Risk Factors for Failure of Total Ankle Replacements: A Data Linkage Study Using the National Joint Registry and NHS Digital.

Background: Despite the increasing numbers of ankle replacements, there remains debate about which patients should undergo an ankle replacement, and there are limited studies analyzing risk factors for failure of an ankle replacement. The primary aim of this study is to analyze the risk factors for failure of total ankle replacements.

Methods: A data linkage study combining the National Joint Registry (NJR) Data and NHS (National Health Service) Digital data was performed. The primary outcome of failure is defined as the removal or exchange of any components of the implanted device. Kaplan-Meier survival charts were used to illustrate survivorship. Multivariable Cox proportional hazards regression models were fitted to analyze potential risk factors for failures or ankle replacements.

Results: The overall 5-year survival was 90.2% (95% CI 89.2%-91.1%). In multivariable (adjusted) Cox regression models, only age (hazard ratio [HR] 0.96, 95% CI 0.94-0.97), body mass index (BMI; HR 1.03, 95% CI 1.01-1.06), and underlying etiology (HR 0.88, 95% CI 0.80-0.97) were associated with an increased risk of failure.

Conclusion: This study demonstrates that younger patients and those with an increased BMI have an increased risk of failure of a primary ankle replacement. We also show that rheumatoid patients have higher survivorship than those with osteoarthritis.

Level of evidence: Level III, retrospective cohort study.