Do COFAS Scores Effect the Outcomes of a 4th Generation Total Ankle Prosthesis? A 2-Year Follow- Up

Category: Ankle Arthritis; Ankle Introduction/Purpose: Fourth generation ankle replacements benefit from improved surgical technique, respect for bony preservation, and increased surgeon awareness of operative indications. In order to better compare and stratify pre-operative ankle arthritis patients, the Canadian Orthopaedic Foot and Ankle (COFAS) pre-operative classification for end-stage ankle arthritis score was developed. The purpose of this study is report on how the COFAS scores effects prospectively collected patient reported outcome measures(PROMs) in a multi-institutional study of a fourth-generation total ankle replacement. Methods: Patients presenting for a total ankle replacement at 9 institutions were prospectively enrolled and implanted in both academic and private settings. Each patient received an INFINITY ankle prosthesis (Stryker, Memphis, TN, USA). Patients had their COFAS pre-operative classification for end-stage ankle arthritis scores, and PROMs recorded pre-operatively and at 6 months,12 months, and 24-month intervals. The following PROMs were collected: Ankle Osteoarthritis Score (AOS), PROMIS Global Physical Health, and Foot and Ankle Outcome Score (FAOS). The preoperative and latest follow-up scores for patients with two years of follow-up were analyzed. Results: A total of 147 patients were prospectively enrolled. for study participation. COFAS types; were delineated as Type 1 (42.6%, isolated ankle arthritis), Type 2 (27.0%, ankle arthritis with varus or valgus deformity, tight Achilles, ankle instability), Type 3(4.7%, ankle arthritis with hindfoot deformity, tibial malunion), and Type 4 (25.8%, Types 1-3, plus hindfoot arthritis). Eighty-eight (88) patients had at least 24 months of follow-up. COFAS Types 1, 2, 3, and 4 patients had significant improvements in all domains of the AOS, PROMIS, and FAOS Scores (p