前路钢板置入固定治疗骶髂关节脱位的三维有限元分析

背景：已有文献报道骶髂关节损伤及固定的生物力学研究，但多是在尸体标本或人工骨模型上模拟骶髂关节损伤。目的：利用三维有限元方法对骶髂关节脱位前路钢板内固定的垂直稳定性进行分析。 方法：在完整骨盆三维有限元模型的基础上，建立一侧骶髂关节脱位后前路钢板内固定模型。对模型施加500 N轴向载荷，经计算得到应力、应变及位移云图，并与完整骨盆的同一工况进行比较分析。结果与结论：在内固定系统处出现了应力集中现象，尤其以靠近骶髂关节的螺钉周围应力最大，远远大于完整骨盆同一工况下的最大应力。应变以健侧骶髂关节最大，内固定侧骶髂关节无应变。位移以损伤侧骶髂关节处最大，约为完整骨盆的2倍。提示前路钢板内固定治疗骶髂关节脱位，骨盆在垂直方向上稳定性较差，且钢板螺钉处出现了应力集中现象。

Three-dimensional finite element analysis of anterior plate fixation for the treatment of sacroiliac joint dislocation

BACKGROUND: Most reported biomechanical studies on sacroiliac joint injury and fixation use cadavers or artificial bone models to simulate the sacroiliac joint injury.OBJECTIVE:To analyze the vertical stability of anterior plate fixation for sacroiliac joint dislocation using three-dimensional finite element method. METHODS: The anterior plate fixation model of unilateral sacroiliac joint dislocation was constructed on the basis of the three-dimensional finite element model of a complete pelvis. An axial load of 500 N was applied on the model; the cloud pictures of stress, strain and displacement were obtained after calculation and compared with that of the complete pelvis under the same conditions.RESULTS AND CONCLUSION:Stress concentration occurred at the internal fixation system; the maximum stress was found at the screws near the injured sacroiliac joint, far greater than the maximum stress of the complete pelvis under the same condition. The maximum strain was found in the healthy sacroiliac joint; the fixed sacroiliac joint had no strain. The maximum displacement was found in the injured sacroiliac joint; it was about twice longer than the complete pelvis. These findings indicate that the vertical stability of pelvis is poor using anterior plate internal fixation treatment for sacroiliac joint dislocation; and stress concentration occurs at the screws and plates.