now be associated with specific overuse injuries experienced by runners. This information in combination with a history of the runner's errors in their training program will lead to a more comprehensive treatment and prevention plan for related injuries.

  13. Development of a biomechanical energy harvester

    Donelan J Maxwell; Naing Veronica; Li Qingguo

    2009-01-01

    Abstract Background Biomechanical energy harvesting–generating electricity from people during daily activities–is a promising alternative to batteries for powering increasingly sophisticated portable devices. We recently developed a wearable knee-mounted energy harvesting device that generated electricity during human walking. In this methods-focused paper, we explain the physiological principles that guided our design process and present a detailed description of our device design with an em...

  14. Biomechanics of pediatric manual wheelchair mobility

    Brooke A. Slavens

    2015-09-01

    Full Text Available Currently, there is limited research of the biomechanics of pediatric manual wheelchair mobility. Specifically, the biomechanics of functional tasks and their relationship to joint pain and health is not well understood. To contribute to this knowledge gap, a quantitative rehabilitation approach was applied for characterizing upper extremity biomechanics of manual wheelchair mobility in children and adolescents during propulsion, starting and stopping tasks. A Vicon motion analysis system captured movement, while a SmartWheel simultaneously collected three-dimensional forces and moments occurring at the hand-rim. A custom pediatric inverse dynamics model was used to evaluate three-dimensional upper extremity joint motions, forces and moments of 14 children with spinal cord injury (SCI during the functional tasks. Additionally, pain and health-related quality of life outcomes were assessed. This research found that joint demands are significantly different amongst functional tasks, with greatest demands placed on the shoulder during the starting task. Propulsion was significantly different from starting and stopping at all joints. We identified multiple stroke patterns used by the children, some of which are not standard in adults. One subject reported average daily pain, which was minimal. Lower than normal physical health and higher than normal mental health was found in this population. It can be concluded that functional tasks should be considered in addition to propulsion for rehabilitation and SCI treatment planning. This research provides wheelchair users and clinicians with a comprehensive, biomechanical, mobility assessment approach for wheelchair prescription, training, and long-term care of children with SCI.

  15. Ergonomic Evaluation of Biomechanical Hand Function

    Lee, Kyung-Sun; Jung, Myung-Chul

    2014-01-01

    The human hand is a complex structure that performs various functions for activities of daily living and occupations. This paper presents a literature review on the methodologies used to evaluate hand functions from a biomechanics standpoint, including anthropometry, kinematics, kinetics, and electromyography (EMG). Anthropometry describes the dimensions and measurements of the hand. Kinematics includes hand movements and the range of motion of finger joints. Kinetics includes hand models for...

  16. A Biomechanical Modeling Guided CBCT Estimation Technique.

    Zhang, You; Tehrani, Joubin Nasehi; Wang, Jing

    2017-02-01

    Two-dimensional-to-three-dimensional (2D-3D) deformation has emerged as a new technique to estimate cone-beam computed tomography (CBCT) images. The technique is based on deforming a prior high-quality 3D CT/CBCT image to form a new CBCT image, guided by limited-view 2D projections. The accuracy of this intensity-based technique, however, is often limited in low-contrast image regions with subtle intensity differences. The solved deformation vector fields (DVFs) can also be biomechanically unrealistic. To address these problems, we have developed a biomechanical modeling guided CBCT estimation technique (Bio-CBCT-est) by combining 2D-3D deformation with finite element analysis (FEA)-based biomechanical modeling of anatomical structures. Specifically, Bio-CBCT-est first extracts the 2D-3D deformation-generated displacement vectors at the high-contrast anatomical structure boundaries. The extracted surface deformation fields are subsequently used as the boundary conditions to drive structure-based FEA to correct and fine-tune the overall deformation fields, especially those at low-contrast regions within the structure. The resulting FEA-corrected deformation fields are then fed back into 2D-3D deformation to form an iterative loop, combining the benefits of intensity-based deformation and biomechanical modeling for CBCT estimation. Using eleven lung cancer patient cases, the accuracy of the Bio-CBCT-est technique has been compared to that of the 2D-3D deformation technique and the traditional CBCT reconstruction techniques. The accuracy was evaluated in the image domain, and also in the DVF domain through clinician-tracked lung landmarks.

  17. Computational Biomechanics Theoretical Background and BiologicalBiomedical Problems

    Tanaka, Masao; Nakamura, Masanori

    2012-01-01

    Rapid developments have taken place in biological/biomedical measurement and imaging technologies as well as in computer analysis and information technologies. The increase in data obtained with such technologies invites the reader into a virtual world that represents realistic biological tissue or organ structures in digital form and allows for simulation and what is called “in silico medicine.” This volume is the third in a textbook series and covers both the basics of continuum mechanics of biosolids and biofluids and the theoretical core of computational methods for continuum mechanics analyses. Several biomechanics problems are provided for better understanding of computational modeling and analysis. Topics include the mechanics of solid and fluid bodies, fundamental characteristics of biosolids and biofluids, computational methods in biomechanics analysis/simulation, practical problems in orthopedic biomechanics, dental biomechanics, ophthalmic biomechanics, cardiovascular biomechanics, hemodynamics...

  18. Biomechanical issues in endovascular device design.

    Moore, James E

    2009-02-01

    The biomechanical nature of the arterial system and its major disease states provides a series of challenges to treatment strategies. Endovascular device design objectives have mostly centered on short-term challenges, such as deployability and immediate restoration of reliable flow channels. The resulting design features may be at odds with long-term clinical success. In-stent restenosis, endoleaks, and loss of device structural integrity (e.g., strut fractures) are all manifestations of a lack of compatibility between the host vessel biomechanical environment and the implant design. Initial attempts to adapt device designs for increased compatibility, including drug-eluting and bioabsorbable stents, barely begin to explore the ways in which implant design can be modulated in time to minimize risk of failure. Biomechanical modeling has the potential to provide a virtual vascular environment in which new designs can be tested for their implications on long-term tissue reaction. These models will be based on high quality, highly resolved imaging information, as well as mechanobiology experiments from the cellular to the whole tissue level. These models can then be extended to incorporate biodegradation mechanics, facilitating the next generations of devices whose designs (including drug delivery profiles) change with time to enhance healing. The possibility of initiating changes in device design or drug release according to information on vascular healing (through clinical intervention or automated methods) provides the opportunity for truly individualized dynamic device design optimization.

  19. Endothelial cells undergo morphological, biomechanical, and dynamic changes in response to tumor necrosis factor-α

    Stroka, Kimberly M.; Vaitkus, Janina A.; Aranda-Espinoza, Helim

    2012-01-01

    The immune response triggers a complicated sequence of events, one of which is release of the cytokine tumor necrosis factor-α (TNF-α) from stromal cells such as monocytes and macrophages. In this work we explored the biophysical effects of TNF-α on endothelial cells (ECs), including changes in cell morphology, biomechanics, migration, and cytoskeletal dynamics. We found that TNF-α induces a wide distribution of cell area and aspect ratio, with these properties increasing on average during tr...

  20. An introduction to biomechanics solids and fluids, analysis and design

    Humphrey, Jay D

    2004-01-01

    Designed to meet the needs of undergraduate students, Introduction to Biomechanics takes the fresh approach of combining the viewpoints of both a well-respected teacher and a successful student. With an eye toward practicality without loss of depth of instruction, this book seeks to explain the fundamental concepts of biomechanics. With the accompanying web site providing models, sample problems, review questions and more, Introduction to Biomechanics provides students with the full range of instructional material for this complex and dynamic field.

  1. An Evidence-Based Videotaped Running Biomechanics Analysis.

    Souza, Richard B

    2016-02-01

    Running biomechanics play an important role in the development of injuries. Performing a running biomechanics analysis on injured runners can help to develop treatment strategies. This article provides a framework for a systematic video-based running biomechanics analysis plan based on the current evidence on running injuries, using 2-dimensional (2D) video and readily available tools. Fourteen measurements are proposed in this analysis plan from lateral and posterior video. Identifying simple 2D surrogates for 3D biomechanic variables of interest allows for widespread translation of best practices, and have the best opportunity to impact the highly prevalent problem of the injured runner.

  2. The biomechanics of soccer: a review.

    Lees, A; Nolan, L

    1998-04-01

    This review considers the biomechanical factors that are relevant to success in the game of soccer. Three broad areas are covered: (1) the technical performance of soccer skills; (2) the equipment used in playing the game; and (3) the causative mechanisms of specific soccer injuries. Kicking is the most widely studied soccer skill. Although there are many types of kick, the variant most widely reported in the literature is the maximum velocity instep kick of a stationary ball. In contrast, several other skills, such as throwing-in and goalkeeping, have received little attention; some, for example passing and trapping the ball, tackling, falling behaviour, jumping, running, sprinting, starting, stopping and changing direction, have not been the subject of any detailed biomechanical investigation. The items of equipment reviewed are boots, the ball, artificial and natural turf surfaces and shin guards. Little of the research conducted by equipment manufacturers is in the public domain; this part of the review therefore concentrates on the mechanical responses of equipment, player-equipment interaction, and the effects of equipment on player performance and protection. Although the equipment has mechanical characteristics that can be reasonably well quantified, the player-equipment interaction is more difficult to establish; this makes its efficacy for performance or protection difficult to predict. Some soccer injuries may be attributable to the equipment used. The soccer boot has a poor protective capability, but careful design can have a minor influence on reducing the severity of ankle inversion injuries. Performance requirements limit the scope for reducing these injuries; alternative methods for providing ankle stability are necessary. Artificial surfaces result in injury profiles different from those on natural turf pitches. There is a tendency for fewer serious injuries, but more minor injuries, on artificial turf than on natural turf pitches. Players adapt to

  3. Role of biomechanics in the understanding of normal, injured, and healing ligaments and tendons

    Jung Ho-Joong

    2009-05-01

    Full Text Available Abstract Ligaments and tendons are soft connective tissues which serve essential roles for biomechanical function of the musculoskeletal system by stabilizing and guiding the motion of diarthrodial joints. Nevertheless, these tissues are frequently injured due to repetition and overuse as well as quick cutting motions that involve acceleration and deceleration. These injuries often upset this balance between mobility and stability of the joint which causes damage to other soft tissues manifested as pain and other morbidity, such as osteoarthritis. The healing of ligament and tendon injuries varies from tissue to tissue. Tendinopathies are ubiquitous and can take up to 12 months for the pain to subside before one could return to normal activity. A ruptured medial collateral ligament (MCL can generally heal spontaneously; however, its remodeling process takes years and its biomechanical properties remain inferior when compared to the normal MCL. It is also known that a midsubstance anterior cruciate ligament (ACL tear has limited healing capability, and reconstruction by soft tissue grafts has been regularly performed to regain knee function. However, long term follow-up studies have revealed that 20–25% of patients experience unsatisfactory results. Thus, a better understanding of the function of ligaments and tendons, together with knowledge on their healing potential, may help investigators to develop novel strategies to accelerate and improve the healing process of ligaments and tendons. With thousands of new papers published in the last ten years that involve biomechanics of ligaments and tendons, there is an increasing appreciation of this subject area. Such attention has positively impacted clinical practice. On the other hand, biomechanical data are complex in nature, and there is a danger of misinterpreting them. Thus, in these review, we will provide the readers with a brief overview of ligaments and tendons and refer them to

  4. Shape memory alloys: metallurgy, biocompatibility, and biomechanics for neurosurgical applications.

    Hoh, Daniel J; Hoh, Brian L; Amar, Arun P; Wang, Michael Y

    2009-05-01

    SHAPE MEMORY ALLOYS possess distinct dynamic properties with particular applications in neurosurgery. Because of their unique physical characteristics, these materials are finding increasing application where resiliency, conformation, and actuation are needed. Nitinol, the most frequently manufactured shape memory alloy, responds to thermal and mechanical stimuli with remarkable mechanical properties such as shape memory effect, super-elasticity, and high damping capacity. Nitinol has found particular use in the biomedical community because of its excellent fatigue resistance and biocompatibility, with special interest in neurosurgical applications. The properties of nitinol and its diffusionless phase transformations contribute to these unique mechanical capabilities. The features of nitinol, particularly its shape memory effect, super-elasticity, damping capacity, as well as its biocompatibility and biomechanics are discussed herein. Current and future applications of nitinol and other shape memory alloys in endovascular, spinal, and minimally invasive neurosurgery are introduced. An understanding of the metallurgic properties of nitinol provides a foundation for further exploration of its use in neurosurgical implant design.

  5. Biomechanics of the Optic Nerve Sheath in VIIP Syndrome

    Ethier, C. Ross; Raykin, Julia; Gleason, Rudy; Mulugeta, Lealem; Myers, Jerry; Nelson, Emily; Samuels, Brian C.

    2014-01-01

    Long-duration space flight carries the risk of developing Visual Impairment and Intracranial Pressure (VIIP) syndrome, a spectrum of ophthalmic changes including posterior globe flattening, choroidal folds, distension of the optic nerve sheath (ONS), optic nerve kinking and potentially permanent degradation of visual function. The slow onset of VIIP, its chronic nature, and certain clinical features strongly suggest that biomechanical factors acting on the ONS play a role in VIIP. Here we measure several relevant ONS properties needed to model VIIP biomechanics. The ONS (meninges) of fresh porcine eyes (n7) was reflected, the nerve proper was truncated near the sclera, and the meninges were repositioned to create a hollow cylinder of meningeal connective tissue attached to the posterior sclera. The distal end was cannulated, sealed, and pressure clamped (mimicking cerebrospinal fluid [CSF] pressure), while the eye was also cannulated for independent control of intraocular pressure (IOP). The meninges were inflated (CSF pressure cycling 7-50 mmHg) while ONS outer diameter was imaged. In another set of experiments (n4), fluid permeation rate across the meninges was recorded by observing the drainage of an elevated fluid reservoir (30 mmHg) connected to the meninges. The ONS showed behavior typical of soft tissues: viscoelasticity, with hysteresis in early preconditioning cycles and repeatable behavior after 4 cycles, and nonlinear stiffening, particularly at CSF pressures 15 mmHg (Figure). Tangent moduli measured from the loading curve were 372 101, 1199 358, and 2050 379 kPa (mean SEM) at CSF pressures of 7, 15 and 30 mmHg, respectively. Flow rate measurements through the intact meninges at 30mmHg gave a permeability of 1.34 0.46 lmincm2mmHg (mean SEM). The ONS is a tough, strain-stiffening connective tissue that is surprisingly permeable. The latter observation suggests that there could be significant CSF drainage through the ONS into the orbit, likely important

  6. A Rare Stapes Abnormality

    Hala Kanona

    2015-01-01

    Full Text Available The aim of this study is to increase awareness of rare presentations, diagnostic difficulties alongside management of conductive hearing loss and ossicular abnormalities. We report the case of a 13-year-old female reporting progressive left-sided hearing loss and high resolution computed tomography was initially reported as normal. Exploratory tympanotomy revealed an absent stapedius tendon and lack of connection between the stapes superstructure and footplate. The footplate was fixed. Stapedotomy and stapes prosthesis insertion resulted in closure of the air-bone gap by 50 dB. A review of world literature was performed using MedLine. Middle ear ossicular discontinuity can result in significant conductive hearing loss. This can be managed effectively with surgery to help restore hearing. However, some patients may not be suitable or decline surgical intervention and can be managed safely conservatively.

  7. Physical limits to biomechanical sensing

    Beroz, Farzan; Münster, Stefan; Weitz, David A; Broedersz, Chase P; Wingreen, Ned S

    2016-01-01

    Cells actively probe and respond to the stiffness of their surroundings. Since mechanosensory cells in connective tissue are surrounded by a disordered network of biopolymers, their in vivo mechanical environment can be extremely heterogeneous. Here, we investigate how this heterogeneity impacts mechanosensing by modeling the cell as an idealized local stiffness sensor inside a disordered fiber network. For all types of networks we study, including experimentally-imaged collagen and fibrin architectures, we find that measurements applied at different points throughout a given network yield a strikingly broad range of local stiffnesses, spanning roughly two decades. We verify via simulations and scaling arguments that this broad range of local stiffnesses is a generic property of disordered fiber networks, and show that the range can be further increased by tuning specific network features, including the presence of long fibers and the proximity to elastic transitions. These features additionally allow for a h...

  8. Biomechanical remodeling of the chronically obstructed Guinea pig small intestine.

    Storkholm, Jan Henrik; Zhao, Jingbo; Villadsen, Gerda E; Hager, H; Jensen, Steen L; Gregersen, Hans

    2007-02-01

    Small intestinal obstruction is a frequently encountered clinical problem. To understand the mechanisms behind obstruction and the clinical consequences, data are needed on the relation between the morphologic and biomechanical remodeling that takes place in the intestinal wall during chronic obstruction. We sought to determine the effect of partial obstruction on mechanical and morphologic properties of the guinea pig small intestine. Partial obstruction was created surgically in 2 groups of animals living for 2 and 4 weeks. Controls were sham operated and lived for 4 weeks. A combined impedance planimetry-high-frequency ultrasound system was designed to measure the luminal cross-sectional area and wall thickness. These measures were used to compute the circumferential stress and strain of the excised intestinal segments. The incremental elastic modulus was obtained by using nonlinear fitting of the stress-strain curve. Histologic analysis and the measurements of total wall collagen were also performed. The luminal cross-sectional area, wall thickness, and elastic modulus in circumferential direction increased in a time-dependent manner proximal to the obstruction site (P 0.25). The circumferential stress-strain curves of the proximal segments in 2- and 4-week groups shifted to the left, indicating the intestinal wall became stiffer. Histologic examination revealed a massive increase in the thickness of the muscle layer especially the circular smooth muscle layer (P < 0.05). The collagen content proximal to the obstruction site was significantly larger in the partially obstructed animals compared to controls (P < 0.05). No difference was found distal to the obstruction site. Strong correlation was found between the collagen content and the elastic modulus at stress levels of 70 kPa stress (P < 0.01) and 10 kPa (P < 0.05) proximal to the obstruction site suggesting that the alteration of collagen has great impact on the mechanical remodeling. The morphologic and

  9. Cataract surgery causes biomechanical alterations to the eye detectable by Corvis ST tonometry

    Kato, Yoshitake; Nakakura, Shunsuke; Asaoka, Ryo; Matsuya, Kanae; Fujio, Yuki; Kiuchi, Yoshiaki

    2017-01-01

    Purpose Modern cataract surgery is generally considered to bring about modest and sustained intraocular pressure (IOP) reduction. However, the pathophysiological mechanism for this remains unclear. Moreover, a change in ocular biomechanical properties after surgery can affect the measurement of IOP. The aim of the study is to investigate ocular biomechanics, before and following cataract surgery, using Corvis ST tonometry (CST). Patients and methods Fifty-nine eyes of 59 patients with cataract were analyzed. IOP with Goldmann applanation tonometry (IOP-G), axial length, corneal curvature and CST parameters were measured before cataract surgery and, up to 3 months, following surgery. Since CST parameters are closely related to IOP-G, linear modeling was carried out to investigate whether there was a change in CST measurements following cataract surgery, adjusted for a change in IOP-G. Results IOP-G significantly decreased after surgery (mean±standard deviation: 11.8±3.1 mmHg) compared to pre-surgery (15.2±4.3 mmHg, Pcataract surgery (Pcataract surgery (Pcataract surgery. Conclusion Corneal biomechanical properties, as measured with CST, were observed to change significantly following cataract surgery. Trial registration Japan Clinical Trials Registry UMIN000014370 PMID:28222145

  10. Long-latency reflexes account for limb biomechanics through several supraspinal pathways

    Isaac Louis Kurtzer

    2015-01-01

    Full Text Available Accurate control of body posture is enforced by a multitude of corrective actions operating over a range of time scales. The earliest correction is the short-latency reflex which occurs between 20-45 ms following a sudden displacement of the limb and is generated entirely by spinal circuits. In contrast, voluntary reactions are generated by a highly distributed network but at a significantly longer delay after stimulus onset (greater than 100 ms. Between these two epochs is the long-latency reflex (around 50-100 ms which but acts more rapidly than of voluntary reactions but shares some supraspinal pathways and functional capabilities. In particular, the long-latency reflex accounts for the arm’s biomechanical properties rather than only responding to local muscle stretch like the short-latency reflex. This paper will review how the long-latency reflex accounts for the arm’s biomechanical properties and the supraspinal pathways supporting this ability. Relevant experimental paradigms include clinical studies, non-invasive brain stimulation, neural recordings in monkeys, and human behavioral studies. The sum of this effort indicates that primary motor cortex and reticular formation contribute to the the long-latency reflex either by generating or scaling its structured response appropriate for the arm’s biomechanics whereas the cerebellum scales the magnitude of the feedback response. Additional putative pathways are discussed as well as potential research lines.

  11. Decreased trabecular bone biomechanical competence, apparent density, IGF-II and IGFBP-5 content in acromegaly

    Ueland, Thor; Ebbesen, Ebbe Nils; Thomsen, Jesper Skovhus;

    2002-01-01

    of these growth factors in relation to biomechanical properties in acromegaly. MATERIALS AND METHODS: Trabecular bone biomechanical competence (compression test), apparent density (peripheral quantitative computed tomography, pQCT), and bone matrix contents of calcium (HCl hydrolysis) and IGFs (guanidinium......-HCl extraction) were measured in iliac crest biopsies from 13 patients with active acromegaly (two women and 11 men, aged 21-61 years) and 21 age- and sex-matched controls (four women and 17 men, aged 23-64 years). RESULTS: Trabecular bone pQCT was reduced in acromegalic patients compared with controls (P = 0...... bone content of IGF-I, IGFBP-3, or osteocalcin. However, IGF-II and IGFBP-5 content was decreased (P acromegaly, supporting previous observations...

  12. Anterolateral Versus Medial Plating of Distal Extra-articular Tibia Fractures: A Biomechanical Model.

    Pirolo, Joseph M; Behn, Anthony W; Abrams, Geoffrey D; Bishop, Julius A

    2015-09-01

    Both medial and anterolateral plate applications have been described for the treatment of distal tibia fractures, each with distinct advantages and disadvantages. The objective of this study was to compare the biomechanical properties of medial and anterolateral plating constructs used to stabilize simulated varus and valgus fracture patterns of the distal tibia. In 16 synthetic tibia models, a 45° oblique cut was made to model an Orthopedic Trauma Association type 43-A1.2 distal tibia fracture in either a varus or valgus injury pattern. Each fracture was then reduced and plated with a precontoured medial or anterolateral distal tibia plate. The specimens were biomechanically tested in axial and torsional loading, cyclic axial loading, and load to failure. For the varus fracture pattern, medial plating showed less fracture site displacement and rotation and was stiffer in both axial and torsional loading (Ptibia fractures.

  13. Tubulin bond energies and microtubule biomechanics determined from nanoindentation in silico

    Kononova, Olga; Theisen, Kelly E; Marx, Kenneth A; Dima, Ruxandra I; Ataullakhanov, Fazly I; Grishchuk, Ekaterina L; Barsegov, Valeri

    2015-01-01

    Microtubules, the primary components of the chromosome segregation machinery, are stabilized by longitudinal and lateral non-covalent bonds between the tubulin subunits. However, the thermodynamics of these bonds and the microtubule physico-chemical properties are poorly understood. Here, we explore the biomechanics of microtubule polymers using multiscale computational modeling and nanoindentations in silico of a contiguous microtubule fragment. A close match between the simulated and experimental force-deformation spectra enabled us to correlate the microtubule biomechanics with dynamic structural transitions at the nanoscale. Our mechanical testing revealed that the compressed MT behaves as a system of rigid elements interconnected through a network of lateral and longitudinal elastic bonds. The initial regime of continuous elastic deformation of the microtubule is followed by the transition regime, during which the microtubule lattice undergoes discrete structural changes, which include first the reversib...

  14. The Undergraduate Biomechanics Experience at Iowa State University.

    Francis, Peter R.

    This paper discusses the objectives of a program in biomechanics--the analysis of sports skills and movement--and the evolution of the biomechanics program at Iowa State University. The primary objective of such a course is to provide the student with the basic tools necessary for adequate analysis of human movement, with special emphasis upon…

  15. Factors Related to Students' Learning of Biomechanics Concepts

    Hsieh, ChengTu; Smith, Jeremy D.; Bohne, Michael; Knudson, Duane

    2012-01-01

    The purpose of this study was to replicate and expand a previous study to identify the factors that affect students' learning of biomechanical concepts. Students were recruited from three universities (N = 149) located in the central and western regions of the United States. Data from 142 students completing the Biomechanics Concept Inventory…

  16. Biomechanics, Exercise Physiology, and the 75th Anniversary of RQES

    Hamill, Joseph; Haymes, Emily M.

    2005-01-01

    The purpose of this paper is to review the biomechanics and exercise physiology studies published in the Research Quarterly for Exercise and Sport (RQES) over the past 75 years. Studies in biomechanics, a relatively new subdiscipline that evolved from kinesiology, first appeared in the journal about 40 years ago. Exercise physiology studies have…

  17. Biomechanical factors associated with the development of tibiofemoral knee osteoarthritis

    van Tunen, Joyce A C; Dell'Isola, Andrea; Juhl, Carsten

    2016-01-01

    INTRODUCTION: Altered biomechanics, increased joint loading and tissue damage, might be related in a vicious cycle within the development of knee osteoarthritis (KOA). We have defined biomechanical factors as joint-related factors that interact with the forces, moments and kinematics in and around...

  18. BIOMECHANICS AND PATHOMECHANICS OF THE PATELLOFEMORAL JOINT.

    Loudon, Janice K

    2016-12-01

    The patellofemoral joint is a joint that can be an area of concern for athletes of various sports and ages. The joint is somewhat complex with multiple contact points and numerous tissues that attach to the patella. Joint forces are variable and depend on the degree of knee flexion and whether the foot is in contact with the ground. The sports medicine specialist must have a good working knowledge of the anatomy and biomechanics of the patellofemoral joint in order to treat it effectively.

  19. Communication and abnormal behaviour.

    Crown, S

    1979-01-01

    In this paper the similarities between normal and abnormal behaviour are emphasized and selected aspects of communication, normal and aberrant, between persons are explored. Communication in a social system may be verbal or non-verbal: one person's actions cause a response in another person. This response may be cognitive, behavioural or physiological. Communication may be approached through the individual, the social situation or social interaction. Psychoanalysis approaches the individual in terms of the coded communications of psychoneurotic symptoms or psychotic behaviour; the humanist-existential approach is concerned more with emotional expression. Both approaches emphasize the development of individual identity. The interaction between persons and their social background is stressed. Relevant are sociological concepts such as illness behaviour, stigma, labelling, institutionalization and compliance. Two approaches to social interactions are considered: the gamesplaying metaphor, e.g. back pain as a psychosocial manipulation--the 'pain game'; and the 'spiral of reciprocal perspectives' which emphasizes the interactional complexities of social perceptions. Communicatory aspects of psychological treatments are noted: learning a particular metaphor such as 'resolution' of the problem (psychotherapy), learning more 'rewarding' behaviour (learning theory) or learning authenticity or self-actualization (humanist-existential).

  20. Jet Methods in Time-Dependent Lagrangian Biomechanics

    Ivancevic, Tijana T

    2009-01-01

    In this paper we propose the time-dependent generalization of an `ordinary' autonomous human biomechanics, in which total mechanical + biochemical energy is not conserved. We introduce a general framework for time-dependent biomechanics in terms of jet manifolds associated to the extended musculo-skeletal configuration manifold, called the configuration bundle. We start with an ordinary configuration manifold of human body motion, given as a set of its all active degrees of freedom (DOF) for a particular movement. This is a Riemannian manifold with a material metric tensor given by the total mass-inertia matrix of the human body segments. This is the base manifold for standard autonomous biomechanics. To make its time-dependent generalization, we need to extend it with a real time axis. By this extension, using techniques from fibre bundles, we defined the biomechanical configuration bundle. On the biomechanical bundle we define vector-fields, differential forms and affine connections, as well as the associat...

