Cementless coated and noncoated Mathys acetabular cups: radiographic and histologic evaluation

This study evaluated 185 cementless Mathys coated and uncoated acetabular cups inserted for total hip replacement since September 1984. All of the cups were high-density polyethylene. Sixty were uncoated (group A), 96 were coated with hydroxyapatite (group B), and 29 were coated with titanium (group C). Cup survival was assessed clinically, histologically, and radiographically, and a computer-assisted EBRA method was used to evaluate cup migration. After a mean follow-up of 8 years, five cups in group A that had previously shown migration were revised as a result of aseptic loosening, while no loosening of hip sockets occurred in groups B and C. These results suggest that Mathys cups should be used only if coated with hydroxyapatite or titanium. Furthermore, the histologic evaluation in four cups from groups B and C revealed normal bone formation without inflammation or fibrotic tissue around the cups, promising long-term survival.