Characteristics of responders, or those who achieve a clinical improvement above the level of a minimal clinically important difference, have not been defined for total ankle arthroplasty (TAA). The purpose of this study was to determine patient characteristics that distinguish possible responders from possible nonresponders after TAA using criteria established for other arthroplasty surgeries.
Patients undergoing TAA who were enrolled into a prospective study at a single academic center evaluating patient-reported outcomes were included. Patients were characterized as possible responders if the relative or absolute improvement in their 2-year follow-up Short Musculoskeletal Function Assessment (SMFA) function score was at least 50% or 20, respectively, compared with their preoperative score, consistent with Outcome Measures in Rheumatoid Arthritis Clinical Trials and the Osteoarthritis Research Society International (OMERACT-OARSI) responder criteria. Patient factors were then associated with possible responder or nonresponder status and a multivariable analysis was performed. A total of 491 patients with complete data and 2-year follow-up were included in this study.
Multivariable analysis demonstrated that a higher baseline 36-Item Short-Form Survey (SF-36) mental component summary (MCS) score (OR [95% CI], 1.02 [1.01, 1.04]; 
Level III, retrospective comparative study.
Our data reveal that a higher baseline SF-36 MCS score was associated with increased improvement in SMFA function scores, while rheumatic disease was associated with worse improvement in SMFA function scores after TAA. Patients with rheumatic disease or poor mental health may not achieve as favorable results after TAA and should be counseled appropriately.