新型无柄股骨假体应力分布的有限元分析

Finite element analysis of new stemless femoral prosthesis

目的通过对比传统有柄股骨假体的应力分布来研究新型无柄股骨假体的生物力学性能。方法利用真实人体股骨上端的CT扫描图像,建立完整股骨、两个或三个固定螺钉的无柄假体、传统有柄假体的三维有限元模型。模拟人单腿直立的载荷情况,分析和比较每种模型的VonMises应力分布。结果(1)无柄假体股骨上的VonMises应力比传统有柄假体和完整股骨上的都要高;(2)与传统有柄假体相比,防止了应力遮挡效应的产生。(3)两个或三个固定螺钉的无柄假体在股骨的VonMises应力分布上没有明显差别。结论新型无柄假体可以防止应力遮挡效应,和传统有柄假体相比能够使股骨上的应力分布更加符合实际的生理情况。

Objective： To investigate the biomechanical performance of a newly designed cervico-trochanteric stemless prosthesis by comparing the stres distribution with that of the traditional stem-type porous-coated anatomic prosthesis. Methods Using CT scanning photographs of real femur, three-dimensional finite element models were created for the intact, cervico-trochanteric （with two or three fixation screws）, and porous-coated anatomic implanted femora with the geometry of a standardized real femur. Analysis was performed for a loading condition simulating the single-legged stance. The von Mises stress distributions of each model were analyzed and compared. Results The results can be summarized as follows： （1） Von Mises stress in the proximal, medial femur for the carvico-trochanteric implanted model was higher than that of the intact model and the porous-coated anatomic implanted model; （2） stress-shielding effect of the cervico-trochanteric models （with two or three fixation screws） were eliminated as compared with the porous-coated anatomic model; （3） no obvious difference in von Mises stress distribution for the cervico-trochanteric implanted model with two or three fixation screws. Conclusion The cervico- trochanteric femoral prosthesis may reduce the stress-shielding effect of the proximal femur and achievea more physiological stress distribution on the proximal femur than that of the porous-coated anatomic prosthesis.