【作者】 李孝林；

【导师】 熊昌源；

【作者基本信息】 湖北中医学院 ， 中医骨伤科学， 2009， 博士

【摘要】 目的：构建脊柱胸腰段以及胸腰椎单纯压缩性骨折的三维非线性有限元模型并进行有效性验证，在此基础上探讨过伸复位法治疗胸腰椎压缩性骨折的机制。方法：依据一例青年男性志愿者脊柱胸腰段超薄CT扫描数据，重建T₁₁-L₂的三维几何形状，自动划分单元网格，根据CT值对骨骼结构的材料属性进行分级定义。手工建立椎间盘的大体模型，划分精细的单元网格，椎间盘各部分之间进行布尔运算。根据解剖学资料建立各组韧带单元，采用6点阶段线性法模拟韧带的力一位移曲线定义韧带单元的材料属性。在关节突关节处添加不同厚度的软骨单元和接触对，模拟关节接触的力学行为。脊柱胸腰段三维非线性有限元模型构建完毕后，施加与尸体标本力学实验相同的静态力矩载荷，模拟脊柱胸腰段的各种运动，对模型的有效性进行验证。在验证有效的脊柱胸腰段三维非线性有限元模型上以施加位移的方式模拟椎体压缩骨折的受伤机制建立T₁₂、T₁₂L₁椎体压缩性骨折的有限元模型，并依据1例临床T₁₂椎体压缩性骨折患者的超薄CT扫描数据直接建立T₁₂椎体压缩性骨折的有限元模型，并对两个模型加载进行有效性验证。在以正常原始资料所建的T₁₂椎体压缩性骨折的有限元模型上于不同的过伸支点模拟临床过伸复位手法，分析复位过程中受伤椎骨不同部位的应力和位移改变。结果：构建的脊柱胸腰段三维非线性有限元模型包含T₁₁-L₂的四个椎骨、3个椎间盘及相应韧带、关节软骨等重要结构。对模型施加生理载荷后，在前屈、后伸、旋转和侧屈运动中的关节活动范围与尸体实验结果接近。在较小载荷范围内，模型获得了较大的运动范围，随着载荷的增加，运动范围的增加量趋于稳定。模型表现出明显的非线性力学行为。两个T₁₂椎体压缩性骨折有限元模型的结构相当，加载后表现出相似的非线性力学行为。骨折模型在不同的过伸支点施加复位载荷后表现出了不同的复位效果，当过伸支点在T₁₂棘突顶点处时其位移改变最明显，受伤椎骨各部位的力学特性最稳定，但是小关节承受了较大的应力。结论：所建脊柱胸腰段和胸腰椎骨折三维非线性有限元模型的生物力学特征基本上符合人体真实的运动规律，可以进一步用于脊柱胸腰段的相关生物力学实验。应用正常原始资料构建相关疾病有限元模型的方法切实可行。过伸复位的支点应选在受伤椎骨的棘突顶点，复位过程中小关节承受较大的应力，可能并发小关节损伤而引起后期的腰背痛。更多还原

【Abstract】 Objective: To construct and validate the effectiveness of the 3-D nonlinear finite element models of thoracolumbar and thoracolumbar vertebral compression fractures and investigate the biomechanical mechanism of the treatment about thoracolumbar vertebral compression fractures by hyperextending.Methods: Reconstructed the 3-dimensional bone-geometry of T₁₁-L₂ based on the ultrathin CT scan datas of a young male volunteer.After automatic element meshing, we defined material property of bones by CT value based grading method. We constructedthe volumeof 3 discs and performed refined meshing by hand. The every part of the disc carry out boolean operating.All ligament-elements were constructed according to their anatomic research datas, whose material property were defined by their forcedisplacement curve that modeled with 6 point staged linear method. The elements of cartilages and contact pairs were constructed on the joint surfaces of the zygapophysial joints to simulate contact behavior of joints. After the 3-D nonlinear finite element model of thoracolumbar was constructed, this model was applied static moment load that equals to cadaver mechanic experiment, to simulate various movements of thoracolumbar and validate the effectiveness of this model. After validation of this finite element model of thoracolumbar to establish the 3-D nonlinear finite element models of the compression fractures of T₁₂ and T₁₂L₁ by imposing displacement and simulating the injury mechanism of thoracolumbar vertebral compression fractures. Then establish the 3-D nonlinear finite element models of the compression fractures of T₁₂ based on the ultrathin CT scan datas of one patient of the compression fractures of T₁₂. Validated the effectiveness of the two models by applying static moment loads. Simulate the clinical reduction approach of hyperextension at the different fulcrum of the 3-D nonlinear finite element models of the compression fractures of T₁₂ based on the original datas from the normal human. Analysing the changes of stress and displacement about the different parts of the injured vertebra in the entire reduction.Results: This 3-D nonlinear finite element model of thoracolumbar included four vertebraes,three discs, the ligaments and all joint cartilages and ligaments. By applying physiological load, the range of movement of flexion, extension, rotation and flexor was similar to results of cadaver mechanic experiment.This model gained large range of movement within small load range. With increasing load, the increment of range of movement trended to constant. This model showed apparent nonlinear mechanic feature.The structures of 2 finite element models of the compression fractures of T₁₂ are similar and they showed simila rnonlinear mechanic feature. This model of compression fracture showed the different reseting-effects after imposing reseting-load at different fulcrum. The change of displacement is the most obvious when the reseting-fulcrum is at the top of spinous process of T₁₂ vertebral, the mechanic feature of various parts of the injured vertebral is the most stable, but the stress of the zygapophysial joints is larger.Conclusion: The biomechanical feature of the 3-D nonlinear finite element models of thoracolumbar and thoracolumbar vertebral compression fractures is mainly consistent with true human movement pattern. The models can be further used in biomechanical experiment of thoracolumbar vertebral.The method of establishing the 3-D nonlinear finite element models of the compression fractures based on the ultrathin CT scan datas of normal human is feasible. The reseting-fulcrum should be elected at the top of the spinous process of the injured vertebra, the stress of the zygapophysial joints is large in the course of the reseting, this is one of the reasons of injury of zygapo-physial joints and later low back pain.更多还原