镍钛记忆合金无柄股骨假体的生物力学研究

Biomechanical study of Ni-Ti shape memory alloy stemless femoral prosthesis

[目的]评价新型记忆合金无柄股骨假体的生物力学特性。[方法]利用成人股骨的螺旋CT图像,使用CAD(计算机辅助设计)软件建立股骨的三维模型,根据股骨模型的结构设计新型记忆合金股骨假体。建立三维股骨模型、传统有柄假体及新型记忆合金无柄股骨假体有限元模型。在静态载荷及行走载荷下,对各种模型的Von Mises应力分布进行分析和比较。[结果]记忆合金无柄股骨假体股骨上的应力分布与正常股骨相近。记忆合金无柄假体股骨近端的应力明显大于传统有柄假体,与正常股骨的相近。记忆合金爪子本身的Von Mises应力最大值仅为13.23MPa,应力分布较均匀没有应力集中的现象。[结论](1)记忆合金无柄假体具有优良的生物力学特性能有效避免应力遮挡效应的发生;(2)记忆合金爪子的固定方式能达到既固定可靠又减少应力集中现象的目的。

[ Objective ] To evaluate the biomechanical features of Ni-Ti shape memory alloy stemless femoral prosthesis. [ Method ] Using CT （ computer tomography） scanning photographs of adult femur, three-dimensional model of the femur was built by CAD （computer aided design） software. Based on the the structure of femoral model, shape memory alloy stemless femoral prosthesis was designed. Three-dimensional finite element model was created for the normal femur, Ni-Ti shape memory alloy stemless femoral prosthesis, and traditional stemmed hip prosthesis. Under static loads and walking loads ,the Von Mises stress distributions of each model were analyzed and compared. [ Result ] The stress distribution of shape memory alloy stemless femoral prosthesis was not obviously different from normal femur, stemless femoral prosthesis＇s proximal femoral stress was close to that of normal femoral model but significantly higher than traditional stemmed hip prosthesis. Von Mises stress of memory alloy claws was distributed evenly, and the Max was only 13.23Mpa, there was no stress concentration. [ Conclusion ] （ 1 ） Ni-Ti shape memory alloy stemless femoral prosthesis has great biomechanical properties, may reduce the stress-shieding effect of the proximal femur. The fixed method that use memory alloy claws can make prosthesis fixed firmly to the bone and reduce stress concentration.