Hybrid Orthosis with Controllable Hip and Knee Joints and Multichannel Fes for Walking in Paraplegia

A hybrid system including trunk-hip-knee-anklefoot (THKAFO) orthosis and multi-channel functional electrical stimulation with implanted electrodes has been designed for walking in paraplegia. The THKAFO has been instrumented with commercially available spring wrap clutches at the hips and knees. Clutches provide free movement in extension and allow flexion only when they are disengaged by solenoids. Microprocessor controlled stimulator provides activation signals for solenoids, in addition, to multi-channel muscle stimulation. This system provides free motion of the hips and knees during swing phase of gait and selectively locks the hips and knees during stance to prevent collapse. The initial use of this hybrid system has shown the importance of close coupling of THKAFO and the body. This hybrid system has a potential to provide gait powered by muscle stimulation without the usual restrictions in joint motion imposed by the bracing but with stability normally seen only with bracing. Further advantages include reduction in required stimulation during standing and support phases of gait. Introduction/Background Standing and short distance walking and stair climbing with multi-channel functional electrical stimulation (FES) in paraplegia has been shown feasible. The FES walking, however, has been limited to short distance due to instability requiring considerable effort of the user, resulting in high metabolic energy consumption. An approach to improve stability during walking has been the use of hybrid orthosis – a combination of FES and extensive bracing. Others have used reciprocating gait orthosis (RGO) combined with FES where the knee and ankle joints were locked and the hips were controlled with a reciprocating mechanism [1]. In other attempts, the knee and hip joints were controlled electromechanically with surface FES assisting the movement [2]. The purpose of this project is to implement a hybrid system combining at least 16 channels of implanted FES to provide power to stand up and to move the body forward during walking together with an electronic THKAFO for stability.