基于有限元方法的全髋关节假体个体化选型分析

Individualized selection of total hip prosthesis based on finite element method

目的研究ISO7206标准对全髋关节置换术临床应用的指导意义。方法建立肌骨数值模型，对正常行走步态进行仿真，以获得下肢的运动学和动力学参数；建立对应的全髋关节假体有限元模型，应用步态载荷进行计算，并对比ISO标准的有限元模型计算结果。结果正常行走步态下，髋关节力分别在20％和54％步态周期出现峰值，以此作为有限元计算的步态载荷，得到20％步态周期时假体应力最大；松动模型中假体柄上最大应力大于无松动模型中假体柄上最大应力，且应力分布趋势存在差异；分析对比ISO测试和不同体重人体步态载荷下的假体最大应力，得到ISO测试中最大应力水平对应108～142kg体重载荷下的假体最大应力。结论ISO测试中合格的假体可满足100kg体重人体正常步态下的强度要求。

Objective To investigate ISO 7206 standard used as a guidance for clinical selection of total hip prosthesis. Methods Kinematics and dynamics process of normal walking gait was simulated by establishing a numerical musculoskeletal model; the corresponding finite element model of total hip prosthesis was constructed, and gait loads were applied to calculate stress distribution on prosthesis, which were compared with that on ISO finite element model. Restdts Peaks of hip joint reaction forces were achieved at 20% gait and 54% gait during normal walking gait, which were used as gait loads for finite element simulation, and the results showed that the maximum Von Mises stress of prosthesis was reached at 20% gait. The maximum Von Mises stress of prosthesis in loosening model was higher than that in non-loosening model, and some differences existed in the distribution pattern. The maximum stresses of prosthesis both under ISO loads and gait loads by different body weights were analyzed and compared, and the maximum stress of prosthesis under ISO loads was equivalent to that under gait loads by body weight between 108 kg and 142 kg. Conclusions The prosthesis that passed ISO test can meet the strength requirement for normal gait loads of 100 kg body weight.