Impact of a thin plantar orthopaedic insert on posture and locomotion

Abstract

Introduction Podiatrists might use thin plantar insert such as EMI® (medio-intern element) to treat postural deficiency. EMI® could induce contralateral medio-lateral (ML) deviation of the Centre of Pressure (CoP) position of healthy participants in quasi-static standing. Our aim is to evaluate EMI® effect on locomotion. Hypothesis Motor control studies on locomotion showed a modified walking stereotypy (eyes closed) after 30\xa0min podokinetic stimulation. We expected a contralateral deviation of the trajectory when EMI® was located under one foot. Material and methods Twenty healthy participants volunteered to the study and were involved in 3\xa0different sessions performed in a randomized order: 1\xa0without EMI®, 2\xa0with EMI® (right or left foot). Each session included: –\xa0static tasks (with and without vision) to compare with previous work; –\xa0dynamic locomotor tasks: 6\xa0conditions, i.e. 3\xa0trajectories (straight, left or right 90° turn), with/without vision. In static conditions, we calculated the average CoP ML position and between and within trials variabilities. In dynamic conditions, we analyzed the difference in the final orientation of the locomotor trajectory with and without vision with a EMI® with respect to this difference without the EMI®. Results No significant effect of the EMI was observed neither for static nor dynamic conditions. Conclusions Our results do not confirm previous work in static conditions. Recently it has been demonstrated that EMI® has an impact on eyes vergence, especially in population with plantar postural dysfunction. Future work is needed to evaluate effect of such insert on participants with postural deficiencies.