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Animal Experiment Rabbit To Demonstrate Changes In Trabecular Bone Mechanical Properties Over Time Using Finite Element Analysis
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Book Synopsis Animal Experiment (rabbit) to Demonstrate Changes in Trabecular Bone Mechanical Properties Over Time Using Finite Element Analysis by : Shuo Yang
Download or read book Animal Experiment (rabbit) to Demonstrate Changes in Trabecular Bone Mechanical Properties Over Time Using Finite Element Analysis written by Shuo Yang and published by . This book was released on 2006 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear heterogeneous finite element analysis was used to calculate trabecular bone apparent strength directly from in vivo micro computational tomography (micro-CT) scans. Through a series of validation experiments, it was shown that this nonlinear modeling is more accurate in evaluating trabecular bone mechanics in osteoporosis than previous work. A parameter driven set of material properties was employed in the finite element models using gray levels in the form of Hounsfield units as the independent variable. This enabled the finite element models to capture the variations of material properties of trabecular bone. The methods and techniques for converting the micro-CT scans into finite element models, defining the finite element models (element type, material properties characteristics) and solving the models are discussed in detail. In addition, the techniques developed for image preprocessing, such as image registration and image degradation, are also provided in this dissertation.
Book Synopsis Trabecular Bone Adaptation to Mechanical Loading on the Rabbit Assessed by Micro-computed Tomography and Finite Element Analysis by : Timothy Garrett Morgan
Download or read book Trabecular Bone Adaptation to Mechanical Loading on the Rabbit Assessed by Micro-computed Tomography and Finite Element Analysis written by Timothy Garrett Morgan and published by . This book was released on 2004 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Multi-axial Fatigue of Trabecular Bone with Respect to Normal Walking by : Mohammad Mostakhdemin
Download or read book Multi-axial Fatigue of Trabecular Bone with Respect to Normal Walking written by Mohammad Mostakhdemin and published by Springer. This book was released on 2015-06-10 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the analysis and treatment of osteoporotic bone based on drug administration, tracking fatigue behavior and taking into consideration the mechanical interaction of implants with trabecular bone. Weak trabeculae are one of the most important clinical features that need to be addressed in order to prevent hip joint fractures.
Book Synopsis Validation of an in Vivo Model for Monitoring Trabecular Bone Quality Changes Using Finite Element Analysis by : Boon Horng Kam
Download or read book Validation of an in Vivo Model for Monitoring Trabecular Bone Quality Changes Using Finite Element Analysis written by Boon Horng Kam and published by . This book was released on 2005 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combination of three techniques---high resolution micro computed tomography (micro CT) scanning, Archimedes-based volume fraction measurement and serial sectioning or milling---were used to determine the volume fraction, trabecular thickness, trabecular separation, trabecular number and micro finite element analysis combined with mechanical testing was used to determine the apparent stiffness and tissue modulus to quantify bone quality in rabbit distal femur trabecular bone. The objectives of this dissertation were two-fold. First, to develop the capabilities of micro CT scanning and micro CT image segmentation based on a slice-by-slice global thresholding technique to investigate trabecular microstructural changes in vivo and in vitro; and second, to develop the capability of translating micro CT scans into three dimensional finite element models based on direct voxel conversion technique. These results were validated within the in vivo and in vitro scans at the same time, and validated with the Archimedes-based volume fraction measurements and serial sectioning or milling experiments. The micro FE models were executed as linear analyses and the same bone cubes of the models were mechanically tested (compressive testing) to determine the correct tissue modulus of the bone specimens. The apparent stiffness of these micro FE models was recalculated using the average tissue modulus.
Book Synopsis Animal Models in Orthopaedic Research by : Yuehuei H. An
Download or read book Animal Models in Orthopaedic Research written by Yuehuei H. An and published by CRC Press. This book was released on 2020-04-30 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt: Animal Models in Orthopaedic Research is a reference book of the major animal models used in the study of orthopaedic conditions and in the in vivo study of biomaterials. Use of animal models provides important knowledge about pathological conditions that can eventually lead to the development of more effective clinical treatment of diseases in bot
Author :MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF METALLURGY AND MATERIALS SCIENCE. Publisher : ISBN 13 : Total Pages :43 pages Book Rating :4.:/5 (227 download)
Book Synopsis A Structural Model for the Mechanical Behaviour of Trabecular Bone by : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF METALLURGY AND MATERIALS SCIENCE.
