Wear Resistance and Mechanical Properties of Highly Cross-linked, Ultrahigh–Molecular Weight Polyethylene Doped With Vitamin E

Our hypothesis was that cross-linked, ultrahigh–molecular weight polyethylene (UHMWPE) stabilized with vitamin E (α-tocopherol) would be wear-resistant and fatigue-resistant. Acetabular liners were radiation cross-linked, doped with vitamin E, and γ-sterilized. Hip simulator wear rate of vitamin E–stabilized UHMWPE was approximately 1 and 6 mg/million-cycles in clean serum and in serum with third-body particles, respectively, a 4-fold to 10-fold decrease from that of conventional UHMWPE. The ultimate strength, yield strength, elongation at break, and fatigue resistance of vitamin E–stabilized UHMWPE were significantly higher than that of 100 kGy–irradiated and melted UHMWPE, and were unaffected by accelerated aging. Rim impingement testing with 3.7-mm-thick acetabular liners up to 2 million-cycles showed no significant damage of the cross-linked liners compared with conventional, γ-sterilized in inert UHMWPE, vitamin E–stabilized liners. The data indicate good in vitro wear properties and improved mechanical and fatigue properties for vitamin E–stabilized, cross-linked UHMWPE.