Individuals with unilateral chronic ankle instability exhibit deficits in bilateral postural control, muscle strength and proprioception.

To investigate whether people with unilateral chronic ankle instability (CAI) have deficits in bilateral static and dynamic postural control, ankle muscle strength and ankle proprioception. A total of 31 participants with CAI and 31 non-CAI controls were recruited. Static postural control was assessed using root mean square (RMS) of the plantar centre of pressure (CoP) displacements during single-leg stance. Dynamic postural control was evaluated by measuring the time to stabilisation (TTS) following a single-leg drop onto a force plate. Ankle proprioception and muscle strength were measured using a proprioception testing device and an isokinetic dynamometer. A linear mixed-effects model of variance was used to examine the group (CAI vs. non-CAI) and limb (affected vs. unaffected) effects and interactions adjusting for activity level, limb dominant and injured side. Compared to non-CAI, those participants with unilateral CAI exhibited greater CoP-RMS(ML) bilaterally (F = 4.392, p = 0.0038); longer TTS bilaterally (4.102 ≤ F ≤ 10.558, 0.002 ≤ p ≤ 0.048); less ankle muscle strength bilaterally (43.126 ≤ F ≤ 5.505, 0.022 ≤ p < 0.001); and larger ankle proprioceptive thresholds bilaterally (26.159 ≤ F ≤ 8.413, 0.005 ≤ p < 0.001). Individuals with unilateral CAI exhibit bilateral deficits in static postural control, dynamic postural control, muscle strength and proprioception. CAI rehabilitation strategies should adopt comprehensive bilateral rehabilitation approaches.