9 Plantar pressure during an unplanned transition task in those with chronic ankle instability: a pilot study

Abstract

Background Individuals with chronic ankle instability (CAI) have been documented to have altered motor control strategies. However, most studies evaluate subjects when they are either starting in the testing position or while performing a planned dynamic task. Objective To determine if there are differences in plantar pressure between those with established CAI compared to healthy controls during an unplanned transition from a double-leg stance to a single-leg stance. Design Cross-sectional. Setting University laboratory. Participants Eight subjects with CAI as determined by a score >12 on the Identification of Functional Ankle Instability (IdFAI) questionnaire (mean IdFAI: 19.0 ± 4.93) and ten healthy control subjects without a history of ever spraining an ankle participated. Interventions Plantar pressure data were collected using an in-shoe pressure system. Subjects stood in a double-leg stance facing a screen. At a random time an arrow appeared on the screen. Subjects transitioned to the leg in which the arrow pointed to and maintained single-leg stance for 10-seconds. Subjects performed the unplanned transition task on both a firm surface as well as a foam surface. Main outcome measurements Trials in which the subjects transitioned to their involved ankle were analysed. The plantar foot was divided into 9 regions. For each region, peak plantar pressure and time to peak pressure from 100 ms pre-transition to 2-seconds post-transition were analysed. Results Overall, during the transition task, individuals with CAI presented with higher peak pressures on the lateral aspect of the foot and healthy controls had higher peak pressures on the medial aspect of the foot. Specifically, the CAI group had significantly less peak pressure in the middle forefoot during both the firm and foam conditions. There were no differences in time to peak pressure. Conclusion During unplanned movements, those with CAI utilise different movement patterns compared to healthy controls.