The purpose of this study is to evaluate a surgically implanted functional electrical stimulation (FES) system to facilitate exercise, standing, stepping and/or balance in people with various degrees of paralysis.

Protocol Outline: Patents undergo surgery in which electrodes are implanted into muscles of the trunk and legs. Electrode leads are connected to an stimulator/telemeter. Following implantation, patients undergo training in standing, transfers and other advanced mobility skills using the functional electrical stimulation system. A prescribed course of exercise, functional training and rehabilitation with the implanted stimulation system, followed by laboratory assessments of strength, balance and functional abilities with and without the system, as well as the technical performance of the implanted components. Home-based training follows prior to discharge for home use of the system.

Patients are followed at 6 and 12 months after discharge and then annually thereafter.

Phase I Inclusion Criteria

1. Skeletal maturity and ability to sign informed consent (>18 years)
2. Non-ventilator dependent paralysis resulting from injuries such as: mid cervical/thoracic (C4 or below) spinal cord injuries, poststroke hemiparesis, TBI, or MS, affecting the trunk and/or lower limbs
3. Innervated and excitable lower extremity and trunk musculature
4. Adequate social support and stability
5. Willingness to comply with follow-up procedures

Phase I Exclusion Criteria

1. Non-English speaking
2. Females who are pregnant
3. Current pressure injuries that would be exacerbated by study activities
4. Severe contractures or uncontrolled spasticity of any major joint of the upper or lower extremities that results in a fixed deformity that would interfere with study activities
5. History of spontaneous fractures or other evidence of excessively low bone density
6. History of vestibular dysfunction, balance problems, or spontaneous falls
7. Acute and or/untreated orthopedic problems that would prevent a participant from weight bearing or exercising such as a dislocation or fracture.