An electrical knee lock system for functional electrical stimulation.

An electrical knee lock system that can be combined with functional electrical stimulation was designed for paraplegic patients. This knee system unlocks the knee electrically and allows knee flexion during the swing phase of the gait. When the knee is extended by electrical stimulation of the knee extensors, the knee is automatically locked by the weight of the locking bar, and the stimulation of the knee extensors is stopped. Since the knee extensors are stimulated for only a short period, muscle fatigue of the knee extensors seldom occurs. We applied this system to a T8 completely paraplegic patient. Standing-up, standing, walking, and sitting-down motions were all restored by our hybrid system. No electrical stimulation was necessary during standing, and the knee extensors were stimulated during only a small percentage of the 1-gait cycle.