为了评估植骨融合术对腰椎运动和应力分布的影响,利用影像诊断技术(CT扫描)和CAD三维重建技术获得人体腰椎三维模型,椎间盘纤维环采用各向异性纤维加强超弹性本构模型,建立了包括椎体、椎间盘和韧带的正常有限元模型以及L3-L4融合的腰椎L2-L4节段有限元模型,并通过对比模拟和实验结果验证其有效性.利用商业有限元软件ABAQUS/Standard进行前屈、后伸和轴向旋转载荷情况下的模拟分析,对比两种模型在不同状态下的运动范围及应力分布情况.模拟结果显示:在相同的载荷情况下,融合模型的运动范围和正常模型相比明显偏小;相邻椎体的应力分布与正常模型明显不同,但植骨融合对相邻椎间盘的影响相对较小.此外,小关节对维持脊椎正常生理功能起着重要作用,小关节功能丧失会使相应节段的椎间盘髓核压力增大.%The aim of this paper is to evaluate the effect of interbody fusion on lumbar spine via finite element (FE) method. Based on CT scanning images and CAD three-dimensional reconstruction technique,detailed and anatomically accurate normal and fused human lumbar spine FE models for the L2-L4 motion segment with or without L3-L4 fusion are built. The lumber spine models include vertebrae, intervertebral disc and various ligaments. A previously developed hyperelastic fiber reinforced constitutive model is used to characterize the nonlinear anisotropic material property of intervertebral disc annulus fibrosus. The proposed FE model is validated by comparing numerical results of axial compressive load-displacement with experimental data available in literature. Commercial FE analysis software package ABAQUS/Standard is used to simulate the normal and fused lumber spine segment under flexion, extension and axial rotation. The lumbar spine motion range and stress distribution of two models under different loading conditions are obtained and compared.Numerical simulation results show that under the same loading condition, the fused model has a much smaller body motion range compared the normal one. Interbody fusion brings out obviously different stress distribution in adjacent vertebral bodies, but has minor impact on adjacent intervertebral disc. The results also suggest that facet joints play an important role in maintaining normal physiological function of spine. The analysis results can provide references and guidelines for human lumbar fusion neurosurgical operation in clinic.
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