A Feasibility Study of a Hybrid Approach Using FES and a Mechanical Orthosis to Restore Hand Movements in Individuals with Tetraplegia

This study explores a novel method combining functional electrical stimulation (FES) with a motorized orthosis to aid prehension in individuals with tetraplegia. Surface FES activates muscles for moving fingers, thumb, and wrist joints, while electric motors lock the joints in desired positions. The goal is to reduce muscle fatigue compared to FES alone and enable prolonged grasping. The feasibility and acceptability of this hybrid orthosis were tested on five participants with upper-limb paralysis due to spinal cord injury. Assessments included grip quality on three different objects for 30 s, perceived effort using the Borg RPE scale, pain using the visual analog scale (VAS), and acceptability using the QUEST and SUS scales. Preliminary results indicate that the hybrid orthosis could add value compared to FES alone, with functionality scores equal to or better than those achieved with FES alone, and successful object grasping for 30 s without muscular fatigue impacting grip quality.