Download or read book A Structural Model for the Mechanical Behaviour of Trabecular Bone written by MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF METALLURGY AND MATERIALS SCIENCE. and published by . This book was released on 1972 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: A quantitative model is developed for trabecular bone by approximating the trabecular geometry with a hypothetical network of compact bone. For the region immediately beneath the articular cartilage in the distal end of the femur, finite element analyses were performed with a high speed computer, assuming a physiological static load. The results indicate that bending and buckling of trabeculae are considerable in any elastic deformation of the bone; that fatigue fracture in some fraction of suitably oriented trabeculae is inevitable in normal ambulation; and that the stiffness varies considerably with lateral position across the subchondral plate. The latter depends totally on trabecular arrangement and may play a role in joint function and degeneration. The adjustments necessary to bring the gross stiffness into agreement with experiment imply that the intertrabecular soft tissues are of no consequence to the mechanical properties and that the compact bone of which trabeculae are made is probably not as stiff as cortical bone. (AUthor).
Book Synopsis Testing and Modeling Mechanical Properties of Ex Vivo Trabecular Bone by :
Download or read book Testing and Modeling Mechanical Properties of Ex Vivo Trabecular Bone written by and published by . This book was released on 2016 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: An osteoporotic fracture occurs approximately every three seconds. Worldwide, this sums to nearly 9 million annual fractures caused by osteoporosis—a systemic, degenerative skeletal disorder that is characterized by low bone mass and increased bone tissue fragility. Although the individual and economic burden of osteoporosis nearly outweighs that of most cancers and many chronic illnesses, the existing methods for treatment are insufficient and many who are at risk remain undiagnosed. To develop improved osteoporosis treatments, prevent osteoporotic fractures, and promote bone health throughout the aging process, it is imperative to understand bone biomechanical behavior and the factors contributing to bone mechanotransduction and adaptation. Consequently, the first objective for the presented research was to characterize the effects and interactions of mechanical stimulus and biochemical signaling activity on the modeling and remodeling response of bovine and human trabecular bone through the use of ex vivo organ culture. The second objective for the research was to simulate the mechanical behavior and dynamic remodeling response of bone tissue through the use of finite element analyses and analytical cell population models. Collectively, the presented research illustrated that bone modeling and remodeling can be affected by the amount and type of applied mechanical stimulus and biochemical exposure. In addition, the research showed that, despite current limitations, simulation and prediction of bone response to applied stimulus is feasible with additional development of existing models.
Book Synopsis Influence Of Bone Volume Fraction On Trabecular Bone Response To Impact Loads by : Filipe Teixeira-Dias
Download or read book Influence Of Bone Volume Fraction On Trabecular Bone Response To Impact Loads written by Filipe Teixeira-Dias and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Disclosures: The last author has recently received research funding from Stryker, which is unrelated to this study. INTRODUCTION: The finite element method is being extensively used to simulate the response of the skeletal system subjected to impact loads such as those due to the occurrence of a sideways fall. Bone behavior and properties under impact loading are not properly understood; these include its dynamic elastic modulus, its strength when subjected to impulsive loads and its post-peak response. Since most simulations (even those representing impact) are conducted using static approaches it is unclear if they represent dynamic response. The aim of this study was to measure and analytically quantify the impact response of trabecular bone using drop tower experiments and numerical simulation. We also developed analytical solutions for verification and comparison. The study also aims to relate the dynamic response of bone to its microstructural parameters, in particular its bone volume fraction (BV/TV). METHODS: Bovine bones were obtained from local butchers which required no ethical approval. Trabecular bone samples (n=31) were extracted by using 10.7 mm inner diameter diamond-coated coring tool (Starlite, Rosemont USA) from femoral heads and greater trochanters. The obtained samples were cut parallel at edges producing cylindrical shape specimens (length 21.87u00b10.31mm) then subjected to micro-CT scans with a resolution of 17.22 u03bcm using Skyscan 1172 (Bruker, Kontich, Belgium) to determine its microstructure. The samples were then dynamically tested under drop test (50 mm release height) with force sensor (ICPu00ae 208C05) attached to the falling 2.5 kg hammer striking specimen along the height to measure the impulsive force history recorded at the impacted surface at 32 kHz sampling frequency. A closed form solution for the elastic response was developed by extending the concept developed by Timoshenko and Goodier (1951) from low impactor-to-sample mass ratio to significantly high representative values for bone impact simulations. Inverse finite element modelling was used