After an acquired brain injury (ABI), children often require extensive physiotherapy (PT) to help them relearn to walk. There is promising evidence in pediatric neuro-motor conditions of the possibility for brain activation pattern changes in response to repetitive, task-oriented functional gait training. Robotic-assisted gait training devices such as the Lokomat (LOK) allow this type of intensive walking retraining. The aim of this study is to assess the safety, feasibility and outcome possibilities linked to a LOK intervention given as 2 of the child's 4 PT weekly sessions over 8-weeks in the early stages of rehabilitation after an ABI.

This is Phase 3 of our three- year ABI Lokomat study . Phase 1 was conducted in 2016-2017 and was a single-group pre- and post-test feasibility study of the Lokomat in pediatric ABI inpatients and daypatients in which we enrolled 9 patient participants. The co-primary outcome measures for this first phase were the Gross Motor Function Measure (GMFM), Canadian Occupational Performance Measure (COPM) . Other measures of function (PEDI-CAT), gait (6 minute walk test and Timed up and GO) and individualized goals (Goal Attainment Scaling) were included. Study feasibility was evaluated via indicators such as enrollment, number of sessions completed, drop out rate, and adverse events. Phase 2 was conducted in 2017-2018 using the same core outcome set, and added a qualitative study component with child and parent and physiotherapist interviews for their perspective on the Lokomat experience and associated outcomes. The investigators enrolled 6 patient participants (quantitative and qualitative) and their caregivers (qualitative). Phase 3 will aim to enroll 6 to 8 more children to strengthen effect size estimates for the GMFM and COPM in particular (proposed co-primary outcome measures for future randomized controlled trial). The investigators will also add in a 10 metre fast walk test to allow children with lower walking tolerance to have a gait measure, and pilot a measure of children's self-efficacy that the investigators will design for this study. Finally, the investigators will take a close look at motor learning strategies (MLS) used by the PTs in both LOK and PT sessions using the validated Motor Learning Strategies Rating Instrument (MLSRI) to begin to get a profile of comparative MLS use in gym-based PT and LOK sessions. The investigators will continue to study feasibility and add to the data from the first 2 phases the ABI LOK project.

Inclusion Criteria:

• Be an inpatient or daypatient in the Brain Injury Rehabilitation program at Holland Bloorview Kids Rehabilitation Hospital with moderate or severe ABI
• Be Gross Motor Function Classification System-equivalent III or IV with primary gait goals
• Have any limb distribution of involvement (spasticity or hypotonicity). The physiotherapist (PT) and Lokomat (LOK) sessions (both about 45-minutes in length) will employ a motor learning strategies approach.
• Have a femur length at least 21 cm (to fit robotic legs) and height no greater than 6' 3" to fit LOK frame
• Be no more than 12 months post-ABI (i.e., still active rehab stage), and
• Be expected by clinical team (confirmed by child's physician) to have at least 8 more weeks of inpatient or daypatient rehab
• Be able to follow Gross Motor Function Measure instructions and participate in > 45 minutes of active PT (as judged by the child's PT)
• Be able to reliably signal pain and discomfort using verbal or nonverbal signals (as assessed at the screening assessment) for LOK operation safety reasons.

Exclusion Criteria:

• A seizure in the last 12 months,
• Inability to tolerate full weightbearing
• A knee flexion contracture > 20 degrees, knee valgus >40 degrees, hip subluxation > 40% migration percentage
• Excessive tone or ataxic or dyskinetic movements may be an exclusion (would be determined at LOK set-up confirmation visit).