摘要目的 通过有限元分析来评定单柄和四桩设计的膝关节假体基座在不同负荷下的生物力学特点.方法 建立单柄和四桩两种胫骨假体基座置换后膝关节的三维有限元模型,对比两种设计在压力负荷和扭转力矩负荷下的不同生物力学反应特点,如峰值接触压力、峰值接触滑动距离、峰值接触应力和金属基座的总位移、骨的峰值Mises应力,来了解两种不同设计的固定强度.同时在假体基座下方松质骨区域的前、后、左、右各选取一条路径,测量压力负荷下此两种基座下方的松质骨每个路径上15个点的Mises应力值,通过该指标来比较这两种设计对近端松质骨的应力遮挡.结果 单柄设计和四桩设计假体基座在1600 N压力负荷和10 N·m扭转力矩负荷下的峰值接触压力、峰值接触滑动距离、峰值接触应力和金属基座的总位移、骨的峰值Mises应力等不同生物力学指标的结果基本相似,没有明显区别;在压力负荷下,单柄设计的基座下方松质骨在相同路径上各点所承受的Mises应力值均小于四桩设计的胫骨假体基座下方松质骨相应位置各点的Mises应力值.结论 四桩设计的基座和单柄设计的基座在固定强度上基本相同.从生物力学角度相比较,单柄设计的基座对胫骨近端松质骨的应力遮挡效应要大于四桩设计的基座.

abstractsObjective To evaluate the biomechanical features of four-pegged and stemmed tibial plate designs under different loads. Methods Three dimensional finite element models of four-pegged and stemmed tibial plate designs implanted on the tibia were constructed. The models were tested under vertical compression loads and rotational loads to compare their biomechanical responses and fixation strength, such as peak contact pressure and contact stress, peak contact sliding distance, displacement of the tibial plate,and peak Mises stress. In order to compare their stress shielding effect on the proximal tibia, four paths in four different locations of the proximal tibial cancellous bone were selected, and the Mises stress in 15 different points of each path were compared. Results The general biomechanical responses of the two designs,as peak contact pressure and contact strain, peak contact sliding distance, displacement of the tibial plate,and peak Mises stress,were similar under vertical loads and rotational loads. The Mises stress of all 15 points in four paths in the cancellous bone below stemmed tibial plate was smaller than that of below fourpegged tibial plate under vertical compression load. Conclusion Four-pegged tibial plate was comparable with stemmed tibial plate in fixation strength. The biomechanical effect of stress shielding in the proximal tibia of the stemmed tibial plate was bigger than that of the four pegged tibial plate.