The Effect of Patient Comorbidities on Intermediate Outcomes After Total Ankle Arthroplasty

Abstract

Category: Ankle Introduction/Purpose: Total ankle arthroplasty (TAA) has shown durable improvements in pain, function, and quality of life. Patient factors could affect intermediate to long-term outcomes after total ankle arthroplasty, and the impact of common medical comorbidities has not been fully characterized. The purpose of this study was to determine if common preoperative patient comorbidities had an effect on patient outcomes. Methods: Patients undergoing TAA between 1/2007 and 12/2016 were enrolled into a prospective study at a single academic center. Patients completed the following outcome measures before surgery and then in follow-up: AOFAS Hindfoot score, 36-item Short Form Survey (SF-36), Foot and Ankle Disability Index (FADI), and the Short Musculoskeletal Function Assessment (SMFA) score. Patient and operative factors along with pre-operative Charlson-Deyo and Elixhauser comorbidities with at least 10% prevalence across the entire population were assessed for association with changes in outcomes from pre-operative to the patient’s most recent follow-up. A minimum of 2 years of follow-up was required. Factors that met a significance threshold of p<0.05 in univariate analyses were incorporated into multivariable outcome models. Results: A total of 538 patients with an average follow-up of 4.3 years (range, 2 to 10 years) were included. While patients had significantly improved pain and function across all outcomes, smoking was associated with smaller improvements in AOFAS hindfoot score, AOFAS hindfoot function subscale, SF-36 physical summary scale, SF-36 total scale, and SMFA function scale. Prior foot and ankle surgery was associated with smaller improvement in AOFAS hindfoot pain subscale as well as VAS pain. Rheumatoid arthritis was associated with smaller improvement in SF-36 total and physical summary subscale scores while obesity was associated with smaller improvement in the FADI. Smoking had the largest impact on results, and produced a moderate effect size. All other variables had trivial to small effect sizes. Conclusion: While patient outcomes improved significantly after TAR at intermediate duration follow-up, smoking, prior surgery, rheumatoid arthritis, and obesity were risk factors for reduced improvement in outcomes. Smoking was associated with a moderate effect size, but all other factors had only small impact on patient-reported outcomes. Active smokers should be counseled on their risk of smaller improvements in outcomes, and it may be inadvisable to perform TAR on these patients.