Combining Mechanical Support With Sensory Augmentation in Orthotic Devices for Postural Stability in Lateral Ankle Instability: A Randomised Controlled Trial

Abstract

Background Lateral ankle instability (LAI) frequently arises from deficits in sensorimotor function. Orthotic devices are regularly used to yield mechanical support, but the use of sensory-enriching modalities such as local vibration with these supports has not been explored. Objective This study was conducted to examine the effect of adding vibration to an orthotic device on postural stability in LAI. Methods In this parallel randomised controlled trial, 32 adults with LAI were entered into a trial group who received an ankle-foot orthotic device incorporating a vibratory strap or into a control group receiving the same orthosis without a vibration strap. Postural stability was evaluated with centre of pressure (COP) velocity on a force plate at four time points: baseline, immediately following intervention, 2-week follow-up, and 4-week follow-up. Finally, 29 participants completed the study protocol. Results There was a significant group & times; time interaction on COP anteroposterior velocity (F (3, 25) = 39.44, p < 0.001, eta 2 = 0.82). The trial arm had a greater decrease in this outcome at 4-week follow-up compared with controls (MD = -0.90 mm/s, p < 0.001, d = -1.59). No differences were found for COP mediolateral velocity or COP resultant velocity, but there was a general trend of reduction in both groups. Conclusion The addition of sensory stimulation to orthotic devices significantly enhances anteroposterior postural stability in LAI subjects, suggesting a synergistic effect of mechanical support and sensory augmentation.