A systematic review of outcome and failure rate of uncemented Scandinavian total ankle replacement

The purpose of this study was to provide cumulative data about the intermediate to long-term outcome of Scandinavian total ankle replacement (STAR) in the literature and to provide a summary of survival rate, implant failure rate and reasons.

A comprehensive search for all relevant articles published in English and German from January 1995 to May 2011 was conducted. Two reviewers evaluated each study to determine whether it was eligible for inclusion and, if so, collected data of interest. The intermediate to long-term outcomes were determined. Evidence-based meta-analytic pooling of results across studies was performed to determine survival and failure rates.

Sixteen primary studies with 2,088 implants were identified. The mean American Orthopaedic Foot and Ankle Society (AOFAS) score was 77.8 points, and the mean Kofoed ankle score was 76.4 points. The pooled mean five year survival rate was 85.9% [95% confidence interval (CI) 80.9-90.3], and the pooled mean ten year survival rate was 71.1% (95% CI 60.9-81.5). Pooled failure rate was 11.1% (95% CI 7.6 -14.9), with a mean follow-up time of 52 months; 41% failed within one year of initial operation. The first three reasons associated with implant failure were aseptic loosening (5.2%), malalignment (1.7%) and deep infection (1.0%).

We found that STAR prosthesis achieved encouraging results in terms of intermediate to long-term outcome. The five and ten year survival rates were acceptable. However, the failure rate was still high. The major reasons for implant failure were aseptic loosening and malalignment. Maybe the increase of surgeons' experience and patient selection could improve outcomes and decrease failure rate.