College of Health

CONTEXT: Deficits in static and dynamic stability during single-leg stance have been noted in individuals with chronic ankle instability (CAI), but few investigators have tested subjects for subtle deficits in dynamic balance. Subtle deficits in dynamic balance during a double-leg stance may reveal changes in the sensorimotor system because of CAI.

OBJECTIVE: To use a standardized tibial nerve stimulation as a perturbation to test for dynamic balance deficits between a group of recreational athletes with CAI and a group of recreational athletes with stable ankles.

DESIGN: Case-control study.

SETTING: Laboratory.

PATIENTS OR OTHER PARTICIPANTS: Twenty recreational athletes with CAI and 20 recreational athletes with stable ankles.

INTERVENTION(S): Balance deficits were assessed for each subject during static and dynamic trials.

MAIN OUTCOME MEASURE(S): Time to stabilization and center-of-pressure excursion path length, velocity, and area from ground reaction forces during double-leg stance were collected through a forceplate. We used an accelerometer to measure tibial acceleration. Data were collected during static stance and during a bilateral perturbation using maximal motor neuron recruitment elicited by electric stimulation of the tibial nerve.

RESULTS: Only time to stabilization in the anterior-posterior direction was significantly different between groups ( P = .04), with the CAI group taking longer to return to a stable range of ground reaction forces. We found no other differences in stability measures between the groups.

CONCLUSIONS: Dynamic balance in double-leg stance as measured by time to stabilization appears to be affected in individuals with CAI. Deficits in the response to external perturbation may indicate subtle central sensorimotor changes.