Walking ability is critically important for pediatric health, well-being, and independence. Children with cerebral palsy (CP), the most prevalent cause of pediatric physical disability, often present an increasingly crouched gait pattern throughout development that negatively impacts walking capacity. Despite efforts to manage crouch gait surgically and with physical therapy, walking deficits frequently remain after treatment; around 50% of affected individuals lose the ability to walk. The overarching goal of this research is to achieve lasting corrections in walking ability in children with CP through the intelligent implementation of wearable assistance training at home and in the community. To inform dosing and implementation guidelines necessary for the design of long-term studies, data on the physiological responses to daily exoskeleton training over intermediate time-frames (e.g. 2 weeks) are needed. Therefore, the objectives of this project are to understand the progression of biomechanical adaptation to exoskeleton assistance during continuous training, and to develop techniques that can be implemented to produce targeted neuromuscular engagement. The central hypothesis is that daily walking with powered extension assistance will improve the interaction between the neuromuscular system and exoskeleton to enhance outcomes; moreover, leveraging bio-feedback to target volitional muscle activity will further improve posture and motor learning. The first specific aim is to quantify how the daily use of an assistive exoskeleton during a two-week training period affects gait biomechanics, neuromuscular control, and metabolic walking economy in children with CP. Participants will walk with knee extension assistance during daily training for 2 weeks. Gait analysis, electromyography, and oxygen consumption data will be measured during walking with and without exoskeleton assistance on days 1, 7, 14, and 1-week after training. It is hypothesized that reductions in antagonist muscle activity will be coupled with improvements in dynamic posture and walking economy over the course of the study during walking with assistance, and participants will exhibit improved muscle activity and posture during unassisted walking on day 14 and 1-week follow-up. The second specific aim is to determine how incorporating real-time postural feedback during exoskeleton-assisted gait training affects functional outcomes and motor learning in children with CP. Auditory and visual feedback of stance- and swing-phase knee extension will be provided in relation to tailored improvement goals as participants walk with assistance. Providing feedback and incentivizing improvement during assisted walking is hypothesized to result in increased knee extension and knee extensor muscle activity compared to assisted walking without feedback. The knowledge gained from this proposal will provide insight into the capacity of motor learning in children with CP, and enhance the ability to optimize the prescription of wearable assistance for treating crouch gait.

Public Health Relevance

Walking ability is critically important for pediatric health, well-being, and independence, yet many children with cerebral palsy, the most prevalent cause of pediatric physical disability, are unable to walk as adults. In the short-term, the fundamental knowledge gained from this proposal will provide insight into the capacity and mechanisms of motor learning during powered gait training in children with cerebral palsy. In the long-term, this research will enhance our ability to optimize the prescription of wearable assistive devices for the sustainable treatment of pediatric gait disorders where early intervention is critical.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Small Research Grants (R03)
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Special Emphasis Panel (ZHD1)
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Quatrano, Louis A
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Northern Arizona University
Engineering (All Types)
Biomed Engr/Col Engr/Engr Sta
United States
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Lerner, Zachary F; Gasparri, Gian Maria; Bair, Michael O et al. (2018) An Untethered Ankle Exoskeleton Improves Walking Economy in a Pilot Study of Individuals With Cerebral Palsy. IEEE Trans Neural Syst Rehabil Eng 26:1985-1993