Salvage ankle fusion after a failed primary ankle replacement - a data linkage study using the National Joint Registry and NHS Digital

T. Jennison, A. Goldberg, I. Sharpe

Introduction: When a total ankle replacement fails it can be converted to an ankle fusion or a revision ankle replacement. Despite the increased numbers of undertaken there is limited research on the management of patients undergoing a conversion to fusion following a failed ankle replacement. The primary aim of this study was to analyse the survival of ankle fusions following a failed ankle replacement using a large dataset from the National Joint Registry.

Methods: A data linkage study combined National Joint Registry (NJR) Data and NHS Digital data. The primary outcome of failure is defined as a revision fusion procedure, conversion to ankle replacement or amputation. Life tables and Kaplan Meier survival charts were used to illustrate survivorship. Cox proportional hazards regression models were fitted to compare failure rates.

Results: 131 underwent conversion to fusion as a salvage procedure. The mean age was 65.7 and 55.7% were males. The mean follow-up was 47.5 months. The mean time from primary ankle replacement to revision to an ankle fusion was 5.3 years. 50 (38.2%) patients required further surgery. Of the 131 patients, 32 patients (24.0%) underwent reoperations other than revision and 29 (22.1%) required revision. 24 (18.3%) underwent re-revision to another fusion and 5 (3.8%) underwent a below-knee amputation. No cases were converted back to a TAR. Failure tended to occur in the first three years with 1-year survival of salvage ankle fusion in 131 patients being 96.0% (95% CI 90.7 to 98.3) and 3-year survival in 69 patients being 77.5% (95% CI: 68.3 to 84.4).

Conclusion: Salvage ankle fusion after a failed ankle replacement demonstrates high rates of failure and re-operations. 38.2% of patients undergo further surgery and 23% require revision within 3 years. Further studies are required to further analyse the outcomes of failed ankle replacements.