骨关节炎患者在不同步态角度下膝关节内部生物力学变化的有限元分析

Finite element analysis of biomechanical changes in the osteoarthritis knee joint in different gait flexion angles

背景:轻度膝骨关节炎患者在日常步态行走中容易诱发疼痛以及关节炎加剧,目前对于此类患者在步态屈膝角度下的膝关节内部生物力学行为变化情况尚不十分清楚,且文献报道较少。目的:基于已证实的轻度骨关节炎膝关节有限元模型,依据步态周期与屈膝角度的变化,模拟其在0°,10°,20°,30°这4个角度下的屈膝行为,研究股骨软骨、胫骨软骨和半月板上的应力分布特征及接触面积变化。方法:对轻度骨关节炎膝关节有限元模型定义材料属性,确定边界条件及不同屈膝角度下的轴向载荷,通过分析胫股关节中非骨性组织的Mises应力、Tresca应力及接触面积,研究膝关节内部的生物力学行为变化。结果与结论:有限元分析结果表明随着屈膝角度的增大,半月板、股骨软骨和胫骨软骨上的Mises应力峰值及Tresca应力峰值呈相对增大趋势,胫股关节总接触面积呈减小趋势,内侧半月板半脱位导致外侧峰值多大于内侧峰值,同时内侧间室接触面积减小,外侧间室的接触面积增大,在屈膝角度达到20°和30°时出现Mises应力峰值和Tresca应力峰值的最大值。结果表明,轻度骨关节炎膝关节在屈膝角度改变时,其内部应力和接触面积变化特征因内侧半月板半脱位而发生改变,内侧接触面积减小,应力峰值增大,外侧接触面积增大,应力峰值增大且增幅大于内侧,关节内部负载平衡打破可能导致关节软骨退变风险增加,促使膝骨关节炎病变的加剧。

BACKGROUND:Patients with mild knee osteoarthritis are prone to induce pain and aggravation of arthritis during daily gait walking.At present,the changes in the biomechanical behavior of the internal knee joints of such patients under the gait flexion angle are not very clear.There are few reports in the literature.OBJECTIVE:Based on the proven finite element model of the mild osteoarthritis knee joint,according to the change of gait cycle and knee flexion angle,to simulate the knee flexion behavior at four angles of 0°,10°,20°,and 30°,and to study the stress distribution characteristics and contact area changes of femoral cartilage,tibial cartilage,and meniscus.METHODS:The material properties of the finite element model of the mild osteoarthritis knee joint were defined.The boundary conditions and the axial load were determined under different knee flexion angles.By analyzing the Mises stress,Tresca stress,and contact area of the non-bone tissue in the tibiofemoral joint,the biomechanical behavior changes inside the knee joint were studied.RESULTS AND CONCLUSION:The results of finite element analysis showed that as the knee flexion angle increased,the peak Mises stress and the peak Tresca stress on the meniscus,femoral cartilage,and tibial cartilage showed a relatively increasing trend.The total contact area of the tibiofemoral joint showed a decreasing trend,and the medial meniscus subluxation caused the lateral peak to be larger than the medial peak.Meanwhile,the contact area of the medial compartment decreased and the contact area of the lateral compartment increased.When the knee flexion angle reached 20°and 30°,the peak of Mises stress and the peak of Tresca stress appeared.Results showed that when the knee flexion angle of the mild osteoarthritis knee joint changed,the internal stress and contact area change characteristics changed because of the medial meniscus subluxation.The medial contact area decreased;the peak stress increased;and the lateral contact area increased.The peak stress increased and the increase was greater than the inside.The breakdown of the internal load balance of the joint may increase the risk of articular cartilage degeneration and promote the aggravation of knee osteoarthritis.