  1. Optic nerve head biomechanics in aging and disease.

    Downs, J Crawford

    2015-04-01

    This nontechnical review is focused upon educating the reader on optic nerve head biomechanics in both aging and disease along two main themes: what is known about how mechanical forces and the resulting deformations are distributed in the posterior pole and ONH (biomechanics) and what is known about how the living system responds to those deformations (mechanobiology). We focus on how ONH responds to IOP elevations as a structural system, insofar as the acute mechanical response of the lamina cribrosa is confounded with the responses of the peripapillary sclera, prelaminar neural tissues, and retrolaminar optic nerve. We discuss the biomechanical basis for IOP-driven changes in connective tissues, blood flow, and cellular responses. We use glaucoma as the primary framework to present the important aspects of ONH biomechanics in aging and disease, as ONH biomechanics, aging, and the posterior pole extracellular matrix (ECM) are thought to be centrally involved in glaucoma susceptibility, onset and progression.

  2. Biomechanics: an integral part of sport science and sport medicine.

    Elliott, B

    1999-12-01

    Biomechanics is one of the disciplines in the field of Human Movement and Exercise Science and it can be divided into three broad categories from a research perspective. Clinical biomechanics involves research in the areas of gait, neuromuscular control, tissue mechanics, and movement evaluation during rehabilitation from either injury or disease. Occupational biomechanics typically involves research in the areas of ergonomics and human growth or morphology as they influence movement. While these two categories will briefly be discussed, the primary aim of this paper is to show the role of biomechanics in sports science and sports medicine. Research in sports biomechanics may take the form of describing movement from a performance enhancement (such as matching of impulse curves in rowing) or injury reduction perspective (such as diving in swimming or the assessment of knee joint loading during downhill walking). However, the strength of sports biomechanics research is the ability to establish an understanding of causal mechanisms for selected movements (such as the role of internal rotation of the upper arm in hitting or striking, and the influence of elastic energy and muscle pre-stretch in stretch-shorten-cycle actions). The growth of modelling and computer simulation has further enhanced the potential use of sports biomechanics research (such as quantification of knee joint ligament forces from a dynamic model and optimising gymnastics performance through simulation of in-flight movements). Biomechanics research may also play an integral role in reducing the incidence and severity of sporting injuries (such as identification of the causes of back injuries in cricket, and the causes of knee joint injuries in sport). In the following discussion no attempt will be made to reference all papers published in each of these areas because of the enormity of the task. Published and current work from the biomechanics laboratory at the Department of Human Movement and

  3. Semen abnormalities with SSRI antidepressants.

    2015-01-01

    Despite decades of widespread use, the adverse effect profile of "selective" serotonin reuptake inhibitor (SSRI) antidepressants has still not been fully elucidated. Studies in male animals have shown delayed sexual development and reduced fertility. Three prospective cohort studies conducted in over one hundred patients exposed to an SSRI for periods ranging from 5 weeks to 24 months found altered semen param-eters after as little as 3 months of exposure: reduced sperm concentration, reduced sperm motility, a higher percentage of abnormal spermatozoa, and increased levels of sperm DNA fragmentation. One clinical trial showed growth retardation in children considered depressed who were exposed to SSRls. SSRls may have endocrine disrupting properties. Dapoxetine is a short-acting serotonin reuptake inhibitor that is chemically related to fluoxetine and marketed in the European Union for men complaining of premature ejaculation. But the corresponding European summary of product characteristics does not mention any effects on fertility. In practice, based on the data available as of mid-2014, the effects of SSRI exposure on male fertility are unclear. However, it is a risk that should be taken into account and pointed out to male patients who would like to father a child or who are experiencing fertility problems.

  4. Integrative Structural Biomechanical Concepts of Ankylosing Spondylitis

    Alfonse T. Masi

    2011-01-01

    Full Text Available Ankylosing spondylitis (AS is not fully explained by inflammatory processes. Clinical, epidemiological, genetic, and course of disease features indicate additional host-related risk processes and predispositions. Collectively, the pattern of predisposition to onset in adolescent and young adult ages, male preponderance, and widely varied severity of AS is unique among rheumatic diseases. However, this pattern could reflect biomechanical and structural differences between the sexes, naturally occurring musculoskeletal changes over life cycles, and a population polymorphism. During juvenile development, the body is more flexible and weaker than during adolescent maturation and young adulthood, when strengthening and stiffening considerably increase. During middle and later ages, the musculoskeletal system again weakens. The novel concept of an innate axial myofascial hypertonicity reflects basic mechanobiological principles in human function, tissue reactivity, and pathology. However, these processes have been little studied and require critical testing. The proposed physical mechanisms likely interact with recognized immunobiological pathways. The structural biomechanical processes and tissue reactions might possibly precede initiation of other AS-related pathways. Research in the combined structural mechanobiology and immunobiology processes promises to improve understanding of the initiation and perpetuation of AS than prevailing concepts. The combined processes might better explain characteristic enthesopathic and inflammatory processes in AS.

  5. Adaptive sports technology and biomechanics: wheelchairs.

    Cooper, Rory A; De Luigi, Arthur Jason

    2014-08-01

    Wheelchair sports are an important tool in the rehabilitation of people with severe chronic disabilities and have been a driving force for innovation in technology and practice. In this paper, we will present an overview of the adaptive technology used in Paralympic sports with a special focus on wheeled technology and the impact of design on performance (defined as achieving the greatest level of athletic ability and minimizing the risk of injury). Many advances in manual wheelchairs trace their origins to wheelchair sports. Features of wheelchairs that were used for racing and basketball 25 or more years ago have become integral to the manual wheelchairs that people now use every day; moreover, the current components used on ultralight wheelchairs also have benefitted from technological advances developed for sports wheelchairs. For example, the wheels now used on chairs for daily mobility incorporate many of the components first developed for sports chairs. Also, advances in manufacturing and the availability of aerospace materials have driven current wheelchair design and manufacture. Basic principles of sports wheelchair design are universal across sports and include fit; minimizing weight while maintaining high stiffness; minimizing rolling resistance; and optimizing the sports-specific design of the chair. However, a well-designed and fitted wheelchair is not sufficient for optimal sports performance: the athlete must be well trained, skilled, and use effective biomechanics because wheelchair athletes face some unique biomechanical challenges.

  6. Inelastic mechanics: A unifying principle in biomechanics.

    Gralka, Matti; Kroy, Klaus

    2015-11-01

    Many soft materials are classified as viscoelastic. They behave mechanically neither quite fluid-like nor quite solid-like - rather a bit of both. Biomaterials are often said to fall into this class. Here, we argue that this misses a crucial aspect, and that biomechanics is essentially damage mechanics, at heart. When deforming an animal cell or tissue, one can hardly avoid inducing the unfolding of protein domains, the unbinding of cytoskeletal crosslinkers, the breaking of weak sacrificial bonds, and the disruption of transient adhesions. We classify these activated structural changes as inelastic. They are often to a large degree reversible and are therefore not plastic in the proper sense, but they dissipate substantial amounts of elastic energy by structural damping. We review recent experiments involving biological materials on all scales, from single biopolymers over cells to model tissues, to illustrate the unifying power of this paradigm. A deliberately minimalistic yet phenomenologically very rich mathematical modeling framework for inelastic biomechanics is proposed. It transcends the conventional viscoelastic paradigm and suggests itself as a promising candidate for a unified description and interpretation of a wide range of experimental data. This article is part of a Special Issue entitled: Mechanobiology.

  7. Biomechanical Energy Harvester Design For Active Prostheses

    Akın Oğuz Kaptı

    2012-06-01

    Full Text Available One of the factors restricting the functions of active prostheses is limited charge times and weights of the batteries. Therefore, some biomechanical energy harvesting studies are conducted for reducing the dependence on batteries and developing the systems that produce energy by utilizing one's own actions during daily living activities. In this study, as a new approach to meet energy needs of active-controlled lower limb prostheses, the design of a biomechanical energy harvester that produces electrical energy from the movements of the knee joint during gait were carried out. This harvester is composed of the generator, planetary gear system and one-way clutch that transmit just the knee extension. Low weight, low additional metabolic power consumption requirement and high electrical power generation are targeted in design process. The total reduction ratio of the transmission is 104, and the knee joint reaction torque applied by the system is 6 Nm. Average electrical powers that can be obtained are 17 W and 5,8 W for the swing extension phase and the entire cycle, respectively. These values seem to be sufficient for charging the battery units of many prostheses and similar medical systems, and portable electronic devices such as mobile phones, navigation devices and laptops.

  8. Biomechanics of Counterweighted One-Legged Cycling.

    Elmer, Steven J; McDaniel, John; Martin, James C

    2016-02-01

    One-legged cycling has served as a valuable research tool and as a training and rehabilitation modality. Biomechanics of one-legged cycling are unnatural because the individual must actively lift the leg during flexion, which can be difficult to coordinate and cause premature fatigue. We compared ankle, knee, and hip biomechanics between two-legged, one-legged, and counterweighted (11.64 kg) one-legged cycling. Ten cyclists performed two-legged (240 W), one-legged (120 W), and counterweighted one-legged (120 W) cycling (80 rpm). Pedal forces and limb kinematics were recorded to determine work during extension and flexion. During counterweighted one-legged cycling relative ankle dorsiflexion, knee flexion, and hip flexion work were less than one-legged but greater than two-legged cycling (all P cycling were greater than one-legged but less than two-legged cycling (all P cycling reduced but did not eliminate differences in joint flexion and extension actions between one- and two-legged cycling. Even with these differences, counterweighted one-legged cycling seemed to have advantages over one-legged cycling. These results, along with previous work highlighting physiological characteristics and training adaptations to counterweighted one-legged cycling, demonstrate that this exercise is a viable alternative to one-legged cycling.

  9. Integrated biomechanical and topographical surface characterization (IBTSC)

    Löberg, Johanna; Mattisson, Ingela; Ahlberg, Elisabet

    2014-01-01

    In an attempt to reduce the need for animal studies in dental implant applications, a new model has been developed which combines well-known surface characterization methods with theoretical biomechanical calculations. The model has been named integrated biomechanical and topographical surface characterization (IBTSC), and gives a comprehensive description of the surface topography and the ability of the surface to induce retention strength with bone. IBTSC comprises determination of 3D-surface roughness parameters by using 3D-scanning electron microscopy (3D-SEM) and atomic force microscopy (AFM), and calculation of the ability of different surface topographies to induce retention strength in bone by using the local model. Inherent in this integrated approach is the use of a length scale analysis, which makes it possible to separate different size levels of surface features. The IBTSC concept is tested on surfaces with different level of hierarchy, induced by mechanical as well as chemical treatment. Sequential treatment with oxalic and hydrofluoric acid results in precipitated nano-sized features that increase the surface roughness and the surface slope on the sub-micro and nano levels. This surface shows the highest calculated shear strength using the local model. The validity, robustness and applicability of the IBTSC concept are demonstrated and discussed.

  10. Biomechanical consequences of epiphytism in intertidal macroalgae.

    Anderson, Laura M; Martone, Patrick T

    2014-04-01

    Epiphytic algae grow on other algae rather than hard substrata, perhaps circumventing competition for space in marine ecosystems. Aquatic epiphytes are widely thought to negatively affect host fitness; it is also possible that epiphytes benefit from associating with hosts. This study explored the biomechanical costs and benefits of the epiphytic association between the intertidal brown algal epiphyte Soranthera ulvoidea and its red algal host Odonthalia floccosa. Drag on epiphytized and unepiphytized hosts was measured in a recirculating water flume. A typical epiphyte load increased drag on hosts by ~50%, increasing dislodgment risk of epiphytized hosts compared with hosts that did not have epiphytes. However, epiphytes were more likely to dislodge from hosts than hosts were to dislodge from the substratum, suggesting that drag added by epiphytes may not be mechanically harmful to hosts if epiphytes break first. Concomitantly, epiphytes experienced reduced flow when attached to hosts, perhaps allowing them to grow larger or live in more wave-exposed areas. Biomechanical interactions between algal epiphytes and hosts are complex and not necessarily negative, which may partially explain the evolution and persistence of epiphytic relationships.

  11. Integrated biomechanical and topographical surface characterization (IBTSC)

    Löberg, Johanna, E-mail: Johanna.Loberg@dentsply.com [Dentsply Implants, Box 14, SE-431 21 Mölndal (Sweden); Mattisson, Ingela [Dentsply Implants, Box 14, SE-431 21 Mölndal (Sweden); Ahlberg, Elisabet [Department of Chemistry and Molecular Biology, University of Gothenburg, SE-41296 Gothenburg (Sweden)

    2014-01-30

    In an attempt to reduce the need for animal studies in dental implant applications, a new model has been developed which combines well-known surface characterization methods with theoretical biomechanical calculations. The model has been named integrated biomechanical and topographical surface characterization (IBTSC), and gives a comprehensive description of the surface topography and the ability of the surface to induce retention strength with bone. IBTSC comprises determination of 3D-surface roughness parameters by using 3D-scanning electron microscopy (3D-SEM) and atomic force microscopy (AFM), and calculation of the ability of different surface topographies to induce retention strength in bone by using the local model. Inherent in this integrated approach is the use of a length scale analysis, which makes it possible to separate different size levels of surface features. The IBTSC concept is tested on surfaces with different level of hierarchy, induced by mechanical as well as chemical treatment. Sequential treatment with oxalic and hydrofluoric acid results in precipitated nano-sized features that increase the surface roughness and the surface slope on the sub-micro and nano levels. This surface shows the highest calculated shear strength using the local model. The validity, robustness and applicability of the IBTSC concept are demonstrated and discussed.

  12. Systemic abnormalities in liver disease

    Masami Minemura; Kazuto Tajiri; Yukihiro Shimizu

    2009-01-01

    Systemic abnormalities often occur in patients with liver disease. In particular, cardiopulmonary or renal diseases accompanied by advanced liver disease can be serious and may determine the quality of life and prognosis of patients. Therefore, both hepatologists and non-hepatologists should pay attention to such abnormalities in the management of patients with liver diseases.

  13. Abnormal pressure in hydrocarbon environments

    Law, B.E.; Spencer, C.W.

    1998-01-01

    Abnormal pressures, pressures above or below hydrostatic pressures, occur on all continents in a wide range of geological conditions. According to a survey of published literature on abnormal pressures, compaction disequilibrium and hydrocarbon generation are the two most commonly cited causes of abnormally high pressure in petroleum provinces. In young (Tertiary) deltaic sequences, compaction disequilibrium is the dominant cause of abnormal pressure. In older (pre-Tertiary) lithified rocks, hydrocarbon generation, aquathermal expansion, and tectonics are most often cited as the causes of abnormal pressure. The association of abnormal pressures with hydrocarbon accumulations is statistically significant. Within abnormally pressured reservoirs, empirical evidence indicates that the bulk of economically recoverable oil and gas occurs in reservoirs with pressure gradients less than 0.75 psi/ft (17.4 kPa/m) and there is very little production potential from reservoirs that exceed 0.85 psi/ft (19.6 kPa/m). Abnormally pressured rocks are also commonly associated with unconventional gas accumulations where the pressuring phase is gas of either a thermal or microbial origin. In underpressured, thermally mature rocks, the affected reservoirs have most often experienced a significant cooling history and probably evolved from an originally overpressured system.

  14. Different implant fixation repairs femoral neck combined with ipsilateral subtrochanteric fractures:comparisons of biomechanical properties%不同植入物内固定修复股骨颈合并同侧转子下骨折:生物力学性能比较

    王延军; 侯军; 万博; 刘刚; 牛刚; 张扬; 党晓谦

    2016-01-01

    背景:选择强度和刚度良好的内固定器植入物是修复股骨颈合并同侧转子下骨折的关键。目的:比较不同植入物内固定修复股骨颈不和同侧转子下骨折的生物力学性能。方法:将24根成年防腐尸体标本制作成为股骨颈骨折合并同侧转子下内侧皮质缺损5 cm的骨折模型,并按照随机数字表法将其均分为股骨近端锁定板组、加长型股骨近端防旋髓内钉组和加长型股骨近端髓内钉组,比较3组轴向压缩实验、扭转实验以及轴向压缩破坏实验结果。结果与结论:加长型股骨近端防旋髓内钉组轴向抗压刚度、破坏载荷大于股骨近端锁定板组和加长型股骨近端髓内钉组,加长型股骨近端髓内钉组大于股骨近端锁定板组,差异有显著性意义(P 0.05)。一定程度上讲,加长型股骨近端防旋髓内钉内固定股骨颈合并同侧转子下骨折相对股骨近端锁定板和加长型股骨近端髓内钉而言,更具有生物力学方面的优势。%BACKGROUND:Choosing internal fixator implants with good strength and stiffness is the key to repair femoral neck combined with ipsilateral subtrochanteric fractures. OBJECTIVE:To compare the biomechanical properties of different implant fixation for femoral neck combined with ipsilateral subtrochanteric fractures. METHODS:Totaly 24 adult antiseptic cadaver specimens were used to produce fracture models with femoral neck fracture combined with 5 cm of ipsilateral subtrochanteri medical cortical defect, and were divided into femoral proximal locking plate group, lengthening proximal femur anti-rotation intramedulary nail group and lengthening proximal femoral nail group according to the random number table method. The results of axial compression test, torsion test and axial compression failure rest in three groups were compared. RESULTS AND CONCLUSION: The axial compressive stiffness and failure load in lengthening proximal femur anti

  15. Teaching undergraduate biomechanics with Just-in-Time Teaching.

    Riskowski, Jody L

    2015-06-01

    Biomechanics education is a vital component of kinesiology, sports medicine, and physical education, as well as for many biomedical engineering and bioengineering undergraduate programmes. Little research exists regarding effective teaching strategies for biomechanics. However, prior work suggests that student learning in undergraduate physics courses has been aided by using the Just-in-Time Teaching (JiTT). As physics understanding plays a role in biomechanics understanding, the purpose of study was to evaluate the use of a JiTT framework in an undergraduate biomechanics course. This two-year action-based research study evaluated three JiTT frameworks: (1) no JiTT; (2) mathematics-based JiTT; and (3) concept-based JiTT. A pre- and post-course assessment of student learning used the biomechanics concept inventory and a biomechanics concept map. A general linear model assessed differences between the course assessments by JiTT framework in order to evaluate learning and teaching effectiveness. The results indicated significantly higher learning gains and better conceptual understanding in a concept-based JiTT course, relative to a mathematics-based JiTT or no JiTT course structure. These results suggest that a course structure involving concept-based questions using a JiTT strategy may be an effective method for engaging undergraduate students and promoting learning in biomechanics courses.

  16. Research of topographic ultra-structure and biomechanical properties of living chondrocytes cells with atomic force microscopy%运用原子力显微术磁驱动模式研究活软骨细胞形貌超微结构和力学特性

    刘广源; 吴志宏; 陈佩佩; 李兵; 谢琳; 韩东; 邱贵兴

    2009-01-01

    目的 运用原子力显微镜(AFM)最新发展的磁驱动轻敲模式(MAC mode)研究体外培养的正常人软骨细胞表面形貌的结构特点及细胞力学特性.方法 体外培养正常人膝关节软骨细胞,运用MAC mode AFM在生理条件下对细胞表面形貌进行高分辨成像,并通过指定区域的力曲线操作,观察软骨细胞核区及胞质区的力学特性.结果 MAC mode AFM可实现生理条件下软骨细胞的表面形貌超微结构的高分辨成像,分辨率可达30 nm.软骨细胞呈现核区突出,胞质区平坦的形貌特点.同时,胞质区与核区对比表现出更高的应力状态及黏着力.结论 MAC mode AFM是研究活细胞微观结构和力学特性的有力工具.%Objective To evaluate the application of a novel tapping mode, magnetic AC mode (MAC mode) of atomic force microscopy (AFM) in observation of the topography and mechanical properties of living chondrocytes. Methods Specimens of normal knee joint was obtained from 5 patients during amputation due to severe trauma of shank. Chondrocytes were isolated and cultured. Cell slides were prepared, underwent immunohistochemical staining, and observed under AFM by MAC mode. Force curve operation was performed at different regions, nuclear and eytoplsamic, to compare the topographic features. Results High-resolution images of the ultra-structure of cell surface were obtained under physiological condition with a resolution level to 30 nm. The cells presented a topical profile, I. E. , the protuberant nuclear region and relatively flatten cell body. The force curve showed much higher stress and adhesion in the cell body region than in the nuclear region. Conclusion MAC mode AFM is very useful in research of the ultra-structure and biomechanical properties of cells.

  17. Structural and biomechanical changes in the Achilles tendon after chronic treatment with statins.

    de Oliveira, L P; Vieira, C P; Guerra, F D; Almeida, M S; Pimentel, E R

    2015-03-01

    Cases of tendinopathy and tendon ruptures have been reported as side effects associated with statin therapy. This work assessed possible changes in the structural and biomechanical properties of the tendons after chronic treatment with statins. Wistar rats were divided into the following groups: treated with atorvastatin (A-20 and A-80), simvastatin (S-20 and S-80) and the group that received no treatment (C). The doses of statins were calculated using allometric scaling, based on the doses of 80 mg/day and 20 mg/day recommended for humans. The morphological aspect of the tendons in A-20, S-20 and S-80 presented signals consistent with degeneration. Both the groups A-80 and S-80 showed a less pronounced metachromasia in the compression region of the tendons. Measurements of birefringence showed that A-20, A-80 and S-80 groups had a lower degree of organization of the collagen fibers. In all of the groups treated with statins, the thickness of the epitenon was thinner when compared to the C group. In the biomechanical tests the tendons of the groups A-20, A-80 and S-20 were less resistant to rupture. Therefore, statins affected the organization of the collagen fibers and decreased the biomechanical strength of the tendons, making them more predisposed to ruptures.

  18. [Biomechanical characteristics of human fetal membranes. Preterm fetal membranes are stronger than term fetal membranes].

    Rangaswamy, N; Abdelrahim, A; Moore, R M; Uyen, L; Mercer, B M; Mansour, J M; Kumar, D; Sawady, J; Moore, J J

    2011-06-01

    The purpose of this study was to determine the biomechanical characteristics of human fetal membranes (FM) throughout gestation. Biomechanical properties were determined for 115 FM of 23-41 weeks gestation using our previously described methodology. The areas of membrane immediately adjacent to the strongest and weakest tested spots were sampled for histomorphometric analysis. Clinical data on the patients whose FM were examined were also collected. FM less than 28 weeks gestation were associated with higher incidence of abruption and chorioamnionitis. Topographically FM at all gestations had heterogeneous biomechanical characteristics over their surfaces with distinct weak areas. The most premature membranes were the strongest. FM strength represented by rupture force and work to rupture decreased with increasing gestation in both weak and strong regions of FM. This decrease in FM strength was most dramatic at more than 38 weeks gestation. The FM component amnion-chorion sublayers were thinner in the weak areas compared to strong areas. Compared to term FM, preterm FM are stronger but have similar heterogeneous weak and strong areas. Following a gradual increase in FM weakness with increasing gestation, there is a major drop-off at term 38 weeks gestation. The FM weak areas are thinner than the stronger areas. Whether the difference in thickness is enough to account for the strength differences is unknown.

  19. A multi-scale biomechanical model based on the physiological structure and lignocellulose components of wheat straw.

    Chen, Longjian; Li, Aiwei; He, Xueqin; Han, Lujia

    2015-11-20

    Biomechanical behavior is a fundamental property for the efficient utilization of wheat straw in such applications as fuel and renewable materials. Tensile experiments and lignocellulose analyses were performed on three types of wheat straw. A multi-scale finite element model composed of the microscopic model of the microfibril equivalent volume element and the macroscopic model of straw tissue was proposed based on the physiological structure and lignocellulose components of wheat straw. The tensile properties of wheat straw were simulated by ANSYS software. The predicted stress-strain data were compared with the observed data, and good correspondence was achieved for all three types of wheat straw. The validated multi-scale finite-element (FE) model was then used to investigate the effect of the lignocellulose components on the biomechanical properties of wheat straw. More than 80% of stress is carried by the cellulose fiber, whereas the strain is mainly carried by the amorphous cellulose.

  20. Diabetic foot and exercise therapy: step by step the role of rigid posture and biomechanics treatment.

    Francia, Piergiorgio; Gulisano, Massimo; Anichini, Roberto; Seghieri, Giuseppe

    2014-03-01

    Lower extremity ulcers represent a serious and costly complication of diabetes mellitus. Many factors contribute to the development of diabetic foot. Peripheral neuropathy and peripheral vascular disease are the main causes of foot ulceration and contribute in turn to the growth of additional risk factors such as limited joint mobility, muscular alterations and foot deformities. Moreover, a deficit of balance, posture and biomechanics can be present, in particular in patients at high risk for ulceration. The result of this process may be the development of a vicious cycle which leads to abnormal distribution of the foot's plantar pressures in static and dynamic postural conditions. This review shows that some of these risk factors significantly improve after a few weeks of exercise therapy (ET) intervention. Accordingly it has been suggested that ET can be an important weapon in the prevention of foot ulcer. The aim of ET can relate to one or more alterations typically found in diabetic patients, although greater attention should be paid to the evaluation and possible correction of body balance, rigid posture and biomechanics. Some of the most important limitations of ET are difficult access to therapy, patient compliance and the transitoriness of the results if the training stops. Many proposals have been made to overcome such limitations. In particular, it is important that specialized centers offer the opportunity to participate in ET and during the treatment the team should work to change the patient's lifestyle by improving the execution of appropriate daily physical activity.

  1. Do cells contribute to tendon and ligament biomechanics?

    Niels Hammer

    Full Text Available Acellular scaffolds are increasingly used for the surgical repair of tendon injury and ligament tears. Despite this increased use, very little data exist directly comparing acellular scaffolds and their native counterparts. Such a comparison would help establish the effectiveness of the acellularization procedure of human tissues. Furthermore, such a comparison would help estimate the influence of cells in ligament and tendon stability and give insight into the effects of acellularization on collagen.Eighteen human iliotibial tract samples were obtained from nine body donors. Nine samples were acellularized with sodium dodecyl sulphate (SDS, while nine counterparts from the same donors remained in the native condition. The ends of all samples were plastinated to minimize material slippage. Their water content was adjusted to 69%, using the osmotic stress technique to exclude water content-related alterations of the mechanical properties. Uniaxial tensile testing was performed to obtain the elastic modulus, ultimate stress and maximum strain. The effectiveness of the acellularization procedure was histologically verified by means of a DNA assay.The histology samples showed a complete removal of the cells, an extensive, yet incomplete removal of the DNA content and alterations to the extracellular collagen. Tensile properties of the tract samples such as elastic modulus and ultimate stress were unaffected by acellularization with the exception of maximum strain.The data indicate that cells influence the mechanical properties of ligaments and tendons in vitro to a negligible extent. Moreover, acellularization with SDS alters material properties to a minor extent, indicating that this method provides a biomechanical match in ligament and tendon reconstruction. However, the given protocol insufficiently removes DNA. This may increase the potential for transplant rejection when acellular tract scaffolds are used in soft tissue repair. Further research

  2. Biomechanical ToolKit: Open-source framework to visualize and process biomechanical data.

    Barre, Arnaud; Armand, Stéphane

    2014-04-01

    C3D file format is widely used in the biomechanical field by companies and laboratories to store motion capture systems data. However, few software packages can visualize and modify the integrality of the data in the C3D file. Our objective was to develop an open-source and multi-platform framework to read, write, modify and visualize data from any motion analysis systems using standard (C3D) and proprietary file formats (used by many companies producing motion capture systems). The Biomechanical ToolKit (BTK) was developed to provide cost-effective and efficient tools for the biomechanical community to easily deal with motion analysis data. A large panel of operations is available to read, modify and process data through C++ API, bindings for high-level languages (Matlab, Octave, and Python), and standalone application (Mokka). All these tools are open-source and cross-platform and run on all major operating systems (Windows, Linux, MacOS X).

