THE EFFECT OF PRE-IRRADIATION VACUUM STORAGE ON THE OXIDATION AND WEAR OF RADIATION STERILIZED UHMWPE

摘要

The adverse biological response to ultra-high molecular weight polyethylene (UHMWPE) wear debris in total joint replacement warrants the need for the material's improved wear resistance. The reaction of oxygen with radiation-induced free radicals within UHMWPE leads to oxidative degradation of the material. This work examines the effect of storing UHMWPE in vacuum at an elevated temperature (70℃) prior to gamma irradiation in an attempt to remove preexisting free oxygen from within the material and hence reduce oxidation that occurs during the irradiation process. UHMWPE specimens, both with and without pre-irradiation vacuum were gamma irradiated to either 4 or 10 Mrad and then artificially aged to simulate the material's long-term oxidative. Oxidation, degree of crosslinking, and wear resistance were measured. The benefit of pre-irradiation vacuum in terms of reduced oxidation, higher degree of crosslinking, and improved wear resistance measured after aging was observed for both 4 and 10 Mrad of irradiation