检索结果-南通市图书馆

Age- and direction-related adaptations of lumbar vertebral trabecular bone with respect to apparent stiffness and tissue level stress distribution

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第1期25卷 121-129页

作者： He Gong Yubo Fan Ming Zhang Ling Qin Department of Health Technology and Informatics The Hong Kong Polytechnic University Hong Kong China Department of Mechanics Jilin University 130025 Changchun China Department of Bioengineering Beihang University 100083 Beijing China Department of Orthopaedics and Traumatology The Chinese University of Hong Kong Hong Kong China

The objective of this study was to study the age-related adaptation of lumbar vertebral trabecular bone at the apparent level, as well as the tissue level in three orthogonal directions. Ninety trabecular specimens were obtained from six normal L4 vertebral bodies of six male cadavers in two age groups, three aged 62 years and three aged 69 years, and were scanned using a high-resolution micro-computed tomography （micro-CT） system, then converted to micro- finite element models to do micro-finite element analyses. The relationship between apparent stiffness and bone volume fraction, and the tissue level yon Mises stress distribution for each trabecular specimen when compressed separately in the longitudinal direction, medial-lateral and anterior-posterior directions （transverse directions） were derived and compared between two age groups. The results showed that at the apparent level, trabecular bones from 69-year group had stiffer bone structure relative to their volume fractions in all three directions, and in both age groups, changes in bone volume fraction could explain more variations in apparent stiffness in the longitudinal direction than the transverse directions; at the tissue level, aging had little effect on the tissue von Mises stress distributions for the compressions in all the three directions. The novelty of the present study was that it provided quantitative assessments on the age and direction- related adaptation of Chinese male lumbar vertebral trabecular bone from two different levels： stiffness at the apparent level and stress distribution at the tissue level. It may help to understand the failure mechanisms and fracture risks of vertebral body associated with aging and direction for the prevention of fracture risks in elder individuals.

关键词： Vertebral body trabecular bone Micro-finite element analysis Apparent stiffness Tissuevon Mises stress

Numerical simulation on the adaptation of forms in trabecular bone to mechanical disuse and basic multi-cellular unit activation threshold at menopause

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2008年第2期24卷 207-214页

作者： He Gong Yubo Fan Ming Zhang Department of Health Technology and Informatics The Hong Kong Polytechnic University Hong Kong China Department of Bioengineering Beihang UniversityBeijing 100083 China Department of Mechanics Jilin University Changchun 130012 China

The objective of this paper is to identify the effects of mechanical disuse and basic multi-cellular unit （BMU） activation threshold on the form of trabecular bone during menopause. A bone adaptation model with mechanical- biological factors at BMU level was integrated with finite element analysis to simulate the changes of trabecular bone structure during menopause. Mechanical disuse and changes in the BMU activation threshold were applied to the model for the period from 4 years before to 4 years after menopause. The changes in bone volume fraction, trabecular thickness and fractal dimension of the trabecular structures were used to quantify the changes of trabecular bone in three different cases associated with mechanical disuse and BMU activation threshold. It was found that the changes in the simulated bone volume fraction were highly correlated and consistent with clinical data, and that the trabecular thickness reduced signi-ficantly during menopause and was highly linearly correlated with the bone volume fraction, and that the change trend of fractal dimension of the simulated trabecular structure was in correspondence with clinical observations. The numerical simulation in this paper may help to better understand the relationship between the bone morphology and the mecha-nical, as well as biological environment; and can provide a quantitative computational model and methodology for the numerical simulation of the bone structural morphological changes caused by the mechanical environment, and/or the biological environment.

关键词： Disuse Activation trabecular bone Menopause Functional adaptation

Evaluation of damage to trabecular bone of the osteoporotic human acetabulum at small strains using nonlinear micro-finite element analyses

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2009年第17期122卷 2041-2047页

作者： DING Hai ZHU Zhen-an DAI Ke-rong Department of Orthopaedics Ninth People's Hospital ShanghaiJiao Tong University School of Medicine Shanghai 200011 China

Background With advance of age, alterations in bone quality, quantity and microarchitecture render osteoporotic trabecular bone become more sensitive to local failure. The aims of the present study were to clarify the extent to which the distribution of tissue-level stresses and strains was affected by structural changes and the extent to which osteoporotic acetabular trabecular bone was damaged at small strains. Methods Using a DAWING 4000A supercomputer, nonlinear micro-finite element （μFE） analyses were performed to calculate the tissue-level strains and stresses for each element in the trabecular bone of one osteoporotic acetabulum at small strains to quantify the tissue-level damage accumulation and mechanical properties. Results In contour plots of the tissue, maximum principal logarithmic strains, high tissue-level strains, both compressive and tensile, were observed in the osteoporotic trabecular bone at small apparent strains from 0.2% to 0.5% strain. The compressive apparent stress-strain curve showed typical nonlinear behavior and tangent modulus reduction with increasing strains. The microdamage curve suggested that microdamage began at 0.2% apparent strain in the osteoporotic trabecular bone and increased sharply, although very few microfractures occurred. The quartiles of the maximum principal logarithmic strains, minimum principal logarithmic strains and Von Mises stresses increased nonlinearly. For the inter-quartile range of the Von Mises stresses, a leap occurred at small strains ranging from 0.2% to 0.3% while microdamage commenced. Conclusions Extensive microdamage was primarily responsible for the large loss in apparent mechanical properties that occurred in the trabecular bone of the osteoporotic acetabulum at small strains. With increasing apparent strains, continuous nonlinear increments of tissue-level strains and stresses resulted in microdamage that propagated throughout the specimen with very few microfractures. Chin Med J 2009; 122（17）：

