Incorporating tissue anisotropy and heterogeneity in finite element models of trabecular bone altered predicted local stress distributions
Incorporating tissue anisotropy and heterogeneity in finite element models of trabecular bone altered predicted local stress distributions
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DOI：
10.1007/s10237-017-0981-8
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发表时间：
2018-04-01
影响因子：
3.5
通讯作者：
Siegmund, Thomas
中科院分区：
文献类型：
--
作者：
Hammond, Max A.;Wallace, Joseph M.;Siegmund, Thomas
松质骨由组织化的矿化胶原纤维组成，这导致组织水平上的不均匀和各向异性的机械性能。最近，生物力学模型计算的应力和应变的骨小梁组织异质性预测的应力和应变的显着影响。然而，组织水平的力学各向异性对松质骨生物力学响应的影响是未知的。在这里，建立了一种计算方法，以自动施加生理相关的方向固有的骨小梁组织上的骨小梁微观有限元模型。然后根据骨矿物质密度和局部组织方向应用空间变化的组织水平各向异性弹性特性。该模型被用来测试的假设，即在均质和非均质模型的各向异性改变预测的应力不变量的分布。线弹性有限元计算进行了3毫米立方体模型从显微计算机断层扫描的人骨小梁从股骨远端。记录了各单元的静水压应力和等效应力，并分析了各单元的静水压应力和等效应力的分布规律。各向异性减少的范围内的静水应力在拉伸和压缩更强烈的相关增加冯米塞斯等效应力。各向异性的影响是独立的空间重新分布高压缩应力，由于组织弹性的异质性。组织的各向异性和异质性可能是保护骨不受破坏的重要机制，应纳入骨小梁的应力分析。
Trabecular bone is composed of organized mineralized collagen fibrils, which results in heterogeneous and anisotropic mechanical properties at the tissue level. Recently, biomechanical models computing stresses and strains in trabecular bone have indicated a significant effect of tissue heterogeneity on predicted stresses and strains. However, the effect of the tissue-level mechanical anisotropy on the trabecular bone biomechanical response is unknown. Here, a computational method was established to automatically impose physiologically relevant orientation inherent in trabecular bone tissue on a trabecular bone microscale finite element model. Spatially varying tissue-level anisotropic elastic properties were then applied according to the bone mineral density and the local tissue orientation. The model was used to test the hypothesis that anisotropy in both homogeneous and heterogeneous models alters the predicted distribution of stress invariants. Linear elastic finite element computations were performed on a 3 mm cube model isolated from a microcomputed tomography scan of human trabecular bone from the distal femur. Hydrostatic stress and von Mises equivalent stress were recorded at every element, and the distributions of these values were analyzed. Anisotropy reduced the range of hydrostatic stress in both tension and compression more strongly than the associated increase in von Mises equivalent stress. The effect of anisotropy was independent of the spatial redistribution high compressive stresses due to tissue elastic heterogeneity. Tissue anisotropy and heterogeneity are likely important mechanisms to protect bone from failure and should be included for stress analyses in trabecular bone.