基于CT图像的下胫腓联合三维有限元模型构建

发布时间：2018-05-21 20:27

本文选题：下胫腓联合 + 三维有限元　；参考：《安徽医科大学》2013年硕士论文

【摘要】：目的以一名男性志愿者的右足螺旋CT扫描图像为依据，利用Mimics、Free-Form、ANSYS等软件构建下胫腓联合三维有限元模型，并对其有效性进行验证，使其能正确反映足踝部的力学特性，为进一步的生物力学研究提供方便快捷的数字化平台。方法选取一健康男性志愿者，30岁，身高170cm，体重60kg，自右踝关节以上20cm至足底进行螺旋CT扫描，扫描参数为：电压120KV，，电流240mA，重建层厚0.625mm，床进速度0.700mm/s，矩阵512×512，最后将CT扫描数据以Dicom格式存储；将Dicom格式的数据文件导入Mimics10.01软件，经蒙皮、分割、光滑等步骤重建出完整的足踝部骨骼及外周软组织的三维结构，并以点云的形式输入逆向工程软件Free-Form中生成几何实体模型，再将实体模型以IGES格式导入到有限元分析软件ANSYS12.0中去；骨骼、外部软组织囊模型采用三维十节点四面体结构实体单元Solid92进行模拟；在踝关节的接触面两侧根据关节间隙分别建立了0.5mm的关节软骨，其它关节软骨则采用仅受压的三维杆单元进行模拟；韧带按解剖数据建模，采用只受拉不受压的线单元Link10来模拟，最终生成下胫腓联合的三维有限元模型。对此模型进行力学加载，将胫腓骨远端的上表面及软组织完全固定，在模型上端加载300N的垂直载荷，进行求解得出正常状态下人足中立相时足底的压力分布情况；随后在同样的约束、加载条件下，对同一志愿者应用足底压力测量系统测量足底压力分布情况，并经结果与有限元模型的相应预测结果进行比较，从而验证模型正确性。结果建立了包括全部骨骼、主要韧带、皮肤及软组织在内的人足有限元模型，整个三维有限元模型共生成了81583个四面体二阶单元，130865个节点。本模型预测的足底接触压力与实测的接触压力在分布趋势、数值大小上基本一致，高接触压力都发生在跟骨区域和第1-5跖骨头下方，且接触压力最大峰值分别是0.240MPa与0.230MPa，初步证明本模型是有效的。结论本模型基于CT扫描数据利用Mimics、Free-Form、ANSYS等软件构建出了包括骨骼、主要韧带、皮肤及软组织在内的三维有限元模型，较客观地反映了其解剖结构和力学特性，模型经验证是有效的，可为下胫腓联合的进一步力学研究提供良好的数字化平台。
[Abstract]:Objective to construct a three-dimensional finite element model of the tibiofibular syndesmosis based on the spiral CT images of a male volunteer, using the software of MimicsFree-Form ANSYS, and to verify its validity so that it can accurately reflect the mechanical properties of the ankle. It provides a convenient and fast digital platform for further biomechanical research. Methods A healthy male volunteer, aged 30 years, who was 170 cm tall and weighed 60 kg, was scanned by spiral CT from 20cm above the right ankle to the sole of the foot. The scanning parameters are as follows: voltage 120kV, current 240mA, reconstruction layer thickness 0.625mm, bed speed 0.700mm / s, matrix 512 脳 512. finally, CT scan data is stored in Dicom format, and the data file of Dicom format is imported into Mimics10.01 software. Smooth steps such as reconstruction of the complete foot and ankle bones and peripheral soft tissue three-dimensional structure, and point cloud in the form of the reverse engineering software Free-Form to generate geometric entity model. Then the solid model is imported into the finite element analysis software ANSYS12.0 in IGES format, and the three-dimensional 10-node tetrahedron structure entity element Solid92 is used to simulate the bone and external soft tissue capsule model. According to the joint space, the articular cartilage of 0.5mm was established on both sides of the contact surface of the ankle joint, and the other articular cartilage was simulated by the compression only three-dimensional bar element, the ligament was modeled according to the anatomical data. Finally, a three-dimensional finite element model of the tibiofibular joint is generated by using the line element Link10, which is only subjected to tension and compression. Under mechanical loading, the upper surface and soft tissue of the distal tibia and fibula were completely fixed, and the vertical load of 300N was loaded on the upper end of the model. Then, under the same constraint and loading condition, the plantar pressure distribution was measured by the plantar pressure measurement system, and the results were compared with the corresponding prediction results of the finite element model to verify the correctness of the model. Results the finite element model of human foot including all bones, main ligaments, skin and soft tissue was established. A total of 81583 tetrahedron second-order elements and 130865 nodes were generated in the whole three-dimensional finite element model. The plantar contact pressure predicted by this model is basically consistent with the measured contact pressure. The high contact pressure occurs in the calcaneal region and below the head of the 1-5 metatarsal bone. The maximum contact pressure is 0.240MPa and 0.230 MPa respectively, which proves that the model is effective. Conclusion based on CT scan data, the 3D finite element model including bone, main ligament, skin and soft tissue was constructed by using the software of Mimicsl Free-Form ANSYS, which objectively reflects the anatomical structure and mechanical properties of the model. The model is proved to be effective. It can provide a good digital platform for further mechanical research of the tibiofibular syndesmosis.
【学位授予单位】：安徽医科大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R681;R816.8

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