Amplify Gait to Improve Locomotor Engagement in Spinal Cord Injury (AGILE SCI)

Spinal cord injury (SCI) affects ~42,000 Veterans. The VA provides the single largest network of SCI care in the nation. The lifetime financial burden of SCI can exceed $3 million. A major cost of SCI is impaired mobility. Limited mobility contributes to decreased ability to work, increased care requirements, secondary injury, depression, bone mineral density loss, diabetes, and decreased cardiovascular health. Among ambulatory individuals with iSCI, residual balance deficits are common and are strongly correlated with both functional walking ability and participation in walking activities. The development of effective rehabilitation tools to improve dynamic balance would substantially improve quality of life for Veterans living with iSCI. Improving mobility through interventions that enhance dynamic balance would positively impact health, independence, and the ability to integrate into social, intellectual, and occupational environments.

Background: Among ambulatory individuals with incomplete spinal cord injury (iSCI), residual balance deficits are common and are a primary factor limiting participation in walking activities. There is broad recognition that effective evidence-based interventions are needed to enhance dynamic balance following iSCI. However, improving dynamic balance after iSCI has proven to be very challenging. Experimental interventions that amplify self-generated movements (e.g. error augmentation) may accelerate motor learning by intensifying sensory motor feedback and facilitating exploration of alternative motor control strategies. These features may be beneficial for retraining dynamic balance after iSCI. The investigators have developed a cable-driven robot to create a movement amplification environment during treadmill walking by applying a continuous viscous force field to the pelvis that is proportional in magnitude to a participant's real-time range of motion (ROM) velocity. The purpose is to investigate if locomotor training performed in a movement amplification environment can effectively improve dynamic balance and increase participation in walking activities of individuals with iSCI. Specific Aims: Aim 1: To evaluate if locomotor training performed in a movement amplification environment is effective for improving dynamic balance of individuals with iSCI. The investigators' pilot data found that following locomotor training performed in a movement amplification environment three individuals with iSCI each improved dynamic balance by more than 30%. These improvements were accompanied by faster over ground walking speeds and improved reactive balance. Thus, the investigators hypothesize that improvements in dynamic balance during walking will be greater when locomotor training is performed in a movement amplification environment when compared to locomotor training performed in a traditional treadmill environment. Aim 2: To evaluate the impact of locomotor training performed in either a movement amplification environment or in a traditional treadmill environment on participation in walking activities. Based on evidence identifying a strong relationship between balance and steps per day in ambulatory individuals with iSCI, the investigators hypothesize that training in the movement amplification environment will positively impact dynamic balance, and in turn increase participating in walking activities. Approach: The investigators will conduct a two-arm parallel-assignment intervention and will enroll 36 ambulatory participants with chronic motor incomplete spinal cord injury. Participants will be randomized into either a Control group receiving locomotor training or an Experimental group receiving locomotor training performed in a movement amplification environment. All participants will receive 20 training sessions. The investigators will assess changes in dynamic balance using measures that span the International Classification of Functioning, Disability and Health (ICF) framework including; 1) clinical outcome measures of gait, balance, and quality of life, 2) biomechanical assessments of the capacity to control COM motion during walking, and 3) data collected from activity monitors to quantify changes in participation in walking activities as evaluated by number of steps taken per day. Impact: Training dynamic balance of individuals with iSCI by amplifying their own self-generated center of mass motion during walking is a radical departure from current practice and may create effective new clinical strategies for addressing balance impairments of individuals with iSCI. Successful outcomes from the proposed trial would motivate development of clinically-feasible tools to first replicate and then to evaluate the movement amplification environment within the VA's clinical care settings. Knowledge gained from this study will expand the understanding of how individuals with iSCI learn dynamic balance and how targeted dynamic balance training impacts participation in walking activities.

The investigators will conduct a two-arm parallel assignment intervention. Participants will be randomized into a high intensity locomotor training intervention that will be conducted in either a normal treadmill environment or in a movement amplification environment.

Participants randomized to the Treadmill group will complete high intensity gait training on a treadmill.

The locomotor training protocol described for the Treadmill group will be used for the Movement Amplification group with one exception. The Movement Amplification group will perform all gait training within the movement amplification environment.

Participants randomized to the Control group will complete high intensity gait training on a treadmill.

The Experimental group will perform all gait training within the movement amplification environment. To create the movement amplification environment, the investigators have constructed a cable-driven robot, the Agility Trainer. The Agility Trainer applies small forces to the pelvis that increase the difficulty to maintain forward walking

The investigators will assess the amount of daily stepping in the home and community during three 1-week periods. Daily stepping will be measured and recorded using an activity monitor.

The Lane width Optimization test will be used to quantify the capacity of individuals to control their lateral center of mass motion during treadmill walking. Participants will walk on the treadmill for 2 minutes. During the test a narrow lane will be projected on the treadmill belt surface. Individuals will be asked to maintain their body position within the lane during walking. If successful the lane will become progressively more narrow. If unsuccessful, the lane will become progressively wider. The width of the lane at the completion of the test will provide a quantitative measure of the individual's ability to control the center of mass motion during walking.

