Background

dl-α-Tocopherol (vitamin E) blended ultra-high molecular weight Polyethylene (UHMWPE) was originally developed as a bearing material for use in knee prostheses ⁽¹⁾. The reduced biological response observed for vitamin E (VE) blended UHMWPE wear particles in in vitro experimentation ⁽²⁾ has also demonstrated the materials potential for use in other orthopedic applications, especially total hip arthroplasty (THR). However, due to the excellent results achieved by highly crosslinked UHMWPE in hip simulator testing ⁽³⁾, the use of VE blended UHMWPE in THR would similarly require crosslinking. It was previously reported that VE radicals are formed during radiation crosslinking of VE blended UHMWPE ⁽⁴⁾, and it is hypothesized that these VE radicals may negatively impact the materials biological activity. In this study, ascorbic acid 6-palmitate (lipophilic vitamin C) was applied to electron-beam-irradiated VE blended UHMWPE in an attempt to oxidatively reduce the VE radicals. Electron Spin Resonance (ESR) was used to measure the number of VE radicals within the material and evaluate the regenerating effect of ascorbic acid 6-palmitate.