Bilateral spatiotemporal postural control impairments are present in participants with chronic ankle instability

Objectives: This study evaluated center-of-pressure (COP) and time-to-boundary (TTB) measures of postural control during a Lateral Step-Down Test in participants with chronic ankle instability (CAI). Design: Cohort study. Setting: Biomechanics laboratory. Participants: Physically active adults with CAI (n = 15) and matched controls (n = 15). Main outcome measures: Traditional COP and TTB measures of postural control were computed in the medial/lateral (ML) and anterior/posterior (AP) directions. Results: No significant results were found for the traditional COP measures (p > 0.05). The CAI group exhibited a lower TTB ML absolute minimum on their affected limb compared to the matched limb of the control group (p < 0.001). Additionally, on average the CAI group displayed significantly lower TTB ML mean of minima (p = 0.004) and TTB standard deviation of minima in the ML (p < 0.001) and AP directions (p = 0.002) regardless of limb. Conclusions: Sensorimotor impairments associated with CAI negatively alter spatiotemporal postural control and may cause a maladaptive reorganization of centrally mediated motor control strategies that results in bilateral postural control deficits during the Lateral Step-Down Test. In addition, traditional COP measures did not reveal any postural control deficits suggesting that a spatiotemporal analysis should be used when assessing postural control in participants with CAI.