REVISION FOR ASEPTIC LOOSENING OF UNCEMENTED CUPS IN 4,352 PRIMARY TOTAL HIP PROSTHESES - A REPORT FROM THE NORWEGIAN-ARTHROPLASTY-REGISTER

From September 1987 until January 1994 the Norwegian Arthroplasty Regi ster recorded 5,021 primary total hip replacements performed with unce mented acetabular components. We compared the survival until revision for aseptic loosening of the cup, in the 11 commonest types (n 4,352). The overall cumulative revision rate for the acetabular components wa s 3.2% after 5 years and 7.1% after 6 years, with large differences am ong the designs. With the hydroxyapatite (HA)-coated cups and the hemi spheric porous-coated cups, the failure rate was less than 0.1%. Of th e unthreaded hemispheric porous-coated cups, Harris-Galante and Gemini (n 626), none had been revised, and of the HA-coated cups, Atoll and Tropic (n 1,943), only 1 had been revised. For the threaded uncoated m etal-backed cups, the results varied from no revisions of the PM cups (n 148) to a cumulative 6-year revision rate of 21% for the Ti-Fit (n 300). The all-polyethylene Endler cups (n 334) had a cumulative revisi on rate of 14%. Women and patients with inflammatory arthritis had poo rer results. However, the type and the design of the cups were of far greater importance for the results than patient-related factors.