  3. Biomechanical properties of a titanium alloy pelvic prosthesis individually manufactured by 3D printing: a finite element analysis%3D打印钛合金个性化骨盆假体生物力学的初步有限元分析

    叶堃; 王金武; 胡志刚; 王成焘; 干耀凯; 韦建和; 江川; 邓源; 李雨

    2015-01-01

    Objective To evaluate the biomechanical properties of a titanium alloy pelvic prosthesis individually manufactured by 3D printing through finite element analysis.Methods A male patient with a huge chondrosarcoma at the right ilium was recruited for the present study who had been arranged for hemipelvectomy and artificial hemi-pelvic replacement.After the patient underwent CT and MRI examinations before operation,scope of tumor invasion around the ilium,surgical margins and plane for osteotomy were determined using the 3D image fusion technique.A finite element model of the pelvis of the patient was established on the basis of the defective area after pelvic osteotomy using computer aided design (CAD).After the finite element analysis,a customized titanium alloy pelvic prosthesis was manufactured using 3D printing technology.The software Abaqus was used to conduct finite element analysis of the model of the pelvic prosthesis manufactured by 3D printing.The von Mises stress,relative displacement and stress concentration point in the finite element model of the pelvis were measured and analyzed.Results The maximum von Mises stress in the titanium alloy pelvic prosthesis manufactured by 3D printing was 25.29 MPa,far smaller than the yield strength of titanium alloy (950 MPa).The stress concentration area was near the nail holes where the prosthesis and the sacrum were connected.The patient was able to walk without crutches 3 months post-surgery.After half a year,the implant was stable and the patient could perform normal activities.Conclusions The titanium alloy pelvic prosthesis individually manufactured by 3D printing based on the results of finite element analysis met the biomechanical requirements of a pelvis.The calculation results of finite element analysis were consistent with the postoperative follow-up outcomes of the patient.This method can provide biomechanical evidence for clinical application of 3D printing implants in orthopedics.%目的 通过

  4. Imaging findings of sternal abnormalities

    Franquet, T. [Dept. of Radiology, Hospital de Sant Pau, Universidad Autonoma de Barcelona (Spain); Gimenez, A. [Dept. of Radiology, Hospital de Sant Pau, Universidad Autonoma de Barcelona (Spain); Alegret, X. [Dept. of Radiology, Hospital de Sant Pau, Universidad Autonoma de Barcelona (Spain); Sanchis, E. [Dept. of Radiology, Hospital de Sant Pau, Universidad Autonoma de Barcelona (Spain); Rivas, A. [Dept. of Radiology, Hospital Vall d`Hebron, Universidad Autonoma de Barcelona (Spain)

    1997-05-01

    Radiographic findings in the sternal abnormalities are often nonspecific, showing appearances from a localized benign lesion to an aggressive lesion as seen with infections and malignant neoplasms. A specific diagnosis of sternal abnormalities can be suggested on the basis of CT and MR characteristics. Familiarity with the presentation and variable appearance of sternal abnormalities may aid the radiologist is suggesting a specific diagnosis. We present among others characteristic radiographic findings of hemangioma, chondrosarcoma, hydatid disease, and SAPHO syndrome. In those cases in which findings are not specific, cross-sectional imaging modalities may help the clinician in their management. (orig.)

  5. Propriedades biomecânicas da fáscia lata e do ligamento cruzado cranial de cães Biomechanical properties of canine fascia lata and cranial cruciate ligament

    A.P. Brendolan

    2001-02-01

    properties were found for the strips of fascia lata straight and twisted, although twisted strips presented a higher deformation than straight ones. External and internal tibial rotation did not influence the maximum force and maximum stress of the cranial cruciate ligament, that were of about 660 Newtons and 75 Megapascal, respectively. Fascia lata strips reached 44% of ligaments maximum force and 37% of maximum strain, and twisted strips reached 70% of ligaments maximum deformation, deserving straight strips to be recommended for cranial cruciate ligament substitution in dogs.

  6. Biomechanics trends in modeling and simulation

    Ogden, Ray

    2017-01-01

    The book presents a state-of-the-art overview of biomechanical and mechanobiological modeling and simulation of soft biological tissues. Seven well-known scientists working in that particular field discuss topics such as biomolecules, networks and cells as well as failure, multi-scale, agent-based, bio-chemo-mechanical and finite element models appropriate for computational analysis. Applications include arteries, the heart, vascular stents and valve implants as well as adipose, brain, collagenous and engineered tissues. The mechanics of the whole cell and sub-cellular components as well as the extracellular matrix structure and mechanotransduction are described. In particular, the formation and remodeling of stress fibers, cytoskeletal contractility, cell adhesion and the mechanical regulation of fibroblast migration in healing myocardial infarcts are discussed. The essential ingredients of continuum mechanics are provided. Constitutive models of fiber-reinforced materials with an emphasis on arterial walls ...

  7. Research in biomechanics of occupant protection.

    King, A I; Yang, K H

    1995-04-01

    This paper discusses the biomechanical bases for occupant protection against frontal and side impact. Newton's Laws of Motion are used to illustrate the effect of a crash on restrained and unrestrained occupants, and the concept of ride down is discussed. Occupant protection through the use of energy absorbing materials is described, and the mechanism of injury of some of the more common injuries is explained. The role of the three-point belt and the airbag in frontal protection is discussed along with the potential injuries that can result from the use of these restraint systems. Side impact protection is more difficult to attain but some protection can be derived from the use of padding or a side impact airbag. It is concluded that the front seat occupants are adequately protected against frontal impact if belts are worn in an airbag equipped vehicle. Side impact protection may not be uniform in all vehicles.

  8. Biomechanics of Posterior Dynamic Stabilization Systems

    D. U. Erbulut

    2013-01-01

    Full Text Available Spinal rigid instrumentations have been used to fuse and stabilize spinal segments as a surgical treatment for various spinal disorders to date. This technology provides immediate stability after surgery until the natural fusion mass develops. At present, rigid fixation is the current gold standard in surgical treatment of chronic back pain spinal disorders. However, such systems have several drawbacks such as higher mechanical stress on the adjacent segment, leading to long-term degenerative changes and hypermobility that often necessitate additional fusion surgery. Dynamic stabilization systems have been suggested to address adjacent segment degeneration, which is considered to be a fusion-associated phenomenon. Dynamic stabilization systems are designed to preserve segmental stability, to keep the treated segment mobile, and to reduce or eliminate degenerative effects on adjacent segments. This paper aimed to describe the biomechanical aspect of dynamic stabilization systems as an alternative treatment to fusion for certain patients.

  9. Biomechanics of the elbow in sports.

    Loftice, Jeremy; Fleisig, Glenn S; Zheng, Nigel; Andrews, James R

    2004-10-01

    In throwing activities, the elbow is sometimes stressed to its biomechanical limits. In this article, forces, torques, angular velocities, and muscle activity about the elbow are reviewed for the baseball pitch, the football pass, the javelin throw, the windmill softball pitch, the tennis serve, and the golf swing. The elbow goes through rapid extension in baseball pitching (about 2400 degrees/s) and rapid flexion in the javelin throw (about 1900 degrees/s). During baseball pitching, the elbow joint is subject to a valgus torque reaching 64 Nm, and requires proximal forces as high as 1000 N to prevent elbow distraction. The ulnar collateral ligament (UCL) rupture in baseball pitching, lateral epicondylitis in the tennis backhand, and other injury mechanisms are also discussed.

  10. Adaptive sports technology and biomechanics: prosthetics.

    De Luigi, Arthur Jason; Cooper, Rory A

    2014-08-01

    With the technologic advances in medicine and an emphasis on maintaining physical fitness, the population of athletes with impairments is growing. It is incumbent upon health care practitioners to make every effort to inform these individuals of growing and diverse opportunities and to encourage safe exercise and athletic participation through counseling and education. Given the opportunities for participation in sports for persons with a limb deficiency, the demand for new, innovative prosthetic designs is challenging the clinical and technical expertise of the physician and prosthetist. When generating a prosthetic prescription, physicians and prosthetists should consider the needs and preferences of the athlete with limb deficiency, as well as the functional demands of the chosen sporting activity. The intent of this article is to provide information regarding the current advancements in the adaptive sports technology and biomechanics in the field of prosthetics, and to assist clinicians and their patients in facilitating participation in sporting activities.

  11. Biomechanical Analysis of T2 Exercise

    DeWitt, John K.; Ploutz-Snyder, Lori; Everett, Meghan; Newby, Nathaniel; Scott-Pandorf, Melissa; Guilliams, Mark E.

    2010-01-01

    Crewmembers regularly perform treadmill exercise on the ISS. With the implementation of T2 on ISS, there is now the capacity to obtain ground reaction force (GRF) data GRF data combined with video motion data allows biomechanical analyses to occur that generate joint torque estimates from exercise conditions. Knowledge of how speed and load influence joint torque will provide quantitative information on which exercise prescriptions can be based. The objective is to determine the joint kinematics, ground reaction forces, and joint kinetics associated with treadmill exercise on the ISS. This study will: 1) Determine if specific exercise speed and harness load combinations are superior to others in exercise benefit; and 2) Aid in the design of exercise prescriptions that will be most beneficial in maintaining crewmember health.

  12. Integrative Role Of Cinematography In Biomechanics Research

    Zernicke, Ronald F.; Gregor, Robert J.

    1982-02-01

    Cinematography is an integral element in the interdisciplinary biomechanics research conducted in the Department of Kinesiology at the University of California, Los Angeles. For either an isolated recording of a movement phenomenon or as a recording component which is synchronized with additional transducers and recording equipment, high speed motion picture film has been effectively incorporated into resr'arch projects ranging from two and three dimensional analyses of human movements, locomotor mechanics of cursorial mammals and primates, to the structural responses and dynamic geometries of skeletal muscles, tendons, and ligaments. The basic equipment used in these studies includes three, 16 mm high speed, pin-registered cameras which have the capacity for electronic phase-locking. Crystal oscillators provide the generator pulses to synchronize the timing lights of the cameras and the analog-to-digital recording equipment. A rear-projection system with a sonic digitizer permits quantification of film coordinates which are stored on computer disks. The capacity for synchronizing the high speed films with additional recording equipment provides an effective means of obtaining not only position-time data from film, but also electromyographic, force platform, tendon force transducer, and strain gauge recordings from tissues or moving organisms. During the past few years, biomechanics research which comprised human studies has used both planar and three-dimensional cinematographic techniques. The studies included planar analyses which range from the gait characteristics of lower extremity child amputees to the running kinematics and kinetics of highly skilled sprinters and long-distance runners. The dynamics of race cycling and kinetics of gymnastic maneuvers were studied with cinematography and either a multi-dimensional force platform or a bicycle pedal with strain gauges to determine the time histories of the applied forces. The three-dimensional technique

  13. Pathogenesis of varicose veins - lessons from biomechanics.

    Pfisterer, Larissa; König, Gerd; Hecker, Markus; Korff, Thomas

    2014-03-01

    The development of varicose veins or chronic venous insufficiency is preceded by and associated with the pathophysiological remodelling of the venous wall. Recent work suggests that an increase in venous filling pressure is sufficient to promote varicose remodelling of veins by augmenting wall stress and activating venous endothelial and smooth muscle cells. In line with this, known risk factors such as prolonged standing or an obesity-induced increase in venous filling pressure may contribute to varicosis. This review focuses on biomechanically mediated mechanisms such as an increase in wall stress caused by venous hypertension or alterations in blood flow, which may be involved in the onset of varicose vein development. Finally, possible therapeutic options to counteract or delay the progress of this venous disease are discussed.

  14. Biomechanics of knee joint — A review

    Madeti, Bhaskar Kumar; Chalamalasetti, Srinivasa Rao; Bolla Pragada, S. K. Sundara siva rao

    2015-06-01

    The present paper is to know how the work is carried out in the field of biomechanics of knee. Various model formulations are discussed and further classified into mathematical model, two-dimensional model and three-dimensional model. Knee geometry is a crucial part of human body movement, in which how various views of knee is shown in different planes and how the forces act on tibia and femur are studied. It leads to know the forces acting on the knee joint. Experimental studies of knee geometry and forces acting on knee shown by various researchers have been discussed, and comparisons of results are made. In addition, static and dynamic analysis of knee has been also discussed respectively to some extent.

  15. The corneoscleral shell of the eye: potentials of assessing biomechanical parameters in normal and pathological conditions

    E. N. Iomdina

    2016-01-01

    Full Text Available The paper reviews modern methods of evaluating the biomechanical properties of the corneoscleral shell of the eye that can be used both in the studies of the pathogenesis of various ophthalmic pathologies and in clinical practice. The biomechanical parameters of the cornea and the sclera have been shown to be diagnostically significant in assessing the risk of complications and the effectiveness of keratorefractive interventions, in the diagnosis and the prognosis of keratoconus, progressive myopia, or glaucoma. In clinical practice, a special device, Ocular Response Analyzer (ORA, has been used on a large scale. The analyzer is used to assess two parameters that characterize viscoelastic properties of the cornea — corneal hysteresis (CH and corneal resistance factor (CRF. Reduced levels of CH and CRF have been noted after eximer laser surgery, especially that administered to patients who demonstrate a regression in the refraction effect or suffer from keratoconus. This fact justifies the use of these biomechanical parameters as additional diagnostic criteria in the evaluation of the state of the cornea. At the same time, ORA data are shown to reflect the biomechanical response to the impact of the air pulse not only from the cornea alone but also from the whole corneoscleral capsule. This is probably the cause of reduced CH in children with progressive myopia and a weakened supportive function of the sclera, as well as such reduction in glaucomatous adult patients. It is hypothesized that a low CH value is a result of remodeling of the connective tissue matrix of the corneoscleral shell of the eye and can be an independent factor testifying to a risk of glaucoma progression. Reduced CH in primary open-angle glaucoma occurs in parallel with the development of pathological structural changes of the optic disc, and deterioration of visual fields, which is an evidence of a specific character and sensitivity of this parameter. The

  16. Biomechanical research in dance: a literature review.

    Krasnow, Donna; Wilmerding, M Virginia; Stecyk, Shane; Wyon, Matthew; Koutedakis, Yiannis

    2011-03-01

    The authors reviewed the literature, published from 1970 through December 2009, on biomechanical research in dance. To identify articles, the authors used search engines, including PubMed and Web of Science, five previous review articles, the Dance Medicine and Science Bibliography, and reference lists of theses, dissertations, and articles being reviewed. Any dance research articles (English language) involving the use of electromyography, forceplates, motion analysis using photography, cinematography or videography, and/or physics analysis were included. A total of 89 papers, theses/dissertations, and abstracts were identified and reviewed, grouped by the movement concept or specialized movements being studied: alignment (n = 8), plié (8), relevé (8), passé (3), degagé (3), développé (7), rond de jambe (3), grand battement (4), arm movements (1), forward stepping (3), turns (6), elevation work (28), falls (1), and dance-specific motor strategies (6). Several recurring themes emerged from these studies: that elite dancers demonstrate different and superior motor strategies than novices or nondancers; that dancers perform differently when using a barre as opposed to without a barre, both in terms of muscle activation patterns and weight shift strategies; that while skilled dancers tend to be more consistent across multiple trials of a task, considerable variability is seen among participants, even when matched for background, years of training, body type, and other variables; and that dance teachers recommend methods of achieving movement skills that are inconsistent with optimal biomechanical function, as well as inconsistent with strategies employed by elite dancers. Measurement tools and the efficacy of study methodologies are also discussed.

  17. Development of a biomechanical energy harvester

    Donelan J Maxwell

    2009-06-01

    Full Text Available Abstract Background Biomechanical energy harvesting–generating electricity from people during daily activities–is a promising alternative to batteries for powering increasingly sophisticated portable devices. We recently developed a wearable knee-mounted energy harvesting device that generated electricity during human walking. In this methods-focused paper, we explain the physiological principles that guided our design process and present a detailed description of our device design with an emphasis on new analyses. Methods Effectively harvesting energy from walking requires a small lightweight device that efficiently converts intermittent, bi-directional, low speed and high torque mechanical power to electricity, and selectively engages power generation to assist muscles in performing negative mechanical work. To achieve this, our device used a one-way clutch to transmit only knee extension motions, a spur gear transmission to amplify the angular speed, a brushless DC rotary magnetic generator to convert the mechanical power into electrical power, a control system to determine when to open and close the power generation circuit based on measurements of knee angle, and a customized orthopaedic knee brace to distribute the device reaction torque over a large leg surface area. Results The device selectively engaged power generation towards the end of swing extension, assisting knee flexor muscles by producing substantial flexion torque (6.4 Nm, and efficiently converted the input mechanical power into electricity (54.6%. Consequently, six subjects walking at 1.5 m/s generated 4.8 ± 0.8 W of electrical power with only a 5.0 ± 21 W increase in metabolic cost. Conclusion Biomechanical energy harvesting is capable of generating substantial amounts of electrical power from walking with little additional user effort making future versions of this technology particularly promising for charging portable medical devices.

  18. Development of a biomechanical energy harvester

    Li, Qingguo; Naing, Veronica; Donelan, J Maxwell

    2009-01-01

    Background Biomechanical energy harvesting–generating electricity from people during daily activities–is a promising alternative to batteries for powering increasingly sophisticated portable devices. We recently developed a wearable knee-mounted energy harvesting device that generated electricity during human walking. In this methods-focused paper, we explain the physiological principles that guided our design process and present a detailed description of our device design with an emphasis on new analyses. Methods Effectively harvesting energy from walking requires a small lightweight device that efficiently converts intermittent, bi-directional, low speed and high torque mechanical power to electricity, and selectively engages power generation to assist muscles in performing negative mechanical work. To achieve this, our device used a one-way clutch to transmit only knee extension motions, a spur gear transmission to amplify the angular speed, a brushless DC rotary magnetic generator to convert the mechanical power into electrical power, a control system to determine when to open and close the power generation circuit based on measurements of knee angle, and a customized orthopaedic knee brace to distribute the device reaction torque over a large leg surface area. Results The device selectively engaged power generation towards the end of swing extension, assisting knee flexor muscles by producing substantial flexion torque (6.4 Nm), and efficiently converted the input mechanical power into electricity (54.6%). Consequently, six subjects walking at 1.5 m/s generated 4.8 ± 0.8 W of electrical power with only a 5.0 ± 21 W increase in metabolic cost. Conclusion Biomechanical energy harvesting is capable of generating substantial amounts of electrical power from walking with little additional user effort making future versions of this technology particularly promising for charging portable medical devices. PMID:19549313

  19. Biomechanics of sprint running. A review.

    Mero, A; Komi, P V; Gregor, R J

    1992-06-01

    Understanding of biomechanical factors in sprint running is useful because of their critical value to performance. Some variables measured in distance running are also important in sprint running. Significant factors include: reaction time, technique, electromyographic (EMG) activity, force production, neural factors and muscle structure. Although various methodologies have been used, results are clear and conclusions can be made. The reaction time of good athletes is short, but it does not correlate with performance levels. Sprint technique has been well analysed during acceleration, constant velocity and deceleration of the velocity curve. At the beginning of the sprint run, it is important to produce great force/power and generate high velocity in the block and acceleration phases. During the constant-speed phase, the events immediately before and during the braking phase are important in increasing explosive force/power and efficiency of movement in the propulsion phase. There are no research results available regarding force production in the sprint-deceleration phase. The EMG activity pattern of the main sprint muscles is described in the literature, but there is a need for research with highly skilled sprinters to better understand the simultaneous operation of many muscles. Skeletal muscle fibre characteristics are related to the selection of talent and the training-induced effects in sprint running. Efficient sprint running requires an optimal combination between the examined biomechanical variables and external factors such as footwear, ground and air resistance. Further research work is needed especially in the area of nervous system, muscles and force and power production during sprint running. Combining these with the measurements of sprinting economy and efficiency more knowledge can be achieved in the near future.

  20. Skin - abnormally dark or light

    ... ency/article/003242.htm Skin - abnormally dark or light To use the sharing features on this page, ... the hands. The bronze color can range from light to dark (in fair-skinned people) with the ...

  1. Pregnancy Complications: Umbilical Cord Abnormalities

    ... defects. These tests may include a detailed ultrasound, amniocentesis (to check for chromosomal abnormalities) and in some ... the provider may recommend additional tests, such as amniocentesis and a detailed ultrasound, to diagnose or rule ...

  2. Biomechanical analysis and modeling of different vertebral growth patterns in adolescent idiopathic scoliosis and healthy subjects

    Driscoll Mark

    2011-05-01

    Full Text Available Abstract Background The etiology of AIS remains unclear, thus various hypotheses concerning its pathomechanism have been proposed. To date, biomechanical modeling has not been used to thoroughly study the influence of the abnormal growth profile (i.e., the growth rate of the vertebral body during the growth period on the pathomechanism of curve progression in AIS. This study investigated the hypothesis that AIS progression is associated with the abnormal growth profiles of the anterior column of the spine. Methods A finite element model of the spinal column including growth dynamics was utilized. The initial geometric models were constructed from the bi-planar radiographs of a normal subject. Based on this model, five other geometric models were generated to emulate different coronal and sagittal curves. The detailed modeling integrated vertebral body growth plates and growth modulation spinal biomechanics. Ten years of spinal growth was simulated using AIS and normal growth profiles. Sequential measures of spinal alignments were compared. Results (1 Given the initial lateral deformity, the AIS growth profile induced a significant Cobb angle increase, which was roughly between three to five times larger compared to measures utilizing a normal growth profile. (2 Lateral deformities were absent in the models containing no initial coronal curvature. (3 The presence of a smaller kyphosis did not produce an increase lateral deformity on its own. (4 Significant reduction of the kyphosis was found in simulation results of AIS but not when using the growth profile of normal subjects. Conclusion Results from this analysis suggest that accelerated growth profiles may encourage supplementary scoliotic progression and, thus, may pose as a progressive risk factor.

  3. Cosmos caudatus enhances fracture healing in ovariectomised rats: A preliminary biomechanical evaluation

    Pamela Godspower Rufus

    2015-01-01

    Full Text Available Summary. Osteoporotic fractures occur in osteoporotic states and affect patients’ quality of life. Cosmos caudatus (ulam raja is a local plant known for its high calcium content and anti-oxidant properties. The present study aimed to investigate the fracture healing properties of C. caudatus water extract in ovariectomised rats by studying the biomechanical properties of tibia. Twenty-four female Sprague-Dawley rats were divided into 4 groups: (i sham operated (ii ovariectomised control (iii ovariectomised + estrogen (100µg/kg/day and (iv ovariectomised + C. caudatus (500mg/kg. Following six weeks of sham operation or ovariectomy, the right tibia of the rats were fractured. Rats were then given their respective treatment for 8 weeks with body weight monitored weekly. Biomechanical analysis indicated that the maximum load, stress and Young’s modulus of the ovariectomised control group (36.2 ± 4.7N, 10.01 ± 1.41MPa, 29.2 ± 9.39MPa respectively were significantly lower compared to sham operated (150.32 ± 32. 6N, 36.75 ± 7.98MPa, 183 ± 53.2MPa respectively and the C. caudatus treated group (136.86 ± 16.95N, 33.45 ± 4.14MPa, 155.13± 58.58MPa respectively. Therefore, C. caudatus extract improved the biomechanical property of the healed bone and may be beneficial for fracture healing in the estrogen deficient state.Industrial Relevance. Post-menopausal osteoporosis is a debilitating disease affecting women worldwide. Hormone replacement therapy (HRT, commonly used for the prevention and treatment of post-menopausal osteoporosis has been associated with several side effects. Thus, in finding alternatives in the treatment of osteoporosis, C. caudatus is a plant of interest. Previous study showed that C. caudatus improved bone histomorphometry in ovariectomized rats by increasing double-labeled surface (dLS/BS, mineral appositional rate (MAR, osteoid volume (OV/BV and osteoblast surface (Ob.S/BS. Therefore, the present study aimed to assess

  4. Keratoconus: A biomechanical perspective on loss of corneal stiffness

    Abhijit Sinha Roy

    2013-01-01

    Full Text Available Keratoconus (KC is progressive disease of corneal thinning, steepening and collagen degradation. Biomechanics of the cornea is maintained by the intricate collagen network, which is responsible for its unique shape and function. With the disruption of this collagen network, the cornea loses its shape and function, resulting in progressive visual degradation. While KC is essentially a stromal disease, there is evidence that the epithelium undergoes significant thinning similar to the stroma. Several topographical approaches have been developed to detect KC early. However, it is now hypothesized that biomechanical destabilization of the cornea may precede topographic evidence of KC. Biomechanics of KC has been investigated only to a limited extent due to lack of in vivo measurement techniques and/or devices. In this review, we focus on recent work performed to characterize the biomechanical characteristics of KC.

  5. Sex differences in E-navigation: Biomechanics versus Cognition

    2011-01-01

    Van Mierlo, C. M., Jarodzka, H., Kirschner, F., & Kirschner, P. A. (2011, 8 September). Sex differences in E-navigation: Biomechanics versus Cognition. Presentation at Learning & Cognition Plenair, Heerlen, The Netherlands.

  6. Soft Tissue Biomechanical Modeling for Computer Assisted Surgery

    2012-01-01

      This volume focuses on the biomechanical modeling of biological tissues in the context of Computer Assisted Surgery (CAS). More specifically, deformable soft tissues are addressed since they are the subject of the most recent developments in this field. The pioneering works on this CAS topic date from the 1980's, with applications in orthopaedics and biomechanical models of bones. More recently, however, biomechanical models of soft tissues have been proposed since most of the human body is made of soft organs that can be deformed by the surgical gesture. Such models are much more complicated to handle since the tissues can be subject to large deformations (non-linear geometrical framework) as well as complex stress/strain relationships (non-linear mechanical framework). Part 1 of the volume presents biomechanical models that have been developed in a CAS context and used during surgery. This is particularly new since most of the soft tissues models already proposed concern Computer Assisted Planning, with ...

  7. Biomechanics as a window into the neural control of movement.

    Latash, Mark L

    2016-09-01

    Biomechanics and motor control are discussed as parts of a more general science, physics of living systems. Major problems of biomechanics deal with exact definition of variables and their experimental measurement. In motor control, major problems are associated with formulating currently unknown laws of nature specific for movements by biological objects. Mechanics-based hypotheses in motor control, such as those originating from notions of a generalized motor program and internal models, are non-physical. The famous problem of motor redundancy is wrongly formulated; it has to be replaced by the principle of abundance, which does not pose computational problems for the central nervous system. Biomechanical methods play a central role in motor control studies. This is illustrated with studies with the reconstruction of hypothetical control variables and those exploring motor synergies within the framework of the uncontrolled manifold hypothesis. Biomechanics and motor control have to merge into physics of living systems, and the earlier this process starts the better.

  8. On seed physiology, biomechanics and plant phenology in Eragrostis tef

    Delden, van S.H.

    2011-01-01

    • Key words: Teff (Eragrostis tef (Zuccagni) Trotter), germination, temperature, model, leaf appearance, phyllochron, development rate, lodging, biomechanics, safety factor, flowering, heading, day length, photoperiod. • Background Teff (Eragrostis tef (Zuccagni) Trotter) is a C4 annual g

  9. Effects of spaceflight on rat humerus geometry, biomechanics, and biochemistry

    Vailas, A. C.; Zernicke, R. F.; Grindeland, R. E.; Kaplansky, A.; Durnova, G. N.; Li, K. C.; Martinez, D. A.

    1990-01-01

    The effects of a 12.5-day spaceflight (Cosmos 1887 biosatellite) on the geometric, biomechanical, and biochemical characteristics of humeri of male specific pathogen-free rats were examined. Humeri of age-matched basal control, synchronous control, and vivarium control rats were contrasted with the flight bones to examine the influence of growth and space environment on bone development. Lack of humerus longitudinal growth occurred during the 12.5 days in spaceflight. In addition, the normal mid-diaphysial periosteal appositional growth was affected; compared with their controls, the spaceflight humeri had less cortical cross-sectional area, smaller periosteal circumferences, smaller anterior-posterior periosteal diameters, and smaller second moments of area with respect to the bending and nonbending axes. The flexural rigidity of the flight humeri was comparable to that of the younger basal control rats and significantly less than that of the synchronous and vivarium controls; the elastic moduli of all four groups, nonetheless, were not significantly different. Generally, the matrix biochemistry of the mid-diaphysial cross sections showed no differences among groups. Thus, the spaceflight differences in humeral mechanical strength and flexural rigidity were probably a result of the differences in humeral geometry rather than material properties.

