膝内、外翻畸形对膝关节影响的三维有限元计算分析

Study of Biomechanic Effects on the Knee Joint Associated with the Genu Varum and Genu Valgum Deformities According to 3-D Finite Element Method

目的 通过对膝内、外翻畸形的三维模型进行有限元分析 ,了解膝内、外翻畸形对膝关节生物力学影响。方法 利用膝关节影像学资料 ,通过Super-Sap软件建立三维有限元模型 ,在内翻 30°至外翻 30°之间 ,按每 2°加载 ,计算各节点的应力应变情况。结果 ①正常膝关节内、外侧均表现为压应力。②膝内翻在 1 2°～ 1 8°之间应力显著集中于内侧胫骨平台。③膝外翻2 0°后应力集中于外侧胫骨平台。结论 膝内翻 1 0°、膝外翻 2 0°为应力集中的临界角度。

Objective Three-D finite element method was used to study the biomechanic effects on the knee joint associated with the genu varum and genu valgum deformities.Methods According to image of knee joint,the finite element were established with the software of Super-Sap,between the genu varum 30 degree and genu valgum 30 degree,we calculated the stress value on every node in the knee joint and determined their stain states at regular intervals of 2 degree deformity.Epoxy Resin materials were formulated according to the practical Youngs elastic modulus of the knee joint,then put them into the polarized light field with loads to observe their stress stripes of interference。Results ①There was a compressive stress on the medial and external sides of normal knee joint.②Stress on the medial side of knee can be increasing after the deformity genu varum 12 to 18 a level of degree.The focus of stress concentrated obviously the medial tibial plateau.③Stress on the external side of knee can be increasing obviously beyond 20 degree genu valgum deformity.The focus of stress mainly concentrated the external tibial plateau.Conclusion Twelve degree inversion or 20 degree eversion is the critical angel of knee joint stress concentration.