Evaluation of tribological behavior of knee prostheses under cyclic load and velocity conditions

During walking motion, the tibial axis load and flexion-extension patterns in the knee joint are complex and these patterns may contribute to the formation of lubricating film. In order to evaluate tribological behavior of knee prostheses, the load and motion patterns were approximated using combinations of sinusoidal curves. The frictional behavior and lubricating film formation were examined under cyclic load and velocity conditions in a knee joint simulator. Fluid film formation in knee prostheses composed of metallic femoral and conductive silicone rubber tibial components was examined using the electric resistance method. The tribological severity was evaluated using the friction coefficient and degree of separation. The importance of the walking pattern in fluid film formation was demonstrated.