The postoperative COFAS end-stage ankle arthritis classification system: interobserver and intraobserver reliability

End-stage an kle arthritis is operatively treated with numerous designs of total an kle replacement and different techniques for an kle fusion. For superior comparison of these procedures, outcome research requires a classification system to stratify patients appropriately. A postoperative 4-type classification system was designed by 6 fellowship-trained foot and an kle surgeons. Four surgeons reviewed blinded patient profiles and radiographs on 2 occasions to determine the interobserver and intraobserver reliability of the classification. Excellent interobserver reliability (κ = .89) and intraobserver reproducibility (κ = .87) were demonstrated for the postoperative classification system. In conclusion, the postoperative Canadian Orthopaedic Foot and Ankle Society (COFAS) end-stage an kle arthritis classification system appears to be a valid tool to evaluate the outcome of patients operated for end-stage an kle arthritis.