Comparison of Polyethylene Wear between Highly Cross linked and Annealed UHMWPE and Conventional UHMWPE against Ceramic Heads in Total Hip Arthroplasty

The purpose of this study was to examine the effects of ceramic femoral head material on the wear of annealed, crosslinked ultra-high molecular weight polyethylene (UHMWPE) (XLPE) in total hip arthroplasty compared to non-crosslinked conventional UHMWPE (CPE). XLPE was fabricated by crosslinking with 60 kGy irradiation and annealing. Femoral heads made from zirconia and alumina ceramics, and cobalt-chrome (CoCr) of 22 mm or 26 mm diameter were used. In this study, the femoral head penetration into the cup was measured digitally on radiographs of 70 hips with XLPE and 50 hips with CPE. The average follow-up periods were 6.1 and 12.7 years, respectively. The steady wear rate of XLPE was significantly lower than those of CPE (0.002 versus 0.08 mm/year, respectively). Zirconia displayed increased wear rates compared to alumina in CPE; however, there was no difference among head materials in XLPE (0.0028, 0.011 and -0.009 mm/year for zirconia, alumina and CoCr, respectively). Neither head size or implantation period impacted XLPE wear. In contrast to CPE, XLPE displayed low wear rates surpassing the effects of varying femoral head material, size, implantation period and patient demographics.