  10. Linking suckling biomechanics to the development of the palate

    Li, Jingtao; Johnson, Chelsey A.; Smith, Andrew A.; Hunter, Daniel J.; Singh, Gurpreet; Brunski, John B.; Helms, Jill A.

    2016-02-01

    Skulls are amongst the most informative documents of evolutionary history but a complex geometry, coupled with composite material properties and complicated biomechanics, have made it particularly challenging to identify mechanical principles guiding the skull’s morphogenesis. Despite this challenge, multiple lines of evidence, for example the relationship between masticatory function and the evolution of jaw shape, nonetheless suggest that mechanobiology plays a major role in skull morphogenesis. To begin to tackle this persistent challenge, cellular, molecular and tissue-level analyses of the developing mouse palate were coupled with finite element modeling to demonstrate that patterns of strain created by mammalian-specific oral behaviors produce complementary patterns of chondrogenic gene expression in an initially homogeneous population of cranial neural crest cells. Neural crest cells change from an osteogenic to a chondrogenic fate, leading to the materialization of cartilaginous growth plate-like structures in the palatal midline. These growth plates contribute to lateral expansion of the head but are transient structures; when the strain patterns associated with suckling dissipate at weaning, the growth plates disappear and the palate ossifies. Thus, mechanical cues such as strain appear to co-regulate cell fate specification and ultimately, help drive large-scale morphogenetic changes in head shape.

  11. Biomechanical Dynamics of Cranial Sutures during Simulated Impulsive Loading

    Z. Q. Zhang

    2015-01-01

    Full Text Available Background. Cranial sutures are deformable joints between the bones of the skull, bridged by collagen fibres. They function to hold the bones of the skull together while allowing for mechanical stress transmission and deformation. Objective. The aim of this study is to investigate how cranial suture morphology, suture material property, and the arrangement of sutural collagen fibres influence the dynamic responses of the suture and surrounding bone under impulsive loads. Methods. An idealized bone-suture-bone complex was analyzed using a two-dimensional finite element model. A uniform impulsive loading was applied to the complex. Outcome variables of von Mises stress and strain energy were evaluated to characterize the sutures’ biomechanical behavior. Results. Parametric studies revealed that the suture strain energy and the patterns of Mises stress in both the suture and surrounding bone were strongly dependent on the suture morphologies. Conclusions. It was concluded that the higher order hierarchical suture morphology, lower suture elastic modulus, and the better collagen fiber orientation must benefit the stress attenuation and energy absorption.

  12. Experimental Injury Biomechanics of the Pediatric Extremities and Pelvis

    Ivarsson, Johan; Okamoto, Masayoshi; Takahashi, Yukou

    The paucity of pediatric postmortem human subjects (PMHS) for biomechanical research has led to the development of biofidelity requirements and injury assessment reference values (IARVs) for pediatric anthropomorphic test devices (ATDs) through geometrical scaling of adult PMHS data. Geometrical scaling relies on the assumption of geometrical similarity between the adult and child and does not account for any differences in tissue material properties. Attempts have been made to improve the accuracy of the scaled responses and IARVs by also accounting for the difference in Young's modulus between adult and pediatric bone (Irwin and Mertz 1997; van Ratingen et al. 1997; Mertz et al. 2001; Ivarsson et al. 2004a, b). However, the development of more biofidelic pediatric ATDs and accurate IARVs requires access to validation data that do not rely on the assumptions and simplifications associated with scaling. Access to accurate data from testing of pediatric tissues and anatomical structures would also facilitate the development of computational models for simulation of the response and injury of pediatric subjects in various loading situations.

  13. Biomechanical and biocompatibility characteristics of electrospun polymeric tracheal scaffolds.

    Ajalloueian, Fatemeh; Lim, Mei Ling; Lemon, Greg; Haag, Johannes C; Gustafsson, Ylva; Sjöqvist, Sebastian; Beltrán-Rodríguez, Antonio; Del Gaudio, Costantino; Baiguera, Silvia; Bianco, Alessandra; Jungebluth, Philipp; Macchiarini, Paolo

    2014-07-01

    The development of tracheal scaffolds fabricated based on electrospinning technique by applying different ratios of polyethylene terephthalate (PET) and polyurethane (PU) is introduced here. Prior to clinical implantation, evaluations of biomechanical and morphological properties, as well as biocompatibility and cell adhesion verifications are required and extensively performed on each scaffold type. However, the need for bioreactors and large cell numbers may delay the verification process during the early assessment phase. Hence, we investigated the feasibility of performing biocompatibility verification using static instead of dynamic culture. We performed bioreactor seeding on 3-dimensional (3-D) tracheal scaffolds (PET/PU and PET) and correlated the quantitative and qualitative results with 2-dimensional (2-D) sheets seeded under static conditions. We found that an 8-fold reduction for 2-D static seeding density can essentially provide validation on the qualitative and quantitative evaluations for 3-D scaffolds. In vitro studies revealed that there was notably better cell attachment on PET sheets/scaffolds than with the polyblend. However, the in vivo outcomes of cell seeded PET/PU and PET scaffolds in an orthotopic transplantation model in rodents were similar. They showed that both the scaffold types satisfied biocompatibility requirements and integrated well with the adjacent tissue without any observation of necrosis within 30 days of implantation.

  14. Biomechanical evaluation of an expansive pedicle screw in calf vertebrae

    雷伟; 吴子祥

    2005-01-01

    Objective: To obtain a comprehensive understanding of the effect of the improvement of fixation strength of a newly designed expansive pedicle screw through biomechanical analyses.Metheds: 100 (200 pedicles) fresh calf lumber vertebrae were used. A total of four instrumentation systems were tested including CDH (CD Horizon), USS (Universal Spine System pedicle screw), Tenor (Sofamor Denek) and expansive pedicle screw (EPS). Pullout and turning-back tests were performed to compare the holding strength of the expansive pedicle screw with conventional screws, i.e. USS, CDH and Tenor. Revision tests were performed to evaluate the mechanical properties of the expansive pedicle screw as a "rescue" revision screw. A fatigue simulation using perpendicular load up to 1 500 000 cycles was carried out.Results: The turning back torque (Tmax) and pull-out force (Fmax) of EPS were significantly greater than those of USS, Tenor and CDH screws (6.5 mm×40 mm). In revision tests, the Fmax of both kinds of EPS (6.5 mm×40 mm; 7.0 mm×40 mm) were greater than that of CDH, USS and Tenor screws significantly (P<0.05). No screws were broken or bent at the end of fatigue tests.Conclusions: EPS can significantly improve the bone purchase and the pull-out strength compared to USS, Tenor and CDH screws with similar dimensions before and after failure simulation. The fatigue characteristic of EPS is similar to that of CDH, USS and Tenor screws.

  15. Numerical method in biomechanical analysis of intramedullary osteosynthesis in children

    A. Krauze

    2006-02-01

    Full Text Available Purpose: The paper presents the biomechanical analysis of intramedullary osteosynthesis in 5-7 year old children.Design/methodology/approach: The numerical analysis was performed for two different materials (stainless steel – 316L and titanium alloy – Ti-6Al-4V and for two different fractures of the femur (1/2 of the bone shaft, and 25 mm above. Furthermore, the stresses between the bone fragments were calculated while loading the femur with forces derived from the trunk mass. In the research the Metaizeau method was applied. This method ensures appropriate fixation without complications.Findings: The numerical analysis shows that stresses in both the steel and the titanium alloy nails didn’t exceed the yield point: for the stainless steel Rp0,2,min = 690 MPa and for the titanium alloy Rp0,2,min = 895 MPa.Research limitations/implications: The obtained results are the basis for the optimization of mechanical properties of the metallic biomaterial.Practical implications: On the basis of the obtained results it can be stated that both stainless steel and titanium alloy nails can be aplied in elastic osteosythesis in femur fractures in children.Originality/value: The obtain results can be used by physicians to ensure elastic osteosythesis that accelerate bone union.

  16. Biomechanical analysis of gait adaptation in the nematode Caenorhabditis elegans.

    Fang-Yen, Christopher; Wyart, Matthieu; Xie, Julie; Kawai, Risa; Kodger, Tom; Chen, Sway; Wen, Quan; Samuel, Aravinthan D T

    2010-11-23

    To navigate different environments, an animal must be able to adapt its locomotory gait to its physical surroundings. The nematode Caenorhabditis elegans, between swimming in water and crawling on surfaces, adapts its locomotory gait to surroundings that impose approximately 10,000-fold differences in mechanical resistance. Here we investigate this feat by studying the undulatory movements of C. elegans in Newtonian fluids spanning nearly five orders of magnitude in viscosity. In these fluids, the worm undulatory gait varies continuously with changes in external load: As load increases, both wavelength and frequency of undulation decrease. We also quantify the internal viscoelastic properties of the worm's body and their role in locomotory dynamics. We incorporate muscle activity, internal load, and external load into a biomechanical model of locomotion and show that (i) muscle power is nearly constant across changes in locomotory gait, and (ii) the onset of gait adaptation occurs as external load becomes comparable to internal load. During the swimming gait, which is evoked by small external loads, muscle power is primarily devoted to bending the worm's elastic body. During the crawling gait, evoked by large external loads, comparable muscle power is used to drive the external load and the elastic body. Our results suggest that C. elegans locomotory gait continuously adapts to external mechanical load in order to maintain propulsive thrust.

  17. Biomechanical analysis of the main masticatory muscles in the rabbit.

    Baron, P; Debussy, T

    1980-09-01

    The main masticatory muscles of the Rabbit (Oryctolagus cuniculus L.) were divided into their 25 component bundles per side. 5 dry skulls were used to determine points of origin and insertion which were then projected onto 3 planes perpendicular to each other, for the establishment of a biomechanical model. By interpreting this model and by examining various mandibular movements, the bundles were classified into 16 functional groups. The findings of other biomechanical studies are contrasted with the results of the study.

  18. The effect of breast support on running biomechanics

    Milligan, Alexandra

    2013-01-01

    Whilst sports bras have been reported to significantly reduce breast kinematics and exercise-related breast pain, little is known about the effect of breast support on running biomechanics. This research area has novel applications and many potential benefits to female athletes. Papers available within this area hypothesise that the reduction of breast kinematics and exercise-related breast pain, provided by a high breast support, ensures running biomechanics are maintained and potentially en...

  19. Interpreting locomotor biomechanics from the morphology of human footprints.

    Hatala, Kevin G; Wunderlich, Roshna E; Dingwall, Heather L; Richmond, Brian G

    2016-01-01

    Fossil hominin footprints offer unique direct windows to the locomotor behaviors of our ancestors. These data could allow a clearer understanding of the evolution of human locomotion by circumventing issues associated with indirect interpretations of habitual locomotor patterns from fossil skeletal material. However, before we can use fossil hominin footprints to understand better the evolution of human locomotion, we must first develop an understanding of how locomotor biomechanics are preserved in, and can be inferred from, footprint morphologies. In this experimental study, 41 habitually barefoot modern humans created footprints under controlled conditions in which variables related to locomotor biomechanics could be quantified. Measurements of regional topography (depth) were taken from 3D models of those footprints, and principal components analysis was used to identify orthogonal axes that described the largest proportions of topographic variance within the human experimental sample. Linear mixed effects models were used to quantify the influences of biomechanical variables on the first five principal axes of footprint topographic variation, thus providing new information on the biomechanical variables most evidently expressed in the morphology of human footprints. The footprint's overall depth was considered as a confounding variable, since biomechanics may be linked to the extent to which a substrate deforms. Three of five axes showed statistically significant relationships with variables related to both locomotor biomechanics and substrate displacement; one axis was influenced only by biomechanics and another only by the overall depth of the footprint. Principal axes of footprint morphological variation were significantly related to gait type (walking or running), kinematics of the hip and ankle joints and the distribution of pressure beneath the foot. These results provide the first quantitative framework for developing hypotheses regarding the

  20. Integrative biomechanics for tree ecology: beyond wood density and strength

    Fournier, Mériem; Dlouhà, Jana; Jaouen, Gaëlle; Almeras, Tancrède

    2013-01-01

    International audience; Functional ecology has long considered the support function as important, but its biomechanical complexity is only just being elucidated. We show here that it can be described on the basis of four biomechanical traits, two safety traits against winds (SW) and self-buckling (SB), and two motricity traits involved in sustaining an upright position, tropic motion velocity (MV) and posture control (PC). All these traits are integrated at the tree scale, combining tree size...

  1. Iliotibial Band Syndrome in Runners: Biomechanical Implications and Exercise Interventions.

    Baker, Robert L; Fredericson, Michael

    2016-02-01

    Iliotibial band syndrome (ITBS) has known biomechanical factors with an unclear explanation based on only strength and flexibility deficits. Neuromuscular coordination has emerged as a likely reason for kinematic faults guiding research toward motor control. This article discusses ITBS in relation to muscle performance factors, fascial considerations, epidemiology, functional anatomy, strength deficits, kinematics, iliotibial strain and strain rate, and biomechanical considerations. Evidence-based exercise approaches are reviewed for ITBS, including related methods used to train the posterior hip muscles.

  2. Chemical and biomechanical characterization of hyperhomocysteinemic bone disease in an animal model

    Howell David S

    2003-02-01

    Full Text Available Abstract Background Classical homocystinuria is an autosomal recessive disorder caused by cystathionine β-synthase (CBS deficiency and characterized by distinctive alterations of bone growth and skeletal development. Skeletal changes include a reduction in bone density, making it a potentially attractive model for the study of idiopathic osteoporosis. Methods To investigate this aspect of hyperhomocysteinemia, we supplemented developing chicks (n = 8 with 0.6% dl-homocysteine (hCySH for the first 8 weeks of life in comparison to controls (n = 10, and studied biochemical, biomechanical and morphologic effects of this nutritional intervention. Results hCySH-fed animals grew faster and had longer tibiae at the end of the study. Plasma levels of hCySH, methionine, cystathionine, and inorganic sulfate were higher, but calcium, phosphate, and other indices of osteoblast metabolism were not different. Radiographs of the lower limbs showed generalized osteopenia and accelerated epiphyseal ossification with distinct metaphyseal and suprametaphyseal lucencies similar to those found in human homocystinurics. Although biomechanical testing of the tibiae, including maximal load to failure and bone stiffness, indicated stronger bone, strength was proportional to the increased length and cortical thickness in the hCySH-supplemented group. Bone ash weights and IR-spectroscopy of cortical bone showed no difference in mineral content, but there were higher Ca2+/PO43- and lower Ca2+/CO32- molar ratios than in controls. Mineral crystallization was unchanged. Conclusion In this chick model, hyperhomocysteinemia causes greater radial and longitudinal bone growth, despite normal indices of bone formation. Although there is also evidence for an abnormal matrix and altered bone composition, our finding of normal biomechanical bone strength, once corrected for altered morphometry, suggests that any increase in the risk of long bone fracture in human hyperhomocysteinemic

  3. ARTIFICIAL INTELLIGENCE IN SPORTS BIOMECHANICS: NEW DAWN OR FALSE HOPE?

    Roger Bartlett

    2006-12-01

    Full Text Available This article reviews developments in the use of Artificial Intelligence (AI in sports biomechanics over the last decade. It outlines possible uses of Expert Systems as diagnostic tools for evaluating faults in sports movements ('techniques' and presents some example knowledge rules for such an expert system. It then compares the analysis of sports techniques, in which Expert Systems have found little place to date, with gait analysis, in which they are routinely used. Consideration is then given to the use of Artificial Neural Networks (ANNs in sports biomechanics, focusing on Kohonen self-organizing maps, which have been the most widely used in technique analysis, and multi-layer networks, which have been far more widely used in biomechanics in general. Examples of the use of ANNs in sports biomechanics are presented for javelin and discus throwing, shot putting and football kicking. I also present an example of the use of Evolutionary Computation in movement optimization in the soccer throw in, which predicted an optimal technique close to that in the coaching literature. After briefly overviewing the use of AI in both sports science and biomechanics in general, the article concludes with some speculations about future uses of AI in sports biomechanics.

  4. Biomechanics of occlusion--implications for oral rehabilitation.

    Peck, C C

    2016-03-01

    The dental occlusion is an important aspect of clinical dentistry; there are diverse functional demands ranging from highly precise tooth contacts to large crushing forces. Further, there are dogmatic, passionate and often diverging views on the relationship between the dental occlusion and various diseases and disorders including temporomandibular disorders, non-carious cervical lesions and tooth movement. This study provides an overview of the biomechanics of the masticatory system in the context of the dental occlusion's role in function. It explores the adaptation and precision of dental occlusion, its role in bite force, jaw movement, masticatory performance and its influence on the oro-facial musculoskeletal system. Biomechanics helps us better understand the structure and function of biological systems and consequently an understanding of the forces on, and displacements of, the dental occlusion. Biomechanics provides insight into the relationships between the dentition, jaws, temporomandibular joints, and muscles. Direct measurements of tooth contacts and forces are difficult, and biomechanical models have been developed to better understand the relationship between the occlusion and function. Importantly, biomechanical research will provide knowledge to help correct clinical misperceptions and inform better patient care. The masticatory system demonstrates a remarkable ability to adapt to a changing biomechanical environment and changes to the dental occlusion or other components of the musculoskeletal system tend to be well tolerated.

  5. Gait biomechanics in the era of data science.

    Ferber, Reed; Osis, Sean T; Hicks, Jennifer L; Delp, Scott L

    2016-12-08

    Data science has transformed fields such as computer vision and economics. The ability of modern data science methods to extract insights from large, complex, heterogeneous, and noisy datasets is beginning to provide a powerful complement to the traditional approaches of experimental motion capture and biomechanical modeling. The purpose of this article is to provide a perspective on how data science methods can be incorporated into our field to advance our understanding of gait biomechanics and improve treatment planning procedures. We provide examples of how data science approaches have been applied to biomechanical data. We then discuss the challenges that remain for effectively using data science approaches in clinical gait analysis and gait biomechanics research, including the need for new tools, better infrastructure and incentives for sharing data, and education across the disciplines of biomechanics and data science. By addressing these challenges, we can revolutionize treatment planning and biomechanics research by capitalizing on the wealth of knowledge gained by gait researchers over the past decades and the vast, but often siloed, data that are collected in clinical and research laboratories around the world.

  6. Effects of nonlinearity in the materials used for the semi-rigid pedicle screw systems on biomechanical behaviors of the lumbar spine after surgery

    Kim, Hyun; Lee, Sung-Jae [Department of Biomedical Engineering, Inje University, Gimhae 621749 (Korea, Republic of); Lim, Do-Hyung [Korea Institute of Industrial Technology, Cheonan 331825 (Korea, Republic of); Oh, Hyun-Ju [Korea Food and Drug Administration, Seoul 363951 (Korea, Republic of); Lee, Kwon-Yong, E-mail: sjl@bme.inje.ac.kr [Department of Mechanical Engineering, Sejong University, Seoul 143747 (Korea, Republic of)

    2011-10-15

    Recently, various types of semi-rigid pedicle screw fixation systems have been developed for the surgical treatment of the lumbar spine. They were introduced to address the adverse issues commonly found in traditional rigid spinal fusion--abnormally large motion at the adjacent level and subsequent degeneration. The semi-rigid system uses more compliant materials (nitinol or polymers) and/or changes in rod design (coiled or twisted rods) as compared to the conventional rigid straight rods made of Ti alloys (E = 114 GPa, {upsilon} = 0.32). However, biomechanical studies on the semi-rigid pedicle screw systems were usually limited to linear modeling of the implant and anatomic elements, which may not be capable of reflecting realistic post-operative motions of the spine. In this study, we evaluated the effects of nonlinearity in materials used for semi-rigid pedicle screw fixation systems to evaluate the changes in biomechanical behaviors using finite element analysis. Changes in range of motion (ROM) and center of rotation (COR) were assessed at the operated and adjacent levels. Actual load-displacement results of the semi-rigid rod from mechanical test were carried out to reflect the nonlinearity of the implant. In addition, nonlinear material properties of various spinal ligaments studies were used for the finite element modeling. The post-operative models were constructed by modifying the previously validated intact model of the L1-S1 spine. Eight different post-operative models were made to address the effects of nonlinearity-with a traditional stiffness modulus rod (with linear ligaments, case 1; with nonlinear ligaments, case 5), with a rigid rod (with linear ligaments, case 2; with nonlinear ligaments, case 6), with a soft rod (with linear ligaments, case 3; with nonlinear ligaments, case 7), and with a nonlinear rod (with linear ligaments, case 4; with nonlinear ligaments, case 8). To simulate the load on the lumbar spine in a neutral posture, follower load

  7. [Diagnosticum of abnormalities of plant meiotic division].

    Shamina, N V

    2006-01-01

    Abnormalities of plant meiotic division leading to abnormal meiotic products are summarized schematically in the paper. Causes of formation of monads, abnormal diads, triads, pentads, polyads, etc. have been observed in meiosis with both successive and simultaneous cytokinesis.

  8. Memetics clarification of abnormal behavior

    2007-01-01

    AIM: Biological medicine is hard to fully and scientifically explain the etiological factor and pathogenesis of abnormal behaviors; while, researches on philosophy and psychology (including memetics) are beneficial to better understand and explain etiological factor and pathogenesis of abnormal behaviors. At present, the theory of philosophy and psychology is to investigate the entity of abnormal behavior based on the views of memetics.METHODS: Abnormal behavior was researched in this study based on three aspects, including instinctive behavior disorder, poorly social-adapted behavior disorder and mental or body disease associated behavior disorder. Most main viewpoints of memetics were derived from "The Meme Machine", which was written by Susan Blackmore. When questions about abnormal behaviors induced by mental and psychological diseases and conduct disorder of teenagers were discussed, some researching achievements which were summarized by authors previously were added in this study, such as aggressive behaviors, pathologically aggressive behaviors, etc.RESULTS: The abnormal behaviors mainly referred to a part of people's substandard behaviors which were not according with the realistic social environment, culture background and the pathologic behaviors resulted from people's various psychological diseases. According to the theory of "meme", it demonstrated that the relevant behavioral obstacles of various psychological diseases, for example, the unusual behavior of schizophrenia, were caused, because the old meme was destroyed thoroughly but the new meme was unable to establish; psychoneurosis and personality disorder were resulted in hard establishment of meme; the behavioral obstacles which were ill-adapted to society, for example, various additional and homosexual behaviors, were because of the selfish replications and imitations of "additional meme" and "homosexual meme"; various instinct behavioral and congenital intelligent obstacles were not significance

  9. Pyridoxine deficiency affects biomechanical properties of chick tibial bone

    Masse, P. G.; Rimnac, C. M.; Yamauchi, M.; Coburn, S. P.; Rucker, R. B.; Howell, D. S.; Boskey, A. L.

    1996-01-01

    The mechanical integrity of bone is dependent on the bone matrix, which is believed to account for the plastic deformation of the tissue, and the mineral, which is believed to account for the elastic deformation. The validity of this model is shown in this study based on analysis of the bones of vitamin B6-deficient and vitamin B6-replete chick bones. In this model, when B6-deficient and control animals are compared, vitamin B6 deficiency has no effect on the mineral content or composition of cortical bone as measured by ash weight (63 +/- 6 vs. 58 +/- 3); mineral to matrix ratio of the FTIR spectra (4.2 +/- 0.6 vs. 4.5 +/- 0.2), line-broadening analyses of the X-ray diffraction 002 peak (beta 002 = 0.50 +/- 0.1 vs. 0.49 +/- 0.01), or other features of the infrared spectra. In contrast, collagen was significantly more extractable from vitamin B6-deficient chick bones (20 +/- 2% of total hydroxyproline extracted vs. 10 +/- 3% p < or = 0.001). The B6-deficient bones also contained an increased amount of the reducible cross-links DHLNL, dehydro-dihydroxylysinonorleucine, (1.03 +/- 0.07 vs. 0.84 +/- 0.13 p < or = 0.001); and a nonsignificant increase in HLNL, dehydro-hydroxylysinonorleucine, (0.51 +/- 0.03 vs. 0.43 +/- 0.03, p < or = 0.10). There were no significant changes in bone length, bone diameter, or area moment of inertia. In four-point bending, no significant changes in elastic modulus, stiffness, offset yield deflection, or fracture deflection were detected. However, fracture load in the B6-deficient animals was decreased from 203 +/- 35 MPa to 151 +/- 23 MPa, p < or = 0.01, and offset yield load was decreased from 165 +/- 9 MPa to 125 +/- 14 MPa, p < or = 0.05. Since earlier histomorphometric studies had demonstrated that the B6-deficient bones were osteopenic, these data suggest that although proper cortical bone mineralization occurred, the alterations of the collagen resulted in changes to bone mechanical performance.

  10. Biomechanical study of patellofemoral joint instability

    Senavongse, Wongwit

    2005-04-01

    Patellofemoral joint instability is a complex clinical problem. It may be a consequence of pre-existing anatomical abnormality or trauma. The objectives of this study were to use experimental mechanics to measure patellar stability and to quantify the effects of pathological abnormalities on patellar stability in vitro. Eight fresh-frozen cadaver knees were studies. The patellar stability was measured using an Instron material testing machine. A total load of 175N was applied to the quadriceps muscles. Patellar force-displacement was tested at different knee flexion angles as the patella was cyclically displaced 10mm laterally and medially. Three pathological abnormalities were applied; VMO malfunction, flat lateral trochlea, and medial retinacular structure rupturing. For the first time, this study has shown comparative and quantitative influence of pathological abnormalities on patellar stability. It was found that a flat lateral trochlea has greater effect than the medial retinacular rupturing whereas the medial retinacular rupturing has greater effect than VMO malfunction on patellar lateral stability. These results are important for future investigations on the treatment of patellofemoral instability.

  11. Biomechanical characteristics of polymeric UHMWPE composites with hybrid matrix and dispersed fillers

    Panin, Sergey; Kornienko, Lyudmila; Shilko, Sergey; Thuc, Nguyen Xuan; Korchagin, Mikhail; Chaikina, Marina

    2015-11-01

    In order to develop artificial joint implants some biomechanical properties of composites with UHMWPE and hybrid (polymer-polymeric) "UHMWPE+PTFE" matrix with dispersed fillers were studied. A comparative analysis of the effectiveness of adding hydroxyapatite micron- and nanopowders as a biocompatible filler was carried out. It was shown that under dry sliding friction the wear rate of nanocomposites with the hybrid matrix is lower as compared with composites with the non-hybrid one. Mechanical activation of components further enhances the durability of nano- and microcomposites to almost double it without any significant reduction in the strength characteristics.

  12. Effects of Bone Young’s Modulus on Finite Element Analysis in the Lateral Ankle Biomechanics

    Niu, W. X.; Wang, L J; Feng, T. N.; Jiang, C.H.; Fan, Y. B.; M. Zhang

    2013-01-01

    Finite element analysis (FEA) is a powerful tool in biomechanics. The mechanical properties of biological tissue used in FEA modeling are mainly from experimental data, which vary greatly and are sometimes uncertain. The purpose of this study was to research how Young’s modulus affects the computations of a foot-ankle FEA model. A computer simulation and an in-vitro experiment were carried out to investigate the effects of incremental Young’s modulus of bone on the stress and strain outcomes ...

