Bilateral alterations in sensorimotor function and altered sensory strategy in individuals with unilateral chronic ankle instability.

Objective: This study aimed to evaluate bilateral sensorimotor function in patients with unilateral CAI. Furthermore, sensory reweighting ability and vestibular modulation were assessed. Methods: Twenty individuals with unilateral CAI and twenty healthy controls participated in this study. All participants executed ankle proprioception, plantar sensation, unilateral stance, Y balance, motor control test (MCT) and sensory organisation test (SOT) assessments. Proprioception assessment included joint position sense and force sense (FS), and plantar sensation evaluation consisted of light-touch, vibration and two-point discrimination (TPD) thresholds at the heel, head of the first metatarsal (1 MF), base of the fifth metatarsal (5 MF), centre of foot and forefoot. MCT and SOT tests were conducted using NeuroCom Balance Manager System. Except for SOT, all tests evaluated bilateral limbs, and the order of limbs was randomly selected. 2 (group) × 2 (limb) mixed model analyses of variance were performed for outcome measures of unilateral stance, Y balance and MCT, and independent Results: For plantar sensation, increased light-touch threshold at heel and 1 MF and the TPD threshold at 1 MF were observed bilaterally in CAI group ( Conclusion: Unilateral CAI presented impaired plantar sensation and ankle proprioception on both sides. Higher visual reliance, delayed motor response and postural instability under unreliable visual clues were also displayed bilaterally. Except for bilateral sensorimotor alterations, reduced ability of sensory reweighting and fixed sensory strategy also presented in CAI group, but the somatosensory clue still served as the main sensory source in CAI.