to evaluate bone properties and the dynamic response was simulated in LS-DYNA (smp d R7.1.1, LSTC, Livermore, California).RESULTS: Typical impact force histories were measured. It was shown that samples with high BV/TV could be simulated numerically using a elastic model and compared well with closed form solution. Samples with low BV/TV required post-elastic modelling for simulating the peak response. For elastoplastic modelling of Fig. 3, we employed perfect plasticity which captures the peak response well but results in a flatter post-peak response. DISCUSSION: BV/TV is found to have a strong influence on the impact response: the peak response decreases dramatically and the pulse width increases with decrease in BV/TV values. This finding is consistent with the closed form solution for impact on elastic bodies, wherein higher sample stiffness results in higher peak and shorter pulse duration. In static applications apparent density is well-known to have a direct relation to boneu2019s elasticity (e.g. Lotz et al. 1990). The presence of growth plate introduces a weak region. The simulation and analytical results have a jagged pattern which represents the dynamic wave bouncing back and forth, this can only be captured experimentally if an extremely high sampling rate were to be employed. Low density samples (or bigger impact forces) result in samples going into post-elastic regime. Attempt to simulate post-elastic behavior requires not only strength parameters but also post-peak evolutionary behavior. This is important as stresses from regions that are unable to carry any more loads are redistributed. The impact response of samples that fail was found to consistently comprise of an initial peak, followed by a drop to a finite non-zero value in the plastic regime which is maintained for a considerable longer time before it returns to zero. This pattern has not been previously demonstrated. The rising branch of the impact force history was used to obtain the elastic modulus using inverse modelling; the results show that the dynamic elastic modulus is considerably higher than the values estimated from BV/TV in previous studies using static tests (Lotz et al. 1990). SIGNIFICANCE/CLINICAL RELEVANCE: The dynamic properties of bone, both elastic and post-elastic, are strongly dependent on bone volume ratio and these are required for simulating impact response. This study will help in the development of computational methods for identifying individuals at risk of hip fractures. REFERENCES:[1] Timoshenko S, Goodier, JN. 1951. Propagation of waves in elastic solid media. In Theory of Elasticity. McGraw-Hill Book Company. 446-450. [2] Lotz JC, Gerhart TN, Hayes HC. 1990. Mechanical properties of trabecular bone from the proximal femur: a quantitative CT study. J. Comput. Assist. Tomogr. 14, 107-114.ACKNOWLEDGEMENTS: The first author is indebted to the Ministry of Education, Malaysia for the award of PhD sponsorship.
Download or read book สารสนเทศพื้นฐานของจังหวัด written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Trabecular Orientation and Presence of Bone Marrow on the Mechanical Properties of Trabecular of Bone Up to Very Large Strains- Relationships with Strain Rate by : Juan Diego Silva Henao
Download or read book Effect of Trabecular Orientation and Presence of Bone Marrow on the Mechanical Properties of Trabecular of Bone Up to Very Large Strains- Relationships with Strain Rate written by Juan Diego Silva Henao and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Bone finite element models, which are increasingly used to assess fracture risk in patients with degenerative bone diseases, require extensive experimental data to adequately model the material properties being assigned. Previous studies have demonstrated that bone elastic mechanical properties are dependent on density as well as strain rate, however, the effect these same variables on the post-yield behaviour of trabecular bone has not been thoroughly studied. For this study, bovine femoral samples were tested at several strain rates using three different tests devices: a conventional constant strain rate apparatus for low strain rates, a Drop Weight Impact Test device for the intermediate regime and a Split Hopkinson Pressure Bar System with magnesium bar and a PVCA pulse shaper for high strain rates." -- Tomado del Formato de Documento de Grado.
Book Synopsis Characterizing the Association Between Mandible Mechanical Properties and Function in the Rabbit by : Brandon M. White
Download or read book Characterizing the Association Between Mandible Mechanical Properties and Function in the Rabbit written by Brandon M. White and published by . This book was released on 2018 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bony defects, especially those in load-bearing bones, represent a significant clinical problem with current therapeutic options that leave much to be desired. The next generation of synthetic bone graft materials should seek to provide the immediate return of functional ability in addition to enhancing long-term healing. The former can be accomplished by providing the defect with the mechanical support necessary to perform under normal physiological conditions. Currently, there is no method to associate mechanical properties of a bone to its useful function (i.e. chewing, walking, etc.). This study seeks to address this gap by developing an animal model in the rabbit that uses their teeth as a functional assay correlated to the whole bone mechanical properties of the mandible using ex-vivo four-point bending. The results of this study suggest that further development of our rabbit model is merited.
