Balance and recovery from a perturbation are impaired in people with functional ankle instability.

OBJECTIVE

To determine if differences in balance and recovery would be found between controls and participants with unilateral or bilateral functional ankle instability (FAI).

DESIGN

Cross-Sectional Study.

SETTING

University laboratory and Community premises.

PARTICIPANTS

Twenty healthy participants(C), 19 participants with unilateral FAI [both the uninjured (UC) and unstable ankle (UI) were included] and 22 participants with bilateral FAI (BI).

MAIN OUTCOME MEASURES

Balance was measured in single leg stance as: number of part foot lifts in 30 s; magnitude of medio-lateral ankle movement in two foot positions; and ability to balance on the ball of the foot. Recovery was determined by time to return to baseline medio-lateral ankle movement after a 15 degree inversion perturbation.

RESULTS

The controls lifted the foot fewer times than the other three groups [C = 12.7 +/- 1.8 (mean +/- SE) foot lifts, UC = 22.9 +/- 2.5, UI = 25.1 +/- 2.3, and BI = 21.1 +/- 2.2, t-test, P = 0.006] and recovered significantly faster than the unstable ankles [C = 1.53 +/- 0.42 sec (median +/- SE), UI = 2.34 +/- 0.30 sec, BI = 2.15 +/- 0.70 sec, P < 0.02]. With FAI measured by the Cumberland Ankle Instability Tool, the external control group balanced on demi-pointe better than both instability groups (P < 0.05), and recovered quicker than all groups.

CONCLUSION

There are differences in balance and recovery between external controls and participants with both unilateral and bilateral FAI but not between the legs of participants with unilateral FAI.