Does the Canadian Orthopaedic Foot and Ankle Society Postoperative COFAS End-Stage Ankle Arthritis Classification System Correlate With Pre- and Postoperative PROMIS Scores for Total Ankle Arthroplasty?

BACKGROUND: Recently, the Canadian Orthopaedic Foot and Ankle Society (COFAS) proposed a classification system addressing adjunct procedures in the treatment for end-stage ankle arthritis. We reviewed Patient-Reported Outcome Measures Information System (PROMIS) data to determine if outcomes of total ankle arthroplasty (TAA) correlated with postoperative COFAS classification. We hypothesize that as COFAS classification increases, patients will demonstrate greater improvement in the change between pre- and postoperative PROMIS scores. METHODS: From June 2015 to December 2018, a total of 127 patients underwent 132 TAA. Demographic factors and preoperative and most recent postoperative PROMIS scores were collected. Univariate, multivariate and post hoc analyses with a significance threshold of P <.05 were performed. RESULTS: Eighty-seven patients with a mean follow-up of 13.6±7.3 months and complete PROMIS scores were classified into COFAS types 1-4. Significant differences were identified in the PROMIS Pain Interference domain comparing COFAS types 2 and 4 and COFAS types 3 and 4. These results demonstrate that more complex ankles with a higher COFAS score had worse interval improvement in PROMIS scores. Additionally, multivariate linear regression showed that age and BMI were associated with worse physical function and depression, whereas diabetes and a history of prior surgeries were associated with improved postoperative function. CONCLUSION: The COFAS postoperative classification system is useful for categorizing end-stage ankle arthritis. Further research into the ideal timing of surgery and higher-level studies to better determine TAA efficacy with different classification systems is warranted. This information can be helpful with preoperative counseling about treatment outcomes. Level of Evidence: Level IV, retrospective analysis of prospectively collected data.