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Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_9 | Pages 102 - 102
1 May 2016
CHEMICAL CROSS-LINKED UHMWPE CONTAINING VITAMIN E
Oral E Gul R Doshi B Neils A Kayandan S Muratoglu O
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Introduction

Highly cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is the most common bearing surface used in total joint arthroplasty due to its excellent wear resistance. While radiation cross-linking is currently used, cross-linking using a cross-linking agent such as a peroxide can also be effective with improved oxidative stability, which can be achived by an antioxidant such as vitamin E. The peroxide cross-linking behavior of UHMWPE in the presence of vitamin E was unknown. We investigated the cross-linking behavior and the clinically relevant mechanical and wear properties of peroxide cross-linked, vitamin E-blended UHMWPE.

Materials and Methods

Medical grade UHMWPE (GUR1050) was blended with vitamin E and the peroxide (2,5-Dimethyl-2,5-di(t-butylperoxy)hexyne-3 or P130) before compression molding. Various vitamin E (0.1, 0.2, 0.3, 0.5, 0.6, 0.8 and 1.0 wt%) and peroxide concentrations (0.5, 1 and 1.5 wt%) were studied. The cross-link density was calculated as previously described (Oral 2010). The wear rate was determined using a custom-designed pin-on-disc wear tester against CoCr polished discs at 2 Hz and a rectangular path of 5 × 10 mm in undiluted bovine serum (Bragdon 2001). Tensile mechanical properties were determined using Type V dogbones according to ASTM D638. Oxidative stability was determined using oxidation induction testing (Braithwaite 2010). Double-notching and IZOD impact testing was performed according to ASTM D256. Samples prepared with vitamin E concentrations of 0.3 wt% and above and P130 concentrations of 0.5 and 1 wt% were also terminally gamma sterilized. Controls were 150-kGy irradiated vitamin E blends of UHMWPE.

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