Book Synopsis On the Rate-dependent Constitutive Response of Cortical and Trabecular Bone by : Timothy Paul Mahal Johnson
Download or read book On the Rate-dependent Constitutive Response of Cortical and Trabecular Bone written by Timothy Paul Mahal Johnson and published by . This book was released on 2010 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: The widespread use of improvised explosive devices (IEDs) against American and coalition forces in the ongoing Iraqi and Afghani conflicts has caused a dramatic increase in the number of traumatic brain injury (TBI) cases seen in recent years. The skull acts as the first and primary line of defense for the brain. Researching this structure's protective capabilities and shortcomings is therefore critical to 1) understanding how blunt impact loads and blast waves are propagated through the skull and transmitted into the brain, and 2) improving and evaluating future combat protection systems. This doctoral study is aimed at mechanically characterizing and modeling the two major constituents of the skull: cortical and trabecular bone. The mechanical behavior of these two materials over a wide range of strain rates is identified through both a review of the existing literature data and our own experimental investigations. For the behavior of compact bone two separate viscoelastic rate-sensitivity regimes are identified and modeled with a Maxwell-Weichert model containing one linear elastic and two linear viscoelastic branches in parallel. The rate-dependent plasticity of the material is further shown to obey a simple power law relationship and the overall material behavior is captured in a generalized three-dimensional viscoelastic, viscoplastic constitutive model formulation. For validation, the three-dimensional constitutive model is implemented as a subroutine within a commercial nonlinear finite element program. Given the similar composition of both cortical bone and the solid portion of trabecular bone, the compact bone constitutive model is subsequently employed in modeling the trabeculae of cancellous bone within two complementary microstructural frameworks. The first approach utilized is to create three-dimensional solid bone models of trabecular architecture directly from micro computed tomography (CT) scans of cancellous bone biopsy samples. The original samples from which these micro CT scans were obtained are then tested experimentally and the resulting stress-strain curves are found to show excellent agreement with the micromechanical model predictions. Successful simulation of specimen loading was found to be contingent upon extracting the trabecular structure from micro CT data in such a way that matched the relative density of the resulting specimen mesh to the experimentally recorded value. Analysis of both the experimental and simulation results further demonstrates that 1) local distributions in strut relative density are highly influential in the determining the compressive strength of trabecular bone and 2) the formation of macroscopic, multi-strut shear bands is responsible for the initial plateau and post-yield softening exhibited by trabecular bone in uniaxial compression. 3 The second microstructural approach employed is to model the trabecular network with an idealized representative volume element (RVE) and apply periodic boundary conditions. This latter approach allows for rapid investigation of the effects of relative density and strain rate in determining trabecular bone's mechanical properties. Specifically, Young's modulus is found to vary in a nearly quadratic manner with relative density and compressive strength is shown to have a power law relationship to relative density with an exponent of 1.5. In addition, compressive strength is shown to have a power law dependence upon strain rate with an exponent of 0.055. These relationships and the magnitude of the values predicted are all found to closely match the experimental trends and values reported in the literature.