  13. Thyroid abnormality in perimenopausal women with abnormal uterine bleeding

    Prasanna Byna

    2015-11-01

    Full Text Available Background: AUB is a common but complicated clinical presentation and occurs in 15-20% of women between menarche to menopause and significantly affects the women's health. Women with thyroid dysfunction often have menstrual irregularities, infertility and increased morbidity during pregnancy. The objective of present study is to find the correlation between thyroid disorders and AUB in perimenopausal women attending gynecology OPD. Methods: In the present study, fifty five patients with AUB were included and were evaluated for the cause including thyroid abnormality. Thyroid function tests were done in all patients. Results: Among 55 patients, 12 patients were diagnosed as hypothyroidism and 7 as hyperthyroidism, women with AUB 36 (65.4% were euthyroid. Among 19 women with thyroid abnormality, heavy menstrual bleeding was seen in 8 (42% women, 6 (31.57% had polymenorrhagia, 5 (26.31% had oligomenorrhoea. The frequent menstrual abnormality in women with hypothyroidism (12 women was heavy menstrual bleeding in 5 (41.6% women, 3 (25% had oligomennorhoea, 4 (33.3% had polymenorrhagia. Out of 7 women with hyperthyroidism, 2 (28.57% had oligomenorrhoea, 3 (42.8% had heavy menstrual bleeding, 2 (28.57% had polymenorrhagia. In a total of 55 patients with AUB, 11 (20% had structural abnormalities in uterus and ovaries. 5 (9% had adenomyosis, 3 (5.4% had ovarian cysts, 3 (5.4% had fibroids. Conclusions: It is important to screen all women for thyroid abnormality who are presenting with AUB especially with non-structural causes of AUB. Correction of thyroid abnormalities also relieves AUB. This will avoid unnecessary hormonal treatment and surgery. [Int J Res Med Sci 2015; 3(11.000: 3250-3253

  14. 负重爬梯与负重跑台运动对大鼠股骨微结构及力学特性的影响%The influence of weight-bearing treadmill running and climbing-ladder exercise on micro-structure and biomechanical properties of rats femur

    唐量; 高小航; 赵新娟; 张静; 孙丽君

    2015-01-01

    观察负重爬梯运动与负重跑台运动对大鼠股骨微结构及生物力学的影响,分别评价两种运动对股骨的作用效果。将28只16周 SD 雄性大鼠随机分为3个组:负重跑台运动组(WR),负重爬梯运动组(LC)以及对照组(CON)。WR 组在晚上进行每周6次持续8周无坡度15 m/min 的负重跑台运动,每组运动2 min,间歇2 min,共10组,周日休息;LC 组在晚上同期进行负重爬梯训练3组,每组10次,每次间歇2 min;CON 组不施加干预。实验8周后,戊巴比妥钠麻醉处死,并按解剖位置截取大鼠左右股骨分别用来进行 Micro-CT 扫描和三点弯曲实验,对其微结构及生物力学参数进行分析。Micro-CT 定量分析显示,与 CON 组对比,WR 组与 CL 组的骨小梁数量(Tb. N)和骨体积分数(BV/TV)均出现显著性增加,骨小梁分离度(Tb.Sp)和结构模型指数(SMI)均呈现显著性降低;三点实验显示,与 WR 组和 CON 组对比,CL 组的弹性模量(MOE)呈现出显著性增加;与 CON 组对比,WR 组与 CL 组的最大载荷(ML)均出现显著性增加,WR 组的刚度出现显著性增加。以上结果表明,经过8周的负重训练,两种训练方式均能在不同程度上改变骨的微结构及生物力学特性,负重爬梯训练的效果优于负重跑台训练。%The aim of the study was to investigate the micro-structure and biomechanical proper-ties of femur of rats that treated with weight-bearing treadmill running and climb ladder,and e-valuating the meaning of two exercise to the femur.Twenty-eight male Sprague-Dawley rats were randomly divided into 3 groups:weight-bearing treadmill group (WR),weight-bearing climbing ladder group (CL),control group (CON).WR group were trained,running on a motor-driven treadmill at a speed of 15 m/min (0 incline)bearing with 35% their body-weight mass added,two minutes running and two minutes intervals

  15. Research on simulation calculation method of biomechanical characteristics of C1-3 motion segment damage mechanism

    HUANG Ju-ying

    2013-11-01

    Full Text Available Objective To develop the finite element model (FEM of cervical spinal C1-3 motion segment, and to make biomechanical finite element analysis (FEA on C1-3 motion segment and thus simulate the biomechanical characteristics of C1-3 motion segment in distraction violence, compression violence, hyperextension violence and hyperflexion violence. Methods According to CT radiological data of a healthy adult, the vertebrae and intervertebral discs of cervical spinal C1-3 motion segment were respectively reconstructed by Mimics 10.01 software and Geomagic 10.0 software. The FEM of C1-3 motion segment was reconstructed by attaching the corresponding material properties of cervical spine in Ansys software. The biomechanical characteristics of cervical spinal C1-3 motion segment model were simulated under the 4 loadings of distraction violence, compression violence, hyperextension violence and hyperflexion violence by finite element method. Results In the loading of longitudinal stretch, the stress was relatively concentrated in the anterior arch of atlas, atlantoaxial joint and C3 lamina and spinous process. In the longitudinal compressive loads, the maximum stress of the upper cervical spine was located in the anterior arch of atlas. In the loading of hyperextension moment, the stress was larger in the massa lateralis atlantis, the lateral and posterior arch junction of atlas, the posterior arch nodules of the atlas, superior articular surface of axis and C2 isthmus. In the loading of hyperflexion moment, the stress was relatively concentrated in the odontoid process of axis, the posterior arch of atlas, the posterior arch nodules of atlas, C2 isthmic and C2 inferior articular process. Conclusion Finite element biomechanical testing of C1-3 motion segment can predict the biomechanical mechanism of upper cervical spine injury.

  16. Biomechanical evaluation of the locking titanium cable in the fixture of distal tibiofibular syndesmosis injury

    Shu-zhi YAO

    2016-08-01

    Full Text Available Objective  The article aims at evaluating the biological properties of tibiofibular titanium cable fixation device in terms of both anti-separation and stress shielding by comparison to the interior fixation with lag screw based on experimental observation. Methods  Six corpse ankle specimens were first tested of pressure-separation and stress measurement, the data from which were compared to the normal group, and then a syndesmosis injury model was established. All the samples are randomly divided into 2 groups of 3 specimens each, which were treated with tibiofibula locked titanium cable and lag screw fixation respectively for syndesmosis injury. Then, the samples were tested for pressure-separation and stress measurement. The biomechanical properties as anti-separation ability and stress shielding were analyzed and compared between the two fixation method. Results  Both tibiofibula locked titanium cables and lag screws were able to provide enough strong lateral anti-separation ability, but strong fixation screws were inferior to tibiofibular titanium cable fixation device in fibular longitudinal stress transduction. Conclusion  Tibiofibular titanium cable fixation device not only provide sufficient lateral anti-separation, but also reduces the tibial and fibular longitudinal stress shielding, thus being superior to the traditional lag screw in biomechanical properties. DOI: 10.11855/j.issn.0577-7402.2016.07.09

  17. Open Knee: Open Source Modeling and Simulation in Knee Biomechanics.

    Erdemir, Ahmet

    2016-02-01

    Virtual representations of the knee joint can provide clinicians, scientists, and engineers the tools to explore mechanical functions of the knee and its tissue structures in health and disease. Modeling and simulation approaches such as finite element analysis also provide the possibility to understand the influence of surgical procedures and implants on joint stresses and tissue deformations. A large number of knee joint models are described in the biomechanics literature. However, freely accessible, customizable, and easy-to-use models are scarce. Availability of such models can accelerate clinical translation of simulations, where labor-intensive reproduction of model development steps can be avoided. Interested parties can immediately utilize readily available models for scientific discovery and clinical care. Motivated by this gap, this study aims to describe an open source and freely available finite element representation of the tibiofemoral joint, namely Open Knee, which includes the detailed anatomical representation of the joint's major tissue structures and their nonlinear mechanical properties and interactions. Three use cases illustrate customization potential of the model, its predictive capacity, and its scientific and clinical utility: prediction of joint movements during passive flexion, examining the role of meniscectomy on contact mechanics and joint movements, and understanding anterior cruciate ligament mechanics. A summary of scientific and clinically directed studies conducted by other investigators are also provided. The utilization of this open source model by groups other than its developers emphasizes the premise of model sharing as an accelerator of simulation-based medicine. Finally, the imminent need to develop next-generation knee models is noted. These are anticipated to incorporate individualized anatomy and tissue properties supported by specimen-specific joint mechanics data for evaluation, all acquired in vitro from varying age

  18. Abnormal insulin levels and vertigo.

    Proctor, C A

    1981-10-01

    Fifty patients with unexplained vertigo (36) or lightheadedness (14) are evaluated, all of whom had abnormal ENGs and normal audiograms. Five hour insulin glucose tolerance tests were performance on all patients, with insulin levels being obtained fasting and at one-half, one, two, and three hours. The results of this investigation were remarkable. Borderline or abnormal insulin levels were discovered in 82% of patients; 90% were found to have either an abnormal glucose tolerance test or at least borderline insulin levels. The response to treatment in these dizzy patients was also startling, with appropriate low carbohydrate diets improving the patient's symptoms in 90% of cases. It is, therefore, apparent that the earliest identification of carbohydrate imbalance with an insulin glucose tolerance test is extremely important in the work-up of the dizzy patients.

  19. Anatomy and biomechanics of quadratus lumborum.

    Phillips, S; Mercer, S; Bogduk, N

    2008-02-01

    Various actions on the lumbar spine have been attributed to quadratus lumborum, but they have not been substantiated by quantitative data. The present study was undertaken to determine the magnitude of forces and moments that quadratus lumborum could exert on the lumbar spine. The fascicular anatomy of quadratus lumborum was studied in six embalmed cadavers. For each fascicle, the sites of attachment, orientation, and physiological cross-sectional area were determined. The fascicular anatomy varied considerably, between sides and between specimens, with respect to the number of fascicles, their prevalence, and their sizes. Approximately half of the fascicles act on the twelfth rib, and the rest act on the lumbar spine. The more consistently present fascicles were incorporated, as force-equivalents, into a model of quadratus lumborum in order to determine its possible actions. The magnitudes of the compression forces exerted by quadratus lumborum on the lumbar spine, the extensor moment, and the lateral bending moment, were each no greater than 10 per cent of those exerted by erector spinae and multifidus. These data indicate that quadratus lumborum has no more than a modest action on the lumbar spine, in quantitative terms. Its actual role in spinal biomechanics has still to be determined.

  20. Biomechanics of seat belt restraint system.

    Sances, Anthony; Kumaresan, Srirangam; Herbst, Brian; Meyer, Steve; Hock, Davis

    2004-01-01

    Seat belt system restrains and protects occupants in motor vehicle crashes and any slack in seat belt system induces additional loading on occupant. Signs of belt loading are more obvious in high-speed frontal collisions with heavy occupants. However subtle changes may occur at low speeds or with low forces from occupants during rollovers. In certain cases, the seat belt webbing is twisted and loaded by the occupant. The loading of webbing induces an observable fold/crimp on the seat belt. The purpose of the study is to biomechanically evaluate the force required to produce such marks using an anthropometric physical test dummy. Two tests were conducted to determine the amount of force required to put an observable fold/crimp in a shoulder belt. A head form designed by Voight Hodgson was used to represent the neck which interacted with the belt. The force was applied with a pneumatic pull ram (central hydraulic 89182 N) and the force was measured with a 44,000 N transducer load cell (DSM-10K). Results indicate that the force of over 1,000 N produced a fold or crimp in the belt.

  1. Physiological and biomechanical aspects of orienteering.

    Creagh, U; Reilly, T

    1997-12-01

    Orienteering is an endurance running event which differs from other running sports both in its cognitive element and in the type of terrain encountered. The demands of overcoming this terrain are not manifest in significant differences between orienteers and road runners in somatotype, though elite female orienteers have consistently been shown to have higher levels of adiposity (> 19%) than elite road runners. High aerobic power in orienteers (up to 63 and 76 ml/kg/min in women and men, respectively) is coupled with lower anaerobic performance. While leg strength is generally not high when compared with other athletic specialties, female orienteers have relatively good leg flexion strength. The energy cost of running is greatly increased in rough terrain. Oxygen cost was 26% higher while running in a forest when compared with road running. Biomechanical differences in stride pattern contribute towards this increased demand. Despite the high energy demands during competition, orienteers pace themselves such that their mean heart rate remains within the range of 167 to 172 beats/min, despite large fluctuations. The rough terrain encountered in orienteering results not only in a high energy cost but also in a higher incidence of sport-specific injuries, particularly to the ankle. Minor injuries such as cuts and bruises are common during competition.

  2. Biomechanics of fencing sport: A scoping review

    Chen, Tony Lin-Wei; Wong, Duo Wai-Chi; Wang, Yan; Ren, Sicong; Yan, Fei

    2017-01-01

    Objectives The aim of our scoping review was to identify and summarize current evidence on the biomechanics of fencing to inform athlete development and injury prevention. Design Scoping review. Method Peer-reviewed research was identified from electronic databases using a structured keyword search. Details regarding experimental design, study group characteristics and measured outcomes were extracted from retrieved studies, summarized and information regrouped under themes for analysis. The methodological quality of the evidence was evaluated. Results Thirty-seven peer-reviewed studies were retrieved, the majority being observational studies conducted with experienced and elite athletes. The methodological quality of the evidence was “fair” due to the limited scope of research. Male fencers were the prevalent group studied, with the lunge and use of a foil weapon being the principal movement evaluated. Motion capture and pedabarography were the most frequently used data collection techniques. Conclusions Elite fencers exhibited sequential coordination of upper and lower limb movements with coherent patterns of muscle activation, compared to novice fencers. These elite features of neuromuscular coordination resulted in higher magnitudes of forward linear velocity of the body center of mass and weapon. Training should focus on explosive power. Sex- and equipment-specific effects could not be evaluated based on available research. PMID:28187164

  3. Biomechanics during exercise with a novel stairclimber.

    Tsai, Y-J; Hsue, B-J; Lin, C-J; Su, F-C

    2011-09-01

    The current study aimed to investigate the stair-climbing biomechanics related to the lower extremities when subjects used the novel designed stair-climber, which could provide opportunity for both sagittal and frontal movements. 12 volunteers were required to step while either keeping the trunk static (STATIC) or allowing the trunk to shift with weight bearing (SHIFT). A motion analysis system and the 6-axis force and torque sensor embedded in the pedal were used to collect data. Foot contact forces and joint moments were calculated to represent loading characteristics. The joint angle and corresponding moments at the terminal point of the stance phase were computed to serve as the indicator of safety. Significant differences were found in peak foot contact forces, knee extensor moment, and hip abductor moment. At the end of the stance phase, various directions of moment between conditions were found in the knee and the ankle. The knee valgus angle, hip abductor moment, and knee extensor moment were significantly greater in SHIFT than in STATIC. The various stepping strategies caused differences in joint loading characteristics; therefore, these findings need to be given greater consideration in the design of training protocols.

  4. Comparative biomechanics: life's physical world (second edition)

    Vogel, Steven

    2013-01-01

    Why do you switch from walking to running at a specific speed? Why do tall trees rarely blow over in high winds? And why does a spore ejected into air at seventy miles per hour travel only a fraction of an inch? Comparative Biomechanics is the first and only textbook that takes a comprehensive look at the mechanical aspects of life--covering animals and plants, structure and movement, and solids and fluids. An ideal entry point into the ways living creatures interact with their immediate physical world, this revised and updated edition examines how the forms and activities of animals and plants reflect the materials available to nature, considers rules for fluid flow and structural design, and explores how organisms contend with environmental forces. Drawing on physics and mechanical engineering, Steven Vogel looks at how animals swim and fly, modes of terrestrial locomotion, organism responses to winds and water currents, circulatory and suspension-feeding systems, and the relationship between size and mech...

  5. CURRENT CONCEPTS IN BIOMECHANICAL INTERVENTIONS FOR PATELLOFEMORAL PAIN

    Meira, Erik P.

    2016-01-01

    Patellofemoral pain (PFP) has historically been a complex and enigmatic issue. Many of the factors thought to relate to PFP remain after patients' symptoms have resolved making their clinical importance difficult to determine. The tissue homeostasis model proposed by Dye in 2005 can assist with understanding and implementing biomechanical interventions for PFP. Under this model, the goal of interventions for PFP should be to re-establish patellofemoral joint (PFJ) homeostasis through a temporary alteration of load to the offended tissue, followed by incrementally restoring the envelope of function to the baseline level or higher. High levels of PFJ loads, particularly in the presence of an altered PFJ environment, are thought to be a factor in the development of PFP. Clinical interventions often aim to alter the biomechanical patterns that are thought to result in elevated PFJ loads while concurrently increasing the load tolerance capabilities of the tissue through therapeutic exercise. Biomechanics may play a role in PFJ load modification not only when addressing proximal and distal components, but also when considering the involvement of more local factors such as the quadriceps musculature. Biomechanical considerations should consider the entire kinetic chain including the hip and the foot/ankle complex, however the beneficial effects of these interventions may not be the result of long-term biomechanical changes. Biomechanical alterations may be achieved through movement retraining, but the interventions likely need to be task-specific to alter movement patterns. The purpose of this commentary is to describe biomechanical interventions for the athlete with PFP to encourage a safe and complete return to sport. Level of Evidence 5 PMID:27904791

  6. Biomechanical Remodeling of the Diabetic Gastrointestinal Tract

    Zhao, Jingbo; Liao, Donghua; Yang, Jian

    2010-01-01

    Gastrointestinal tract sensory-motor abnormalities are common in patients with diabetes mellitus with symptoms arising from the whole GI tract. Common complaints include dysphasia, early satiety, reflux, constipation, abdominal pain, nausea, vomiting, and diarrhea. The pathogenesis of GI symptoms...... in diabetes mellitus is complex in nature, multi-factorial (motor dysfunction, autonomic neuropathy, glycemic control, psychological factors, etc.) and is not well understood. Histologically, many studies have demonstrated prominent proliferation of different GI wall layers during diabetes. During the past...

  7. Cardiac abnormalities after subarachnoid hemorrhage

    Bilt, I.A.C. van der

    2016-01-01

    Aneurysmal subarachnoid hemorrhage(aSAH) is a devastating neurological disease. During the course of the aSAH several neurological and medical complications may occur. Cardiac abnormalities after aSAH are observed often and resemble stress cardiomyopathy or Tako-tsubo cardiomyopathy(Broken Heart Syn

  8. Congenital abnormalities in methylmercury poisoning

    Gilani, S.H.

    1975-04-01

    This study was undertaken to determine the teratogenic potential of methylmercury on chick embryogenesis. Methylmercuric chloride was dissolved in sodium bicarbonate (0.2%) and administered to the chick embryos at doses ranging from 0.0009 to 0.010 mg per egg. The injections were made at days 2 and 3 on incubation (Groups A and B). All the embryos including controls were examined on the 7th day of incubation. Methylmercury poisoning was observed to be both embryolethal and teratogenic. Within the two groups, embryolethality was higher in Group A. The following congenital abnormalities were observed: exencephaly, shortened and twisted limbs, microphthalmia, shortened and twisted neck, beak abnormalities, everted viscera, reduced body size and hemorrhage all over the body. Exencephaly and limb abnormalities were very common. No differences in the incidence and types of gross abnormalities within both the groups (A and B) were noted. The incidence of malformations among the controls was low. The results of present investigation show that methylmercury poisoning is both embryolethal and teratogenic to early chick embryogenesis. (auth)

  9. Ti-Ni Rods with Variable Stiffness for Spine Stabilization: Manufacture and Biomechanical Evaluation

    Brailovski, Vladimir; Facchinello, Yann; Brummund, Martin; Petit, Yvan; Mac-Thiong, Jean-Marc

    2016-03-01

    A new concept of monolithic spinal rods with variable flexural stiffness is proposed to reduce the risk of adjacent segment degeneration and vertebral fracture, while providing adequate stability to the spine. The variability of mechanical properties is generated by locally annealing Ti-Ni shape memory alloy rods. Ten-minute Joule effect annealing allows the restoration of the superelasticity in the heated portion of the rod. Such processing also generates a mechanical property gradient between the heated and the unheated zones. A numerical model simulating the annealing temperature and the distributions of the mechanical properties was developed to optimize the Joule-heating strategy and to modulate the rod's overall flexural stiffness. Subsequently, the rod model was included in a finite element model of a porcine lumbar spine to study the effect of the rod's stiffness profiles on the spinal biomechanics.

  10. A three-dimensional finite element model for biomechanical analysis of the hip.

    Chen, Guang-Xing; Yang, Liu; Li, Kai; He, Rui; Yang, Bin; Zhan, Yan; Wang, Zhi-Jun; Yu, Bing-Nin; Jian, Zhe

    2013-11-01

    The objective of this study was to construct a three-dimensional (3D) finite element model of the hip. The images of the hip were obtained from Chinese visible human dataset. The hip model includes acetabular bone, cartilage, labrum, and bone. The cartilage of femoral head was constructed using the AutoCAD and Solidworks software. The hip model was imported into ABAQUS analysis system. The contact surface of the hip joint was meshed. To verify the model, the single leg peak force was loaded, and contact area of the cartilage and labrum of the hip and pressure distribution in these structures were observed. The constructed 3D hip model reflected the real hip anatomy. Further, this model reflected biomechanical behavior similar to previous studies. In conclusion, this 3D finite element hip model avoids the disadvantages of other construction methods, such as imprecision of cartilage construction and the absence of labrum. Further, it provides basic data critical for accurately modeling normal and abnormal loads, and the effects of abnormal loads on the hip.

  11. Abnormal bone collagen morphology and decreased bone strength in growth hormone-deficient rats

    Lange, Martin; Qvortrup, Klaus; Svendsen, Ole Lander

    2004-01-01

    , (2) biomechanical properties, (3) serum insulin-like growth factor I (IGF-I) and IGF binding protein 3 (IGFBP-3), and (4) collagen morphology of cortical bone from the right femurs was examined by scanning and transmission electron microscopy. A significant decrease was found in serum IGF-I, IGFBP-3...... collagen morphology and bone mineralisation in cortical bone as well as bone strength in GHD rats to try to clarify the explanation for the increased fracture rate. The Dw-4 rat was used as a model for GHD. This strain of rats has an autosomal recessive disorder, reducing GH synthesis to approximately 10...... and biomechanical properties in GHD rats compared to controls (P collagen microfibrils in GHD...

  12. Biomechanics Strategies for Space Closure in Deep Overbite

    Harryanto Wijaya

    2013-07-01

    Full Text Available Space closure is an interesting aspect of orthodontic treatment related to principles of biomechanics. It should be tailored individually based on patient’s diagnosis and treatment plan. Understanding the space closure biomechanics basis leads to achieve the desired treatment objective. Overbite deepening and losing posterior anchorage are the two most common unwanted side effects in space closure. Conventionally, correction of overbite must be done before space closure resulted in longer treatment. Application of proper space closure biomechanics strategies is necessary to achieve the desired treatment outcome. This cases report aimed to show the space closure biomechanics strategies that effectively control the overbite as well as posterior anchorage in deep overbite patients without increasing treatment time. Two patients who presented with class II division 1 malocclusion were treated with fixed orthodontic appliance. The primary strategies included extraction space closure on segmented arch that employed two-step space closure, namely single canine retraction simultaneously with incisors intrusion followed by enmasse retraction of four incisors by using differential moment concept. These strategies successfully closed the space, corrected deep overbite and controlled posterior anchorage simultaneously so that the treatment time was shortened. Biomechanics strategies that utilized were effective to achieve the desired treatment outcome.

  13. A new methodology to measure the running biomechanics of amputees.

    Wilson, James Richard; Asfour, Shihab; Abdelrahman, Khaled Zakaria; Gailey, Robert

    2009-09-01

    We present a new methodology to measure the running biomechanics of amputees. This methodology combines the use of a spring-mass model and symmetry index, two standard techniques in biomechanics literature, but not yet used in concert to evaluate amputee biomechanics. The methodology was examined in the context of a pilot study to examine two transtibial amputee sprinters and showed biomechanically quantifiable changes for small adjustments in prosthetic prescription. Vertical ground reaction forces were measured in several trials for two transtibial amputees running at constant speed. A spring-mass model was used in conjunction with a symmetry index to observe the effect of varying prosthetic height and stiffness on running biomechanics. All spring-mass variables were significantly affected by changes in prosthetic prescription among the two subjects tested (p < 0.05). When prosthetic height was changed, both subjects showed significant differences, in Deltay(max), Deltal and contact time (t(c)) on the prosthetic limb and in k(vert) and k(leg) on the sound limb. The symmetry indices calculated for spring-mass variables were all significantly affected due to changes in prosthetic prescription for the male subject and all but the peak force (F(peak)) for the female subject. This methodology is a straight-forward tool for evaluating the effect of changes to prosthetic prescription.

  14. Biomechanics of the thorax - research evidence and clinical expertise.

    Lee, Diane Gail

    2015-07-01

    Understanding the biomechanics of the thorax is critical for understanding its role in multiple conditions since the thorax is part of many integrated systems including the musculoskeletal, respiratory, cardiac, digestive and urogynecological. The thorax is also an integrated system within itself and an element of the whole body/person. Therefore, understanding the biomechanics of the thorax is fundamental to all forms of treatment for multiple conditions. The interpretation of movement examination findings depends on one's view of optimal biomechanics and the influential factors. This article will provide a synopsis of the current state of research evidence as well as observations from clinical experience pertaining to the biomechanics of the thorax in order to help clinicians organise this knowledge and facilitate evidence-based and informed management of the, often complex, patient with or without thoracic pain and impairment. The integrated systems model (ISM) will be introduced as a way to determine when the noted biomechanical findings are relevant to a patient's clinical presentation.

  15. MR elastography to measure the effects of cancer and pathology fixation on prostate biomechanics, and comparison with T 1, T 2 and ADC

    McGrath, Deirdre M.; Lee, Jenny; Foltz, Warren D.; Samavati, Navid; van der Kwast, Theo; Jewett, Michael A. S.; Chung, Peter; Ménard, Cynthia; Brock, Kristy K.

    2017-02-01

    MRI is under evaluation for image-guided intervention for prostate cancer. The sensitivity and specificity of MRI parameters is determined via correlation with the gold-standard of histopathology. Whole-mount histopathology of prostatectomy specimens can be digitally registered to in vivo imaging for correlation. When biomechanical-based deformable registration is employed to account for deformation during histopathology processing, the ex vivo biomechanical properties are required. However, these properties are altered by pathology fixation, and vary with disease. Hence, this study employs magnetic resonance elastography (MRE) to measure ex vivo prostate biomechanical properties before and after fixation. A quasi-static MRE method was employed to measure high resolution maps of Young’s modulus (E) before and after fixation of canine prostate and prostatectomy specimens (n  =  4) from prostate cancer patients who had previously received radiation therapy. For comparison, T 1, T 2 and apparent diffusion coefficient (ADC) were measured in parallel. E (kPa) varied across clinical anatomy and for histopathology-identified tumor: peripheral zone: 99(±22), central gland: 48(±37), tumor: 85(±53), and increased consistently with fixation (factor of 11  ±  5 p  biomechanics of the clinical prostate specimens varied greatly with fixation, and to a lesser extent with disease and anatomy. The data obtained will improve the precision of prostate pathology correlation, leading to more accurate disease detection and targeting.