The lower extremity motor score assess strength of five muscle groups representing neurological levels L2 to S1. Muscle function is grade on a range from 0 (total paralysis) to 5 (active movement, full ROM against gravity and sufficient resistance to be considered normal.

The WISCI II evaluates the amount of physical assistance needed for gait after spinal cord injury. The index ranges from 0 (client is unable to stand and/or participate in assisted walking) to 20 (ambulates with no devices, no braces and no physical assistance, 10 meters).

The FGA is a ten-item test that evaluates dynamic balance and postural stability during gait. Each item on the test is scored from 0 (severe impairment) to 3 (normal ambulation).

The ABC scale is a 16-item self-report measurement of an individual's confidence while performing numerous postural and ambulatory activities. Each item is rated on a scale of 0 (no confidence) to 100 (complete confidence). Overall score is calculated by adding item scores and then dividing by the total number of items.

The BESTest is used to assess balance impairments across six different domains of postural control. We will use only the reactive balance item from the BESTest to assess changes in the capacity to react to fore-aft, and lateral perturbations. Each item will be scored on a range from 0 (severe impairment) to 3 (no impairment).

The BBS is a 14-item measure that assesses static balance. Each item is scored on a range of 0 to 4. A total score is determined by summing scores on the all the individual items. A higher score indicates better balance.

The WHOQOL-BREF is a 26 item self-report quality of life assessment focusing on areas such as physical, psychological, social and environmental health. Scores range from 0-100 with 100 indicating higher quality of life.

International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-UI SF)

The ICIQ-UI SF is a 4-item self-report of urinary incontinence to document changes in bladder function. Scores range from 0-21, with greater values indicating increased severity.

The investigators will perform biomechanical laboratory assessments to make quantitative measures of changes in dynamic balance during walking. The investigators will record 3D coordinates of reflective markers placed on anatomical landmarks. These markers will be used to quantify changes in an individual's preferred step width (lateral distance between calcaneal markers) during treadmill walking.

The investigators will perform biomechanical laboratory assessments to make quantitative measures of changes in dynamic balance during walking. The investigators will record 3D coordinates of reflective markers placed on anatomical landmarks. These markers will be used to quantify changes in an individual's preferred step length (anterior - posterior distance between calcaneal markers) during treadmill walking.

The investigators will perform biomechanical laboratory assessments to make quantitative measures of changes in dynamic balance during walking. The investigators will record 3D coordinates of reflective markers placed on anatomical landmarks. These markers will be used to quantify changes in an individual's average minimum lateral margin of stability (distance between a velocity weighted whole body center of mass position and the edge of the base of support) occurring each step during treadmill walking.

The investigators will perform biomechanical laboratory assessments to make quantitative measures of changes in dynamic balance during walking. The investigators will record 3D coordinates of reflective markers placed on anatomical landmarks. These markers will be used to quantify changes in an individual's average peak lateral center of mass speed occurring each step during treadmill walking.

The investigators will perform biomechanical laboratory assessments to make quantitative measures of changes in dynamic balance during walking. The investigators will record 3D coordinates of reflective markers placed on anatomical landmarks. These markers will be used to quantify changes in an individual's average lateral center of mass excursion occurring each step during treadmill walking.

Inclusion Criteria: Medically stable with medical clearance from a physician to participate Neurologic level of the SCI between C1-T10 with American Spinal Injury Association (ASIA) Impairment Scale (AIS) C or D > 6 months since initial injury Passive range of motion of the legs within functional limits and not restricting the ability to engage in locomotor training Able to ambulatory 10m with no physical assistance, use of assistive devices (e.g. single cane, rolling walker), and/or braces that do not cross the knee joint (e.g. anklefoot orthosis) are permitted Able to provide transportation to and from the testing location. Exclusion Criteria: Excessive spasticity in the lower limbs as measured by a score of > 3 on the Modified Ashworth Scale Inability to tolerate 30 minutes of standing Severe cardiovascular and pulmonary disease History of recurrent fractures or known orthopedic problems in the lower extremities (i.e. heterotopic ossification) Concomitant central or peripheral neurological injury (i.e. traumatic head injury or peripheral nerve damage in lower limbs) Inability to provide informed consent due to cognitive impairments Presence of unhealed decubiti or other skin compromise Enrollment in concurrent physical therapy or research involving locomotor training Use of braces/orthotics crossing the knee joint Known pregnancy

The investigators will create and share de-identified, anonymized data sets. Data sets will be open file formats that include documentation of the material. The investigators will link data sets to associated study publications. Final data sets will be made available as per Hines VA Hospital local policy for long term storage and access until enterprise-level resources become available. These data will be available upon request by researchers and scientists in accordance with federal guidelines and Hines local policy. The final data sets will be sufficient for anyone to perform analogous or supplemental analyses that would permit validation of the analysis and results. The sharing of data will enable others to evaluate the data and to validate and interpret the data independently.