Contrôle de l’équilibre et port unilatéral d’une orthèse rigide de cheville. Partie I : effets sur des sujets sains évalués debout en unipédie

In order to assess the effects induced by wearing a rigid ankle orthosis, 14 healthy adults, without traumatic previous injuries at this level, were tested in a one-legged postural task. The subjects stood upright on a force platform and were required to remain still, eyes open. Ten trials lasting 32 s were recorded in a random order in two conditions: with a rigid orthosis model worn at the ankle level of the supporting leg (Thuasne, Ligastrap Immo^®) and with an elastic stocking. Balance strategies have been quantified by studying the centre of pressure (CP) trajectories, that is, the successive positions of the resultant reaction forces, and processed through a frequency analysis. The results indicate that slight decreases occur for the CP displacements intervening along the medio-lateral axis whereas statistically significant trends were found for those intervening along the anteroposterior one. This finding a priori suggests that wearing a rigid orthosis affects one-legged standing in healthy individuals but mainly along an axis not usually weakened by sprained ankles.