Evaluation of an Advanced Lower Extremity Neuroprostheses

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.