Combining Virtual Reality and Ankle Perturbations to Improve Ankle Function

Ankle sprains are among the most common injuries to athletes during sport and recreationally active individuals during activity of daily life. Approximately 40-70% of lateral ankle sprains progress to chronic ankle instability (CAI), a condition characterized by recurring sensations of the ankle “giving way” or feeling unstable during physical activity. This condition can lead to decreased physical activity levels and impair quality of life. Current rehabilitation of CAI typically involves stability-based training (SBT). Following treatment, CAI patients often present with strength and range of motion scores similar to uninjured individuals. However, high rates of ankle reinjury and increasing kinesiophobia over time reveal current stability-based methods aren’t effective for CAI. Virtual reality (VR) interventions in rehabilitation settings with CAI have been studied, however no previous report has evaluated the impact of immersive 1st person VR combined with ankle perturbations, a sub-set of SBT. The purpose of this preliminary study was to evaluate the how integrating physical sensory perturbations with a non-interactive 1st person VR environment will affect characteristics of CAI. 14 people with CAI were allocated to two groups via sex stratified randomization. The experiment followed a pretest-posttest protocol where subjects came in on three successive days with 24 hours between each visit: baseline, intervention, and retention. Outcome measures were taken at four time points across the three visits. To evaluate ankle function, three outcome measures were used. A neurocognitive protocol was used to evaluate dual-tasking ability. This test challenged subjects’ ability to memorize specific letters and respond to specific colors simultaneously. A hop-to-stabilization protocol was used to evaluate dynamic balance, which measured muscle activation and postural stability indices. A novel uneven stepping task was used to evaluate motor planning, taking measures of ground reaction forces, muscle activation, and step timing. Groups were the VR only (VRO) group, where participants were only shown the VR video, or the VR + Perturbations (VRP) group, where participants experienced VR and perturbations concomitantly. The VR video was a 10-minute video shown from a 1st person perspective walking down a hiking trail. The VRP group was given ankle “rockings” at timings and intensities that correlated to what subjects experienced in the virtual environment in real-time. No significant differences were found between groups and across time points, however trends toward improvement with moderate to large effect sizes in dual-tasking ability (11.04% improvement in memorization), decrease in step time (np2=0.297), and reduction of impulse in the anteroposterior (np2=0.088) and vertical planes (np2=0.187) were observed. Further studies should aim to expand the intervention timeframe beyond a single session as well as include a perturbation only group to directly compare SBT against VR.