摘要
目的 研究UKA胫骨托盘背部设计对单髁膝关节置换(unicompartmental knee arthroplasty,UKA)骨-假体固定界面的生物力学影响.方法 构建膝关节内侧置换的固定式UKA有限元模型,以膝关节行走运动下的关节载荷和关节运动为边界条件,对比研究大龙骨型、小龙骨型、两立柱带鳍骨型、三斜立柱型和三直立柱型UKA胫骨托盘背部设计下胫骨von Mises等效应力、骨-假体固定界面接触应力以及微动的差异.结果 在膝关节内侧最大受力时刻,相对于两立柱带鳍骨型的胫骨von Mises等效应力、骨-假体固定界面接触应力和微动,大龙骨型分别减小8%和 15.9%、增大 9.9%;小龙骨型分别减小12.3%、增大7.5%和1.6%;三斜立柱型分别减小10%和10.5%、增大1.2%;三直立柱型分别减小 7.7%、14.7%、1.6%.而骨-假体固定界面的最大微动发生在步态周期 21%时刻,相对于两立柱带鳍骨型的骨-假体固定界面微动,大龙骨型增大 1.2%,小龙骨型增大 1.6%,三斜立柱型减小 0.4%,三直立柱型减小 2.3%.结论 为了提高胫骨假体的长期固定效果,建议UKA胫骨托盘设计应重点考虑两直立柱带鳍骨或小龙骨的组合设计,从而有效地平衡应力传递和界面微动,在保证假体稳定性的同时降低无菌性松动的风险.
Abstract
Objective To investigate the biomechanical effects of the backside design of tibial trays on the bone-prosthesis fixation interfaces in unicompartmental knee arthroplasty(UKA).Methods Finite element models of medial knee arthroplasty were constructed using a fixed UKA prosthesis.The knee joint load and joint motion under walking motion were considered as boundary conditions,and the differences in tibial von Mises stress,contact stress,and micromotion of the bone-prosthesis fixation interface of the UKA tibial trays with big keel,small keel,two-peg with fin,three-oblique peg,and three-upright peg types were compared.Results At the maximum medical knee force moment,compared to the two-peg with fin type,the tibial von Mises stress,contact stress,and micromotion of the bone-prosthesis fixation interface decreased by 8%and 15.9%and increased by 9.9%for the big keel type;decreased by 12.3%and increased by 7.5%and 0.9%for the small keel type;decreased by 10%,10.5%,and increased by 1.2%for the three-oblique peg type;and decreased by 7.7%,14.7%,and 1.6%for the three-upright peg type,respectively.However,the maximum micromotion of the bone-prosthesis fixation interface occurred at 21%of the gait cycle.Compared to the two-peg with fin type,the micromotion of the bone-prosthesis fixation interface increased by 11.6%for the big keel type,increased by 1.6%for the small keel type,decreased by 0.4%for the three-oblique peg type,and decreased by 2.3%for the three-upright peg type.Conclusions To improve the long-term fixation effects of tibial prostheses,it is recommended to focus on a two-upright peg with fin or small keel designs when UKA tibial trays are designed,which can effectively balance the stress transfer and interface micromotion,thereby ensuring prosthesis stability and reducing the risk of aseptic loosening.
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