Contact Analysis of Artificial Knee Joint during Gait Movement.

Ultrahigh-molecular-weight polyethylene (UHMWPE) is used for the material of the contact surface in artificial knee joints, but the wear of this material becomes a serious problem to extend the life of the joint. In order to understand the wear mechanism of the UHMWPE in gait movement, the cyclic contact behavior of the UHMWPE is analyzed using the constitutive equation for cyclic plasticity because the UHMWPE is subjected to cyclic contact deformation during gait movement. In this analysis, the contact pressure distribution which is determined from the simple indentation analysis of femoral and tibial components is translated on the UHMWPE, changing its value so as to simulate the realistic movement of the joint. For the analytical model, the posterior cruciate ligament (PCL) retention-type artificial knee joint is employed. As a result, it is clarified that local deformation is caused in this artificial knee joint, and the effect of the stress history, to which the UHMWPE has been subjected, on the wear machanism of the UHMWPE is significant.