非球面人工髋关节接触力学

目的由于受制造技术的局限性、可能的设计优化考虑以及临床应用的磨损等因素影响,人工髋关节轴承表面表现为非球面几何特征,可以利用有限元分析方法对非球面人工髋关节的接触力学行为进行研究。方法对球面网格数据模型进行非球关节面重建,研究不同取向椭球面股骨头对球面髋臼几何特征的非球面金属对金属人工髋关节的接触力学表现。结果非球面股骨头接触区域中心位置的平均曲率半径在一定范围内增大时,能有效降低相应关节接触面上的最大接触压力,同时接触面积有所增加;在同样载荷下,髋臼相对股骨头不同倾斜状态对非球面股骨头的接触压力峰值和面积影响较小,但压力分布有所不同。结论良好地控制人工髋关节的非球表面特征,有利于改善人工髋关节最大接触压力幅值大小和接触区域分布。所发展的非球面人工髋关节接触模型及数值模拟过程能够有效地运行,这为非球面关节动态接触及磨损预测问题研究提供了条件。

Contact mechanics of non-spherical hip joint replacements

Objective Due to the limitation of manufacturing techniques, possible design optimization selecting and influence of its wearing in clinical application, the bearing surface of hip joint replacements is presented as non-spherical geometry, and the finite element method can be used to study the contact mechanics behavior in such kind of non-spherical hip joint replacement. MethodsThe reconstructing of non-spherical articular surface based on spherical-grid-data model (SGDM) was developed to investigate the effect of contact mechanics of an ellipsoidal head against a spherical cup in a typical metal-on-metal hip joint replacement. Results The maximum contact pressure of the non-spherical bearing was decreased effectively, and meanwhile the contact area was increased when curvature radius of the ellipsoidal head around the centre of the contact zone was increased, while the effects of the cup inclination angle on the maximum contact pressure and contact area of the non spherical bearing under the same load showed relatively small, but the contact pressure distributions were different. Conclusions A well-controlled non-sphericity can improve the magnitude and distribution of contact pressures on metal-on-metal hip joint replacements. In addition, the developed model and evaluation method in this paper can be used for simulation of dynamic contact and wear prediction of non-spherical hip joint replacements.