Wear Testing of UHMWPE Tibial Components: Influence of Oxidation

An AMTI knee stimulator was used to evaluate the wear of UHMWPE tibial inserts which were gamma sterilized in air and displayed a high or low level of oxidation. After 5 million cycles, four out of five samples from the high oxidation group displayed subsurface cracking and/or delamination. The five specimens in the low oxidation group experienced burnishing only. These results indicate that gamma irradiation in air together with high oxidation due to shelf aging can increase susceptibility to wear. The appearance of the wear scars indicates that knee simulator testing is a valid method of producing burnishing, cracking, and delamination similar to that seen in-vivo.