Dynamic stability during walking in children with and without cerebral palsy

Background: Cerebral palsy (CP) is associated with a high risk of falling during walking. Many gait abnormalities associated with CP likely alter foot placement and center of mass (CoM) movement in a way that affects anterior or lateral dynamic stability, in turn influencing fall risk. Research question: Do children with CP demonstrate altered anterior or lateral dynamic stability compared to typically-developing (TD) children? Methods: In this case-control, observational study, we measured gait kinematics of two groups of children (15 CP, 11 GMFCS level I, 4 GMFCS level II; 14 TD; age 5-12) in walking conditions of a preferred speed, a fast speed, and a preferred speed while completing a cognitive task. For dominant and non-dominant limbs, the margin of stability (MoS), a spatial measure of dynamic stability, was calculated as the distance between the edge of the base of support and the CoM position after accounting for scaled velocity. Statistical comparisons of were made using mixed factorial ANOVAs. Post hoc comparisons were Sidak adjusted. Results: The anterior MoS before foot strike and at mid-swing differed between each condition but not between groups. Based on the minimum lateral MoS, children with CP had more stability when bearing weight on their non-dominant limb compared to TD children. These differences were not apparent when on the dominant limb. Significance: This high-functioning group of children with CP exhibited a more conservative lateral stability strategy during walking when bearing weight with the non-dominant limb. This strategy may be protective against lateral falls. We observed no between-group differences in anterior stability. Because CP has been previously associated with impaired anterior balance reactions, and there was no observed compensation in anterior gait stability, this lack of group differences could contribute to a higher risk of falling in that direction.