Development of a practical electrical stimulation system for restoring gait in the paralyzed patient.

A percutaneous functional neuromuscular stimulation (FNS) system is being developed for restoring function in the lower extremities of spinal cord injured people with lesions between T4 and T11. Limitations of the current system are electrode failure, muscle fatigue, cumbersome electrical hardware, and an inefficient user-machine interface. Transforming this experimental system into a practical FNS system requires achieving acceptable levels of safety, reliability, function, metabolic energy requirement, ease of use, cosmesis, and cost. This eventually can be accomplished with development of implantable stimulators and totally implantable electrodes, intimate command devices with tactile feedback, and closed-loop control of muscle stimulation.