Effect of shelf versus accelerated aging of UHMWPE on delamination in knee wear simulation

Severe delamination wear, fracture and subsurface embrittlement caused by oxidation have been observed in gamma-irradiation-sterilized UHMWPE tibial components of knee prostheses. In the present study, gamma-air-sterilized, shelf aged UHMWPE disks delaminated and fractured within a few hours of testing in a ball-on-flat knee wear simulator. In an earlier study, gamma-air-sterilized disks subjected to accelerated aging showed only moderate adhesive wear in 8 week wear tests. The fact that established methods of accelerated aging did not cause clinically relevant damage should be noted because these methods are commonly used in the evaluation of new types of UHMWPE developed for clinical use.