中文摘要：

目的建立全腰椎及骶椎的有限元模型，为分析L4～5之间纤维环易破裂的病理提供可靠的模型。方法利用健康成人椎骨的CT影像，采用Mimics医学图像处理软件和Geomagic逆向工程软件建立IJl～Sl椎骨和椎间盘i维模型，再导人有限元软件Hypermesh中划分网格，并附加腰椎相关韧带，赋予材料属性，建立边界条件，构建腰椎加骶椎有限元模型；模拟腰椎受轴向压力、前弯、侧弯和后伸4种载荷下的生物力学反应。结果模型在受到10N·m载荷作用分别发生前屈、侧弯和后伸运动下的整体刚度分别为0．61、0．7和0．75N·m／（°），与实验结果较为吻合；轴向施加力和弯矩时IA～5之间的纤维环应变较大；纤维环在各种载荷下均出现较明显的应力集中。结论IA～5之间纤维环局部应力集中和应变较大是导致其易破裂的原因之一；所建立的Ll～s1椎体三维有限元模型符合脊柱生物力学特性，可用于脊柱生物力学的进一步研究。关键词：腰椎；力学特性；有限元分析；载荷；生物力学

英文摘要：

Objective To develop an accurate finite element （FE） model of human L1-SI spine segment for in- vestigating the pathology of annulus fibrosus rupture of L4-5. Methods Based on CT images of a healthy adult, three-dimensional （3D） model of vertebras and intervertebral discs of lumbar L15 and sacral St segment was re- constructed by Mimics t0. O1 and Geomagic 10.0 software. The 3D model was then imported into Hypermesh for meshing. With adding various ligaments and assigning material properties of all components, the FE model of L1- S1 segment was established to investigate its biomechanical responses under various loading conditions including axial compression, flexion, lateral bending and extension. Results The global stiffness of the model under flex- ion, lateral bending, extension with 10 N · m load was 0.61,0.7 and 0.75 N · m/（°）, respectively, which was in good agreement with the experimental results. The strain of annulus fibrosus between L4 and 1_5 was higher un- der axial compressive force and bending moment; annulus fibrosus showed obviously stress concentration under any of the different loads. Conclusions The stress concentration and higher strain in annulus fibrosus between L4 and L5 could be one of the reasons leading to rupture. The developed 3D FE model of L1 - St motion segment demonstrated to be effective in reflecting the biomechanical response of spine and could be used for further spine biomechanics study.