Measuring advanced motor skills in children with cerebral palsy: development of normative data and percentile curves for the Challenge-20 assessment

The Challenge-20 is an assessment of advanced motor skills of children with cerebral palsy. The purpose of this study was to develop age-related norms and percentile curves for the Challenge-20 with typically developing children ( n = 150, 7 through 11 years), and compare Challenge-20 scores of independently ambulatory children with CP, Gross Motor Function Classification System level I ( n = 135) and II ( n = 56) to these age norms. Younger TD children (7 years) scored lowest, and older children (11 years) scored highest on the Challenge-20 , showing similar developmental trajectories. Challenge-20 scores of 15% of children in GMFCS level I were situated above the lower 2.5th percentile curve of the typically developing children's Challenge-20 growth curve, that is, overlapping into the typically developing child zone. The Challenge-20 is sensitive to the progression of advanced gross motor skills in typically developing children. Children with cerebral palsy, GMFCS I follow similar, albeit lower, Challenge score trajectory to that of typically developing children, and in some cases come close to lower level abilities of typically developing children. The reference values with typically developing children extend the Challenge-20 's utility when assessing advanced gross motor skill of independently ambulatory children with cerebral palsy for physiotherapy intervention and physical activity planning and open the door to re-thinking more about advanced gross motor interventions for children with cerebral palsy in GMFCS levels I and II given their potential to progress along the developmental trajectory.