Surface cross-linked UHMWPE can enable the use of larger femoral heads in total joints

Limiting cross-linking to the articular surfaces of ultrahigh molecular weight polyethylene (UHMWPE) to increase wear resistance while preventing detrimental effects of cross-linking on mechanical strength has been a desirable goal. A surface cross-linked UHMWPE can be achieved by blending UHMWPE with a free radical scavenger, such as vitamin E, consolidating the blend into an implant shape, extracting the vitamin E from the surface, and radiation cross-linking the surface extracted blend. This process results in high cross-link density in the vitamin E-depleted surface region because vitamin E hinders cross-linking during irradiation. In this study, we described the properties of successful extraction media and the manipulation of the wear and mechanical properties of extracted, irradiated blends. We showed that these formulations could have similar wear and significantly improved mechanical properties compared to currently available highly cross-linked UHMWPEs. We believe that these materials can enable thinner implant forms and more anatomical designs in joint arthroplasty and may provide a feasible alternative to metal-on-metal implants. (c) 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:5966, 2012