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

Abstract

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.

Does Obesity Affect Total Ankle Replacement Outcomes?

“…They reported that lower age, increased BMI, and indication for surgery have a significantly increased risk of TAR failure. 8 The literature has been largely consistent on this topic. Most studies have reported similar levels of complications, infection, and failure regardless of BMI.…”

“…In this issue of FAI, 2 articles provide important insights into the effect of body mass index (BMI) on TAR outcomes. 8,9 Kim et al 9 evaluated the effect of obesity on complication rates and patient-reported outcome (PRO) measure scores in a single-institution, retrospective comparative study of 1093 primary TARs. They found that obese patients did not experience increased rates of complication, revision, or infection after TAR.…”

“…9 In addition, patients with obesity reported, on average, worse pre-and postoperative function, pain, and general health status; however, the magnitude of the change in PRO scores was similar across the BMI groups. More broadly, Jennison et al 8 analyzed various risk factors for failure of TAR in a retrospective UK registry-based study of 5562 patients. They reported that lower age, increased BMI, and indication for surgery have a significantly increased risk of TAR failure.…”

“…The importance of Kim et al 9 and Jennison et al 8 is primarily their large sample size, follow-up length, and treatment of potential confounders. Simply, previous studies may not have been powered sufficiently to detect differences.…”

“…Moreover, both studies adjust for potential confounders to improve the accuracy and validity of their findings. Kim et al 9 adjust for age, sex, and ASA score, whereas Jennison et al 8 adjust for age, sex, indication, laterality, ASA score, Charlson Comorbidity Index score, surgeon grade, deformity, plantar and dorsal range of motion, and subtalar joint. The conflicting results are frustrating, but may be due to the confounders considered or not considered by each study, or how confounders were defined or measured.…”