Obstacle crossing in 7-9-year-old children with Down syndrome

This study aimed to investigate obstacle crossing in 7-9-year-old children with Down syndrome (DS). Fifteen children with DS, age- and gender-matched with 15 typically developing (TD) children, were recruited to walk and cross obstacles with heights of 10%, 20% and 30% of their leg lengths. End-point and kinematic variables of obstacle crossing were obtained using a three-dimensional motion analysis system. The results showed that children with DS tend to adopt a lower speed and larger step width when they perceive instability. Moreover, unlike TD children, children with DS adopt a pelvic strategy (i.e., greater pelvic leading-side listing and forward rotation) to achieve a higher leading toe clearance with a longer step length, presumably for safety reasons. This pelvic strategy increased the frontal plane motion of the whole leg and trunk, and thus possibly stability, during obstacle crossing. However, this strategy may be inefficient. Trailing toe clearance did not differ significantly between two groups. The results of this study suggest that children with DS tend to use inefficient and conservative strategies for obstacle crossing. Knowledge of both end-point and kinematic control of obstacle crossing in children with DS is useful for understanding the mechanisms of obstacle-related falls. Moreover, obstacle crossing can be used as a task-oriented rehabilitation program for children with DS.