不稳定股骨转子间骨折不同内固定方式的三维有限元分析

Three-dimensional finite element analysis of unstable intertrochanteric fracture in different fixation ways

背景:由于不稳定型股骨转子间骨折骨骼的形态及力学传递比较复杂,普通的实验方法难以全面完整的分析其生物力学变化特点,并且普通实验成本高、周期长、重复性比较差等缺陷使其在生物力学方面的研究受到限制。目的:应用三维有限元法分析不稳定股骨转子间骨折不同内固定方式的生物力学特点。方法:建立股骨转子间骨折锁定动力髋螺钉内固定模型(C1)、Gamma钉内固定模型(C2)以及股骨近端解剖锁定钢板内固定模型(C3),将股骨远端固定,施加髋关节反作用力2 800 N及外展肌力分别为1 200 N。三维有限元法分析不稳定股骨转子间骨折3种内固定模型不同部位的应力分布、应力集中部位以及最大位移情况。结果与结论:1骨折断面应力值:C3骨折断面前外侧应力值和前内侧应力值均最大,C3骨折断面后外侧应力值和后内侧应力值均最小,3组比较差异均有显著性意义(P均<0.05)。2骨折间隙应力值:C1、C2和C3的前外侧应力值、前内侧应力值、后外侧应力值和后内侧应力值之间比较差异有显著性意义(P<0.05)。其中C1前外侧应力值明显大于C2前外侧应力值(P<0.05),C3的前外侧应力值明显小于C1前外侧应力值和C2前外侧应力值(P<0.05),C3的前内侧应力值明显小于C1前内侧应力值和C2前内侧应力值(P<0.05);C1后外侧应力值明显大于C2后外侧应力值和C3后外侧应力值(P<0.05),C1后内侧应力值明显大于C2后内侧应力值(P<0.05),C3的后内侧应力值明显小于C1后内侧应力值和C2后内侧应力值(P<0.05)。3螺钉顶部周围骨质应力值:3组之间比较差异有显著性意义(P<0.05),其中C3的螺钉顶部周围骨质应力值明显大于C1和C2(P<0.05)。4由此可见,锁定动力髋螺钉、Gamma钉和股骨近端解剖锁定钢板3种内固定方式修复不稳定股骨转子间骨折各有优缺点,可以根据需要选择合适的内固定装置。

BACKGROUND：The morphological and mechanical transfers of unstable intertrochanteric fractures were complicated,so it is difficult to analyze the biomechanical characteristics of the common experimental methods in a comprehensive way.Moreover,the high cost,long cycle and poor repeatability of common tests limit its application in biomechanics.OBJECTIVE：To analyze the biomechanical characteristics of unstable intertrochanteric fracture in different fixation ways by three-dimensional finite element analysis.METHODS：Intertrochanteric fracture locking dynamic hip fixation model（C1）,Gamma nail fixation model（C2） and proximal femoral anatomical locking plate model（C3） were established.The distal end of the femur was fixed,and subjected to the hip reaction force of 2 800 N and abduction muscle strength of 1 200 N.Three-dimensional finite element analysis was used to analyze the stress distribution,stress concentration and maximum displacement of unstable intertrochanteric fracture in three different fixation ways.RESULTS AND CONCLUSION：（1） Stress：the anterolateral stress and anteromedial stress of C3 were the maximum.Posterolateral stress and posteromedial stress of C3 were the minimum.There were significant differences among the three groups（all P〈 0.05）.（2） Stress of fracture space：significant differences in anterolateral stress,anteromedial stress,posterolateral stress and posteromedial stress were determined in C1,C2 and C3（P〈 0.05）.Anterolateral stress of C3 was significantly less than anterolateral stresses of C1 and C2（P〈 0.05）.Anteromedial stress of C3 was significantly less than that of C1 and C2（P〈 0.05）.Posterolateral stress of C1 was significantly larger than that of C2 and C3（P〈 0.05）.Posteromedial stress of C1 was significantly larger than that of C2（P〈 0.05）.Posteromedial stress of C3 was significantly less than that of C1 and C2（P〈 0.05）.（3） Significant differences in bone stress around the screw top were detected among the three groups（P〈 0.05）.Bone stress around the screw top of C3 was significantly larger than that of C1 and C2（P〈 0.05）.（4） Thus,locking dynamic hip screw,Gamma nail and proximal femoral anatomical locking plate have their advantages and disadvantages for treatment of unstable intertrochanteric fracture of the femur.The appropriate internal fixation device should be selected according to the need.