腰椎运动节段流固耦合有限元模型的建立与验证*

背景：传统的脊柱生物力学体外实验难以取得椎间盘液体相关的力学性能数据，国外可见多孔弹性有限元模型用于腰椎的固液二相性的研究，然而国内罕见相关报道。 目的：利用ANSYS12.1有限元分析软件，建立腰椎运动节段流固耦合有限元模型，旨在推动有限元分析技术在脊柱生物力学方面的广泛应用。 方法：对1名健康男性志愿者进行L4~5运动节段的螺旋CT扫描成像，利用医学图像处理软件Mimics10.01对其进行预处理，再利用逆向工程软件Geomagic9.0对模型进行NURBS曲面重构，然后导入有限元软件ANSYS12.1重建椎体皮质骨、松质骨、纤维环和髓核等结构，最后通过划分网格、定义材料属性、定义接触、加载求解等操作建立了腰椎运动节段流固耦合三维有限元模型，并将椎间盘高度随时间变化的数据与文献数据进行比较，以验证模型的有效性。 结果与结论：建立了L4~5运动节段的流固耦合有限元模型，模型的总节点数210 718个，总单元数85 973个。将本模型所测得的椎间盘高度数据与文献数据进行比较，结果基本一致。腰椎流固耦合有限元模型更加符合人体的生物力学特点。

Establishment and validation of a fluid-solid coupling finite element model of the lumbar motion segment

BACKGROUND: Fluid related biomechanical behavior of intervertebral disc is difficult to acquire from traditional research on spinal biomechanics. A few porous elastic finite element models are applied to investigate the behavior of lumbar two-phase at abroad. However, there are rarely related reports in China. OBJECTIVE: To establish the fluid-solid coupling finite element model of the lumbar motion segment by the ANSYS12.1 software and to promote the wide application of finite element method in the spinal biomechanics. METHODS: Spiral CT scan was performed in the L4-5 motion segment of a male volunteer without any spinal disease. The CT data was imported to the software of Mimics10.01 to create the geometric model of the L4-5 motion segment which was re-constructed to the 3D NURBS surface with the software of Gomagic9.0. The solid model was established using ANSYS12.1 software, and the model included cortical bone, cancellous bone, cartilaginous endplates, nucleus pulposus, and annulus matrix. A three-dimensional fluid-solid coupling finite element model of the L4-5 motion segment was established after a series of processes such as assigning parameters, meshing models, boundary setting, loading and solution. The height change of intervertebral disc of the model was compared with the vivo results to verify the validity of the model. RESULTS AND CONCLUSION: The established fluid-solid coupling finite element models of L4-5 motion segment has 210 718 nodes and 85 973 elements. The height change of the intervertebral disc was consistent with that of the in vivo results. The fluid-solid coupling finite element model of porous media has accurately simulated biomechanical features of human lumbar spine.