关键词： mechanical property trabecular bone nonlinear micro-finite element analysis acetabulum osteoporosis

Research on Damage in trabecular bone of the Healthy Human Acetabulum at Small Strains Using Nonlinear Micro-finite Element Analysis

在线全文

学校读者我要写书评

暂无评论

Journal of Shanghai Jiaotong university(Science) 2008年第5期13卷 623-628页

作者：丁海朱振安戴克戎叶铭王承焘 Department of Orthopaedics Shanghai 9th People's Hospital School of Medicine Institute of Biomedical Manufacturing and Life Quality Engineering School of Mechanical Engineering Shanghai Jiaotong University

The mechanical properties of the pelvic trabecular bone have been studied at the continuum level. However, nothing is known about the tissue-level damage in the trabecular bone of the healthy human acetabulum at apparent small strains characteristic of habitual. By a DAWING 4000 A supercomputer, nonlinear micro-finite element (μFE) analysis was performed to quantify tissue-level damage accumulation in trabecular bone at small strains. The data indicate that damage in trabecular bone commence at 0.2% apparent strain. The findings imply that tissue yielding can initiate at very low strains in the trabecular bone of the healthy acetabulum and that this local failure has negative consequences on the apparent mechanical properties of trabecular bone.

关键词： mechanical property trabecular bone microcomputed tomography (μCT) nonlinear micro-finite element (μFE) analysis acetabulum

Microstructure-based Finite Element Modelling and Characterisation of Bovine trabecular bone

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2006年第1期3卷 3-9页

作者： R. Akhtar S. J. Eichhorn P. M. Mummery School of Materials University of Manchester Grosvenor Street Manchester M1 7HS UK

The mechanical behaviour of trabecular bone is dependent on both the properties of individual trabeculae as well as their three-dimensional arrangement in space. In this study, nanoindentation was used to determine trabecular stiffness of bovine bone, both dehydrated and rehydrated. Values of 18.3 GPa and 14.3 GPa were obtained for dehydrated and rehydrated trabeculae respectively. These values were then used for finite element analysis where the mesh was generated directly from an X-ray microtomography dataset. The relationship between intrinsic tissue properties and apparent stiffness was explored. Moreover, the important role of collagen in bone micromechanics was demonstrated by complementing the study with Raman spectroscopy.

关键词： trabecular bone nanoindentation X-ray microtomography finite element modelling

EFFECTS OF ALENDRONATE ON STRUCTURAL PROPERTIES OF trabecular bone IN DOGS

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Sciences Journal 2002年第4期17卷 210-214页

作者：胡建华张良赵立连黄公怡 Department of Orthopaedics Beijing Hospital Beijing 100730 China

Objective. To evaluate the effects of alendronate on the structural properties of trabecular ***. Alendronate was administered at a daily p. o. dose of 0. 5 mg/kg over a 12-week period in hound dogs (n = 8 for both the control and treated group), and the structural indices of the lumbar vertebral (LI and L2) trabecular bone were assessed directly from 3-D ***. Treatment with alendronate increased bone volume fraction by 9. 5% and 7. 7% in L1 and L2 respectively. trabecular thickness significantly increased after alendronate treatment, whereas trabecular separation remained constant. The degree of anisotropy for the alendronate - treated group was decreased compared with that of the control group. bone surface to volume ratio declined significantly in the alendronate-reated group, whereas alendronate induced a higher bone surface ***. Alendronate increased the structural properties of canine trabecular bone after short-term treatment at a dose of 0. 5 mg · kg-1·day-1.