  16. Anthropometry and Biomechanics Facility Spring 2016 Internship

    Boppana, Abhishektha

    2016-01-01

    The Anthropometry and Biomechanics Facility (ABF) at Johnson Space Center supports the Space Human Factors Engineering portfolio of the Human Research Program. ABF provides capability to verify the accommodation and comfort of crewmembers through anthropometry and biomechanics analyses. Anthropometric measurements are derived from three-dimensional (3D) whole body scan images. The scans are currently taken by a Human Solutions Vitus 3D Laser Scanning System. ABF has purchased a 3dMD photogrammetry scanner system to speed up the process of collecting 3D scans. The photogrammetry scanner system features a faster data collection time, as well as fewer holes in the scans. This internship was mainly focused on developing calibration, measurement, data acquisition, and analysis processes for the new system. In addition, I also participated in a project to validate the use of a pressure mat sensor on the shoulder during in-suit testing. My duties for the scanner validation project started with identifying and documenting a calibration process. The calibration process proved vital to using the system as the quality of the scans was directly related to the success of the calibration. In addition, the calibration process suggested by the system vendor required the user to hold a large calibration board at precise locations. To aid in this, I built a calibration stand which held a calibration board at constant positions throughout numerous calibration process. The calibration process was tested extensively until proven acceptable. The standardized process reduced calibration time from over 10 minutes to just below three minutes. As a result, the calibration process could be completed painlessly and precisely, and scan quality was constant between sessions. After standardizing the calibration process, I proceeded to modify the locations of the cameras in order to capture the full volume of a person. The scanning system needed to capture a full T-pose of a person in one scan

  17. Hangman's fracture: a historical and biomechanical perspective.

    Rayes, Mahmoud; Mittal, Monika; Rengachary, Setti S; Mittal, Sandeep

    2011-02-01

    The execution technique of hanging, introduced by the Angle, Saxon, and Jute Germanic tribes during their invasions of the Roman Empire and Britain in the 5th century, has remained largely unchanged over time. The earliest form of a gallows was a tree on which prisoners were hanged. Despite the introduction of several modifications such as a trap door, the main mechanism of death remained asphyxiation. This created the opportunity for attempted revival after the execution, and indeed several well-known cases of survival following judicial hanging have been reported. It was not until the introduction of the standard drop by Dr. Samuel Haughton in 1866, and the so-called long drop by William Marwood in 1872 that hanging became a standard, humane means to achieve instantaneous death. Hangmen, however, fearing knot slippage, started substituting the subaural knot for the traditional submental knot. Subaural knots were not as effective, and cases of decapitation were recorded. Standardization of the long drop was further propagated by John Berry, an executioner who used mathematical calculations to estimate the correct drop length for each individual to be hanged. A British committee on capital sentences, led by Lord Aberdare, studied the execution method, and advocated for the submental knot. However, it was not until Frederic Wood-Jones published his seminal work in 1913 that cervical fractures were identified as the main mechanism of death following hanging in which the long drop and a submental knot were used. Schneider introduced the term "hangman's fracture" in 1965, and reported on the biomechanics and other similarities of the cervical fractures seen following judicial hangings and those caused by motor vehicle accidents.

  18. Theoretical Considerations and a Mathematical Model for the Analysis of the Biomechanical Response of Human Keratinized Oral Mucosa

    Aikaterini Tsaira

    2016-08-01

    Full Text Available Removable complete and partial dentures are supported by the residual alveolar ridges consisting of mucosa, submucosa, periosteum and bone. An understanding of the biomechanical behavior of the oral mucosa is essential in order to improve the denture-bearing foundations for complete and partially edentulous patients. The purpose of this paper was to examine the biomechanical behavior of the soft tissues supporting a removable denture and develop a model for that reason. Keratinized oral mucosa blocks with their underlying bone were harvested from the maxillary palatal area adjacent to the edentulous ridges of a cadaver. The compressive response of the oral mucosa was tested by using atomic force microscopy. The specimens were first scanned in order their topography to be obtained. The mechanical properties of the specimens were tested using a single crystal silicon pyramidal tip, which traversed towards the keratinized oral mucosa specimens. Loading-unloading cycles were registered and four mathematical models were tested using MATLAB to note which one approximates the force-displacement curve as close as possible: a. spherical, b. conical, c. third order polynomial, d. Murphy (fourth order polynomial, non-linear Hertzian based. The third order polynomial model showed the best accuracy in representing the force-displacement data of the tested specimens. A model was developed in order to analyze the biomechanical behavior of the human oral keratinized mucosa and obtain information about its mechanical properties.

  19. [Angle-fixed plate fixation or double-plate osteosynthesis in fractures of the proximal humerus: a biomechanical study].

    Hessmann, Martin H; Korner, Jan; Hofmann, Alexander; Sternstein, Werner; Rommens, Pol M

    2008-06-01

    Internal fixation of fractures of the proximal humerus needs a high stability of fixation to avoid secondary loss of fixation. This is especially important in osteoporotic bone. In an experimental study, the biomechanical properties of the angle-fixed Philos plate (internal fixator) and a double-plate osteosynthesis using two one-third tubular plates were assessed. The fracture model was an unstable three-part fracture (AO type B2). Eight pairs of human cadaveric humeri were submitted to axial load and torque. In the first part of the study, it was assessed to which degree the original stiffness of the humeri could be restored after the osteotomy by the osteosynthesis procedure. Subsequently, subsidence during 200 cycles of axial loading and torque was analysed. During axial loading, the Philos plate was significantly stiffer and showed less irreversible deformation. Two double-plate fixations, but none of the Philos plate osteosynthesis, failed. During torsion, there were no significant differences between the two implants. From the biomechanical point of view, the angle-fixed Philos plate represents the implant of choice for the surgical fixation of highly unstable three-part fractures of the proximal humerus, as the internal fixator system is characterised by superior biomechanical properties.

  20. Corneal Viscoelastic Properties from Finite-Element Analysis of In Vivo Air-Puff Deformation

    Kling, Sabine; Bekesi, Nandor; Dorronsoro, Carlos; Pascual, Daniel; Marcos, Susana

    2014-01-01

    Biomechanical properties are an excellent health marker of biological tissues, however they are challenging to be measured in-vivo. Non-invasive approaches to assess tissue biomechanics have been suggested, but there is a clear need for more accurate techniques for diagnosis, surgical guidance and treatment evaluation. Recently air-puff systems have been developed to study the dynamic tissue response, nevertheless the experimental geometrical observations lack from an analysis that addresses specifically the inherent dynamic properties. In this study a viscoelastic finite element model was built that predicts the experimental corneal deformation response to an air-puff for different conditions. A sensitivity analysis reveals significant contributions to corneal deformation of intraocular pressure and corneal thickness, besides corneal biomechanical properties. The results show the capability of dynamic imaging to reveal inherent biomechanical properties in vivo. Estimates of corneal biomechanical parameters will contribute to the basic understanding of corneal structure, shape and integrity and increase the predictability of corneal surgery. PMID:25121496

  1. Computational biomechanics for medicine imaging, modeling and computing

    Doyle, Barry; Wittek, Adam; Nielsen, Poul; Miller, Karol

    2016-01-01

    The Computational Biomechanics for Medicine titles provide an opportunity for specialists in computational biomechanics to present their latest methodologies and advancements. This volume comprises eighteen of the newest approaches and applications of computational biomechanics, from researchers in Australia, New Zealand, USA, UK, Switzerland, Scotland, France and Russia. Some of the interesting topics discussed are: tailored computational models; traumatic brain injury; soft-tissue mechanics; medical image analysis; and clinically-relevant simulations. One of the greatest challenges facing the computational engineering community is to extend the success of computational mechanics to fields outside traditional engineering, in particular to biology, the biomedical sciences, and medicine. We hope the research presented within this book series will contribute to overcoming this grand challenge.

  2. Biomechanics of Kuzushi-Tsukuri and Interaction in Competition

    Sacripanti, Attilio

    2010-01-01

    In this paper it is performed the comparative biomechanical analysis of the Kuzushi (Unbalance) -Tsukuri (the entry and proper fitting of Tori's body into the position taken just before throwing) phases of Judo Throwing techniques. The whole effective movement is without separation, as already stated by old Japanese biomechanical studies (1972 -1978), only one skilled connected action, but the biomechanical analysis is able to separate the whole in didactic steps called Action Invariants. The first important finding singled out is the existence of two classes of Action Invariants the first the General one' connected to the whole body motion is specific of shortening distance in the Kuzushi Tsukuri Phase. The second one, the Specific Action Invariants is connected to the superior and inferior kinetic chains motion and right positioning connected both to Kuzushi and Tsukuri phases. Some interesting findings derive from this analysis: among throwing techniques, couple techniques could be independent from Kuzushi...

  3. The increasing importance of the biomechanics of impact trauma

    Murray Mackay

    2007-08-01

    The evolution of experimental biomechanics and crash injury research is summarized briefly to show that they both play a major role in mitigating traffic deaths and injuries. Historically, the subject has been based largely in western countries and thus focused on vehicle occupants, whereas some 80% of traffic casualties in the world are outside the vehicle as pedestrians, cyclists and motorcyclists. The subject is close to the regulatory process which controls vehicle design and is thus heavily influenced by government and industry, yet it is now in an expanding period because of new techniques to replicate the human frame’s response to impact forces. New knowledge is likely to emerge from addressing population variations and combining real world accident investigations with experimental biomechanics. The application of impact biomechanics to the vulnerable road users is of particular importance.

  4. Biomechanically Excited SMD Model of a Walking Pedestrian

    Zhang, Mengshi; Georgakis, Christos T.; Chen, Jun

    2016-01-01

    estimated from a known walking frequency and the pedestrian's weight, assuming that pedestrians always walk in displacement resonance and retain a constant damping ratio of 0.3. Thus, biomechanical forces were extracted using the measured SMD dynamic responses and the estimated SMD parameters. Extracted...... of biomechanical forces, was used to model a pedestrian for application in vertical human-structure interaction (HSI). Tests were undertaken in a gait laboratory, where a three-dimensional motion-capture system was used to record a pedestrian's walking motions at various frequencies. The motion-capture system...... produced the pedestrian's center of mass (COM) trajectories from the captured motion markers. The vertical COM trajectory was approximated to be the pedestrian SMD dynamic responses under the excitation of biomechanical forces. SMD model parameters of a pedestrian for a specific walking frequency were...

  5. Vertical Jump Biomechanics Altered With Virtual Overhead Goal.

    Ford, Kevin R; Nguyen, Anh-Dung; Hegedus, Eric J; Taylor, Jeffrey B

    2017-04-01

    Virtual environments with real-time feedback can simulate extrinsic goals that mimic real life conditions. The purpose was to compare jump performance and biomechanics with a physical overhead goal (POG) and with a virtual overhead goal (VOG). Fourteen female subjects participated (age: 18.8 ± 1.1 years, height: 163.2 ± 8.1 cm, weight 63.0 ± 7.9 kg). Sagittal plane trunk, hip, and knee biomechanics were calculated during the landing and take-off phases of drop vertical jump with different goal conditions. Repeated-measures ANOVAs determined differences between goal conditions. Vertical jump height displacement was not different during VOG compared with POG. Greater hip extensor moment (P biomechanical testing, screening, and training conditions.

  6. [Air transport biomechanical risk: reduced mobility passengers' handling].

    Draicchio, F; Campoli, G; Silvetti, A; Badellino, E; Forzano, F; Ranavolo, A; Iavicoli, S; Campagna, G; Raffaele, G; Gismondi, M

    2012-01-01

    As the airport traffic increases there is a continuous increase of passengers with different motor disabilities. Disabled passenger's assistance causes a biomechanical overload in airport workers. Some disabled passengers are classified by IATA as WCHC (wheel chair in cabin or Charlie). Our study, was performed in one of the most important Italian airport on Charlie passengers (about 10% of all assistances). We identified four critical points: 1) wheelchair and baggage moving (unstable load), 2) inclined ramps with worker's backwards steps and braked wheelchair to prevent passenger tipping or falling, 3) transfer from standard wheelchair to bicycle wheelchair, specifically designed for the aisle; 4.) transfer from bicycle wheelchair to aircraft seat. The last two points required sometimes to lift passengers over the armrest and positioning them on a window side seat, causing a serious increase of biomechanical load. For each critical point we have proposed technical and organizational measures to reduce airport worker's biomechanical risk.

  7. Computational biomechanics for medicine new approaches and new applications

    Miller, Karol; Wittek, Adam; Nielsen, Poul

    2015-01-01

    The Computational Biomechanics for Medicine titles provide an opportunity for specialists in computational biomechanics to present their latest methodologiesand advancements. Thisvolumecomprises twelve of the newest approaches and applications of computational biomechanics, from researchers in Australia, New Zealand, USA, France, Spain and Switzerland. Some of the interesting topics discussed are:real-time simulations; growth and remodelling of soft tissues; inverse and meshless solutions; medical image analysis; and patient-specific solid mechanics simulations. One of the greatest challenges facing the computational engineering community is to extend the success of computational mechanics to fields outside traditional engineering, in particular to biology, the biomedical sciences, and medicine. We hope the research presented within this book series will contribute to overcoming this grand challenge.

  8. Biomechanical analysis technique choreographic movements (for example, "grand battman jete"

    Batieieva N.P.

    2015-04-01

    Full Text Available Purpose : biomechanical analysis of the execution of choreographic movement "grand battman jete". Material : the study involved students (n = 7 of the department of classical choreography faculty of choreography. Results : biomechanical analysis of choreographic movement "grand battman jete" (classic exercise, obtained kinematic characteristics (path, velocity, acceleration, force of the center of mass (CM bio parts of the body artist (foot, shin, thigh. Built bio kinematic model (phase. The energy characteristics - mechanical work and kinetic energy units legs when performing choreographic movement "grand battman jete". Conclusions : It was found that the ability of an athlete and coach-choreographer analyze the biomechanics of movement has a positive effect on the improvement of choreographic training of qualified athletes in gymnastics (sport, art, figure skating and dance sports.

  9. Influence of locomotion speed on biomechanical subtask and muscle synergy.

    Gui, Kai; Zhang, Dingguo

    2016-10-01

    This paper investigates the relationship of biomechanical subtasks, and muscle synergies with various locomotion speeds. Ground reaction force (GRF) of eight healthy subjects is measured synchronously by force plates of treadmill at five different speeds ranging from 0.5m/s to 1.5m/s. Four basic biomechanical subtasks, body support, propulsion, swing, and heel strike preparation, are identified according to GRF. Meanwhile, electromyography (EMG) data, used to extract muscle synergies, are collected from lower limb muscles. EMG signals are segmented periodically based on GRF with the heel strike as the split points. Variability accounted for (VAF) is applied to determine the number of muscle synergies. We find that four muscle synergies can be extracted in all five situations by non-negative matrix factorization (NMF). Furthermore, the four muscle synergies and biomechanical subtasks keep invariant as the walking speed changes.

  10. Biomechanical Profile of Danish Elite and Sub-elite Soccer Goalkeepers

    Sørensen, Henrik; Thomassen, Martin; Zacho, Morten

    2008-01-01

    The purpose of this study was to define a biomechanical profile of the soccer goalkeeper. We tested whether the skill level of 6 goalkeepers correlated with a number of biomechanical tests. The skill level of each goalkeeper was defined as the league he played in. The biomechanical tests were...

  11. Developmental biomechanics of the cervical spine: Tension and compression.

    Nuckley, David J; Ching, Randal P

    2006-01-01

    Epidemiological data and clinical indicia reveal devastating consequences associated with pediatric neck injuries. Unfortunately, neither injury prevention nor clinical management strategies will be able to effectively reduce these injuries or their effects on children, without an understanding of the cervical spine developmental biomechanics. Thus, we investigated the relationship between spinal development and the functional (stiffness) and failure biomechanical characteristics of the cervical spine in a baboon model. A correlation study design was used to define the relationships between spinal tissue maturation and spinal biomechanics in both tension and compression. Eighteen baboon cervical spine specimens distributed across the developmental spectrum (1-26 human equivalent years) were dissected into osteoligamentous functional spinal units. Using a servo-hydraulic MTS, these specimens (Oc-C2, C3-C4, C5-C6, C7-T1) were non-destructively tested in tension and compression and then displaced to failure in tension while measuring the six-axes of loads and displacements. The functions describing the developmental biomechanical response of the cervical spine for stiffness and normalized stiffness exhibited a significant direct relationship in both tension and compression loading. Similarly, the tensile failure load and normalized failure load demonstrated significant maturational increases. Further, differences in biomechanical response were observed between the spinal levels examined and all levels exhibited clinically relevant failure patterns. These data support our understanding of the child cervical spine from a developmental biomechanics perspective and facilitate the development of injury prevention or management schema for the mitigation of child spine injuries and their deleterious effects.

  12. Parameters that effect spine biomechanics following cervical disc replacement.

    Goel, Vijay K; Faizan, Ahmad; Palepu, Vivek; Bhattacharya, Sanghita

    2012-06-01

    Total disc replacement (TDR) is expected to provide a more physiologic alternative to fusion. However, long-term clinical data proving the efficacy of the implants is lacking. Limited clinical data suggest somewhat of a disagreement between the in vitro biomechanical studies and in vivo assessments. This conceptual paper presents the potential biomechanical challenges affecting the TDR that should be addressed with a hope to improve the clinical outcomes and our understanding of the devices. Appropriate literature and our own research findings comparing the biomechanics of different disc designs are presented to highlight the need for additional investigations. The biomechanical effects of various surgical procedures are analyzed, reiterating the importance of parameters like preserving uncinate processes, disc placement and its orientation within the cervical spine. Moreover, the need for a 360° dynamic system for disc recipients who may experience whiplash injuries is explored. Probabilistic studies as performed already in the lumbar spine may explore high risk combinations of different parameters and explain the differences between "standard" biomechanical investigations and clinical studies. Development of a patient specific optimized finite element model that takes muscle forces into consideration may help resolve the discrepancies between biomechanics of TDR and the clinical studies. Factors affecting long-term performance such as bone remodeling, subsidence, and wear are elaborated. In vivo assessment of segmental spine motion has been, and continues to be, a challenge. In general, clinical studies while reporting the data have placed lesser emphasis on kinematics following intervertebral disc replacements. Evaluation of in vivo kinematics following TDR to analyze the quality and quantity of motion using stereoradiogrammetric technique may be needed.

  13. Study on diagnosis of micro-biomechanical structure using optical coherence tomography

    Saeki, Souichi; Hashimoto, Youhei; Saito, Takashi; Hiro, Takafumi; Matsuzaki, Masunori

    2007-02-01

    Acute coronary syndromes, e.g. myocardial infarctions, are caused by the rupture of unstable plaques on coronary arteries. The stability of plaque, which depends on biomechanical properties of fibrous cap, should be diagnosed crucially. Recently, Optical Coherence Tomography (OCT) has been developed as a cross-sectional imaging method of microstructural biological tissue with high resolution 1~10 μm. Multi-functional OCT system has been promising, e.g. an estimator of biomechanical characteristics. It has been, however, difficult to estimate biomechanical characteristics, because OCT images have just speckle patterns by back-scattering light from tissue. In this study, presented is Optical Coherence Straingraphy (OCS) on the basis of OCT system, which can diagnose tissue strain distribution. This is basically composed of Recursive Cross-correlation technique (RC), which can provide a displacement vector distribution with high resolution. Furthermore, Adjacent Cross-correlation Multiplication (ACM) is introduced as a speckle noise reduction method. Multiplying adjacent correlation maps can eliminate anomalies from speckle noise, and then can enhance S/N in the determination of maximum correlation coefficient. Error propagation also can be further prevented by introducing to the recursive algorithm (RC). In addition, the spatial vector interpolation by local least square method is introduced to remove erroneous vectors and smooth the vector distribution. This was numerically applied to compressed elastic heterogeneous tissue samples to carry out the accuracy verifications. Consequently, it was quantitatively confirmed that its accuracy of displacement vectors and strain matrix components could be enhanced, comparing with the conventional method. Therefore, the proposed method was validated by the identification of different elastic objects with having nearly high resolution for that defined by optical system.

  14. Quadriceps tendon allografts as an alternative to Achilles tendon allografts: a biomechanical comparison.

    Mabe, Isaac; Hunter, Shawn

    2014-12-01

    Quadriceps tendon with a patellar bone block may be a viable alternative to Achilles tendon for anterior cruciate ligament reconstruction (ACL-R) if it is, at a minimum, a biomechanically equivalent graft. The objective of this study was to directly compare the biomechanical properties of quadriceps tendon and Achilles tendon allografts. Quadriceps and Achilles tendon pairs from nine research-consented donors were tested. All specimens were processed to reduce bioburden and terminally sterilized by gamma irradiation. Specimens were subjected to a three phase uniaxial tension test performed in a custom environmental chamber to maintain the specimens at a physiologic temperature (37 ± 2 °C) and misted with a 0.9 % NaCl solution. There were no statistical differences in seven of eight structural and mechanical between the two tendon types. Quadriceps tendons exhibited a significantly higher displacement at maximum load and significantly lower stiffness than Achilles tendons. The results of this study indicated a biomechanical equivalence of aseptically processed, terminally sterilized quadriceps tendon grafts with bone block to Achilles tendon grafts with bone block. The significantly higher displacement at maximum load, and lower stiffness observed for quadriceps tendons may be related to the failure mode. Achilles tendons had a higher bone avulsion rate than quadriceps tendons (86 % compared to 12 %, respectively). This was likely due to observed differences in bone block density between the two tendon types. This research supports the use of quadriceps tendon allografts in lieu of Achilles tendon allografts for ACL-R.

  15. Nail abnormalities in rheumatoid arthritis.

    Michel, C; Cribier, B; Sibilia, J; Kuntz, J L; Grosshans, E

    1997-12-01

    Many nail abnormalities have traditionally been described in association with rheumatoid arthritis (RA), but their specificity has never been assessed in a controlled study. Our purpose was to evaluate the frequency and the specificity of nail changes associated with RA in a case-controlled study including 50 patients suffering from RA and 50 controls. For each patient, a general skin examination was performed and the 20 nails were examined. The nail features were noted and classified. A chi 2 test or a Fisher test was used to compare the two groups. The only nail abnormalities significantly associated with RA were longitudinal ridging on nine or 10 finger nails (29 patients in the RA group vs. three in the controls, chi 2: P nail (24 patients vs. 10, chi 2: P nail changes were noticed but were not frequent enough to be significant. The presence of longitudinal ridging on the finger nails was significantly associated with RA.

  16. Neuroendocrine abnormalities in Parkinson's disease.

    De Pablo-Fernández, Eduardo; Breen, David P; Bouloux, Pierre M; Barker, Roger A; Foltynie, Thomas; Warner, Thomas T

    2017-02-01

    Neuroendocrine abnormalities are common in Parkinson's disease (PD) and include disruption of melatonin secretion, disturbances of glucose, insulin resistance and bone metabolism, and body weight changes. They have been associated with multiple non-motor symptoms in PD and have important clinical consequences, including therapeutics. Some of the underlying mechanisms have been implicated in the pathogenesis of PD and represent promising targets for the development of disease biomarkers and neuroprotective therapies. In this systems-based review, we describe clinically relevant neuroendocrine abnormalities in Parkinson's disease to highlight their role in overall phenotype. We discuss pathophysiological mechanisms, clinical implications, and pharmacological and non-pharmacological interventions based on the current evidence. We also review recent advances in the field, focusing on the potential targets for development of neuroprotective drugs in Parkinson's disease and suggest future areas for research.

  17. Biomechanical factors associated with shoe/pedal interfaces. Implications for injury.

    Gregor, R J; Wheeler, J B

    1994-02-01

    The principal demand on the body during cycling is on the lower extremities as they are responsible for producing a majority of the energy imparted to the bike. As a result the legs, due to high reactive forces between the foot and pedal, experience high loads on the joints. These loads may adversely affect joint tissues and contribute to overuse injuries, e.g. knee pain. The mechanical link between the leg and the bike is the shoe/pedal interface. This transmission site, by design, can either create smooth transfer of energy or abnormally high repetitive loads which are potentially injurious to the body. Incidence of lower extremity injury in cycling is high, and historically biomechanical analyses of this activity have focused their attention on either the rider or the bike, but not the link between the two. Recently, pedal designs have changed in response to complaints of sore knees with the development of pedals allowing varying degrees of float. This form of transmission is intended to enhance power transfer from rider to bike as well as minimise trauma to the legs by permitting the foot to rotate during the pedalling cycle in a toe-in/heel-out or heel-in/toe-out movement pattern. Recent evidence suggests this type of pedal design does reduce trauma and maintains power output. This article reviews common lower extremity overuse injuries and biomechanical factors during the pedalling cycle with the primary focus on the shoe/pedal interface. We will summarise information available on lower extremity kinematics and kinetics as well as recent data specifically related to shoe/pedal interface kinetics, evaluation of different pedal types-specifically comparison between clipless 'fixed' and clipless 'float' systems-and discuss their resultant effect on lower extremity dynamics and their implications for injury.

  18. Quantification of collagen ultrastructure after penetrating keratoplasty - implications for corneal biomechanics.

    Craig Boote

    Full Text Available PURPOSE: To quantify long-term changes in stromal collagen ultrastructure following penetrating keratoplasty (PK, and evaluate their possible implications for corneal biomechanics. METHODS: A pair of 16 mm post-mortem corneo-scleral buttons was obtained from a patient receiving bilateral penetrating keratoplasty 12 (left/28 (right years previously. Small-angle x-ray scattering quantified collagen fibril spacing, diameter and spatial order at 0.5 mm or 0.25 mm intervals along linear scans across the graft margin. Corresponding control data was collected from two corneo-scleral buttons with no history of refractive surgery. Wide-angle x-ray scattering quantified collagen fibril orientation at 0.25 mm (horizontal×0.25 mm (vertical intervals across both PK specimens. Quantification of orientation changes in the graft margin were verified by equivalent analysis of data from a 13 year post-operative right PK specimen obtained from a second patient in a previous study, and comparison made with new and published data from normal corneas. RESULTS: Marked changes to normal fibril alignment, in favour of tangentially oriented collagen, were observed around the entire graft margin in all PK specimens. The total number of meridional fibrils in the wound margin was observed to decrease by up to 40%, with the number of tangentially oriented fibrils increasing by up to 46%. As a result, in some locations the number of fibrils aligned parallel to the wound outnumbered those spanning it by up to five times. Localised increases in fibril spacing and diameter, with an accompanying reduction in matrix order, were also evident. CONCLUSIONS: Abnormal collagen fibril size and spatial order within the PK graft margin are indicative of incomplete stromal wound remodelling and the long term persistence of fibrotic scar tissue. Lasting changes in collagen fibril orientation in and around PK wounds may alter corneal biomechanics and compromise the integrity of the graft

  19. Forward lunge knee biomechanics before and after partial meniscectomy

    Hall, Michelle; Nielsen, Jonas Høberg; Holsgaard-Larsen, Anders

    2015-01-01

    partial meniscectomy (APM) on knee joint mechanics. The purpose of this study was to evaluate changes in knee joint biomechanics during a forward lunge in patients with a suspected degenerative meniscal tear from before to three months after APM. METHODS: Twenty-two patients (35-55years old......) with a suspected degenerative medial meniscal tear participated in this study. Three dimensional knee biomechanics were assessed on the injured and contralateral leg before and three months after APM. The visual analogue scale was used to assess knee pain and the Knee Injury Osteoarthritis Outcome Score was used...

  20. The modern biomechanics technology in practice of preparedness athletes.

    Akhmetov R.F.

    2011-01-01

    Full Text Available The generalized information about directions of application of biomechanics technologies in modern sport is resulted. Some aspects of the use of biomechanics ergogenical tools of the moved delayed action in the system of preparation of athletes-jumpers are considered. Presents the possibility of using training complex «easy leading» for perfection of structure of motive actions of sportsmen, specialized in high jumps. The introduction of a vast arsenal of technical tools in practice the training process open new prospects associated with increased efficiency in the preparation of athletes.

  1. Biomechanical Response and Behavior of Users under Emergency Buffer Crash

    R. Miralbes

    2013-01-01

    Full Text Available This paper aims to study the biomechanical effects on elevator users and the injuries sustained should an elevator crash happen. The analysis will focus on buffer impact, signaling that the earlier mentioned buffer is usually located at the bottom of the pit. In order to carry out this analysis, a numerical technique based on finite element method will be used, while elevator users will be simulated by means of automotive dummies. Two crash factors will be studied, namely, location of dummy and fall velocity. The analysis criteria will be damages sustained by the dummy, based on biomechanical index such as HIC, CSI, forces, and accelerations.

  2. Biomechanics of metastatic disease in the vertebral column.

    Whyne, Cari M

    2014-06-01

    Metastatic disease in the vertebral column compromises the structural stability of the spine leading to increased risk of fracture. The complex patterns of osteolytic and osteoblastic disease within the bony spine have motivated a multimodal approach to better characterize the biomechanics of tumor-involved bone. This review presents our current understanding of the biomechanical behavior of metastatically involved vertebrae, and experimental and computational image-based approaches that have been employed to quantify structural integrity in preclinical models with translation to clinical data sets.

  3. Radiological appearances of sinonasal abnormalities

    El-Beltagi, A.H.; Sobeih, A.A.; Valvoda, M.; Dahniya, M.H.; Badr, S.S

    2002-08-01

    The aim of this pictorial review is to present a variety of abnormalities of the sinonasal cavities to emphasize the diversity of lesions occurring in this region. These include congenital, neoplastic and granulomatous disorders and some allergic and inflammatory lesions with uncommon radiological appearances, as well as expanding lesions of the facial bones or of dental origin with secondary involvement of the related sinus(es). El-Beltagi, A.H. et al. (2002). Clinical Radiology 57, 702-718.

