Contrôle de l'équilibre et port unilatéral d'une orthèse rigide de cheville. Partie II : effets sur des sujets sains évalués debout en bipédie

In order to compare the effects induced by the unilateral wearing of a rigid orthosis (Thuasne, Ligacast Immo®) in comparison to a reference model consisting of an elastic stocking, balance control strategies of 14 healthy subjects have been evaluated in two-legged standing. To this aim, 10 trials lasting 32 s have been recorded through a device made of two separate force platform allowing the separate measurement of the reaction forces intervening under each foot. Balance strategies have been assessed from the centre of pressure trajectories issued from the left (CPG) and right feet (CPD) and, through a calculation, from the resultant CP (CPRes). These various trajectories, projected along mediolateral (ML) and anteroposterior (AP) axes, have been then analysed in the frequency domain. If no difference has been observed for the CPRes trajectories, the separate analysis of each support has furnished statistically significant results for the CP trajectories measured under the foot wearing the orthosis since the amplitudes decrease along both ML and AP axes. Contrary to what was observed in the previous study conducted in one-legged standing, with effects occurring only along the AP axis, these results appear thus in better accordance with the objectives of an orthosis since diminishing the involvement of the lateral ligaments. This kind of protocol appears thus more relevant for characterising in situ the effects of an orthosis made of two rigid shells.