非骨水泥型人工髋关节假体固定界面骨整合力学分析

目的：探讨不同假体粗糙面和界面压配下,非骨水泥型人工髋关节假体固定界面初始稳定性以及对骨长入,继发稳定性的影响.方法：采用Mimics软件模拟髋关节置换术重建人工髋关节三维可视化模型.构建假体柄-骨界面摩擦系数为0、0.15、0.40及1.00,代表不同的假体表面粗糙程度;根据实际操作,构建假体柄-骨界面压配为0、0.01、0.05及0.10 mm,选择人体45％步态相模拟人体攀爬楼梯工况,计算并比较骨-假体界面的微动以及相对应的应力分布情况.结果：界面压配为0.05 mm情况下,摩擦系数为0、0.15、0.40和1.00相对应的假体-骨界面正向压力分别为230、231、222和275 MN,随着摩擦系数的增加,正向压力总体趋势变化不大;界面的相对滑移量分别为0.529、0.129、0.107和0.087 mm,表明两界面之间的相对滑移量不断减少.摩擦系数为0.40情况下,界面压配为0、0.01、0.05及0.10 mm相对应的假体-骨界面摩擦力分别为56.0、67.7、60.4和49.6 MN,界面的相对滑移量分别为0.064、0.062、0.043和0.042 mm,说明随着压配量的增加,股骨假体与骨通道之间的正向压力呈下降趋势,摩擦力在压配量为0.01 mm时达到最大值,界面之间的相对滑移量则不断减少.结论：髋关节置换术后,假体和骨组织之间存在骨改建、骨整合的动态过程,其程度决定了假体的远期使用效果.骨-假体界面的间隙和摩擦系数是决定骨假体界面骨整合的关键因素.

Three-dimensional finite element analysis on mechanical behavior of the bone remodeling and bone integration between the bone-implant interface after hip replacement

Objective: To discuss the primary stability of the fixed interface between the cementless prosthesis and femur,and its influence on bone ingrowth and secondary stability under the roughened surface and press fit of different prostheses by finite element analysis.Methods: A three-dimensional finite element module of total hip arthroplasty(THA) was developed with Mimics software. There was a collection of data when simulating hip arthroplasty. The frictional coefficient between the fixed interface was 0,0.15,0.40 and 1.00 representing the roughness of prosthesis surface. The press fit was 0,0.01,0.05 and 0.10 mm according to the operation. The Vion Mises stress distribution and the contact pressure,friction stress and relative sliding displacement between the interface were analysed and compared when simulating the maneuver of climbing stairs.Results: At a fixed press fit of 0.05 mm,the contact pressure between the interface was 230,231,222 and 275 MN under four different frictional coefficient(0,0.15,0.40 and 1.00) with little change; the relative sliding displacement was 0.529,0.129,0.107 and 0.087 mm with a consistent and obvious decline. As the fixed frictional coefficient was 0.40,the contact pressure between the interface were 56.0,67.7,60.4 and 49.6 MN under four different press fit (0,0.01,0.05 and 0.10 mm) with a reduction; the relative sliding displacement was 0.064,0.062,0.043 and 0.042 mm with an obvious decline,and there was a maximal friction stress when press fit of 0.01 mm.Conclusion: There is a dynamic process of the bone remodeling and bone integration between the interface after hip replacement,determining the long-term outcome. The interface clearance and the frictional coefficient are the key factors of the bone integration.