Abstract
Lateral ankle sprains are the most common musculoskeletal injury and can develop into chronic ankle instability (CAI). People with CAI rely more on visual and somatosensory information to maintain stability in static and dynamic tasks. Researchers use the Sensory Organization Test (SOT) to systematically perturb the visual and somatosensory inputs to assess sensory reweighting through changes in double-leg balance in six increasingly difficult conditions. Similarly, the Locomotor Sensory Organization Test (LSOT) perturbs visual and somatosensory inputs to assess sensory reweighting during gait in six increasingly difficult conditions. The purpose of this study was to determine if there was a difference in SOT and LSOT performance in individuals with CAI compared to uninjured, healthy controls. Forty-four individuals with (n = 23) and without (n = 21) self-reported CAI were assessed in both the SOT and the LSOT. The primary outcome of SOT performance was measured using an equilibrium score that evaluates the movement of center of pressure. The primary outcomes of LSOT performance were assessed by calculating spatiotemporal gait variables including cycle, stance, and swing time and stride length and width. Separate 2 × 6 generalized linear mixed model ANOVAs were performed for the SOT and LSOT to examine the main effects of Condition, Group, and their interaction. Both the SOT and the LSOT showed a significant Condition main effect, indicating altered motor output as sensory systems were progressively perturbed. Additionally, the SOT showed a significant Group × Condition interaction, indicating that the CAI group showed better balance in condition 5 than the uninjured, healthy control group. These findings suggest that both somatosensory and visual perturbations influence balance equally in both groups, as no between-group differences were observed on the SOT. During the LSOT we observed a Condition main effect with significant differences in the spatiotemporal variables across conditions, with treadmill belt speed perturbations causing the largest disruption to gait outcomes. There were no differences between groups, indicating that both people with and without CAI choose stability when possible to properly navigate perturbations during gait. This data suggests that progressive sensory perturbations alter movement in individuals with and without CAI during constrained tasks.