五种内固定方式固定髋臼后柱骨折生物力学特性的有限元分析

Five internal fixation methods for acetabular posterior column fracture:a finite element analysis

目的应用有限元分析比较5种内固定方式固定髋臼后柱骨折的生物力学特性。方法选取1例健康女性志愿者,年龄为50岁,身高160 cm,体重63 kg,体重指数为24.6 kg/m2。将志愿者CT扫描数据以DICOM格式导入Mimics15.0软件生成骨盆三维模型,应用ANSYS 14.5软件建立骨盆三维有限元模型,并验证其有效性。然后生成髋臼后柱骨折模型,建立内髂坐钢板、常规后柱钢板、顺行空心拉力螺钉、经坐骨小切迹逆行空心拉力螺钉及经坐骨结节逆行空心拉力螺钉固定模型。对5种固定模型行应力加载,比较5种固定模型髋臼后柱骨折线的位移及应力集中部位。结果髋臼后柱骨折线上节点的平均位移:站立位时,常规后柱钢板固定模型(6.13μm)<经坐骨结节逆行空心拉力螺钉固定模型(6.85μm)<经坐骨小切迹逆行空心拉力螺钉固定模型(7.07μm)<内髂坐钢板固定模型(7.08μm)<顺行空心拉力螺钉固定模型(7.85μm);坐位时,常规后柱钢板固定模型(7.77μm)<内髂坐钢板固定模型(9.65μm)<顺行拉力螺钉固定模型(9.69μm)<经坐骨小切迹逆行空心拉力螺钉固定模型(10.1μm)<经坐骨结节逆行空心拉力螺钉固定模型(10.20μm)。5种内固定模型的应力均主要集中于骨折断端。结论内髂坐钢板及常规后柱钢板固定髋臼后柱骨折的稳定性较空心螺钉(顺行空心拉力螺钉、经坐骨结节逆行空心拉力螺钉、经坐骨小切迹逆行空心拉力螺钉)固定好。

Objective To compare the biomechanical performance between 5 internal fixation methods for fracture of the acetabular posterior column using finite element analysis.Methods One healthy female volunteer(50 years old,160 cm in height and 63 kg in weight with a body mass index of 24.6 kg/m2)was recruited for this study to undergo CT scan.Her CT scan data were imported into software Mimics15.0 in the format of DICOM to generate a 3D model of the pelvis.After pre-processing and accessory ligament structures added,a 3D finite element model of the pelvis was established and verified by software ANSYS.Next,software ANSYS was used to generate a model of acetabular posterior column fracture,on which models of 5 internal fixation methods(internal iliac-ischial plating,conventional posterior column plating,anterograde tensile screwing,lesser sciatic notch screwing and ischial tuberosity screwing)were established.Then stress was loaded onto the 5 internal fixation models to compare stress displacements of the fracture line on the articular surface and sites of stress concentration between the 5 internal fixation models.Results The average stress displacement of the fracture line at the standing position was 6.13μm for conventional posterior column plating,<6.85μm for ischial tuberosity screwing,<7.07μm for lesser sciatic notch screwing,<7.08μm for internal iliac-ischial plating,and<7.85μm for anterograde tensile screwing;the average stress displacement of the fracture line at the sitting position was 7.77μm for conventional posterior column plating,<9.65μm for internal iliac-ischial plating,<9.69μm for anterograde tensile screwing,<10.1μm for lesser sciatic notch screwing,and<10.20μm for ischial tuberosity screwing.In all the 5 internal fixation models,the stress was chiefly concentrated at fracture ends.Conclusion Internal iliac-ischial plating and conventional posterior column plating provide better stability than the hollow screws(anterograde tensile screwing,ischial tuberosity screwing and lesser sciatic notch screwing)for fracture of the acetabular posterior column.