Effects Of Stroboscopic Vision On Postural Control In Individuals With And Without Chronic Ankle Instability

Abstract

Chronic ankle instability (CAI) patients have consistently displayed postural control deficits. Previous research postulated that CAI patients rely more on the utilization of visual feedback than controls to compensate for the proprioceptive deficits after lateral ankle sprains. However, little is known about how reduced visual feedback would alter dynamic postural control in CAI patients relative to controls and copers. PURPOSE: To identify the effect of visual feedback disruption via stroboscopic glasses on dynamic postural control among groups of CAI, coper, and control. METHODS: 20 CAI (10M, 10F, 23.6±3.9 yr, 174.5±11.8 cm, 76.3±17.5 kg), 20 coper (10M, 10F, 22.2±1.4 yr, 176.4±10.2 cm, 69.3±10.9 kg), and 20 control (10M, 10F, 22.6±2.7 yr, 174.4±7.2 cm, 80.0±24.4 kg) subjects were categorized according to the Foot and Ankle Ability Measure (FAAM) and Modified Ankle Instability Index (MAII) questionnaires. Each subject performed three trials of a single-leg-hop stabilization test with eyes open (EO) and stroboscopic vision (SV). Force data (200 Hz) were collected using an in-ground force plate to calculate the dynamic postural stability index (DPSI) and directional stability indices (medial/lateral, anterior/posterior, vertical). Two-way repeated ANOVAs (group × condition) were used to examine the differences between condition (EO, SV) and group (CAI, coper, control). RESULTS: Visual condition main effect was driven by differences between EO and SV during dynamic postural control (p<0.001). Only CAI patients displayed altered DPSI scores between EO and SV (p=0.005). However, no differences were observed in copers (p=0.31) and controls (p=0.99). Regardless of visual condition, CAI patients displayed dynamic postural control deficits relative to controls (p=0.003) but no differences between CAI patients and copers (p=0.45). For the directional stability indices, each group displayed no differences between visual conditions. CONCLUSION: CAI patients rely more on visual feedback during dynamic postural control than copers and controls. However, they may have decreased ability to compensate for the disrupted visual feedback during dynamic movement. Stroboscopic glasses could be effective visual-disruption devices during dynamic movement tasks regardless of lateral ankle sprain history.