Cam型髋关节撞击综合征关节软骨接触力学的有限元分析

Finite element analysis on contact mechanics of cartilage in hips with Cam type femoroacetabular impingement

目的通过有限元方法探讨不同严重程度的Cam型髋关节撞击综合征(femoroacetabular impingement,FAI)关节软骨接触力学的变化。方法建立正常髋关节及不同α角的Cam型FAI髋关节三维有限元模型,计算行走、坐下、起立等日常活动下的关节软骨接触压力和应力。结果完整步态周期加载过程中,不同α角的Cam型FAI软骨接触压力分布与正常髋关节接近,无高接触压力和Von Mises应力集中区域;坐下、起立加载过程中,Cam型FAI软骨接触压力均大于正常髋关节,且随α角的增加而增大,其接触区域主要位于髋臼缘前上方,局部出现过高压力和Von Mises应力集中。结论 Cam型FAI软骨接触力学变化的关键影响因素是运动方式,关节软骨过高的接触压力和Von Mises应力,可能是其引起软骨退变并最终导致骨性关节炎的力学原因。

Objective To compare contact mechanics of cartilage in normal hip and that in hip with Cam-type fem- oroacetabular impingement （FAI） using finite element method. Methods The 3 D finite element models of normal hip and Cam-type FAI hip joints with varied Alpha angles were constructed. The contact pressures and stresses of intra-arUcular cartilages during routine daily activities, such as walking, sitting and standing, were calculated. Results During the whole gait cycle, the distribution of cartilage contact pressures on Cam-type FAI hip models with varied Alpha angles was similar to that in normal hip model, and no concentrated areas of high contact pres- sures and Von Mises stresses appeared. While during the motion of sitting and standing, the cartilage contact pressure on Cam-type FAI hip models was higher than that in normal hip model and increased with the Alpha angle increasing, and the contact area was mainly located at anterosuperior region of acetabular rim, where a con- centration of high contact pressures and Von Mises stresses appeared, Conclusions Mode of motion is the key factor which causes changes of cartilage contact mechanics in Cam-type FAI joints. Abnormally high cartilage contact pressures and Von Mises stresses might be the inducement to cartilage degeneration and eventually lead to osteoarthritis.