A Sensor-Based Multichannel FES System to Control Knee Joint and Reduce Stance Phase Asymmetry in Post-Stroke Gait.

Benoît Sijobert,Sahara Graf,Christine Azevedo,Joanna Pontier,Charles Fattal

doi:10.3390/s21062134

Abstract

Most of the studies using functional electrical stimulation (FES) in gait rehabilitation have been focused on correcting the drop foot syndrome. Using FES to control the knee joint in individuals with central nervous system (CNS) disorders could also play a key role in gait recovery: spasticity decrease, higher range of motion, positive effect on balance, limiting hyperextension and flexion in stance phase, reducing joint overload, etc. In stance phase, an accurate timing and a fine tuning of stimulation parameters are however required to provide a proper control of the knee stimulation while ensuring a safe and efficient support. In this study, 11 participants were equipped with inertial measurements units (IMU) and foot pressure insoles after supratentorial ischemic or hemorrhagic stroke, informing on knee angle and gait events used to online adapt FES during a 10 m walking protocol. Asymmetry of stance time and weight bearing were monitored as well as gait quality and physiological cost through a series of relevant markers. Vertical trunk motion has been significantly reduced during gait with FES (p-value = 0.038). Despite no significant improvement of stance phase asymmetry has been found, this preliminary work shows evidence of promising technical and rehabilitative potentials of a sensor-based multichannel FES system to control knee joint in post-stroke gait.

Highlights

Numerous strategies using functional electrical stimulation (FES) have been investigated over the past fifty years to assist or restore gait [1]
The state-of-the-art reflects a substantial lack of interest in using FES to improve knee joint control in central nervous system (CNS) disorders, where this problematic is classically handled by using a knee orthosis
Being able to finely control the knee angle could play a key role in gait recovery of people with CNS disorders

Summary

Introduction

Numerous strategies using functional electrical stimulation (FES) have been investigated over the past fifty years to assist or restore gait [1] Most of these studies have been conducted in post-stroke individuals and have focused on correcting the drop foot syndrome by supplementing the absence of dorsiflexion [2]. The state-of-the-art reflects a substantial lack of interest in using FES to improve knee joint control in central nervous system (CNS) disorders, where this problematic is classically handled by using a knee orthosis Focusing on this specific joint could play a key role in post-stroke gait recovery. Chantraine et al [9] proposed to use an implanted DFS and to extend the timing of the CP nerve stimulation during the stance phase in order to tilt the tibia forward This appeared to effectively limit the knee hyperextension, with continued positive outcomes more than 12 months following implantation. In the absence of voluntary control, Kobetic et al [12] observed that a premature deactivation of the knee extensors at the end of the stance phase before the leg is fully unloaded can lead to a fall

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