Ankle strength deficits in a cohort of college athletes with chronic ankle instability

Context: Lateral ankle sprains commonly occur in an athletic population and can lead to chronic ankle instability. Objective: To compare ankle strength measurements in athletes who have mechanical laxity and report functional instability after a history of unilateral ankle sprains. Design: Retrospective cohort. Setting: Athletic Training Research Lab. Participants: A total of 165 National Collegiate Athletic Association Division I athletes, 97 males and 68 females, with history of unilateral ankle sprains participated. Main Outcome Measures: Functional ankle instability was determined by Cumberland Ankle Instability Tool scores and mechanical ankle instability by the participant having both anterior and inversion/eversion laxity. Peak torque strength measures, concentric and eccentric, in 2 velocities were measured. Results: Of the 165 participants, 24 subjects had both anterior and inversion/eversion laxity and 74 self-reported functional ankle instability on their injured ankle. The mechanical ankle instability group presented with significantly lower plantar flexion concentric strength at 30°/s (139.7 [43.7] N·m) (P = .01) and eversion concentric strength at 120°/s (14.8 [5.3] N·m) (P = .03) than the contralateral, uninjured ankle (166.3 [56.8] N·m, 17.4 [6.2] N·m, respectively). Conclusion: College athletes who present with mechanical laxity on a previously injured ankle exhibit plantar flexion and eversion strength deficits between ankles