OBJECTIVES: Ankle sprains often lead to a history of recurrent injuries and functional joint instability. This study evaluated a new method for assessing functional impairment in patients with chronic ankle instability.
DESIGN: Case-control study for construct validation purpose. SETTING: The participants were tested during one-leg standing for 20 s on an instrumented wobble board and on a balance platform. PARTICIPANTS: Twenty-five young people with previous ankle sprain and an instability score >11 in the "Identification of Functional Ankle Instability questionnaire" and an age-matched control group of 25 healthy individuals. MAIN OUTCOME MEASURES: Wobble board variation of tilt angle measured by two accelerometers placed horizontally in the board.
RESULTS: The variation in angular tilt of the wobble board in the medio-lateral direction (standard deviation of tilt angle) was higher in the group with perceived ankle instability than in the control group: 1.5 (0.7) versus 1.1 (0.3). ICC for intra-tester reliability: 0.87 and correlation with COP area measures from the stable balance platform: 0.64.
CONCLUSIONS: People with functional ankle instability display poorer postural stability in the medio-lateral direction when challenged on an unstable surface. The instrumented wobble board may serve as a relevant tool in the clinical evaluation of functional ankle stability.