Project Summary Ambulatory children with cerebral palsy (CP) can have profound impairments of the lower extremities including physical deformities, loss of motor function, and resultant poor quality of life. Orthopedic multi-level surgery (MLS) is standard of care to address lower extremity impairments and children experience a decrease in function requiring extensive physical therapy (PT) for up to two years to regain function. Evidence for post-surgical PT best practices is vastly unknown. This application proposes a pilot project to obtain preliminary data examining the variation in PT frequency and type of intervention delivered during usual care across settings to ambulatory children with CP following MLS, and describe the relationship between type of intervention and recovery of gait at 6 months. Participants will be recruited from two large academic centers where MLS surgery is performed. Sixteen ambulatory children with CP that undergo MLS, consisting of at least one bony and any number of soft tissue procedures, will be recruited and evaluated at baseline before surgery and 6 months post-surgery. Using a published path model for studying dose in CP, comprehensive details about therapy frequency and type will be captured via our successful EHR implemented flowsheet for children treated at the two academic sites, and via REDCap surveys, with identical fields to the flowsheet, from outpatient community therapists. This study will capture details on all types of PT intervention delivered with specific interest in the five types delivered to children with CP following MLS, with the most recent evidence (in children that have not undergone surgery), to improve gait. These five types include mobility training, treadmill training, partial body weight supported treadmill training, fitness training and ankle foot orthoses (AFOs). We will count the total number of PT Interventions to improve Gait (PTIG) delivered and describe the relationship between PITGs to the recovery of gait at six months post-surgery. We hypothesize that children seen by academic therapists for post-surgical PT will have greater frequency of therapy sessions and higher count of PTIGS than children seen by community outpatient therapists. We also hypothesize that the count of PTIGs delivered will have a positive relationship with gait measured in two ways; self- selected walking speed and walking performance (steps/day). The proposed research is innovative and will guide development of precision rehabilitation approaches that are translatable to clinical practice. The proposed research is significant because findings will inform future work to determine the most effective strategies to improve health and motor outcomes for children with CP after MLS.