陶瓷髋关节股骨头直径尺寸与动态微分离条件下边缘负载的关系

Relationship between femoral head diameter and edge load under dynamic micro-separation of ceramic hip joints

背景:建立人工髋关节动力学仿真模型能有效模拟人体髋关节股骨头与臼杯动态分离过程,并探究股骨头与臼杯分离条件下的边缘接触现象。目的:研究人工髋关节股骨头假体直径尺寸对髋关节动态微分离下边缘负载的影响,为陶瓷髋关节因边缘负载产生的早期高磨损问题提供生物力学分析基础,也为髋关节假体设计和临床应用提供理论依据。方法:利用前期已经验证过的仿真模拟方法,即基于Adams动力学仿真软件的人工髋关节边缘接触的动力学模型,模拟髋关节在步态周期内发生动态微分离和边缘接触的现象。结果与结论:(1)髋关节臼杯与股骨头动态微分离产生边缘负载的最大接触力值随股骨头尺寸增大而小幅减小;(2)髋关节假体体积磨损度量指数,即边缘接触力与其作用时间的乘积,随股骨头尺寸增大而增大,直径36 mm股骨头髋关节假体的磨损度量指数比直径28 mm股骨头髋关节假体大0.6%,直径55 mm股骨头髋关节假体磨损度量指数比直径28mm,36mm股骨头髋关节假体大2.7%;(3)提示陶瓷髋关节股骨头尺寸变化对边缘负载接触力影响较小。

BACKGROUND:The dynamic computational model of artificial hip joints can effectively simulate the dynamic separation of femoral head and acetabular cup and explore edge contact between the head and cup.OBJECTIVE:To study the effect of the femoral head diameter on the edge load under dynamic micro-separation of hip joints,to provide a basis for biomechanical analysis of ceramic hip joints corresponding to early high wear problems caused by edge loading,and provide theoretical analyses for hip prosthesis design and clinical application.METHODS:Using the previously validated method,the dynamic model of artificial hip joint for edge contact based on Adams dynamic simulation software was used to predict dynamic micro-separation and edge contact force in the gait cycle of the hip joint.RESULTS AND CONCLUSION:(1)The maximum contact force of the edge loading under micro-separation of the cup and femoral head slightly reduced as the femoral head size increased.(2)The severity of edge contact was computed as the product of the edge contact force and its acting time.The severity parameter ofφ36 mm head was 0.6%larger than that ofφ28 mm one.The parameter of diameter 55 mm hip was 2.7%larger than that ofφ28 mm andφ36 mm heads.(3)The change of the ceramic hip femoral head size has negligible effect on the edge loading.