成年人腰椎-骨盆的三维有限元模型的建立及验证

Establishment and verified three-dimensional finite element model of normal adult L_2-pelvis

目的建立成年人正常腰椎2-骨盆的三维有限元模型,并验证其有效性。方法选择24岁男性志愿者1例,自腰椎1至骨盆水平进行薄层CT扫描,获得577幅水平截图。将扫描的数据资料导入到Mimics软件中,通过阈值划分、区域增长、蒙版编辑等处理后生成三维表面模型。再导入Solid Works逆向工程软件构建实体模型,再导入到Hyper Mesh软件中划分四面体网格,按照解剖部位和形态建立终板、纤维环、髓核及椎体前后的韧带和骨盆周围韧带,以及上下关节突软骨、骶髂关节软骨、耻骨联合部软骨。参照既往文献数据,对模型进行赋值,用Abaqus软件分析。结果建立了腰椎2-骨盆的三维有限元模型,在约束臼顶,腰椎2椎体上缘施加1 000 N的轴向载荷后,腰椎5椎体上缘参考点的位移值为1.813 mm,腰椎5椎体上缘最大应力值为19.139 MPa,轴向压缩刚度为551.572 N/mm。施加7 N·m的弯曲载荷时,模型在前屈、后伸、右侧屈、左侧屈、右旋转、左旋转工况下角位移分布为5.641 15°、5.568 84°、2.101 90°、2.103 57°、2.186 61°、1.426 59°,平均轴向扭转刚度为4.05 N·m/(°)。测试结果与文献结果相当。结论建立的正常人体腰椎2-骨盆的三维有限元模型,精确度及准确度均较高,受力情况与实际情况相符合,可供下一步的研究。

Objective To establish three-dimensional finite element model of normal adult L2- pelvis based on computed tomography scan data and verify its effectiveness. Methods One 24-year-old male volunteer was performed CT scan from L1 to pelvis and 577 images were obtained. The scan data was imported into Mimics software, then three-dimensional（3D）surface model was generated by ＂thresholding＂, ＂region growing＂, ＂edit masks＂ and other procedures. The data of 3D surface model was imported into Solid Works software to establish 3D solid model, and 3D solid model was divided into mesh model by using Hyper Mesh software. The endplate, annulus, nucleus pulposus, before and after vertebral ligament, pelvic ligament, upper and lower facet cartilage, sacroiliac joint cartilage and pubic symphysis cartilage were established in anatomy and mor-phology. The model was given material properties by reference to previous literature data and analyzed by Abaqus software.Results The 3D finite element model of L2 to pelvis was established, the displacement at the upper edge of L5 was 1.813 mm when constrained the top of double acetabulum and applied vertical load of 1 000 N. The maximum stress value of the upper edge of L5 was 19.139 MPa, and axial compression rigidity was 551.572 N/mm. When the bending load of 7 N·m was applied,the angular displacements in flexion, extension, right lateral flexion, left lateral flexion, right rotation, left rotation conditions were 5.641 15°, 5.568 84°, 2.101 90°, 2.103 57°, 2.186 61°, 1.426 59°, respectively. The mean axial torsional rigidity was4.05 N·m/（°）. The test result was consistent with the results reported in literature. Conclusion It is demonstrated that establishment of 3D finite element model of human L2-pelvis can effectively reflect the biomechanical characteristics of lumbopelvis with high precision and accuracy, which provides experimental data for further researches.