Effects of a dynamic-ankle-foot orthosis (Liberté®) on kinematics and electromyographic activity during gait in hemiplegic patients with spastic foot equinus.

Abstract

A dynamic-ankle-foot orthosis has recently emerged and consists of an elastic band allowing the variation of stiffness degree and adjusts dorsiflexion assistance in swing. The aim of this study was to quantify the biomechanical adaptations induced by this orthosis during gait in hemiplegic patients. Twelve hemiplegic patients performed two gait analyses (without and with the ankle-foot orthosis). Spatiotemporal, kinematic, kinetic and electromyographic gait parameters were quantified using an instrumented gait analysis system during the stance and swing phases. During swing, peak ankle dorsiflexion was greater with the orthosis and associated with a decrease of pelvic obliquity angle. In stance, peak ankle plantarflexion and dorsiflexion were greater with the orthosis and associated with an increase of ankle angle at heel strike and toe-off. Electromyographic activities of both the tibialis anterior and the medial gastrocnemius were greater with the orthosis. This dynamic-ankle-foot orthosis improved gait in hemiplegic patients with spastic foot equinus. The spatiotemporal adaptations seem to be caused mainly by the increase of ankle dorsiflexion during stance and swing phases. The changes in electromyographic activity were related to an active dorsiflexion in stance and swing phases and an active plantarflexion in stance phase.