UNCEMENTED THREADED ACETABULAR CUPS - SHORT-TERM RESULTS OF 112 CASES

Between January 1982 and December 1987 we used 112 threaded acetabular cups in 102 patients undergoing total hip replacement. The clinical a nd radiographic results of 107 implants are reported in this survey. U sing the functional grading of the hip advocated by Merle d'Aubigne an d Postel, 62% can be classified as excellent, very good or good. On x- ray only 35% of the cups show neither radiolucency at the bone-implant interface nor migration of the component. There is a statistically si gnificant correlation between a radiolucency in 2 of the 3 areas at th e bone-implant interface and the clinical result. The revision rate fo r failure of the cup is 11.6% (13 implants). The actuarial survival of the threaded cup decreased from 0.95 in the 1st year to 0.75 in the 5 th year after implantation. Analysis of our failures and of published data suggest that the problem lies in the lack of primary bone integra tion. We describe our difficulties in assessing risk factors, in inter preting the radiographs and in the intraoperative determination of com ponent instability. The disappointing short term results have prompted us to abdandon the use of threaded cups.