  4. Computed tomography of thymic abnormalities

    Schnyder, P.; Candardjis, G.

    1987-05-01

    Computed tomographic examinations of 38 patients with surgically and histologically proven diagnosis were reviewed. Twenty subjects (52%) had an invasive thymoma and 16% an hyperplastic thymus. Myasthenia gravis was present in 6 cases (16%) of thymic abnormalities, four (10,5%) with invasive thymoma and two (5%) with thymic hyperplasia. Graves' disease was also present in one case of thymic hyperplasia. We emphasize the contribution of CT to the diagnosis and the prognosis.

  5. Meiotic abnormalities in infertile males.

    Egozcue, J; Sarrate, Z; Codina-Pascual, M; Egozcue, S; Oliver-Bonet, M; Blanco, J; Navarro, J; Benet, J; Vidal, F

    2005-01-01

    Meiotic anomalies, as reviewed here, are synaptic chromosome abnormalities, limited to germ cells that cannot be detected through the study of the karyotype. Although the importance of synaptic errors has been underestimated for many years, their presence is related to many cases of human male infertility. Synaptic anomalies can be studied by immunostaining of synaptonemal complexes (SCs), but in this case their frequency is probably underestimated due to the phenomenon of synaptic adjustment. They can also be studied in classic meiotic preparations, which, from a clinical point of view, is still the best approach, especially if multiplex fluorescence in situ hybridization is at hand to solve difficult cases. Sperm chromosome FISH studies also provide indirect evidence of their presence. Synaptic anomalies can affect the rate of recombination of all bivalents, produce achiasmate small univalents, partially achiasmate medium-sized or large bivalents, or affect all bivalents in the cell. The frequency is variable, interindividually and intraindividually. The baseline incidence of synaptic anomalies is 6-8%, which may be increased to 17.6% in males with a severe oligozoospermia, and to 27% in normozoospermic males with one or more previous IVF failures. The clinical consequences are the production of abnormal spermatozoa that will produce a higher number of chromosomally abnormal embryos. The indications for a meiotic study in testicular biopsy are provided.

  6. [Biomechanical test study of rat femurs growing under different stress environment].

    Liu, Yingxi; Zhao, Wenzhi; Zhang, Jun; Li, Shouju; Li, Jingnian; Sun, Xiaojiang

    2005-06-01

    By creating two kinds of stress environment in the same animal model, we performed a three-point bending test and a compressing test on the rat femurs growing under different stress conditions to characterize the effect of stress on bone mechanical properties. The right hindlimbs were subjected to sciatic nerve resection to become cripple and were used as unloading group; the left hindlimbs bore excess load and made up the overloading group; the normal rats were used as control group. The animals were encouraged to exercise for half an hour everyday in the morning, noon and evening. The experiment observation finished in four weeks. The biomechanical parameters of femur diaphyses were measured. The experiment results showed that stress environment may change several mechanical parameters of rat femurs. This study indicated that bone tissues can adapt to its stress environment by changing its mechanical properties. The experimental model in this article is practical and reliable.

  7. Sensory and biomechanical responses to distension of the renal pelvis in kidney stone patients

    Pedersen, Katja Venborg; Liao, Donghua; Osther, Susanne Sloth;

    pressure in the renal pelvis corresponded positively to the sensory ratings but the referred pain area was diffuse located and varied in size. The present study provides a method for describing the mechanosensory properties and 3D deformation of the complex renal pelvis geometry. Although...... there was a relation between pressure and pain score, the non-homogenous spatial strain distribution suggests that the 3D biomechanical properties of the renal pelvis are not reflected by simple estimates of tension based on pressure and volume....... for first sensation and for pain. 3D deformation and strain were calculated in five patients. The deformation of pelvis during distension was not uniform due to the complex geometry. The pelvis deformed to 113 ± 6% and 115 ± 11% in the longitudinal and circumferential directions, respectively. Endoluminal...

  8. Rabbit Achilles tendon full transection model – wound healing, adhesion formation and biomechanics at 3, 6 and 12 weeks post-surgery

    Meier Bürgisser, Gabriella; Calcagni, Maurizio; Bachmann, Elias; Fessel, Gion; Snedeker, Jess G.; Giovanoli, Pietro

    2016-01-01

    ABSTRACT After tendon rupture repair, two main problems may occur: re-rupture and adhesion formation. Suitable non-murine animal models are needed to study the healing tendon in terms of biomechanical properties and extent of adhesion formation. In this study 24 New Zealand White rabbits received a full transection of the Achilles tendon 2 cm above the calcaneus, sutured with a 4-strand Becker suture. Post-surgical analysis was performed at 3, 6 and 12 weeks. In the 6-week group, animals received a cast either in a 180 deg stretched position during 6 weeks (adhesion provoking immobilization), or were re-casted with a 150 deg position after 3 weeks (adhesion inhibiting immobilization), while in the other groups (3 and 12 weeks) a 180 deg position cast was applied for 3 weeks. Adhesion extent was analyzed by histology and ultrasound. Histopathological scoring was performed according to a method by Stoll et al. (2011), and the main biomechanical properties were assessed. Histopathological scores increased as a function of time, but did not reach values of healthy tendons after 12 weeks (only around 15 out of 20 points). Adhesion provoking immobilization led to an adhesion extent of 82.7±9.7%, while adhesion inhibiting immobilization led to 31.9±9.8% after 6 weeks. Biomechanical properties increased over time, however, they did not reach full strength nor elastic modulus at 12 weeks post-operation. Furthermore, the rabbit Achilles tendon model can be modulated in terms of adhesion formation to the surrounding tissue. It clearly shows the different healing stages in terms of histopathology and offers a suitable model regarding biomechanics because it exhibits similar biomechanics as the human flexor tendons of the hand. PMID:27635037

  9. Failure modes and materials design for biomechanical layer structures

    Deng, Yan

    Ceramic materials are finding increasing usage in the area of biomechanical replacements---dental crowns, hip and bone implants, etc.---where strength, wear resistance, biocompatibility, chemical durability and even aesthetics are critical issues. Aesthetic ceramic crowns have been widely used in dentistry to replace damaged or missing teeth. However, the failure rates of ceramic crowns, especially all-ceramic crowns, can be 1%˜6% per year, which is not satisfactory to patients. The materials limitations and underlying fracture mechanisms of these prostheses are not well understood. In this thesis, fundamental fracture and damage mechanisms in model dental bilayer and trilayer structures are studied. Principle failure modes are identified from in situ experimentation and confirmed by fracture mechanics analysis. In bilayer structures of ceramic/polycarbonate (representative of ceramic crown/dentin structure), three major damage sources are identified: (i) top-surface cone cracks or (ii) quasiplasticity, dominating in thick ceramic bilayers; (iii) bottom-surface radial cracks, dominating in thin ceramic bilayers. Critical load P for each damage mode are measured in six dental ceramics: Y-TZP zirconia, glass-infiltrated zirconia and alumina (InCeram), glass-ceramic (Empress II), Porcelain (Mark II and Empress) bonded to polymer substrates, as a function of ceramic thickness d in the range of 100 mum to 10 mm. P is found independent of d for mode (i) and (ii), but has a d 2 relations for mode (iii)---bottom surface radial cracking. In trilayer structures of glass/core-ceramic/polycarbonate (representing veneer porcelain/core/dentin structures), three inner fracture origins are identified: radial cracks from the bottom surface in the (i) first and (ii) second layers; and (iii) quasiplasticity in core-ceramic layer. The role of relative veneer/core thickness, d1/d 2 and materials properties is investigated for three core materials with different modulus (114--270GPa

  10. BIOMECHANICAL REMODELING OF BIODEGRADABLE SMALL-DIAMETER VASCULAR GRAFTS IN SITU

    T. V. Glushkova

    2016-01-01

    Full Text Available Aim: to evaluate the biomechanical remodeling of polymer grafts modified with vascular endothelial growth factor (VEGF after implantation into rat abdominal aorta.Materials and methods. Vascular grafts of2 mmdiameter were fabricated by electrospinning from polycaprolactone (PCL and a mixture of poly (3-hydroxybutyrate-co-3-hydroxyvalerate and PCL. The grafts were modified with VEGF by biphasic electrospinning. Morphology of the grafts was assessed by scanning electron microscopy. Physico-mechanical properties of PCL and PHBV/PCL grafts were estimated using uniaxial tensile test and physiological circulating system equipped with state-of-theart ultrasound vascular wall tracking system. Physico-mechanical testing of PCL/VEGF and PHBV/PCL/VEGF was performed before and after implantation into rat abdominal aorta for 6 months. The modeling of coronary artery bypass grafting (CABG was performed by finite element analysis for modified grafts.Results. Durability of PCL and PHBV/PCL grafts did not differ from that of human internal mammary artery; however, elasticity and stiffness of these grafts were higher compared to internal mammary artery. Viscoelastic properties of the grafts were comparable to those of native blood vessels. Modification of the grafts with VEGF reduced material stiffness. Six months postimplantation, PCL/VEGF and PHBV/PCL/VEGF were integrated with aortic tissue that induced changes in the physico-mechanical properties of the grafts similar to the native vessel. Biomechanical modeling confirmed the functioning of modified grafts in bypass position for CABG.Conclusion. PCL/VEGF and PHBV/PCL/VEGF grafts have satisfactory physico-mechanical properties and can be potentially used in the reconstruction of blood vessels. 

  11. Computational biomechanics of bone's responses to dental prostheses - osseointegration, remodeling and resorption

    Li, Wei; Rungsiyakull, Chaiy; Field, Clarice; Lin, Daniel; Zhang, Leo; Li, Qing; Swain, Michael

    2010-06-01

    Clinical and experimental studies showed that human bone has the ability to remodel itself to better adapt to its biomechanical environment by changing both its material properties and geometry. As a consequence of the rapid development and extensive applications of major dental restorations such as implantation and fixed partial denture (FPD), the effect of bone remodeling on the success of a dental restorative surgery is becoming critical for prosthetic design and pre-surgical assessment. This paper aims to provide a computational biomechanics framework to address dental bone's responses as a result of dental restoration. It explored three important issues of resorption, apposition and osseointegration in terms of remodeling simulation. The published remodeling data in long bones were regulated to drive the computational remodeling prediction for the dental bones by correlating the results to clinical data. It is anticipated that the study will provide a more predictive model of dental bone response and help develop a new design methodology for patient-specific dental prosthetic restoration.

  12. Biomechanical testing of a polymer-based biomaterial for the restoration of spinal stability after nucleotomy

    Kaps Christian

    2009-07-01

    Full Text Available Abstract Background Surgery for disc herniations can be complicated by two major problems: painful degeneration of the spinal segment and re-herniation. Therefore, we examined an absorbable poly-glycolic acid (PGA biomaterial, which was lyophilized with hyaluronic acid (HA, for its utility to (a re-establish spinal stability and to (b seal annulus fibrosus defects. The biomechanical properties range of motion (ROM, neutral zone (NZ and a potential annulus sealing capacity were investigated. Methods Seven bovine, lumbar spinal units were tested in vitro for ROM and NZ in three consecutive stages: (a intact, (b following nucleotomy and (c after insertion of a PGA/HA nucleus-implant. For biomechanical testing, spinal units were mounted on a loading-simulator for spines. In three cycles, axial loading was applied in an excentric mode with 0.5 Nm steps until an applied moment of ± 7.5 Nm was achieved in flexion/extension. ROM and NZ were assessed. These tests were performed without and with annulus sealing by sewing a PGA/HA annulus-implant into the annulus defect. Results Spinal stability was significantly impaired after nucleotomy (p Conclusion PGA/HA biomaterial seems to be well suited for cell-free and cell-based regenerative treatment strategies in spinal surgery. Its abilities to restore spinal stability and potentially close annulus defects open up new vistas for regenerative approaches to treat intervertebral disc degeneration and for preventing implant herniation.

  13. Corneal biomechanical data and biometric parameters measured with Scheimpflug-based devices on normal corneas

    Nemeth, Gabor; Szalai, Eszter; Hassan, Ziad; Lipecz, Agnes; Flasko, Zsuzsa; Modis, Laszlo

    2017-01-01

    AIM To analyze the correlations between ocular biomechanical and biometric data of the eye, measured by Scheimpflug-based devices on healthy subjects. METHODS Three consecutive measurements were carried out using the corneal visualization Scheimpflug technology (CorVis ST) device on healthy eyes and the 10 device-specific parameters were recorded. Pentacam HR-derived parameters (corneal curvature radii on the anterior and posterior surfaces; apical pachymetry; corneal volume; corneal aberration data; depth, volume and angle of the anterior chamber) and axial length (AL) from IOLMaster were correlated with the 10 specific CorVis ST parameters. RESULTS Measurements were conducted in 43 eyes of 43 volunteers (age 61.24±15.72y). The 10 specific CorVis ST data showed significant relationships with corneal curvature radii both on the anterior and posterior surface, pachymetric data, root mean square (RMS) data of lower-order aberrations, and posterior RMS of higher-order aberrations and spherical aberration of the posterior cornea. Anterior chamber depth showed a significant relationship, but there were no significant correlations between corneal volume, anterior chamber volume, mean chamber angle or AL and the 10 specific CorVis ST parameters. CONCLUSIONS CorVis ST-generated parameters are influenced by corneal curvature radii, some corneal RMS data, but corneal volume, anterior chamber volume, chamber angle and AL have no correlation with the biomechanical parameters. The parameters measured by CorVis ST seem to refer mostly to corneal properties of the eye. PMID:28251079

  14. Histopathological and biomechanical evaluation of tenocyte seeded allografts on rat Achilles tendon regeneration.

    Güngörmüş, Cansın; Kolankaya, Dürdane; Aydin, Erkin

    2015-05-01

    Tendon injuries in humans as well as in animals' veterinary medicine are problematic because tendon has poor regenerative capacity and complete regeneration of the ruptured tendon is never achieved. In the last decade there has been an increasing need of treatment methods with different approaches. The aim of the current study was to improve the regeneration process of rat Achilles tendon with tenocyte seeded decellularized tendon matrices. For this purpose, Achilles tendons were harvested, decellularized and seeded as a mixture of three consecutive passages of tenocytes at a density of 1 × 10(6) cells/ml. Specifically, cells with different passage numbers were compared with respect to growth characteristics, cellular senescence and collagen/tenocyte marker production before seeding process. The viability of reseeded tendon constructs was followed postoperatively up to 6 months in rat Achilles tendon by histopathological and biomechanical analysis. Our results suggests that tenocyte seeded decellularized tendon matrix can significantly improve the histological and biomechanical properties of tendon repair tissue without causing adverse immune reactions. To the best of our knowledge, this is the first long-term study in the literature which was accomplished to prove the use of decellularized matrix in a clinically relevant model of rat Achilles tendon and the method suggested herein might have important implications for translation into the clinic.

  15. Biomechanical analyses of prosthetic mesh repair in a hiatal hernia model.

    Alizai, Patrick Hamid; Schmid, Sofie; Otto, Jens; Klink, Christian Daniel; Roeth, Anjali; Nolting, Jochen; Neumann, Ulf Peter; Klinge, Uwe

    2014-10-01

    Recurrence rate of hiatal hernia can be reduced with prosthetic mesh repair; however, type and shape of the mesh are still a matter of controversy. The purpose of this study was to investigate the biomechanical properties of four conventional meshes: pure polypropylene mesh (PP-P), polypropylene/poliglecaprone mesh (PP-U), polyvinylidenefluoride/polypropylene mesh (PVDF-I), and pure polyvinylidenefluoride mesh (PVDF-S). Meshes were tested either in warp direction (parallel to production direction) or perpendicular to the warp direction. A Zwick testing machine was used to measure elasticity and effective porosity of the textile probes. Stretching of the meshes in warp direction required forces that were up to 85-fold higher than the same elongation in perpendicular direction. Stretch stress led to loss of effective porosity in most meshes, except for PVDF-S. Biomechanical impact of the mesh was additionally evaluated in a hiatal hernia model. The different meshes were used either as rectangular patches or as circular meshes. Circular meshes led to a significant reinforcement of the hiatus, largely unaffected by the orientation of the warp fibers. In contrast, rectangular meshes provided a significant reinforcement only when warp fibers ran perpendicular to the crura. Anisotropic elasticity of prosthetic meshes should therefore be considered in hiatal closure with rectangular patches.

  16. A biomechanical research of growth control of spine by shape memory alloy staples.

    Zhang, Wei; Zhang, Yonggang; Zheng, Guoquan; Zhang, Ruyi; Wang, Yan

    2013-01-01

    Shape memory alloy (SMA) staples in nickel titanium with shape memory effect are effective for spinal growth control. This study was designed to evaluate the biomechanical properties of the staples and observe the stability of the fixed segments spine after the staples were implanted. According to the vertical distance of the vertebrae, SMA staples of 5, 6.5, and 8 mm were designed. The recovery stress of 24 SMA staples in three groups was measured. The pullout strength of SMA staples and stainless steel staples in each functional spinal unit was measured. Each of the six fresh specimens was divided into three conditions: normal, single staple, and double staples. Under each condition, the angle and torque of spinal movements in six directions were tested. Results show that the differences in recovery stress and maximum pullout strength between groups were statistically significant. In left and right bending, flextion, and extention, the stability of spine was decreased in conditions of single staple and double staples. Biomechanical function of SMA staples was superior to stainless steel staple. SMA staples have the function of hemiepiphyseal compression and kyphosis and scoliosis model of thoracic vertebrae in goat could be successfully created by the fusionless technique.

  17. Biomechanical comparison of four different miniscrew types for skeletal anchorage in the mandibulo-maxillary area.

    Mischkowski, R A; Kneuertz, P; Florvaag, B; Lazar, F; Koebke, J; Zöller, J E

    2008-10-01

    This study compared four miniscrew types for skeletal anchorage (Aarhus, FAMI, Dual Top and Spider) regarding their biomechanical properties contributing to primary stability. Insertion torque measurements and pull-out tests in axial (0 degrees ) as well as in the 20 degrees and 40 degrees direction were performed. Stiffness of the screw-bone construct was calculated from the load-displacement curve. Conic FAMI and Dual Top screws had higher insertion torques. Insertion torques were raised by drill-free insertion of FAMI and Dual Top screws. Statistically significant differences were found between the 4 screw types in pull-out tests. The highly significant differences between the four screws for peak load in the axial (0 degrees ) and 20 degrees direction were not apparent in 40 degrees angular loads. For the conical screws, peak load values increased in angular compared with axial load. The Dual Top screw achieved the highest values for peak load and stiffness. 12 Dual Top and 1 Spider screw heads fractured in the pull-out tests. A conical drill-free screw design achieves higher primary stability compared with cylindrical self-tapping screws. This effect was more obvious in insertion torque estimations rather than in pull-out tests. The Dual Top screws, although biomechanically superior to other screw types, were most prone to fractures.

  18. Cancellous Screws Are Biomechanically Superior to Cortical Screws in Metaphyseal Bone.

    Wang, Tim; Boone, Christopher; Behn, Anthony W; Ledesma, Justin B; Bishop, Julius A

    2016-09-01

    Cancellous screws are designed to optimize fixation in metaphyseal bone environments; however, certain clinical situations may require the substitution of cortical screws for use in cancellous bone, such as anatomic constraints, fragment size, or available instrumentation. This study compares the biomechanical properties of commercially available cortical and cancellous screw designs in a synthetic model representing various bone densities. Commercially available, fully threaded, 4.0-mm outer-diameter cortical and cancellous screws were tested in terms of pullout strength and maximum insertion torque in standard-density and osteoporotic cancellous bone models. Pullout strength and maximum insertion torque were both found to be greater for cancellous screws than cortical screws in all synthetic densities tested. The magnitude of difference in pullout strength between cortical and cancellous screws increased with decreasing synthetic bone density. Screw displacement prior to failure and total energy absorbed during pullout strength testing were also significantly greater for cancellous screws in osteoporotic models. Stiffness was greater for cancellous screws in standard and osteoporotic models. Cancellous screws have biomechanical advantages over cortical screws when used in metaphyseal bone, implying the ability to both achieve greater compression and resist displacement at the screw-plate interface. Surgeons should preferentially use cancellous over cortical screws in metaphyseal environments where cortical bone is insufficient for fixation. [Orthopedics.2016; 39(5):e828-e832.].

  19. Quantitative modelling of the biomechanics of the avian syrinx

    Elemans, C.P.H.; Larsen, O.N.; Hoffmann, M.R.; Leeuwen, van J.L.

    2003-01-01

    We review current quantitative models of the biomechanics of bird sound production. A quantitative model of the vocal apparatus was proposed by Fletcher (1988). He represented the syrinx (i.e. the portions of the trachea and bronchi with labia and membranes) as a single membrane. This membrane acts

  20. Early Specialization in Youth Sport: A Biomechanical Perspective

    Mattson, Jeffrey M.; Richards, Jim

    2010-01-01

    This article examines, from a biomechanical perspective, three issues related to early specialization: overuse injuries, the developmental aspects, and the performance aspects. It concludes that "there is no evidence that early specialization causes overuse injuries or hinders growth and maturation." At the same time, early specialization has…

  1. Lower Extremity Biomechanical Demands During Saut de Chat Leaps.

    Jarvis, Danielle N; Kulig, Kornelia

    2016-12-01

    In dance, high demands are placed on the lower extremity joints during jumping tasks. The purpose of this study was to compare biomechanical demands placed on the lower extremity joints during the takeoff and landing phases of saut de chat leaps.

  2. Pathobiology of obesity and osteoarthritis: integrating biomechanics and inflammation

    Rita I. Issa

    2012-05-01

    Full Text Available Obesity is a significant risk factor for developing osteoarthritis in weight-bearing and non-weight-bearing joints. Although the pathogenesis of obesity-associated osteoarthritis is not completely understood, recent studies indicate that pro-inflammatory metabolic factors contribute to an increase in osteoarthritis risk. Adipose tissue, and in particular infrapatellar fat, is a local source of pro-inflammatory mediators that are increased with obesity and have been shown to increase cartilage degradation in cell and tissue culture models. One adipokine in particular, leptin, may be a critical mediator of obesity-associated osteoarthritis via synergistic actions with other inflammatory cytokines. Biomechanical factors may also increase the risk of osteoarthritis by activating cellular inflammation and promoting oxidative stress. However, some types of biomechanical stimulation, such as physiologic cyclic loading, inhibit inflammation and protect against cartilage degradation. A high percentage of obese individuals with knee osteoarthritis are sedentary, suggesting that a lack of physical activity may increase the susceptibility to inflammation. A more comprehensive approach to understanding how obesity alters daily biomechanical exposures within joint tissues may provide new insight into the protective and damaging effects of biomechanical factors on inflammation in osteoarthritis.

  3. Changing step width alters lower extremity biomechanics during running.

    Brindle, Richard A; Milner, Clare E; Zhang, Songning; Fitzhugh, Eugene C

    2014-01-01

    Step width is a spatiotemporal parameter that may influence lower extremity biomechanics at the hip and knee joint. The purpose of this study was to determine the biomechanical response of the lower extremity joints to step width changes during running. Lower extremity data from 30 healthy runners, half of them male, were collected during running in three step width conditions: preferred, wide, and narrow. Dependent variables and step width were analyzed using a mixed model ANOVA and pairwise t-tests for post hoc comparisons. Step width was successfully altered in the wide and narrow conditions. Generally, frontal plane peak values decreased as step width increased from narrow to preferred to wide. Peak hip adduction and rearfoot eversion angles decreased as step width increased from narrow to wide. Peak knee abduction moment and knee abduction impulse also decreased as step width increased from narrow to wide. Although men and women ran differently, gender only influenced the effect of step width on peak rearfoot inversion moment. In conclusion, step width influences lower extremity biomechanics in healthy runners. When step width increased from narrow to wide, peak values of frontal plane variables decreased. In addition to previously reported changes at the rearfoot, the hip and knee joint biomechanics were also influenced by changes in step width.

  4. How to Assess the Biomechanical Risk Levels in Beekeeping.

    Maina, G; Rossi, F; Baracco, A

    2016-01-01

    Beekeepers are at particular risk of developing work-related musculoskeletal disorders, but many of the studies lack detailed exposure assessment. To evaluate the biomechanical overload exposure in a specific farming activity, a multitasking model has been developed through the characterization of 37 basic operational tasks typical of the beekeeping activity. The Occupational Repetitive Actions (OCRA) Checklist and the National Institute for Occupational Safety and Health (NIOSH) Lifting Index methodologies have been applied to these elementary tasks to evaluate the exposure, and the resulting risk indices have been time-weighted averaged. Finally, an easy access, computer-assisted toolkit has been developed to help the beekeepers in the biomechanical risk assessment process. The risk of biomechanical overload for the upper limbs ranges from acceptable (maintenance and recovery of woody material and honey packaging with dosing machine tasks) to high (distribution of the top supers) risk level. The risk for back injury is always borderline in women and increases with exposure time, whereas it ranges from acceptable to borderline in men. The definition of the biomechanical risk levels allows for planning of corrective actions aimed at preventing and reducing the risk of musculoskeletal disorders through engineering, administrative, and behavioral interventions. The methodology can be used for risk assessment in other mainly manual agricultural activities.

  5. Quantitative modelling of the biomechanics of the avian syrinx

    Elemans, Coen P. H.; Larsen, Ole Næsbye; Hoffmann, Marc R.

    2003-01-01

    We review current quantitative models of the biomechanics of bird sound production. A quantitative model of the vocal apparatus was proposed by Fletcher (1988). He represented the syrinx (i.e. the portions of the trachea and bronchi with labia and membranes) as a single membrane. This membrane acts...

  6. Focusing on the Hard parts: A Biomechanics Laboratory Exercise

    Fingerut, Jonathan; Orbe, Kristina; Flynn, Daniel; Habdas, Piotr

    2013-01-01

    As part of a biomechanics course aimed at both upper-division Biology and Physics majors, this laboratory exercise introduces students to the ingenious ways in which organisms vary the composition and form of support and defensive structures such as bone and shell to maximize their strength while minimizing the energetic cost needed to produce…

  7. Using Clinical Gait Case Studies to Enhance Learning in Biomechanics

    Chester, Victoria

    2011-01-01

    Clinical case studies facilitate the development of clinical reasoning strategies through knowledge and integration of the basic sciences. Case studies have been shown to be more effective in developing problem-solving abilities than the traditional lecture format. To enhance the learning experiences of students in biomechanics, clinical case…

  8. Biomechanics Curriculum: Its Content and Relevance to Movement Sciences

    Hamill, Joseph

    2007-01-01

    While the National Association for Sport and Physical Education (NASPE) has outlined a number of learning outcomes for undergraduate biomechanics, there are a number of factors that can influence the curriculum in such courses. These factors create a situation that indeed can influence students and their attitude towards these classes.…

  9. LUMBAR SPINAL STENOSIS. A REVIEW OF BIOMECHANICAL STUDIES

    戴力扬; 徐印坎

    1998-01-01

    ObjectS. To investigate the biomechanical aspects of etiology, pathology, clinical manifestation, diagnosis and surgical treatment of the lumbar spinal stenosis. Methods. A series of biomechanical methods, such as three-dimensional finite element models, threedimensional kinematic measurement, cadeveric evaluation, and imaging assessment was applied to correlate lumbar biomechanics and lumber spinal stenosls. Surgery of lumber spinal stenosis has been improved. Results.The stresses significantly concentrate on the posterolateral part of the annulus fibrcsms of disc, the posterior surface of vertebral body, the pedlcle, the interarticularis and the beet joints. This trend is intensified by disc degeneration and lumber backward extension. Posterior elcxnent resection has a definite effect upon the biomechanical behavior of lumbar vertebrae. The improved operations proved satisfactory. Conclusion. Stress concentration in the lumber vertebrae is of importance to the etiology of degenerative lumbar spinal stenosls, and disc degeneratkm is the initial key of this process. Than these will be aggravatnd by backward extension. Functloval radiography and myelography are of assistance to the diagnosis of the lumhar spinal stenosls. For the surgcal treatment of the lumber spinal stenosis, destruction of the posterior element should be avoid as far as possible based upon the thorough decmnpression. Maintaining the lumbar spine in flexion by fusion after decorapression has been proved a useftd method. When developmental spinal stenoals is combined with disc herniation, discectoray through laminotomy is recommend for decompression.

