Comparing the Effect of Implanted Peroneal Nerve Stimulation and Ankle-Foot Orthosis on Gait Kinematics in Chronic Hemiparesis: A Randomized Controlled Trial

Objective: Impaired ankle dorsiflexion in hemiparesis may be treated with ankle-foot orthosis or functional electrical stimulation. Semi-implanted selective functional electrical stimulation uses independent stimulations of deep and superficial peroneal nerves. The aim of this study was to compare gait kinematics using ankle-foot orthosis or semi-implanted selective functional electrical stimulation over 6 months in hemiparesis. Methods: Subjects with chronic hemiparesis, randomized into ankle-foot orthosis or semi-implanted selective functional electrical stimulation groups, underwent comfortable gait analysis without and with device OFF and ON, before, and 3 and 6 months after treatment onset. The effects of condition, visit and group on gait kinematics (analysis of variance; ANOVA) were analysed. Results: A total of 27 subjects were included (ankle-foot orthosis, n = 13; semi-implanted selective functional electrical stimulation, n = 14). The only between-group difference in changes from OFF to ON conditions was a deteriorated ankle dorsiflexion speed with ankle-foot orthosis at month 6 (condition*group, p = 0.04; ankle-foot orthosis, –60%, p = 0.02; semi-implanted selective functional electrical stimulation, non significant). Both groups pooled, from OFF to ON gait speed (+ 0.07 m/s; + 10%), cadence (+ 4%), step length (+ 6%) and peak ankle dorsiflexion (+ 6°) increased, and peak ankle inversion (–5°) and peak knee flexion (–2°) decreased (p < 0.001); finally, peak knee flexion in the OFF condition increased (+ 2°, p = 0.03). Conclusion: Semi-implanted selective functional electrical stimulation and ankle-foot orthosis similarly impacted gait kinematics in chronic hemiparesis after 6 months of use. Ankle dorsiflexion speed in swing deteriorated markedly with ankle-foot orthosis. LAY ABSTRACT After a central nervous system injury, walking disorders are associated with ankle dorsiflexion and foot eversion in the paretic limb during the swing phase. Movement of the ankle can be partially corrected with ankle-foot orthosis (AFO) or functional electrical stimulation (FES). The semi-implanted selective FES (SIS-FES) is an advanced FES device using independent stimulations of deep and superficial peroneal nerves, to separately control movements of ankle dorsiflexion, hallucis extension and foot eversion, and to optimize FES-associated walking improvements. This study compared walking using AFO or SIS-FES over 6 months in hemiparesis. A total of 27 patients with chronic hemiparesis, randomized into AFO or SISFES groups, underwent comfortable walking analysis without and with device OFF and ON, before, and 3 and 6 months after treatment onset. SIS-FES and AFO similarly improved walking speed, cadence, step length, ankle dorsiflexion and foot eversion, while ankle dorsiflexion speed in swing markedly deteriorated with AFO.