压配型髋臼假体置换后骨性髋臼的微有限元分析

Micro-finite Element Analysis of Bony Acetabulum with a Press-fit Acetabular Cup

目的探讨压配型髋臼假体置换术后骨性髋臼皮质骨和松质骨的骨小梁应力分布模式及松质骨是否参与承载负荷。方法应用显微CT扫描骨性髋臼的骨小梁,建立骨性髋臼的三维微有限元模型。计算压配型髋臼假体置换后骨性髋臼骨小梁的应力和应变,分析骨性髋臼骨小梁应力、应变的生物力学特征。结果当压配型金属髋臼假体植入髋臼后,骨性髋臼外表面的最高应力区位于耻骨区,最高应力为1.389 MPa。在臼顶区,高应力区的面积最大。在骨性髋臼内部的松质骨,高应力区主要分布在臼顶区,分布区域相对较广。当施加1.372 k N载荷后,骨性髋臼外表面面积较大高应力区位于臼顶区域和耻骨区域,臼顶区的最高拉应力为0.604 MPa,耻骨区骨小梁出现微损伤。在骨性髋臼内部的松质骨,面积较大高应力区主要分布在臼顶区和耻骨区。结论高应力区沿着骨性髋臼外表面呈现3点式环形分布,集中分布于耻骨区、坐骨区、臼顶区;髋臼内部松质骨骨小梁通过形变导致应力分布更加均匀。髋臼松质骨具有承受载荷功能。

Objective To investigate the trabecular stress distributions on the cortical bone and determine whether the cancellous bone can share the load of the acetabulum with a press-fit acetabular cup. Methods The acetabulum was scanned via micro-computed tomography（ CT） to build a three-dimensional micro-finite element analysis（ μFEA） model of the acetabulum. The trabecular stress and strain of the bony acetabulum were calculated following total hip arthroplasty（ THA） to investigate the biomechanical characteristics of their distributions.Results With the implantation of the press-fit acetabular cup into the acetabulum,the high-stress zone of the articular surface was found to be located in the pubic bone area,with a maximum stress of 1. 398 MPa. The largest high-stress zone within the articular surface was at the craniomedial part where it was supported by the iliac. For the cancellous bone within the acetabulum,the high stress was relatively widely distributed on the craniomedial part. When a 1. 372 k N load was applied,the high stress was found at the craniomedial and anterior-inferior parts of the articular surface where it was supported by the iliac and pubic bone,with a trabecular micro-damage occurring in the anterior-inferior part. The highest tensile stress at the craniomedial part was 0. 604 MPa. For the cancellous bone within the acetabulum,the high stress was mainly distributed on the craniomedial and anterior-inferior parts. Conclusions The high stress near the periphery of the articular surface showed a three-point circular distribution,which was mainly distributed on the iliac,ischial,and pubic bone area. The stress was distributed more uniformly owing to the deformation of the cancellous bone in the acetabulum. The cancellous bone in the acetabulum has the function of load-bearing.