关键词： trabecular bone alendronate structural property

Micro-computed tomography assessment of human femoral trabecular bone for two disease groups(fragility fracture and coxarthrosis):Age and gender related effects on the microstructure

在线全文

学校读者我要写书评

暂无评论

Journal of Biomedical Science and Engineering 2013年第2期6卷 175-184页

作者： Ana Catarina Vale Manuel F.C.Pereira Antonio Maurício Bruno Vidal Ana Rodrigues Joana Caetano-Lopes Ara Nazarian Joao E.Fonseca Helena Canhao Maria Fatima Vaz Institute of Materials and Surface Science and Engineering LisbonPortugal Rheumatology Research Unit Instituto de Medicina MolecularFaculdade de Medicina de LisboaLisbonPortugal Center of Petrology and Geochemistry Instituto Superior TécnicoUniversidade Técnica de LisboaLisbonPortugal Rheumatology and Metabolic bone Diseases Department Hospital de Santa MariaLisbonPortugal Orthopedic Biomechanics Laboratory Beth Israel Deaconess Medical CenterHarvard Medical SchoolBostonUSA Mechanical Engineering Department Instituto Superior TecnicoUniversidade Tecnica de LisboaLisbonPortugal

The aim of this study was to identify three-dimensional microstructural changes of trabecular bone with age and gender, using micro-computed tomography. Human trabecular bone from two disease groups, osteoporosis and osteoarthritis was analyzed. A prior analysis of the effects of some procedure variables on the micro-CT results was performed. Preliminary micro-CT scans were performed with three voxel resolutions and two acquisition conditions. On the reconstruction step, the image segmentation was performed with three different threshold values. Samples were collected from patients, with coxarthrosis (osteoarthritis) or fragility fracture (osteoporosis). The specimens of the coxarthrosis group include twenty females and fifteen males, while the fragility fracture group was composed by twenty three females and seven males. The mean age of the population was 69 ± 11 (females) and 67 ± 10 years (males), in the coxarthrosis group, while in the fragility fracture group was 81 ± 6 (females) and 78 ± 6 (males) years. The 30 μm voxel size provided lower percentage difference for the microarchitecture parameters. Acquisition conditions with 160 μA and 60 kV permit the evaluation of all the volume’s sample, with low average values of the coefficients of variation of the microstructural parameters. No statistically significant differences were found between the two diseases groups, neither between genders. However, with aging, there is a decrease of bone volume fraction, trabecular number and fractal dimension, and an increase of structural model index and trabecular separation, for both disease groups and genders. The parameters bone specific surface, trabecular thickness and degree of anisotropy have different behaviors with age, depending on the type of disease. While in coxarthrosis patients, trabecular thickness increases with age, in the fragility fracture group, there is a decrease of trabecular thickness with increasing age. Our findings indicate that disease, age and

关键词： trabecular bone Micro-Computed Tomography Coxarthrosis Fragility Fracture Age Gender

Comparison Fatigue Life Time Prediction of Femoral Ball and Condyle Bovine trabecular bone

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Comparison Fatigue Life Time Prediction of Femoral Ball and ...

Comparison of methods for determining orthotropic axes in 3D femur remodeling

2012 2nd International Conference on Biomedical Engineering and Technology（ICBET 2012）

作者： Fatihhi, S.J. Ardiyansyah Syahrom Harun, M.N. Abdul Kadir, M.R. Department of Solid Mechanics and Design Faculty of Mechanical Engineering Universiti Teknologi Malaysia Skudai 81310 Malaysia Department of Biomechanics and Biomaterial Faculty Biomedical Engineering and Health SciencesUniversiti Teknologi Malaysia 81310 Malaysia

Fatigue of trabecular bone under physiological loading can give new insight on fatigue life and behavior under certain human habitual activities. The aim of study is to characterize the fatigue strain on trabecular and compare the strain in fatigue condition of different two anatomic parts. Loading condition were applied depends on normal human walking forces acting on hip. Hip contact loads were used for simulated the human gait while walking were chosen from the maximum load on hip and 75 % of that loading transferred to the trabecular for stress range 16 % - 55 % from that loads. The result showed different anatomic parts on trabecular adapt different physiological apparent loading due to orientation in human anatomic axis and give different hysteresis loop with the largest variation in strain. The huge different in strain gap after 10 4 cycles in both anatomic part is show that the femoral ball is more capable than condyle to sustain the prolonged loading.

关键词： cancellous bone trabecular bone fatigue.

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第12期17卷 1405-1411页

作者： Lau Jaclyn Beijing 100084 China Department of Biomedical Engineering Tsinghua University

The density distribution and internal structure of trabecular bone are modulated by local mechanical environment. In this study, an orthotropic adaptation algorithm was applied to the 3D femur model to simulate the variations of stiffness and orientation of trabecular bone under multi-loading conditions. This algorithm includes the determination of orthotropic axes and the stiffness modification of trabecular bone. Three methods were used to determine the orthotropic axes, i.e. the maximal cycle method, the stress maximum method, and the composite method. We found that the composite method was better than the other two. Firstly, the characteristics of density distribution obtained by using the composite method agreed better with those in real proximal femur. Secondly, the material orientation aligned with the known trabeculaer pattern. Finally, the ratios of the longitudinal modulus to the transverse modulus were also shown to be realistic in three local regions of the proximal femur.

关键词： orthotropic axes trabecular bone adaptation algorithm stiffness variation.