Postural control responses during single-leg balance in individuals with chronic ankle instability under graded...

Chronic ankle instability (CAI) is a common sequela of lateral ankle sprain and is associated with recurrent injury, persistent functional limitations, sensorimotor deficits, and impaired postural control. However, how individuals with CAI adapt to graded and combined sensory feedback disruption remains unclear. This study aimed to determine whether individuals with CAI exhibit altered postural control during single-leg stance across graded visual, somatosensory, and combined visual-somatosensory disruption compared with healthy controls.

Fifty-two participants (26 CAI, 26 healthy controls) performed single-leg balance tasks on a force plate under seven sensory conditions: one baseline condition and two graded conditions for each of three sensory disruption types: visual, somatosensory, and combined visual-somatosensory disruption conditions. Balance performance was assessed using center-of-pressure (COP) measures and quantified as percent change from baseline. Separate 2 × 2 mixed-design ANOVAs were conducted for each sensory disruption type and COP outcome.

Significant group-by-level interactions were observed under visual disruption for total COP velocity (F = 4.886, p = 0.032) and mediolateral COP velocity (F = 6.420, p = 0.014). Under lower-occlusion visual disruption, the CAI group showed greater postural deterioration than controls, whereas no between-group difference was observed under higher-occlusion visual disruption. No significant group-by-level interactions were found under somatosensory or combined visual-somatosensory disruption. However, under somatosensory disruption, the CAI group showed greater overall deterioration than controls for COP area, total COP velocity, and mediolateral COP velocity. Under combined disruption, both groups showed larger balance declines, with greater deterioration in the CAI group than in controls for total and mediolateral COP velocity.

Individuals with CAI demonstrated greater postural deterioration than healthy controls under several disrupted sensory conditions, while retaining graded responses to somatosensory and combined disruption. The visual disruption findings suggest that individuals with CAI may be particularly vulnerable when visual feedback is partially degraded. These findings may provide a preliminary rationale for informing the development of sensory-targeted rehabilitation strategies aimed at improving functional stability, although future studies using more controlled visual manipulations are warranted.