US vs the World: Exploring European Superiority in the Realm of Total Ankle Arthroplasty

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: Ankle arthrodesis (AA) has long been the gold standard in the treatment of patients with end-stage ankle osteoarthritis. However, total ankle arthroplasty (TAA) has been increasing in popularity, with preservation of ankle joint range of motion being a commonly touted benefit over AA. There are stark differences in TAA implant design usage between geographical regions, with fixed-bearing implants historically being more heavily utilized in the United States (US) and mobile-bearing implants having a greater presence outside the US. However, to date, no studies exist directly comparing TAA outcomes with respect to geographical location. This study aims to augment the existing literature regarding TAA outcomes and provide insight into any observed geographical differences. Methods: This was a multi-institutional study, with surgeries performed by four different surgeons across four different sites. Two surgeons were based in the continental United States with the remaining two based in Europe. Database records were pulled for all TAAs performed by the surgeons between January 2016 and December 2023. Inclusion criteria were if the patient had a primary TAA performed during the specified timeframe. Patients were excluded if they were lost to followup, had inadequate followup, or chose to withdraw from the database. The initial database query resulted in 440 patients from the US and 263 from Europe. After exclusions, 391 US patients and 263 European patients remained for analysis. Statistical analysis of demographic data between groups included Student t-tests to assess for any differences. Postoperative results, including functionality scores, pain, and occurrence of adverse events, were compared using ANOVA. Results: Analysis of the demographics revealed a significantly older (p < 0.001) and heavier (p < 0.001) US cohort compared to the European patients. Of the comorbidities, inflammatory arthritis, hypertension, heart disease, diabetes, and chronic renal failure were seen to have a greater prevalence in the US patients (Table 1). Operative time and tourniquet time were both significantly less in the European group (p < 0.001). At a followup of three years, outcomes for European patients were better as measured by American Orthopedic Foot and Ankle Society (AOFAS) scores (83.3 ± 13.9, US; 96.0 ± 8.73, Europe; p < 0.001); however, no difference was observed in recorded visual analog scale (VAS) pain scores (1.36 ± 1.95, US; 1.55 ± 2.68, Europe; p = 0.612). Conclusion: In this first-of-its-kind study, outcomes for TAA were compared between the United States and Europe. Functionally, European patients fared significantly better than their American counterparts as measured by AOFAS scores at three years of followup. Multiple contributing factors may play a role in the findings of the study; US patients were burdened with more comorbidities in addition to being older and heavier. However, we pose that in addition to patient demographics, the usage of mobile-bearing implants may also positively affect European patients’ functional outcomes. This finding is intended to spur further research into the efficacy and designs of mobile-bearing implants.