[Acetabular revision surgery with the oblong revision cup : clinical and radiological results of 217 cases]

Abstract

Background: Deficiencies of the acetabular bone stock are an increasing and challenging problem in revision hip surgery. The LOR oblong revision cup is a valuable option in revision hip surgery. The purpose of this study was to assess outcomes with the LOR revision cup in hips with acetabular bone deficiency, analyze the complications, and identify predictors of survival rate.

Patients and methods: From 1996 to 2002, 217 revision surgeries were performed with LOR cups. The mean patient age at operation was 67.5 years (range 29-87 years). The mean postoperative follow-up was 4 years (range 4-100 months). The patients were evaluated clinically and with the Harris hip score (HHS), UCLA score, and WOMAC index. A continuous radiographic assessment was done to detect heterotopic ossifications and radiolucencies or loosening on the basis of the Mayo hip score. Predictors of survival rate were estimated using Kaplan-Meier survivorship analysis.

Results: Twenty-four patients (7.4%) died during the study period. Seven patients (3.1%) had revisions because of aseptic loosening and two patients (0.9%) because of infection. Clinical assessment at follow-up showed a significantly improved mean HHS from 45 points preoperatively to 78 points postoperatively. At the most recent follow-up, patients with a body mass index below 30 or those classified as Charnley A had a significantly better HHS. Because of migration on the latest radiographs, revision was indicated in 4.8% of the cases. The survival rate of all LOR implants based on implant removal was 96% after 40 months and 87% after 80 months. Based on radiographic evidence of loosened implants, the survival rate was 94% after 40 months and 79% after 80 months. Patients with more than two revisions had reduced implant survivorship compared with those having one or two revisions. The factors "age at operation", "gender", "obesity", "ASA score", "Charnley score", and "activity according to the UCLA score" did not influence the survival rate.

Conclusion: We recommend this component in revision surgery on the basis of satisfactory clinical and radiological results at a mean of 48 months of follow-up. We identified the number of revisions as a predictor of survival rate.