Reduction of Total Knee Replacement Wear with Vitamin E doped highly cross linked UHMWPE

Introduction: Ultra high molecular weight polyethylene (UHMWPE) is a common bearing component in Total Knee Replacement (TKR) implants, and its susceptibility to wear continues to be the long-term limiting factor in the life of these implants. Novel material modifications have been introduced to reduce UHMWPE wear rates and thus improve the life of TKRs. Radiation and crosslinking of UHMWPE have been shown to reduce wear, but can give rise to free radicals in the crystalline regions of the polyethylene which can result in oxidative embrittlement and reduced fatigue life of the implant [1]. The addition of Vitamin E (VitE), a natural antioxidant, to the highly cross linked (HXL) UHMWPE has been shown to prevent oxidative degradation by donating a hydrogen atom to free radicals [2]. Although the mechanical properties of HXL VitE doped UHMWPE have been studied [3], very few implant wear testing studies have been performed to date. In this study, we hypothesize that VitE doped HXL UHMWPE inserts will exhibit a lower wear rate as compared to standard direct compression molded (DCM) UHMWPE inserts under physiologic loading during TKR simulation.