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.
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.
unwilling to discontinue from anti-spasticity medications
Untreated painful problems with joints, muscles or bones.
Unhealed fracture.
Pressure sore or urinary tract infection.
Parallel
The Tethered Pelvic Assist Device (TPAD)
Devicea 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.
Neuromuscular Recovery Scale (NRS)
Research participants will undergo a series of tasks to test the level of muscle activation and amount of assistance required during standing and stepping in a body-weight supported treadmill environment, as well as overground motor tasks. Arm, trunk/leg movement recovery and independency will be measured by the NRS using 14 motor tasks (sit, reverse sit up, sit up, sitting truck extension, overhead press, forward reach and grasp, door pull and open, can open and manipulation, sit to stand, stand, walking, stand adaptability, step retraining, and step adaptability) and combined with EMG, kinematic, and kinetic analyses on the upper and lower extremities and/or trunk. Based on the performance across categories, 4 phase scores can be assigned:1- greatest impairment relative to normal movement patterns (non-ambulatory), 2- begins to stand and weight support independently, 3- walking with varying skill levels, and 4- normal locomotor and transfer performance with adaptability.
Sitting Assessment
Research participants will sit on a padded table and perform tasks to challenge their balance control (reaching/shifting weight in multiple directions). Assistance for sitting will be provided at the trunk by the TPAD or by the trainer. EMG and kinematic analysis will be performed on the lower extremities, trunk and upper extremities during sitting. The trunk force and position controller data from the TPAD will be also collected; these data will be synchronized with EMG and kinematic data. Muscle activation patterns will be evaluated recording EMG from different muscle groups. The TPAD/trainer will then generate controlled loss of balance during sitting. EMG onset and burst duration relative to perturbation onset, loss of balance onset and return to balance will be compared. EMG mean and integrated amplitudes from each muscle will be compared between the beginning and end of the study.
Standing Assessment
Participants will stand as long as possible and undergo a series of standing tasks. Electromyography (EMG), kinematic and kinetic analysis will be performed on the lower extremities and trunk during standing. The pelvic, trunk and knee force and position controller data from the TPAD will be collected and synchronized. Muscle activation patterns will be evaluated recording EMG from different muscle groupings. When appropriate, ground reaction forces will be measured. Blood pressure and heart rate will be measured. The TPAD will then generate controlled loss of balance during standing. Participants will regain balance with/without grasping a fixed object. Investigators will compare EMG onset and burst duration relative to perturbation onset, loss of balance onset and return to balance if applicable. EMG mean and amplitudes from each muscle will be compared before and after the study.
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