CEMENTED ACETABULAR REVISION OF ASEPTIC C EMENTED HIP ARTHROPLASTIES LOOSENING USING A SUPERIOR STRUCTURAL BONE-GRAFT AND A MULLER RING

Introduction One reason for the limited longevity of total hip replace ment is the progressive bone loss resulting from iterative loosenings of acetabular components. In the early 80's was developed an experienc e at our institution for revision surgery of aseptically failed cement ed acetabular components using a Muller ring. At that time, this devic e was used in combination with structural grafts. This appeared to us to be the safest method to adress severe acetabular destructions. We a re now able to report long term results. Material and methods We carri ed out a retrospective study on 81 cemented acetabular revision arthro plasties performed at our institution between 1981 and 1991. In all ca ses, there was a segmental or an important cavitary roof defect. Recon struction of the acetabulum was performed using a superior structural bone graft combined with a Muller ring. Results are given with a mean follow up of 8 years (5-14 years), except in the survivor analysis, in which all patients were included. Results There was 15 iterative asep tic loosenings of the acetabular component (in which 5 repeated revisi ons). Using iterative aseptic loosening of the acetabular component re vised or not as an end point, the 10 year cumulative survival rate (CS R) was 0,72 +/- 0,14 and the 11 year CSR was 0,55 +/- 0,24. The positi on of the hip biomechanical center, the polyethylene thickness, or the type of the superior defect (segmental or cavitary) were not found to influence significantly roentgenographic results. Discussion Reconstr uction of severely destroyed acetabuli using this method gave satisfac tory results within the first decade. However, the hip function could not be reliably maintained over 10 years. Mechanical failures were rel ated to resorption of weight bearing structural bone grafts. Aseptic i terative loosenings are often moderately symptomatic and yearly roentg enographic controls are necessary to detect late migrations. The lack of long term follow up may result in major bone loss, which can impair the conditions of iterative acetabular reconstructions.