Book Synopsis Marcus and Feldman's Osteoporosis by : David W. Dempster
Download or read book Marcus and Feldman's Osteoporosis written by David W. Dempster and published by Academic Press. This book was released on 2020-10-08 with total page 1950 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marcus and Feldman's Osteoporosis, Fifth Edition, is the most comprehensive, authoritative reference on this disease. Led by a new editorial team, this fifth edition offers critical information on reproductive and hormonal risk factors, new therapeutics, ethnicity, nutrition, therapeutics, management and economics, comprising a tremendous wealth of knowledge in a single source not found elsewhere. Written by renowned experts in the field, this two-volume reference is a must-have for biomedical researchers, research clinicians, fellows, academic and medical libraries, and any company involved in osteoporosis drug research and development. Summarizes the latest research in bone biology and translational applications in a range of new therapeutic agents, including essential updates on therapeutic uses of calcium, vitamin D, SERMS, bisphosphonates, parathyroid hormone, and new therapeutic agents Recognizes the critical importance of new signaling pathways for bone health, including Wnt, OPG and RANK, of interest to both researchers who study bone biology and clinicians who treat osteoporosis Offers new insights into osteoporosis associated with menopause, pre-menopause, chronic kidney disease, diabetes, HIV and other immune disorders
Book Synopsis Osteoporosis Research by : Gustavo Duque
Download or read book Osteoporosis Research written by Gustavo Duque and published by Springer Science & Business Media. This book was released on 2011-05-23 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: Osteoporosis Research - Animal Models, presents in a very illustrative and practical manner, general methodologies of bone studies in animals, as well as the particular features of the most commonly used animal models in the field. Research in the field of osteoporosis has grown in recent years. This has resulted in significant advances in determining the causes of osteoporosis, assessing risk factors, and creating new treatment methods. The use of animal models provides important knowledge about pathological conditions that can eventually lead to the development of more effective clinical treatment of diseases in both humans and animals. Osteoporosis Research - Animal Models, is an essential tool for researchers in the bone field. This book aids researchers in selecting their appropriate model and highlights the experiments that can be strategically designed to optimize the potential of an animal to develop the cardinal features of osteoporosis in humans. This book addresses the importance of recent findings from animal models and their significance on the pathogenesis of osteoporosis in relation to human disease.
Book Synopsis Effects of Spaceflight- and Clinically-relevant Ionizing Radiation Exposure on Bone Biomechanics by : Megan Marie Pendleton
Download or read book Effects of Spaceflight- and Clinically-relevant Ionizing Radiation Exposure on Bone Biomechanics written by Megan Marie Pendleton and published by . This book was released on 2018 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bones are exposed to in vivo ionizing radiation exposure in applications of spaceflight, clinical radiotherapy, and ex vivo ionizing radiation exposure in applications of allograft sterilization. Elevated fracture risk has been shown after irradiation at the higher clinical doses, and it is uncertain if there are similar risks with exposure to spaceflight irradiation. Irradiation leads to an early loss of cancellous bone tissue and microarchitecture quality, and reduced matrix quality in the form of increased collagen crosslinks, but it is unclear which of these radiation-induced changes contribute to reduced bone mechanics. While the effects of space- and clinically-related levels of radiation on bone strength have been studied for monotonic (one-time) loading, much less is known about the effects for cyclic (repeated) loading, also referred to as fatigue. The possible increase in collagen crosslinks may have a larger effect on fatigue life by possibly impeding fibrillar sliding, reducing plasticity, and increasing the rate of microcrack growth during cyclic loading. Therefore, the goal of this research was to characterize the cyclic and monotonic mechanical properties after irradiation at spaceflight- and clinically-relevant doses, and to better understand the factors influencing the resulting mechanical behavior. To address this, we conducted in vivo and ex vivo irradiation experiments using a murine model with a range of radiation doses, including spaceflight (≤ 2 Gy), clinically-relevant (≤ 50 Gy), and sterilization (≤ 35,000 Gy). To compare irradiated bone to healthy tissue, we performed micro-CT to analyze bone quantity and microarchitecture, biochemical assays to characterize the collagen network and material quality, and cyclic and monotonic compression testing to characterize the mechanical behavior. To conduct cyclic mechanical testing on experimental tissue, we first developed a precise method for ex vivo cyclic compressive loading of isolated mouse vertebral bodies. In small animals, such as in mice and rats, cyclic loading experiments are particularly challenging to perform in a precise manner due to the small size of the bones and difficult-to-eliminate machine compliance. Our method has three main characteristics: 3D-printed support jigs for machining plano-parallel surfaces of the tiny vertebrae; pivotable loading platens to ensure uniform contact and loading of specimen surfaces; and specimen-specific micro-CT-based finite element analysis