四桩型胫骨假体基座的优化设计

目的通过三维有限元分析来研究和评定各种不同设计的四桩型膝关节胫骨假体基座在不同负荷下的生物力学特点,并对其进行优化。方法建立不同长短、粗细、位置四桩胫骨假体基座置换后膝关节的三维有限元模型,对比不同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,包括应力、应变、位移和接触变量。通过比较研究对四桩型胫骨平台假体基座的设计进行优化。结果在压力负荷和扭转力矩负荷下,不同设计的生物力学反应特点基本相似,没有明显的区别;而扭转力矩下如果去除胫骨平台骨质表面和金属基座下表面之间的接触影响后（假设二者之间为无摩擦的接触形式）,将固定桩变短、变细和内移使得反映假体固定强度的一些指标有不同程度的下降,不利于假体固定的旋转稳定性。结论在固定金属基座时胫骨平台骨质表面和金属基座下表面之间的固定起着主要的作用;四桩设计的金属基座,适当增加桩的长度和直径以及将固定桩适当外移有利于增加固定的旋转稳定性。

Optimization of four-pegged tibial plate designs: a three dimensional finite element analysis

Objective To evaluate the biomechanical features of different four-pegged tibial plate designs under different loads and to optimize the design.Methods Three dimensional finite element models of different four-pegged tibial plate designs（including different lengths,different diameters and different coronal plane locations of the four pegs） implanted on the tibia were constructed.And the models were tested under vertical compression loads and rotational loads in order to compare their biomechanical responses and fixation strength,such as strain,stress,displacement and contact variables. Results The general biomechanical responses of the different designs were similar under vertical loads and rotational loads.But when the contact effect between the downside of the tibial plate and the upside of the tibial bone was re- moved,shorter and thinner pegged plate and more medial positioned pegged plate showed decreased rotational fixation stability under rotational loads.Conclusion The fixation between the downside of the tibial plate and the upside of the tibial bone is important in prosthesis fixation.Proper increase of the lengths and diameters of the pegs,and more laterally positioned pegs seem to increase the rotational stability of the prosthesis.