The Effect of Sequential Irradiation and Annealing on Wear Performance of Polyethylene

INTRODUCTION Highly crosslinked polyethylenes were introduced for hip arthroplasty more than 10 years ago [1]. The creation of highly crosslinked polyethylenes involves irradiation of the material followed by annealing or remelting. Higher doses of irradiation are desirable because it provides a sufficient level of cross-linking for wear reduction, which is why highly crosslinked polythethylenes are typically irradiated between 50-100 kGy [1,2]. One particular second generation highly crosslinked polyethylene uses a sequential irradiation and annealing process to achieve a final irradiation dose of 90 kGy. It is believed that the sequential process produces wider cross-links and provides more chain mobility for additional crosslinking while preserving the crystalline structure of the polyethylene [1,3]. The purpose of this study was to assess the wear performance of polyethylene with a single high dose of irradiation and annealing in comparison to sequentially irradiated and annealed polyethylene to determine if the sequential treatment process truly has an effect.