全膝关节置换股骨假体植入定位参数有限元分析及优化

摘要

Objective To optimize the positioning parameters of the femoral component in order to reduce the peak surface pressure on the polyethylene insert by using finite element analysis and orthogonal experiment. Methods According to the total knee arthroplasty( TKA ) surgical technique, finite element models of the prosthetic knee were developed. As the variables of the orthogonal experiment, valgus angle, external rotation angle and medial-lateral translation were determined in this study. Finite element analysis of the prosthetic knee was performed to study the peak surface pressure distribution on the polyethylene insert following the definition of material properties, boundary conditions and load. Based on the obtained results, the effect of each variable was evaluated and compared through the range and variance analysis. The optimum positioning parameters of the femoral component, which resulted in the minimum peak pressure on the polyethylene insert, was defined. Results The peak surface pressure distributions of nine finite element models of the prosthetic knee required in this study were obtained. Based on the range and variance analysis, it was conformed that the effect on the peak pressure value on the polyethelene insert was: the medial-lateral translation > the external rotation angle > the valgus angle, and the optimum positioning parameters were: 6° of valgus, 3 ° of external rotation and 0 mm of medial-lateral translation. Conclusions The peak pressure distribution on the polyethylene insert is sensitive to the femoral component positioning, and small positioning change can result in abnormal pressure distribution at the interface between the femoral component and polyethylene insert. Therefore accurate positioning of the femoral component is important in actual TKA surgery.%目的 通过有限元分析,结合正交试验方法,优化膝关节股骨假体植入的定位参数,有助于降低聚乙烯衬垫表面压应力峰值以减少磨损.方法 依据全膝关节置换(TKA)基本原则,构建TKA膝关节有限元模型,以股骨假体外翻角度、外旋角度以及内外平移量作为正交试验的影响因素,对模型进行材料属性定义、边界条件建立并施加载荷,以聚乙烯衬垫上表面压应力峰值为研究指标,进行有限元分析,并对分析结果进行极差和方差分析,比较各因素变化对聚乙烯衬垫上表面压应力分布的影响,确定聚乙烯衬垫上表面压应力峰值最小的股骨假体植入定位参数的最优组合.结果 通过有限元分析获得不同参数组合下9个TKA膝关节有限元模型聚乙烯衬垫上表面的压应力峰值,由极差分析,明确内外平移对分析结果影响最大,其次是外旋角度,外翻角度影响最小.确定股骨假体植入定位参数最优组合为外翻6°、外旋3°、平移0 mm.结论 聚乙烯衬垫所受的压应力峰值受股骨假体位置变化影响,微小的植入位置变化可导致股骨-聚乙烯衬垫假体间的应力异常分布,提示术中要对股骨假体进行精确定位.