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目的 :利用三维非线性有限元分析 ,研究 15 0 0N压力和 15Nm弯矩下的脊椎前屈、后伸、侧弯和扭转运动时腰椎应力分布 ,探讨腰椎运动损伤的力学机制。方法 :基于L3-L4节段的CT扫描数据建立有限元模型。根据腰椎三关节复合体结构 ,观察椎间盘膨出内陷尺度、纤维环应力水平、小关节负荷水平及后部结构等效应力分布来评价运动负荷导致的力学变化。结果 :压力和前屈负荷引起椎间盘前部受压膨出 ,后伸和侧弯负荷引起椎间盘在后部和后外侧部膨出。扭转不仅引起单侧小关节高负荷承载 ,还造成椎间盘后外侧区纤维环应力集中。后伸时小关节负荷虽低于扭转 ,但高于侧弯和前屈。椎弓根和椎弓峡部在压力和后伸负荷下等效应力较高。结论 :椎间盘对压力的耐受性好于拉力 ,椎间盘后外侧区是各负荷下变形最大的区域 ,该部纤维环易于出现高应力而失败。小关节对腰椎活动特性有重要作用 ,扭转、后伸和高压力负荷引起小关节承受高负荷和小关节应力失败有关。椎弓根和椎弓峡部以及椎体前上部皮质骨区在屈伸和压力负荷下容易出现与应力相关的破坏。
OBJECTIVE: To study the stress distribution of lumbar spine under 15 000N pressure and bending moment of 15Nm by using three-dimensional nonlinear finite element analysis, and to explore the mechanism of lumbar motion injury. METHODS: A finite element model was established based on CT scan data of L3-L4 segments. The mechanical changes caused by exercise load were evaluated according to the structure of the lumbar-occipital joint complex, the size of disc invagination, the stress level of the annulus fibrosus, the load level of the facet joint and the equivalent stress distribution of the posterior structure. RESULTS: Pressure and flexion load caused compression and bulging of anterior intervertebral discs, and posterior and lateral bending loads caused the intervertebral discs to bulge in the posterior and posterolateral parts. Torsion not only caused by unilateral small joints bearing high load, but also caused by fibrosis after posterior lateral disc stress concentration. After the extension of the joint load is lower than the twist, but higher than the curve and flexion. Pedicle and pedicle isthmus stress and post-extension load higher equivalent stress. CONCLUSION: The intervertebral disc is more resistant to pressure than the tension, and the posterolateral area of the intervertebral disc is the area with the most deformation under each load. The fiber annulus is prone to high stress and fails. Small joints on the lumbar activity has an important role in the role of torsion, extension and high pressure load caused by the small joints to withstand high load and small joint stress failure related. Pedicle and pedicle isthmus and anterior superior cortical bone area prone to stress-related damage under flexion and extension and stress loads.