Reliability and Sensitivity of the Foot and Ankle Disability Index in Subjects With Chronic Ankle Instability

Context: Despite the importance of patient's subjective reports of function, little research has addressed their use in the athletic population.Objective: To examine the following measurement properties of the Foot and Ankle Disability Index (FADI) and the FADI Sport: (1) intersession reliability during 1- and 6-week intervals, (2) sensitivity to differences between healthy subjects and subjects with chronic ankle instability (CAI), and (3) sensitivity to changes in function in those with CAI after rehabilitation.Design: Test-retest design.Setting: Laboratory setting.Patients or Other Participants: Fifty recreationally active subjects.Main Outcome Measure(s): FADI and FADI Sport.Results: Intraclass correlation coefficients (ICC 2,1) for the FADI and FADI Sport at 1 week were 0.89 and 0.84, respectively, for the involved limbs. Over 6 weeks, the ICC values for the involved limb of subjects who did not complete rehabilitation were 0.93 and 0.92, respectively. For both surveys, scores were significantly less for the involved limbs of subjects with CAI compared with their uninvolved limbs (P < .05). No significant side-to-side differences were noted among the healthy subjects. Scores on both surveys increased significantly after rehabilitation (FADI: P < .05, effect size = 0.52; FADI Sport: P < .05, effect size = 0.71).Conclusions: The FADI and FADI Sport appear to be (1) reliable in detecting functional limitations in subjects with CAI, (2) sensitive to differences between healthy subjects and subjects with CAI, and (3) responsive to improvements in function after rehabilitation in subjects with CAI.