Establishing Maximal Subjective Outcome Improvement after Total Ankle Arthroplasty

Abstract

Category: Ankle; Ankle Arthritis Introduction/Purpose: Total ankle arthroplasty is considered one of the most common treatments for end stage osteoarthritis of the ankle. This procedure results in significant long-term improvements in pain and function while preserving pre-operative range of motion. Patients also demonstrate improvements in patient reported outcome measures (PROMs) - a modality that quantifies patient’s subjective well-being. Understanding the time to maximal subjective medical improvement (MMI) following total ankle arthroplasty can help guide resource allocation and manage patient expectations. The purpose of this investigation is to establish when patients perceive MMI according to PROMs following total ankle arthroplasty. Methods: A systematic review was conducted on the PubMed database to identify studies on total ankle arthroplasty which reported consecutive PROMs for at least two years postoperatively. Pooled analysis was done at 3-months, 6-months, 12-months, and 24-months postoperatively. The minimal clinically important difference (MCID) was established by a distribution-based method, which is one-half of the standard deviation of outcome score change for a given instrument. Clinically significant improvement was determined between pairs of intervals that exceeded the MCID. Results: A total of 12 studies and 1514 patients met the inclusion criteria for this review. Clinically significant improvement was seen up to 6 months postoperatively in both the American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Score (AOFAS) and Visual Analog Scale (VAS) scoring systems but was not demonstrated at later intervals. The Short Musculoskeletal Function Assessment (SMFA) Function and Bother subsections were scored individually and both demonstrated clinically significant improvement until 1 year postoperatively. Conclusion: After total ankle arthroplasty, the maximal subjective medical improvement based on PROMs is seen until one year postoperatively, with clinically insignificant improvement beyond one year. The SMFA scoring system may offer greater sensitivity to subjective improvements compared to the AOFAS or VAS scales. This trajectory may help guide patients in managing their expectations in their functional outcomes during preoperative patient education.