A new surface structure with a regular patterning of the frictional surfaces of the artificial joints were designed to improve the wear problems.

The lubrication properties for the cup (ultra high molecular weight polyethylene, UHMWPE) vs. ball (Co-Cr alloy) were examined to evaluate the coefficient of friction, wear and surface roughness. The surface structure is a dent pattern, which has diameter of 0.3-0.8 mm, a pitch of 1.2 mm. In this study, such surface patterns were applied to artificial hip joints, and the effects of regular patterning on the frictional surface were examined using a pendulum type hip joint simulator.

The coefficient of friction between the cup and a patterned ball showed the same value between the cup and the non-patterned ball. However, the amount of wear of the cup, which was in contact with the patterned head, was only 45% that of the cup, which was in contact with the non-patterned head, and the surface roughness of the cup with the non-patterned head was three times greater than that of the cup with a patterned head.

These results demonstrate that the lubrication properties can be improved by patterning the frictional surface of the artificial joint. Consequently, patterning on the frictional surfaces can exted the life of an artificial joint.