个性化踝关节假体的设计及三维有限元分析

Design and 3D finite element analysis of personalized ankle prosthesis

目的针对当前踝关节假体失效率高、临床应用风险大的问题,提出一种个性化解剖型踝关节假体的设计。方法首先建立正常人体足踝系统的三维有限元非线性模型,对模型的有效性进行验证;设计解剖型踝关节假体,对全踝关节假体置换进行几何仿真,建立假体-足踝系统的三维有限元模型;施加步态载荷,计算分析假体的生物力学特性。结果正常踝关节系统足底最大接触应力为214.6 k Pa,足骨最大等效应力为8.96 MPa。对比文献与仿真所得足底反力与足骨应力,验证了正常足踝有限元模型的可靠性。假体植入后,仿真所得距骨钛合金假体、聚乙烯衬垫、胫骨假体等效应力峰值分别为23.88、19.24、73.01 MPa,足踝假体应力相较正常足踝应力有大幅度上升。结论有限元分析的对比结果考察了个性化踝关节假体的可行性,为进一步假体设计优化以及临床应用提供参考。

Objective To propose a personalized design of anatomic ankle prosthesis that can avoid and reduce the high failure rate and risk of ankle prosthesis in clinic. Methods The 3D finite element non-linear model of normal human ankle system was established and verified. The anatomic ankle prosthesis was then designed to simulate total ankle replacement, and the 3D finite element model with both the prosthesis and ankle system was established. The biomechanical characteristics of this prosthesis were calculated and analyzed after gait loads were applied. Results For the normal ankle system, the maximum plantar contact stress was 214.6 kPa and the maximum Von Mises stress of foot bone was 8.96 MPa. The reliability of the normal ankle system model was verified by comparing the simulated results with those reported by literature. After the prosthesis implantation, the simula- ted maximum Von Mises stresses of talus prosthesis, tibial UHMWPE liner, tibial prosthesis were 23.88, 19.24 and 73.01 MPa, respectively. The stress of the ankle prosthesis increased drastically compared with that of normal ankle system. Conclusions The comparison results by finite element analysis examine the feasibility of the personalized ankle prosthesis, and provide references for optimization of prosthesis design and its clinical application.