L4/5关节突关节融合后椎间盘 应力变化的三维有限元分析

Stress changes of intervertebral disc after fusion of L4/5 facet joints: a finite element analysis

中文关键词:  腰椎  三维有限元分析  椎间盘  关节突关节融合  活动度

英文关键词:Lumbar  Three-dimensional finite element  Intervertebral disc  Facet fusion  Range of motion

中文摘要:

  【摘要】 目的：建立正常人L3~L5三维非线性有限元模型，运用有限元分析方法模拟分析L4/5双侧关节突关节未融合与融合后L4/5椎间盘的应力分布情况和L4/5节段活动度。方法：选取1例健康成年男性志愿者，年龄27岁，身高175cm，体重70kg，既往无腰痛病史。采用64排螺旋CT对T12~S1行薄层平扫，得到Dicom格式数据，经Mimics软件选取L3~L5椎体二维图像数据，再经Geomagic软件简化、光滑处理，3-matic软件划分面网格和体网格，Mimics软件赋值，最终导入Ansys软件中重建腰椎关节突关节未融合和融合（融合L4/5双侧关节突关节）的三维有限元模型。利用Ansys软件约束L5椎体下表面各向活动度，给予L3椎体上表面垂直向下的面载荷500N，并给予7.5N·m的力矩模拟正常人体垂直压缩、前屈、后伸、左侧屈、右侧屈、左旋转、右旋转7种运动状态，对L4/5双侧关节突未融合与融合后L4/5椎间盘的应力分布情况和L4/5节段活动度进行分析。结果：成功建立了正常人L3~L5关节突关节未融合和融合的三维有限元模型，未融合模型L3/4、L4/5节段活动度与既往文献中腰椎活动度趋势一致。与未融合模型比较，关节突关节融合模型在各运动状态下L4/5椎间盘后方应力明显减小，差异有统计学意义（P<0.05）；前方应力未见明显改变。关节突关节融合模型L4/5节段活动度明显减小。结论：腰椎关节突关节融合可以降低融合节段椎间盘后方应力，减少融合节段的活动度，有利于维持节段的稳定性。

英文摘要:

  【Abstract】 Objectives: A three-dimensional nonlinear finite element model of L3-L5 based on biomechanical characteristics was established, and to simulate the stress distribution of L4/5 intervertebral disc after the non-fusion and fusion of the bilateral lumbar facet joint of L4/5, also to analyze the L4/5 segment activity. Methods: A 27-year-old healthy adult male volunteer with 175cm height, 70kg weight and no previous history of low back pain was selected. The L3-L5 vertebral two-dimensional image data were obtained by scanning the T12-S1 vertebral body with 64 slice spiral CT. After simplification and smooth processing by Geomagic software, dividing surface and volume meshes by 3-matic software, and assignment by Mimics, the three-dimensional finite element model of lumbar facet joint with non-fusion or fusion was reconstructed finally after importing Ansys software. While the surface anisotropy activity of L5 vertebra constrained, a 500N surface load was given to the top surface of L3 vertebra and a moment of 7.5Nm was exerted to simulate the normal human 7 motion state, including vertical compression, flexion, extension, left and right flexion, left and right rotation. The stress distribution of L4/5 intervertebral disc after non-fusion and fusion, and the L4/5 segment activity was analyzed after operation. Results: The model was established, and the ranges of motion of L3/4 and L4/5 segments were corresponding to previous literatures on lumbar mobility. When compared to the facet non-fusion model, the posterior stress of facet fusion model decreased sharply and the activity of L4/5 segment was significantly reduced in each different motion state, and the difference was statistically significant(P<0.05). Conclusions: Lumbar facet joint fusion can be a good way to reduce the posterior stress of intervertebral disc, to maintain the stability of segment, to avoid the damage of the posterior intervertebral disc and the tear of annulus fibrosus.