Improving Balance After Spinal Cord Injury Using a Robotic Upright Stand Trainer and Spinal Cord Epidural Stimulation

The purpose of this study is to understand how standing and sitting balance control is altered after spinal cord injury and how a new type of robotic assistive device may be used with spinal stimulation to improve muscle function. The investigators will be testing a device called the Tethered Pelvic Asist Device (or "TPAD") in this study. The TPAD may be helpful in two ways. It can be used to help control and support of the trunk, pelvis, and knees during stand training. Also, the TPAD can be used as a training tool by providing controlled "pushes" or "perturbations" that must be corrected by the person with spinal cord injury in order to maintain proper posture and upright balance. This could be helpful for improving muscle function after spinal cord injury. Participants will be placed into one of two groups based on availability and preference. Group 1 will receive TPAD training with stimulation and assessments with and without stimulation. Participation in this group lasts approximately 4 months. Group 2 will only receive assessments with and without stimulation. Participation in this group last approximately 3 weeks.