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.

The aims of the proposed study are to (a) examine the muscle activation patterns generated during stable and perturbed standing in spinal cord injured individuals using spinal cord epidural stimulation (scES) and robotic TPAD-assistance or self-assistance for balance, and (b and c) to examine the effectiveness of TPAD-assisted stand training in the improvement of postural control during stable and perturbed standing and sitting in spinal cord injured individuals using spinal cord epidural stimulation (scES).

The Tethered Pelvic Assist Device (TPAD) is a light-weight cable-driven robotic stand trainer that (i) can provide assistance-as-needed by applying corrective forces on the trunk and pelvis in response to their movement outside a pre-programmed area, and (ii) can apply controlled forces on the trunk and pelvis to perturb them from their nominal configuration during standing.

A total of 20 spinal cord injured participants who were previously implanted with a scES unit will be enrolled in this study. They will be split into two groups with 10 participants in each. All participants will undergo a physical examination and classification of their spinal cord injury to determine eligibility criteria, which are the same for both groups. Participants will then be placed into one of the two groups based on their availability and preference to be enrolled in a longer or shorter study. Group 1 will consist of individuals with SCI and an scES implant that will receive TPAD training with stimulation and assessments with and without stimulation. Group 2 will consist of individuals with SCI and an scES implant that will only receive assessments with and without stimulation.

Each individual will serve as their own control, to reduce variability. All participants will undergo the Stable Standing Assessment, Postural Perturbation Assessment, Stable Sitting Assessment and Postural Perturbation Assessment in Sitting. Only Group 1 will also perform the Neuromuscular Recovery Scale and attend training sessions with the TPAD system.

Eligibility Criteria:
Inclusion Criteria:

* At least 18 years old
* Stable medical condition.
* Has a spinal cord injury caused by trauma (fall, car accident, etc.) for at least one year that is not getting worse over time
* Has an implanted spinal cord epidural stimulation unit that is eligible for software upgrade as part of a previous study.
* Unable to stand independently with epidural stimulation turned off.

Exclusion Criteria:

* unwilling to discontinue from anti-spasticity medications
* Untreated painful problems with joints, muscles or bones.
* Unhealed fracture.
* Pressure sore or urinary tract infection.
* History of bone disease (except for decreased bone mineral density due to spinal cord injury).
* Ongoing drug abuse.
* Untreated psychiatric disorders or clinical depression.
* Received Botox injections in the lower extremities in the prior six months.
* Heart or lung disease that may interfere with assessments.
* Untreated severe and persistent problems regulating blood pressure, heart rate, body temperature or other automatic functions.