to measure stiffness to prescribe force levels that produce the same specified level of strain for all test specimens. We found reduced scatter of the mechanical behavior for this new method compared to commonly used methods from literature. We conclude that this new method for cyclic loading of small-animal vertebrae produces highly reproducible measurements of fatigue behavior and an effective tissue elastic modulus, potentially important elements of bone quality. To investigate effects of in vivo irradiation, we conducted whole-body, acute, gamma-radiation experiments on 17-week old (skeletally-mature) C57BL/6J, male mice at space- and clinically-relevant doses (1 and 5 Gy) and collected lumbar vertebrae at 11-days and 12-weeks after exposure. We found with a 5 Gy dose, short-term deficits (i.e. 11-days after exposure) in cancellous microarchitecture (-29.7% Conn.D) that persisted into the long term (i.e. 12-weeks) (-49.5% Conn.D) and led to reduced fatigue life (-15.1% cycles to failure) in the long term. Results were similar for aging alone. In contrast, short-term, irradiation-induced deficits in bone quantity (-22.3% bone volume fraction) and elevated non-enzymatic collagen crosslinks (+85.5% AGEs) did not have a significant impact on monotonic or cyclic mechanics. We conclude that degraded trabecular microarchitecture with radiation (or aging) can lead to profound deficits in cyclic mechanical properties, more so than molecular changes via collagen crosslinks or reduced bone volume fraction. Lastly, to assess the non-cellular effects of irradiation on whole-bone and to determine the type of collagen network degradation which primarily impacts the mechanical properties, we conducted an ex vivo x-ray radiation experiment spanning doses from radiotherapy up to sterilization of bone allografts. Excised mouse lumbar vertebrae from 20-week old, female, C57BL/6J mice were irradiated with doses of 0, 50, 1,000, 17,000, and 35,000 Gy. We found lower collagen molecular weight at 17,000 Gy and above (≥ 74%) compared to the control, indicating collagen backbone fragmentation, which coincided with a loss in monotonic strength (≥ 50%) and cyclic mechanical properties at 17,000 Gy and above. In contrast, AGEs, representing non-enzymatic collagen crosslinks, was greater for all radiation doses (67%, 95%, 96%, and 108% for 50, 1,000, 17,000 and 35,000 Gy, respectively), but did not coincide with a reduction in strength or any other mechanical property for 50 and 1000 Gy. We conclude that mechanical properties of ex vivo irradiation are dominated by the direct effects of irradiation through fragmentation of the collagen backbone, and are negligibly influenced by the indirect effects of non-enzymatic crosslinks. Our findings suggest that to maintain mechanical integrity following exposure to ionizing radiation, bone allograft specimens should be sterilized at a dose below 17,000 Gy. In summary, we have provided the field with a novel and precise methodology for fatigue testing of small animal bone. To our knowledge, this research was the first to conduct fatigue testing after radiation exposure related to spaceflight and clinical radiotherapy. Our in vivo irradiation results highlighted the critical role of bone microarchitecture, compared to bone quantity or collagen crosslinks, in maintaining cyclic mechanical behavior with radiation exposure and aging. Our ex vivo irradiation results clarified primary mechanisms of collagen fragmentation, compared to collagen crosslinks, that led to deficits in monotonic and cyclic mechanics.
Book Synopsis A Novel Method for the Evaluation of Mechanical Properties of Cancellous Bone in the Rat Distal Femur by : Matthew W. Lucas
Download or read book A Novel Method for the Evaluation of Mechanical Properties of Cancellous Bone in the Rat Distal Femur written by Matthew W. Lucas and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanical properties of the cancellous bone in the laboratory rat animal model are of great interest to the research community for the evaluation of treatments for osteoporosis. Cancellous bone responds rapidly and dramatically to disuse, various pathologies, nutritional deficiencies, and hormonal deficiencies and hence is often a primary focus in animal studies. Previous methods for evaluating the mechanical properties of cancellous bone in rat test specimens included both cortical and cancellous bone. This thesis introduces a new method to core cancellous specimens using a diamond wire saw in concert with specially designed fixtures. This method has been termed Isolated Cancellous Coring (ICC). The location and the geometry of the cored specimens were determined based on uCT analysis. The isolated cancellous specimens were subjected to uni-axial compression testing to evaluate the mechanical properties. Furthermore, the new method is evaluated by directly applying it to a study investigating the effects of estrogen replacement therapy in post-menopausal osteoporosis as simulated by the ovariectomized rat model. The results show that the ICC method can be applied to bone specimens with a large range in density and micro-architecture parameters. The compression testing of the isolated cancellous specimens provides a sensitive indicator of the effects of osteoporosis and treatment on the mechanical properties of the cancellous bone in the distal rat femur. Also, the results indicate a possible discordant relationship between bone mineral density and bone strength with respect to estrogen treatment. Power law regressions show that approximately 50% of the variation in ultimate strength can be accounted for with bone mineral density and the percent of bone volume per total volume.
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2004 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:
