This is a randomized clinical trial to quantify the effects of exoskeleton-assisted gait on the musculoskeletal system and health-related quality of life.

Investigators will test if exoskeleton-assisted ambulation confers skeletal benefits in a dose-dependent fashion. Investigators also will test if reintroduction of ambulation will be associated with improvements in quality of life due to improvements in mood, pain, and functional connectivity of emotional networks in the brain.

Inclusion Criteria:

• 3 years or more after injury,
• Non-ambulatory AIS A-D spinal cord injury (C7-T12),
• 158-188 centimeters tall,
• Weigh less than 100 kilograms,
• Have a Modified Ashworth Scale (MAS) score of less than 3 in both lower extremities, and
• Have sufficient upper body strength to complete sit to sit transfers.
• Women of childbearing potential must agree to use contraceptive measures during participation in the study. They also will be required to have a negative pregnancy test (urine or serum) before receiving an imaging studies.

Exclusion Criteria:

• Current enrollment in another clinical trial
• Pregnancy
• Anyone with an initial blood pressure>140/90 mmHg, orthostatic hypotension with symptomatic fall in blood pressure >30 mmHg when upright,
• An active grade 2 or greater pressure ulcer that can be worsened by walking in the device,
• Lower extremity contractures that interfere with the ability to wear the device,
• An unhealed limb or pelvic bone fracture history of other neurological disease (e.g. stroke, peripheral neuropathy, myopathy),
• Active treatment for epilepsy,
• Current use of medications potentially affecting bone health (bisphosphonates, androgenic steroids, estrogenic steroids, lithium, glucocorticoid use for more than 3 months).
• Subjects with MRI-incompatible implants, pumps, or neurostimulators will be excluded.