Objective: To investigate the deficit of static and dynamic postural control in patients with chronic ankle sprain using dynamic posturography.

Method: Twenty patients with unilateral recurrent ankle sprain and functional instability were assessed by Samsung medical center ankle injury score and by computerized dynamic posturography (EquiTest^Ⱂ system, Neurocom^Ⱂ, international, INC; USA).

The posturography test was performed 3 times at 6 different simulated conditions such as fixed of force platform/open eyes/fixed of screen (condition 1), fixed/closed/fixed (condition 2), fixed/open/movement (condition 3), sway/open/fixed (condition 4), sway/closed/fixed (condition 5), sway/open/movement (condition 6). We evaluated anteroposterior sway of center of gravity of the patients and calculated equilibrium scores. We compared the equilibrium scores of patient group and normal data reported previously. We also compared the equilibrium scores of two subgroups of the patients according to severity of ankle injury.

Results: Patients showed significantly low equilibrium scores than normal one at the condition 4, 5 and 6 (p＜0.05). The group B with severe ankle injury revealed low equilibrium scores at the condition 4, 5 and 6. Especially the group B showed statistically significance at condition 5 (p＜0.05).

Conclusion: Patients with chronic ankle sprain showed the deficit of dynamic postural control due to the proprioceptive dysfunction of injured ankle than normal person.

Objective: The purpose of this investigation was to document the isokinetic performance deficiencies of the invertor and evertor muscles of chronically sprained ankles.

Method: Eversion/Inversion testing was performed by a Cybex 6000 isokinetic dynamometer at the speeds of 60^o/sec and 120^o/sec on 17 subjects who had unilateral chronic ankle sprain. Values were compared between the involved and uninvolved sides.

Results: The inversion peak torque deficits between the involved and uninvolved extremities were significantly greater than eversion deficits at 60^o/sec and 120^o/sec. Evertor/Invertor peak torque ratios of involved sides at 60^o/sec were significantly greater than uninvolved sides.

Conclusion: We conclude that chronic ankle sprains associate an ankle invertor weakness rather than an evertor weakness. Ankle invertor weakness might be resulted from a disuse atrophy and painful ankle inversion. Further prospective study is needed to determine the relationship between the invertor weakness and the chronic ankle sprain.