Effects of implantable peroneal nerve stimulation on gait quality, energy expenditure, participation and user satisfaction in patients with post-stroke drop foot using an ankle-foot orthosis.

Purpose: To investigate whether an implantable functional electrical stimulation (FES) system of the common peroneal nerve (ActiGait®) improves relevant aspects of gait in chronic stroke patients with a drop foot typically using an ankle-foot orthosis (AFO).

Methods: Ten community-dwelling patients participated, of whom eight patients could be analysed. Gait quality (kinematic, kinetic, and spatiotemporal characteristics) during a 10-meter comfortable walk test, normalised net energy expenditure during a 6-minute walk test, participation (physical activity and stroke impact) and user satisfaction were tested before implantation and at various moments after FES-system activation up to 26 weeks.

Results: Walking with FES yielded increased maximum paretic ankle plantarflexion (FES: -0.12; AFO: -4.79°, p <  0.01), higher paretic peak ankle power (FES: 1.46; AFO: 0.98 W/kg, p <  0.05) and better step length symmetry (FES: 14.90; AFO: 21.45% , p <  0.05). User satisfaction was higher for FES, but was unrelated to objective gait improvements. Energy expenditure and participation did not change.

Conclusion: Implantable FES improved the use of residual ankle plantarflexion motion, ankle power of the paretic leg and step length symmetry compared to using an AFO, however, not resulting in decreased energy expenditure or improved participation. User satisfaction was highest with FES, but this was not related to the observed gait improvements.