COMPLICATIONS OF TOTAL HIP-ARTHROPLASTY ASSOCIATED WITH THE USE OF ANACETABULAR COMPONENT WITH A HYLAMER LINER

We observed early failure and radiographic signs of accelerated wear a s early as one to three years after insertion, without cement, of a me tal-backed acetabular component with a liner made of Hylamer (DePuy), This finding prompted us to review a larger cohort of patients in whom that liner had been used, Two hundred and thirty-three components wit h a Hylamer liner, evaluated at a minimum of two years, had a mean rat e of wear of 0.27 millimeter per year compared with 0.12 millimeter pe r year for a contemporaneous group of fifty acetabular cups with a con ventional ultra-high molecular weight polyethylene liner made by anoth er manufacturer, At a mean of 3.2 years, we found a significant differ ence (p < 0.000000006) between the mean rate of wear (0.20 millimeter per year) when the Hylamer liner articulated with a DePuy modular coba lt-chromium femoral head and the mean rate (0.29 millimeter per year) when the liner articulated with an Osteonics modular cobalt-chromium f emoral head, Radiographic evaluation revealed a significant correlatio n between the total linear wear and the prevalence of osteolytic lesio ns (r(2) = 0.76, linear regression analysis), We found that wear of 1. 5 millimeters or more could be detected by the unaided eye, Because of the positive correlation between osteolysis and wear of 1.5 millimete rs or more, we defined a hip with a liner that had that amount of wear as a hip at risk, We concluded that the wear characteristics of a Hyl amer liner in vivo are inferior to those of a conventional ultra-high molecular weight polyethylene liner, Also, the rate of wear of the lin er is greater when the femoral head is from a manufacturer other than DePuy. A patient who has a total hip replacement that includes a Hylam er liner should be monitored frequently for signs of wear and osteolyt ic changes, Additional investigations, with longer durations of follow -up and larger populations, are needed to understand fully the importa nce of our findings.