Highly cross-linked polyethylene: the debate is over--in opposition

Highly cross-linked polyethylene compared to conventional ultra high molecular weight polyethylene (UHMWPE) results in significantly decreased wear in hip simulators and early prospective randomized clinical studies. However, the contact stresses in a total knee bearing surface are much higher than in a total hip. As a result, fatigue wear mechanisms occur more typically in total knee compared with total hip arthroplasty. Cross-linking reduces the mechanical properties of UHMWPE including fatigue crack propagation resistance, which may limit its role in total knee arthroplasty. Although the in vitro and in vivo studies provide compelling evidence that highly cross-linked polyethylene may improve the longevity of total hip arthroplasty, it does not appear to offer similar benefits for total knee arthroplasty.