A phase I/II trial evaluating long-term use of a Pediatric Robotic Exoskeleton (P.REX/Agilik) to improve gait in children with movement disorders

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Abstract

This is a single site outpatient study at the National Institutes of Health Clinical Center, Rehabilitation Medicine Department, Neurorehabilitation and Biomechanics Section. This is a study of a novel device. It is a pivotal study, analogous to phase 1, designed to assess both safety and effectiveness of the intervention. This is a study of pediatric outpatients split into two participant pools, one with crouch gait from cerebral palsy (CP) and the other knee extension deficiency from another neuromuscular disorders such as muscular dystrophy (MD), spina bifida (SB), and incomplete spinal cord injury (iSCI). The design of the study will be structured as a randomized, crossover study. The target intervention dosage will be constant across all participants (5 days/week, 1 hour/day). These two subject pools will complete the study design independent of each other including separate randomization into Groups A (who will receive the exoskeleton intervention first, followed by an observation period) and B (who will complete the observation period first, followed by the exoskeleton intervention) following inclusion in the protocol at visit 0. Both the CP and Neuromotor Disorder subject pools will complete the same study design, but will be analyzed independent of each other. The aim of the study is to investigate the safety and effectiveness of a robotic exoskeleton for overground gait training targeting improvements to knee angle profile, posture, and gait speed. As previous studies at the NIH have demonstrated the orthotic effects and immediate benefits of an extension-assist robotic exoskeleton on the target population of children with CP (protocol #13-CC-0210), this study will investigate longer-term benefits using this technology outside of the clinical setting and in application to a broader patient population including children and adults with knee extension deficiency from a diagnosis of SB, MD or iSCI. We hypothesize that use of a robotic exoskeleton for 1 hour/day, 5 days/week over a 12-week training period will lead to functional improvements in overground walking without the exoskeleton by (i) increasing peak knee extension angle, (ii) improving overground gait speed, and (iii) improving knee extensor, including the vastus lateralis and rectus femoris, muscle activation and strength. In addition, we hypothesize that regular use of a robotic exoskeleton over a 12-week training period will also improve volitional gait speed and the observed functional improvements in overground walking will persist following completion of the exoskeleton intervention training. The robotic exoskeleton used as the intervention in this study consists of two orthotic braces, one for each limb, with each device containing a single robotically actuated degree of freedom at the sagittal plane knee joint (flexion/extension direction) and the associated embedded electronics and sensors to power and control the device. The exoskeleton applied torques delivered during the intervention period are customized to each patient to aid in rehabilitation of the knee extension deficiency by applying appropriately timed and scaled resistive torque during walking, requiring increased effort from the user to facilitate strength training and improved muscle activation. This is a multi-visit study with outcome assessments of the same measures at various points in the protocol. These measures include peak knee extension, knee extension at initial contact, step length, gait speed, knee moment, peak and mean activation of knee extensor and flexor muscles during walking, gross motor function classification system (GMFCS) categorization, pediatric evaluation of disability inventory-computer adaptive test (PEDI-CAT), gross motor function measure (GMFM-66), 6 minute walk test, timed up and go, modified Ashworth scale, Tardieu scale, and isometric strength test (Biodex) of knee flexion and extension. This study is ongoing. Recruitment was initiated in May 2023. Total accrual to date is fourteen participants: ten in the group with cerebral palsy and four in the group with other neuromotor disorders. Seven participants have completed all study procedures (five in the group with CP, two in the group with other neuromotor disorders), spanning 36 total weeks. Two participants have withdrawn from the study (one from each group); this withdrawal rate is within the expected range of the protocol (20%). Five participants are currently enrolled and completing study procedures. The total recruitment target is 13 participants within each group, and interim analysis is planned for after 50% of the enrollment target is reached.