BACKGROUND:Three-dimensional finite element simulation has been widely used in biomechanics. However, there is little research in knee joint replacement. The study of femoral prosthesis is less. OBJECTIVE:To analyze the optimal positioning parameters of knee replacement and femoral prosthesis implantation, and to verify the efficacy of Gemini-PS knee prosthesis in total knee arthroplasty. METHODS: (1) Knee finite element model in total knee replacement was constructed. Orthogonal experiment was performed in femoral osteotomy positioning parameters. The shift amount A, external rotation degree B, and valgus degree C of femoral prosthesis were selected as the relevant factors for orthogonal experiment. Three values were taken for each parameter to establish orthogonal tables. Nine experimental combined knee replacement finite element models were created and analyzed with finite element. Analysis of variance and range analysis were used by optimization. (2) Totally 42 patients (47 knees) with knee osteoarthritis received total knee arthroplasty with Gemini-PS knee joint prosthesis. Knee joint function was evaluated after replacement with Hospital for Special Surgery knee score and American Knee Society knee score. Knee pain was assessed with Visual Analogue Scale score. RESULTS AND CONCLUSION:(1) Minimal polyethylene substrate surface compressive stress peak was translation 0 mm, external rotation of 3°, valgus 6°; the peak stress was 15.9 MPa. Among the influential factors, the effects of internal and external translation were larger than that of external rotation angle, and greater than that of valgus angle. The optimal positioning parameter combination was pan 0 mm, external rotation 3°, valgus 6° by range analysis and variance analysis. Orthogonal experiment was valid by simulation. (2) 42 patients were folowed up for 12-36 months. One patient affected subcutaneous fat liquefaction of the lower segment of the incision. Hospital for Special Surgery knee score and American Knee Society knee score were significantly higher after implantation (P < 0.05). Visual Analogue Scale score was significantly lower after replacement (P < 0.05). X-ray films showed that osteolysis, dislocation or loosening was not found. The recovery of knee joint was good after operation. (3) These findings%背景：三维有限元仿真分析在生物力学中有着广泛应用，但在膝关节置换中的研究不多，对股骨假体的研究也比较少。 目的：有限元分析膝关节置换股骨假体置入的优化定位参数，并对Gemini-PS膝关节假体全膝关节置换进行临床验证。 方法：①构建全膝关节置换膝关节有限元模型，对股骨假体截骨定位参数进行正交实验，选择股骨假体的平移量A、外旋度数B、外翻度数C 3个参数作为正交实验的相关因素，每个参数取3个值建立正交表，创建9个实验组合的全膝关节置换膝关节的有限元模型，对9个模型进行有限元分析，通过优化处理进行方差和极差分析。②纳入42例(47膝)中老年膝骨关节炎患者，采用Gemini-PS 膝关节假体进行全膝关节置换，采用美国特种外科医院膝关节评分及美国膝关节协会评分评价置换前后膝关节功能，以疼痛目测类比评分评估置换前后膝关节疼痛程度。 结果与结论：①聚乙烯衬底表面压应力峰值最小的为平移0 mm，外旋3°，外翻6°组合，压应力峰值为15.9 MPa；聚乙烯衬垫表面压应力的影响因素中，内外平移的影响大于外旋角度的影响大于外翻角度的影响；通过极差分析和方差分析发现股骨假体置入的最佳定位参数组合为平移0 mm，外旋3°，外翻6°；通过仿真计算证明正交实验是有效的；②42例患者均得到随访，随访时间12-36个月，1例发生术口下段皮下脂肪液化；置换后末次随访患膝美国特种外科医院膝关节评分及美国膝关节协会评分均较置换前显著提高(P <0.05)；置换后疼痛目测类比评分较置换前显著降低(P <0.05)。X射线检查未发现骨溶解、假体脱位及松动等并发症，置换后膝关节功能恢复良好；③结果提示，股骨假体置入位置的微小变化都会引起聚乙烯衬垫表面压应力峰值的异常分布，全膝关节置换术中对股骨假体进行准确定位可以取得良好的置换效果。
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