Bad clinical results of cemented caps with metal-backed acetabular components. 124 cases with 21 months follow-up

Objective: The authors reviewed with short term follow-up 124 total hip arthroplasties using a cemented metal-backed acetabular component. The purpose of the study was to evaluate clinical and radiological results because of early periacetabular radiolucent lines reported by Ritter.

Methods: Surgical procedures were performed in 1988 and 1989 with Saint-Antoine prosthesis (PSA) including cemented titanium metal-backed socket. Functional results were appreciated with Postel-Merle d'Aubigne's score. Radiological results were appreciated using De Lee and Charnley's criterias for radiolucent lines and Yoder's criterias for socket's migrations. We studied correlation between radiolucent line and age, weight, hip disease, associated bone graft, socket size and technical errors.

Results: With short term follow-up (21 months), we found 60.4 per cent hips with a maximal PMA score (18) with an average score of 17.5 per cent. We observed 26.4 per cent of complete periacetabular radiolucent lines with 3 sockets loosening with migration. No significant correlation were found between radiolucent lines and age, weight, hip disease, associated bone graft, socket size, and technical errors.

Conclusions: This periacetabular radiolucent line rate was comparable to the results of the series using such a cemented metal-backed socket. This rate was clearly higher than the results of others series using cemented polyethylene sockets. These bad results were not correlated to those of finite elements analysis. We think that this is due to metal-backed socket excessive rigidity. Conclusions: Because of this high periacetabular radiolucent line rate, despite of finite elements analysis results, we no more use cemented metal-backed acetabular socket since 1991.