Abstract
Mid and long-term follow-up of Charnley total hip arthroplasty (THA) demonstrated good functional results with 85% survivorship at 25-year follow-up. However dislocation still remains an unsolved problem. Dislocation may occur all along the patient and implant life. The aim of this study is to answer the question: does Dual Mobility Cup (DMC) decrease the dislocation risk? Method: We report comparative results at ten years of follow-up of 2 groups of primary cemented Charnley-type THA, one with a standard polyethylene cup (group 1, n=215) and the other one with a DMC (group 2, n=105). Results: In group 1, twenty-six dislocations (12.9%) occurred. In group 2 only one dislocation (0.9%) occurred. This dislocation was successfully reduced by close reduction, without any recurrence. This difference was statistically significant (p=0.0018). In group 1, reason for revision was recurrent dislocation in twenty one cases. Five patients have been revised for other reasons. The global revision rate was 12.9%. In group 2, two patients needed revision surgery for aseptic loosening. The global revision rate was 2.1%. This difference was statistically significant (p=0.0054). The goal was reached for the patients of group 2 who had more risks factors of dislocation (age, aetiology, ASA and Devane scores) than those of group 1. When using a DMC, we observed a low rate of dislocation in primary THA (0.9%). This surgical choice seems to be a secure and effective technique in Charnley-type THA, especially in a high risk population.
