The survival of total ankle replacements: a data linkage study from the National Joint Registry

T. Jennison, A. Goldberg, I. Sharpe

Introduction: Despite the increasing numbers of ankle replacements that are being performed there are still limited studies on the survival of ankle replacements and comparisons between different implants. The primary aim of this study is to link NJR data with NHS digital data to determine the true failure rates of ankle replacements. Secondary outcomes include analysis risk factors for failure, patient demographics and outcomes of individual prosthesis.

Methods: A data linkage study combined National Joint Registry Data and NHS Digital data.The primary outcome of failure is defined as the removal or exchange of any components of the implanted device inserted during ankle replacement surgery. Life tables and Kaplan Meier survival charts demonstrated survivorship. Cox proportional hazards regression models with the Breslow method used for ties were fitted to compare failure rates.

Results: 5,562 primary ankle replacement were recorded on the NJR. The 1-year survivorship was 98.8% (95% CI 98.4%-99.0%), 5-year survival in 2725 patients was 90.2% (95% CI89.2%-91.1%), and 10-year survival in 199 patients was 86.2% (95% CI 84.6%-87.6%).When using a Cox regression model for all implants with over 100 implantations using the Infinity as the reference, only the STAR (Hazard ratio 1.60 95% CI 0.87-2.96) and Inbone (HR0.38 95% CI 0.05-2.84) did not produce significantly worse survivorship.

Conclusion: Ankle replacements have increased in numbers over the past decade, and the currently used implants have lower failure rates than older prosthesis. It is expected that in the future the outcomes of ankle replacements will continue to improve.