Examination of wear in duraloc acetabular components: Two- to five-year evaluation of hylamer and enduron liners

Abstract

To help increase the longevity of polyethylene components used in total joint arthroplasty, new forms of ultrahigh molecular weight polyethylene (UHMWPE) have been developed. This study reports on the in vivo performance of Hylamer (DePuy DuPont Orthopaedics, Newark, DE), a high crystalline form of UHMWPE, and on the performance of conventional Enduron polyethylene (DePuy, Warsaw, IN). With the use of a specially designed computer system, the time course of two-dimensional femoral head penetration into 80 Hylamer and 140 Enduron acetabular liners in situ from two to five years was compared. At the most recent follow-up (mean, 3.6 years), the rate of femoral head penetration into the Hylamer liners was lower than the rate of head penetration into the Enduron liners (0.15 mm/year versus 0.20 mm/year, P = .10). Temporal analysis revealed that the Hylamer liners had lower penetration rates than those of the conventional polyethylene liners in the first three postoperative years, but that head-penetrationrates between the two groups became similar with increased time in situ. Continued examination of both types of polyethylene components is imperative before conclusions on long-term performance can be drawn.