  10. Biomechanics research in ski jumping, 1991-2006.

    Schwameder, Hermann

    2008-01-01

    In this paper, I review biomechanics research in ski jumping with a specific focus on publications presented between 1991 and 2006 on performance enhancement, limiting factors of the take-off, specific training and conditioning, aerodynamics, and safety. The first section presents a brief description of ski jumping phases (in-run, take-off, early flight, stable flight, and landing) regarding the biomechanical and functional fundamentals. The most important and frequently used biomechanical methods in ski jumping (kinematics, ground reaction force analyses, muscle activation patterns, aerodynamics) are summarized in the second section. The third section focuses on ski jumping articles and research findings published after the establishment of the V-technique in 1991, as the introduction of this technique has had a major influence on performance enhancement, ski jumping regulations, and the construction of hill profiles. The final section proposes topics for future research in the biomechanics of ski jumping, including: take-off and early flight and the relative roles of vertical velocity and forward somersaulting angular momentum; optimal jumping patterns utilizing the capabilities of individual athletes; development of kinematic and kinetic feedback systems for hill jumps; comparisons of simulated and hill jumps; effect of equipment modifications on performance and safety enhancement.

  11. Biomechanics of the elbow joint in tennis players.

    Eygendaal, D.; Rahussen, F.T.; Diercks, R.L.

    2007-01-01

    Elbow injuries constitute a sizeable percentage of tennis injuries. A basic understanding of biomechanics of tennis and analysis of forces, loads and motions of the elbow during tennis can will improve the understanding of the pathophysiology of these injuries. All different strokes in tennis have a

  12. Biomechanical and Clinical Studies in EndoVascular Aortic Repair

    Nauta, FJH

    2016-01-01

    Objectives This thesis investigates biomechanical and clinical performances of endovascular repair for thoracic aortic dissection (AD) and aneurysm. Insights from both medical and bio-engineering perspectives are pursued with the aim of providing scientific data that will help guide endovascular aor

  13. Applied Biomechanics Research for the United States Ski Team.

    Dillman, Charles J.

    1982-01-01

    Assisted by a team of physicians and sports scientists, the United States Ski Team has developed its own sports medicine program, the purpose of which is to assist coaches and athletes in controlling and optimizing factors which influence skiing performance. A number of biomechanical research projects which have been undertaken as part of this…

  14. Qualitative Biomechanics and the Tennis Ground Strokes. Revised

    Errington, Joseph

    This tennis stroke analysis, based on the application of biomechanic principles, is designed to help those who play tennis only once or twice a week. It is noted that, because the tennis player has a limited power potential, the only way to increase his racket head speed is to rotate his body. The mechanics of tennis are discussed by dividing it…

  15. Use of deterministic models in sports and exercise biomechanics research.

    Chow, John W; Knudson, Duane V

    2011-09-01

    A deterministic model is a modeling paradigm that determines the relationships between a movement outcome measure and the biomechanical factors that produce such a measure. This review provides an overview of the use of deterministic models in biomechanics research, a historical summary of this research, and an analysis of the advantages and disadvantages of using deterministic models. The deterministic model approach has been utilized in technique analysis over the last three decades, especially in swimming, athletics field events, and gymnastics. In addition to their applications in sports and exercise biomechanics, deterministic models have been applied successfully in research on selected motor skills. The advantage of the deterministic model approach is that it helps to avoid selecting performance or injury variables arbitrarily and to provide the necessary theoretical basis for examining the relative importance of various factors that influence the outcome of a movement task. Several disadvantages of deterministic models, such as the use of subjective measures for the performance outcome, were discussed. It is recommended that exercise and sports biomechanics scholars should consider using deterministic models to help identify meaningful dependent variables in their studies.

  16. Biomechanics of sport concussion: quest for the elusive injury threshold.

    Guskiewicz, Kevin M; Mihalik, Jason P

    2011-01-01

    Previous concussion biomechanics research has relied heavily on the animal model or laboratory reconstruction of concussive injuries captured on video footage. Real-time data collection involves a novel approach to better understanding the medical issues related to sport concussion. Recent studies suggest that a concussive injury threshold is elusive and may, in fact, be irrelevant when predicting the clinical outcome.

  17. A highly versatile autonomous underwater vehicle with biomechanical propulsion

    Simons, D.G.; Bergers, M.M.C.; Henrion, S.; Hulzenga, J.I.J.; Jutte, R.W.; Pas, W.M.G.; Van Schravendijk, M.; Vercruyssen, T.G.A.; Wilken, A.P.

    2009-01-01

    An autonomous underwater vehicle with a biomechanical propulsion system is a possible answer to the demand for small, silent sensor platforms in many fields. The design of Galatea, a bio-mimetic AUV, involves four aspects: hydrodynamic shape, the propulsion, the motion control systems and payload. T

  18. Future of crash dummies and biomechanical mathematical models

    Wismans, J.S.H.M.

    2000-01-01

    Thorough knowledge of the characteristics of the human body and its behaviour under extreme loading conditions is essential in order to prevent the serious consequences of road and other accidents. This field of research is called injury or impact biomechanics. In order to study the human body respo

  19. The biomechanical and physiological effect of two dynamic workstations

    Botter, J.; Burford, E.M.; Commissaris, D.; Könemann, R.; Mastrigt, S.H.V.; Ellegast, R.P.

    2013-01-01

    The aim of this research paper was to investigate the effect, both biomechanically and physiologically, of two dynamic workstations currently available on the commercial market. The dynamic workstations tested, namely the Treadmill Desk by LifeSpan and the LifeBalance Station by RightAngle, were com

  20. Computational Biomechanics of Human Red Blood Cells in Hematological Disorders.

    Li, Xuejin; Li, He; Chang, Hung-Yu; Lykotrafitis, George; Em Karniadakis, George

    2017-02-01

    We review recent advances in multiscale modeling of the biomechanical characteristics of red blood cells (RBCs) in hematological diseases, and their relevance to the structure and dynamics of defective RBCs. We highlight examples of successful simulations of blood disorders including malaria and other hereditary disorders, such as sickle-cell anemia, spherocytosis, and elliptocytosis.

  1. Low-set ears and pinna abnormalities

    Low-set ears; Microtia; "Lop" ear; Pinna abnormalities; Genetic defect-pinna; Congenital defect-pinna ... conditions: Abnormal folds or location of the pinna Low-set ears No opening to the ear canal ...

  2. Energetics, Biomechanics, and Performance in Masters' Swimmers: A Systematic Review.

    Ferreira, Maria I; Barbosa, Tiago M; Costa, Mário J; Neiva, Henrique P; Marinho, Daniel A

    2016-07-01

    Ferreira, MI, Barbosa, TM, Costa, MJ, Neiva, HP, and Marinho, DA. Energetics, biomechanics, and performance in masters' swimmers: a systematic review. J Strength Cond Res 30(7): 2069-2081, 2016-This study aimed to summarize evidence on masters' swimmers energetics, biomechanics, and performance gathered in selected studies. An expanded search was conducted on 6 databases, conference proceedings, and department files. Fifteen studies were selected for further analysis. A qualitative evaluation of the studies based on the Quality Index (QI) was performed by 2 independent reviewers. The studies were thereafter classified into 3 domains according to the reported data: performance (10 studies), energetics (4 studies), and biomechanics (6 studies). The selected 15 articles included in this review presented low QI scores (mean score, 10.47 points). The biomechanics domain obtained higher QI (11.5 points), followed by energetics and performance (10.6 and 9.9 points, respectively). Stroke frequency (SF) and stroke length (SL) were both influenced by aging, although SF is more affected than SL. Propelling efficiency (ηp) decreased with age. Swimming performance declined with age. The performance declines with age having male swimmers deliver better performances than female counterparts, although this difference tends to be narrow in long-distance events. One single longitudinal study is found in the literature reporting the changes in performance over time. The remaining studies are cross-sectional designs focusing on the energetics and biomechanics. Overall, biomechanics parameters, such as SF, SL, and ηp, tend to decrease with age. This review shows the lack of a solid body of knowledge (reflected in the amount and quality of the articles published) on the changes in biomechanics, energetics, and performance of master swimmers over time. The training programs for this age-group should aim to preserve the energetics as much as possible and, concurrently, improve the

  3. Non-invasive MRI Assessments of Tissue Microstructures and Macromolecules in the Eye upon Biomechanical or Biochemical Modulation.

    Ho, Leon C; Sigal, Ian A; Jan, Ning-Jiun; Yang, Xiaoling; van der Merwe, Yolandi; Yu, Yu; Chau, Ying; Leung, Christopher K; Conner, Ian P; Jin, Tao; Wu, Ed X; Kim, Seong-Gi; Wollstein, Gadi; Schuman, Joel S; Chan, Kevin C

    2016-08-26

    The microstructural organization and composition of the corneoscleral shell (CSS) determine the biomechanical behavior of the eye, and are important in diseases such as glaucoma and myopia. However, limited techniques can assess these properties globally, non-invasively and quantitatively. In this study, we hypothesized that multi-modal magnetic resonance imaging (MRI) can reveal the effects of biomechanical or biochemical modulation on CSS. Upon intraocular pressure (IOP) elevation, CSS appeared hyperintense in both freshly prepared ovine eyes and living rat eyes using T2-weighted MRI. Quantitatively, transverse relaxation time (T2) of CSS increased non-linearly with IOP at 0-40 mmHg and remained longer than unloaded tissues after being unpressurized. IOP loading also increased fractional anisotropy of CSS in diffusion tensor MRI without apparent change in magnetization transfer MRI, suggestive of straightening of microstructural fibers without modification of macromolecular contents. Lastly, treatments with increasing glyceraldehyde (mimicking crosslinking conditions) and chondroitinase-ABC concentrations (mimicking glycosaminoglycan depletion) decreased diffusivities and increased magnetization transfer in cornea, whereas glyceraldehyde also increased magnetization transfer in sclera. In summary, we demonstrated the changing profiles of MRI contrast mechanisms resulting from biomechanical or biochemical modulation of the eye non-invasively. Multi-modal MRI may help evaluate the pathophysiological mechanisms in CSS and the efficacy of corneoscleral treatments.

  4. State-of-the-art research in lower-limb prosthetic biomechanics-socket interface: a review.

    Mak, A F; Zhang, M; Boone, D A

    2001-01-01

    Scientific studies have been conducted to quantify attributes that may be important in the creation of more functional and comfortable lower-limb prostheses. The prosthesis socket, a human-machine interface, has to be designed properly to achieve satisfactory load transmission, stability, and efficient control for mobility. The biomechanical understanding of the interaction between prosthetic socket and the residual limb is fundamental to such goals. The purpose of this paper is to review the recent research literature on socket biomechanics, including socket pressure measurement, friction-related phenomena and associated properties, computational modeling, and limb tissue responses to external mechanical loads and other physical conditions at the interface. There is no doubt that improved biomechanical understanding has advanced the science of socket fitting. However, the most recent advances in the understanding of stresses experienced at the residual limb have not yet led to enough clinical consensus that could fundamentally alter clinical practice. Efforts should be made to systematically identify the major discrepancies. Further research should be directed to address the critical controversies and the associated technical challenges. Developments should be guided to offer clinicians the quantification and visualization of the interaction between the residual limb and the prosthetic socket. An understanding of comfort and optimal load transfer as patterns of socket interface stress could culminate in socket design expert systems.

  5. [Phenomenology of abnormal body perceptions].

    Schäfer, M L

    1983-01-01

    The present paper deals with the problematic nature of the phenomenological grasping of the consciousness of the body and its pathological modifications. The reasoning is oriented by the doctrine of Husserl of the so-called sentiments as the fundamentals of the experience of the own body. This basic approach does not only seem to be basically for a psychology of the consciousness of the body, but also to give the theoretical-conceptual structure for a great number of psychopathological modifications. Subsequent to a criticism of the conventional use of the term 'hallucination of the body' we attempt to chart elements of a scheme of the abnormal consciousness of the body.

  6. On Regularity of Abnormal Subriemannian Geodesics

    Tan, Kanghai

    2012-01-01

    We prove the smoothness of abnormal minimizers of subriemannian manifolds of step 3 with a nilpotent basis. We prove that rank 2 Carnot groups of step 4 admit no strictly abnormal minimizers. For any subriemannian manifolds of step less than 7, we show all abnormal minimizers have no corner type singularities, which partly generalize the main result of Leonardi-Monti.

  7. Chromosomal phenotypes and submicroscopic abnormalities

    Devriendt Koen

    2004-01-01

    Full Text Available Abstract The finding, during the last decade, that several common, clinically delineated syndromes are caused by submicroscopic deletions or, more rarely, by duplications, has provided a powerful tool in the annotation of the human genome. Since most microdeletion/microduplication syndromes are defined by a common deleted/duplicated region, abnormal dosage of genes located within these regions can explain the phenotypic similarities among individuals with a specific syndrome. As such, they provide a unique resource towards the genetic dissection of complex phenotypes such as congenital heart defects, mental and growth retardation and abnormal behaviour. In addition, the study of phenotypic differences in individuals with the same microdeletion syndrome may also become a treasury for the identification of modifying factors for complex phenotypes. The molecular analysis of these chromosomal anomalies has led to a growing understanding of their mechanisms of origin. Novel tools to uncover additional submicroscopic chromosomal anomalies at a higher resolution and higher speed, as well as the novel tools at hand for deciphering the modifying factors and epistatic interactors, are 'on the doorstep' and will, besides their obvious diagnostic role, play a pivotal role in the genetic dissection of complex phenotypes.

  8. Abnormal visuomotor processing in schizophrenia

    Siân E. Robson

    2016-01-01

    Full Text Available Subtle disturbances of visual and motor function are known features of schizophrenia and can greatly impact quality of life; however, few studies investigate these abnormalities using simple visuomotor stimuli. In healthy people, electrophysiological data show that beta band oscillations in sensorimotor cortex decrease during movement execution (event-related beta desynchronisation (ERBD, then increase above baseline for a short time after the movement (post-movement beta rebound (PMBR; whilst in visual cortex, gamma oscillations are increased throughout stimulus presentation. In this study, we used a self-paced visuomotor paradigm and magnetoencephalography (MEG to contrast these responses in patients with schizophrenia and control volunteers. We found significant reductions in the peak-to-peak change in amplitude from ERBD to PMBR in schizophrenia compared with controls. This effect was strongest in patients who made fewer movements, whereas beta was not modulated by movement in controls. There was no significant difference in the amplitude of visual gamma between patients and controls. These data demonstrate that clear abnormalities in basic sensorimotor processing in schizophrenia can be observed using a very simple MEG paradigm.

  9. Long memory of abnormal investor attention and the cross-correlations between abnormal investor attention and trading volume, volatility respectively

    Fan, Xiaoqian; Yuan, Ying; Zhuang, Xintian; Jin, Xiu

    2017-03-01

    Taking Baidu Index as a proxy for abnormal investor attention (AIA), the long memory property in the AIA of Shanghai Stock Exchange (SSE) 50 Index component stocks was empirically investigated using detrended fluctuation analysis (DFA) method. The results show that abnormal investor attention is power-law correlated with Hurst exponents between 0.64 and 0.98. Furthermore, the cross-correlations between abnormal investor attention and trading volume, volatility respectively are studied using detrended cross-correlation analysis (DCCA) and the DCCA cross-correlation coefficient (ρDCCA). The results suggest that there are positive correlations between AIA and trading volume, volatility respectively. In addition, the correlations for trading volume are in general higher than the ones for volatility. By carrying on rescaled range analysis (R/S) and rolling windows analysis, we find that the results mentioned above are effective and significant.

  10. Inverse problems biomechanical imaging (Conference Presentation)

    Oberai, Assad A.

    2016-03-01

    It is now well recognized that a host of imaging modalities (a list that includes Ultrasound, MRI, Optical Coherence Tomography, and optical microscopy) can be used to "watch" tissue as it deforms in response to an internal or external excitation. The result is a detailed map of the deformation field in the interior of the tissue. This deformation field can be used in conjunction with a material mechanical response to determine the spatial distribution of material properties of the tissue by solving an inverse problem. Images of material properties thus obtained can be used to quantify the health of the tissue. Recently, they have been used to detect, diagnose and monitor cancerous lesions, detect vulnerable plaque in arteries, diagnose liver cirrhosis, and possibly detect the onset of Alzheimer's disease. In this talk I will describe the mathematical and computational aspects of solving this class of inverse problems, and their applications in biology and medicine. In particular, I will discuss the well-posedness of these problems and quantify the amount of displacement data necessary to obtain a unique property distribution. I will describe an efficient algorithm for solving the resulting inverse problem. I will also describe some recent developments based on Bayesian inference in estimating the variance in the estimates of material properties. I will conclude with the applications of these techniques in diagnosing breast cancer and in characterizing the mechanical properties of cells with sub-cellular resolution.

  11. 后路单钉棒治疗骶髂关节脱位的生物力学特性及其有效性%Biomechanical properties and the effectiveness of posterior nail-rod for the treatment of sacroiliac joint dislocation

    和利; 贾健; 梁彦; 葛振新; 马宝通

    2012-01-01

    BACKGROUND: Sacroiliac screw has been widely used in the treatment of the sacroiliac joint dislocation, but it cannot achieve strong mechanical intensity due to its poor biomechanical properties. OBJECTIVE: To explore the mechanical intensity and clinical efficacy of posterior nail-rod for the treatment of sacroiliac joint dislocation. METHODS: ㏕welve cadaveric pelvis specimens, six males and six females, were selected to make the sacroiliac joint dislocation model and pubic symphysis separation model by cutting off the sacroiliac joint ligaments and pubic symphysis structure. Specimens were randomly divided into two groups: iliosacral screw fixation group and pelvis posterior single nail-rod fixation group, specimens in the two groups were fixed with iliosacral screw and pelvis posterior single nail-rod respectively. ㏕he clinical indications of ingle nail-rod system were set up, and the clinical data of 16 sacroiliac joint dislocation patients were collected, Mears image evaluation standard and pelvic fractures Majeed curative effect were used to assess data statistics and score. RESULTS AND CONCLUSION: In the same load, the displacement, axial stiffness, ultimate-load and yield-load of the posterior single nail-rod group were larger than those of iliosacral screw group (P < 0.05). All the 16 patients were followed-up for an average of 23.2 months (3-45 months). According to Mears image standard, there were 13 cases of anatomical replacement, and 3 cases in satisfaction. Pelvic fractures Majeed score was 60 to 100 points, 82 points in average; the good rate of Ci type fracture was 82%, and good rate of C2 type fracture was 80%. Compared with iliosacral screw fixation, the single nail-rod fixation for the treatment of sacroiliac joint dislocation has reliable strength stiffness and clinical curative effect.%背景:目前骶髂螺钉广泛应用于治疗骶髂关节脱位,但是生物力学性能较差,不能达到坚强内固定.目的:探讨应用单钉棒治

  12. The Use of Fiber Bragg Grating Sensors in Biomechanics and Rehabilitation Applications: The State-of-the-Art and Ongoing Research Topics

    Faisal Rafiq Mahamd Adikan

    2012-09-01

    Full Text Available In recent years, fiber Bragg gratings (FBGs are becoming increasingly attractive for sensing applications in biomechanics and rehabilitation engineering due to their advantageous properties like small size, light weight, biocompatibility, chemical inertness, multiplexing capability and immunity to electromagnetic interference (EMI. They also offer a high-performance alternative to conventional technologies, either for measuring a variety of physical parameters or for performing high-sensitivity biochemical analysis. FBG-based sensors demonstrated their feasibility for specific sensing applications in aeronautic, automotive, civil engineering structure monitoring and undersea oil exploration; however, their use in the field of biomechanics and rehabilitation applications is very recent and its practicality for full-scale implementation has not yet been fully established. They could be used for detecting strain in bones, pressure mapping in orthopaedic joints, stresses in intervertebral discs, chest wall deformation, pressure distribution in Human Machine Interfaces (HMIs, forces induced by tendons and ligaments, angles between body segments during gait, and many others in dental biomechanics. This article aims to provide a comprehensive overview of all the possible applications of FBG sensing technology in biomechanics and rehabilitation and the status of ongoing researches up-to-date all over the world, demonstrating the FBG advances over other existing technologies.

  13. Abnormal Returns and Contrarian Strategies

    Ivana Dall'Agnol

    2003-12-01

    Full Text Available We test the hypothesis that strategies which are long on portfolios of looser stocks and short on portfolios of winner stocks generate abnormal returns in Brazil. This type of evidence for the US stock market was interpreted by The Bondt and Thaler (1985 as reflecting systematic evaluation mistakes caused by investors overreaction to news related to the firm performance. We found evidence of contrarian strategies profitability for horizons from 3 months to 3 years in a sample of stock returns from BOVESPA and SOMA from 1986 to 2000. The strategies are more profitable for shorter horizons. Therefore, there was no trace of the momentum effect found by Jagadeesh and Titman (1993 for the same horizons with US data. There are remaing unexplained positive returns for contrarian strategies after accounting for risk, size, and liquidity. We also found that the strategy profitability is reduced after the Real Plan, which suggests that the Brazilian stock market became more efficient after inflation stabilization.

  14. History of spine biomechanics: part I--the pre-Greco-Roman, Greco-Roman, and medieval roots of spine biomechanics.

    Naderi, Sait; Andalkar, Niteen; Benzel, Edward C

    2007-02-01

    The roots of spine biomechanics reside in the Antiquity and the Medieval and Renaissance periods. A review of historical treatises reveals detailed information regarding this often historically neglected discipline. Ancient medical, philosophical, and physical documents were reviewed, as they pertained to the historical foundation of spine biomechanics. These included medical case reports and observations of nature and motion by ancient philosophers and scientists. These documents heavily influenced the portion of the scientific literature that we now regard as "spine biomechanics" up through the Renaissance. The focus of Part I of this two-part series is placed on the ancient and medieval biomechanics-related literature and on associated literature that influenced the development of the field of modern spine biomechanics.

  15. Modeling Analysis of Biomechanical Changes of Middle Ear and Cochlea in Otitis Media

    Gan, Rong Z.; Zhang, Xiangming; Guan, Xiying

    2011-11-01

    A comprehensive finite element (FE) model of the human ear including the ear canal, middle ear, and spiral cochlea was developed using histological sections of human temporal bone. The cochlea was modeled with three chambers separated by the basilar membrane and Reissner's membrane and filled with perilymphatic fluid. The viscoelastic material behavior was applied to middle ear soft tissues based on dynamic measurements of tissues in our lab. The model was validated using the experimental data obtained in human temporal bones and then used to simulate various stages of otitis media (OM) including the changes of morphology, mechanical properties, pressure, and fluid level in the middle ear. Function alterations of the middle ear and cochlea in OM were derived from the model and compared with the measurements from temporal bones. This study indicates that OM can be simulated in the FE model to predict the hearing loss induced by biomechanical changes of the middle ear and cochlea.

  16. Quantification of Subjective Scaling of Friction Using a Fingertip Biomechanical Model

    Mohammad Abdolvahab

    2012-01-01

    Full Text Available Subjective scaling of friction is important in many applications in haptic technology. A nonhomogeneous biomechanical finite element model of fingertip is proposed in order to predict neural response of sensitive mechanoreceptors to frictional stimuli (Slowly Adapting SAII receptors under the glabrous skin. In a guided psychophysical experiment, ten human subjects were asked to scale several standard surfaces based on the perception of their frictional properties. Contact forces deployed during the exploratory time of one of the participants were captured in order to estimate required parameters for the model of contact in the simulation procedure. Consequently, the strain energy density at the location of a selective mechanoreceptor in the finite element model as a measure of discharge rate of the neural unit was compared to the subject’s perceptual evaluation of the relevant stimuli. It was observed that the subject’s scores correlate with the discharge rate of the given receptor.

  17. Biomechanical performance of locked intramedullary nail systems in comminuted femoral shaft fractures.

    Johnson, K D; Tencer, A F; Blumenthal, S; August, A; Johnston, D W

    1986-05-01

    The biomechanical properties of commercially available locked nail systems designed for use in comminuted femoral shaft fractures were compared and evaluated. Ender nails as well as three forms of interlocking nails, Brooker-Wills (B-W), Klenm-Schellman (K-S), and Grosse-Kempf (G-K), were implanted in cadaver femora. The femora were tested in torsion, bending, and axial loading to failure. Two fracture models were tested--a 3 cm subtrochanteric defect and an 8 cm midshaft defect. Results of the testing revealed the three interlocking nails to be comparable to each other and superior to Ender nails in bending and torsion. However, the distally bolted locked nails (K-S, G-K) resisted significantly higher loads than either the distally bladed locked nail (B-W) or Ender nails when tested to failure by axial loading.

  18. Review of fiber-optic pressure sensors for biomedical and biomechanical applications

    Roriz, Paulo; Frazão, Orlando; Lobo-Ribeiro, António B.; Santos, José L.; Simões, José A.

    2013-05-01

    As optical fibers revolutionize the way data is carried in telecommunications, the same is happening in the world of sensing. Fiber-optic sensors (FOS) rely on the principle of changing the properties of light that propagate in the fiber due to the effect of a specific physical or chemical parameter. We demonstrate the potentialities of this sensing concept to assess pressure in biomedical and biomechanical applications. FOSs are introduced after an overview of conventional sensors that are being used in the field. Pointing out their limitations, particularly as minimally invasive sensors, is also the starting point to argue FOSs are an alternative or a substitution technology. Even so, this technology will be more or less effective depending on the efforts to present more affordable turnkey solutions and peer-reviewed papers reporting in vivo experiments and clinical trials.

  19. Iliotibial band syndrome: soft tissue and biomechanical factors in evaluation and treatment.

    Baker, Robert L; Souza, Richard B; Fredericson, Michael

    2011-06-01

    Muscle performance factors and altered loading mechanics have been linked to a variety of lower extremity musculoskeletal disorders. In this article, biomechanical risk factors associated with iliotibial band syndrome (ITBS) are described, and a strategy for incorporating these factors into the clinical evaluation of and treatment for that disorder is presented. Abnormal movement patterns in runners and cyclists with ITBS are discussed, and the pathophysiological characteristics of this syndrome are considered in light of prior and current studies in anatomy. Differential diagnoses and the use of imaging, medications, and injections in the treatment of ITBS are reviewed. The roles of hip muscle strength, kinematics, and kinetics are detailed, and the assessment and treatment of muscle performance factors are discussed, with emphasis on identifying and treating movement dysfunction. Various stages of rehabilitation, including strengthening progressions to reduce soft-tissue injury, are described in detail. ITBS is an extremely common orthopedic condition that presents with consistent dysfunctional patterns in muscle performance and movement deviation. Through careful assessment of lower quarter function, the clinician can properly identify individuals and initiate treatment.

  20. Meshless methods in biomechanics bone tissue remodelling analysis

    Belinha, Jorge

    2014-01-01

    This book presents the complete formulation of a new advanced discretization meshless technique: the Natural Neighbour Radial Point Interpolation Method (NNRPIM). In addition, two of the most popular meshless methods, the EFGM and the RPIM, are fully presented. Being a truly meshless method, the major advantages of the NNRPIM over the FEM, and other meshless methods, are the remeshing flexibility and the higher accuracy of the obtained variable field. Using the natural neighbour concept, the NNRPIM permits to determine organically the influence-domain, resembling the cellulae natural behaviour. This innovation permits the analysis of convex boundaries and extremely irregular meshes, which is an advantage in the biomechanical analysis, with no extra computational effort associated.   This volume shows how to extend the NNRPIM to the bone tissue remodelling analysis, expecting to contribute with new numerical tools and strategies in order to permit a more efficient numerical biomechanical analysis.