中文摘要：

目的研究人体腰椎椎体有限元建模中有限元的单元尺寸和类型、松质骨材料属性分配方式以及皮质骨结构模拟方法对有限元结果的影响。方法基于定量CT扫描人体腰椎的影像,采用6种不同的单元尺寸（0.5、1.0、1.5、2.0、2.5、3.0 mm）、2种松质骨材料属性分配方法、2种松质骨非均匀材料属性分配梯度（150、300）、2种皮质骨结构建模方法,建立22个去除后部结构的腰椎L2段椎体有限元模型,计算获得22个有限元模型的最大位移、应变能、平均应力、轴向刚度,并对这些结果进行统计分析和验证。结果单元尺寸为0.5 mm时,10、150、300三种非均匀材料属性分配梯度下,模型的轴向刚度值出现明显差异;不同单元尺寸下,松质骨在150种非均匀材料属性分配梯度下,模型的平均应力波动变化平缓;利用最外层六面体单元模拟皮质骨结构方法,其平均应力大于利用在最外层添加蒙皮（skin）模拟皮质骨结构方法。结论在进行腰椎椎体有限元建模时,选取0.5 mm尺寸的六面体单元、为椎体松质骨分配150种非均匀材料属性、利用最外层六面体单元模拟椎体皮质骨结构的建模方法,建立的有限元模型更加合理和有效。研究结果为后续大批量、个体化腰椎椎体模型的建立奠定基础。

英文摘要：

Objective To investigate the effects of element size and type,material property distributions of vertebral cancellous bone and simulation methods of cortical bone structure on the finite element（ FE） results during the finite element modeling of lumbar vertebral body. Methods Based on QCT images of lumbar spine,22 FE models of L2 without posterior structure were built by using 6 element sizes（ 0. 5,1. 0,1. 5,2. 0,2. 5,3. 0 mm）,2 kinds of material property distribution methods of cancellous bone,2 heterogeneous material distribution methods of cancellous bone（ 150,300） and 2 cortical bone modeling methods. The maximum displacement,strain energy,average stress and axial stiffness of these models were obtained to analyze and verify the results.Results When the element size was 0. 5 mm,the axial stiffness among the models with 10,150 and 300 kinds of heterogeneous materials showed obvious differences; for the vertebral cancellous bone with 150 kinds of materials,the average stress appeared no distinct variation under different element sizes; the average stress of the model using the outermost hexahedral elements to simulate cortical bone structure was larger than that of the model appending the skin to the outmost. Conclusions It is more reasonable and effective to build the FE model of lumbar vertebral body with the method by using 0. 5 mm element size,8-noded hexahedral elements,150 kinds of heterogeneous materials,and using the outermost hexahedral elements to simulate the cortical bone structure.The research findings will lay a foundation for building subject-specific FE models of lumbar vertebral body on a large scale in future.