Dynamic postural control but not mechanical stability differs among those with and without chronic ankle instability

The purpose of this investigation was to compare dynamic postural control and mechanical ankle stability among patients with and without chronic ankle instability (CAI) and controls. Seventy‐two subjects were divided equally into three groups: uninjured controls, people with previous ankle injury but without CAI, and people with CAI. Subjects completed a single‐leg hop‐stabilization task, and then had an anterior drawer test and lateral ankle radiograph performed bilaterally. The dynamic postural stability index was calculated from the ground reaction forces of the single‐leg hop‐stabilization task. Ankle joint stiffness (N/m) was measured with an instrumented arthrometer during the anterior drawer test, and fibula position was assessed from the radiographic image. Patients with previous ankle injuries but without CAI demonstrated higher frontal plane dynamic postural stability scores than both the uninjured control and CAI groups (P