Predictors of Walking Efficiency in Children With Cerebral Palsy: Lower-Body Joint Angles, Moments, and Power

BACKGROUND: People with cerebral palsy (CP) experience increased muscle stiffness, muscle weakness, and reduced joint range of motion. This can lead to an abnormal pattern of gait, which can increase the energy cost of walking and contribute to reduced participation in physical activity. OBJECTIVE: The aim of the study was to examine associations between lower-body joint angles, moments, power, and walking efficiency in adolescents with CP. DESIGN: This was a cross-sectional study. METHODS: Sixty-four adolescents aged 10 to 19 years with CP were recruited. Walking efficiency was measured as the net nondimensional oxygen cost (NNcost) during 6 minutes of overground walking at self-selected speed. Lower-body kinematics and kinetics during walking were collected with 3-dimensional motion analysis, synchronized with a treadmill with integrated force plates. The associations between the kinematics, kinetics, and NNcost were examined with multivariable linear regression. RESULTS: After adjusting for age, sex, and Gross Motor Function Classification System level, maximum knee extension angle (β = −0.006), hip angle at midstance (β = −0.007), and maximum hip extension (β = −0.008) were associated with NNcost. Age was a significant modifier of the association between the NNcost and a number of kinematic variables. LIMITATIONS: This study examined kinetic and kinematic variables in the sagittal plane only. A high interindividual variation in gait pattern could have influenced the results. CONCLUSIONS: Reduced knee and hip joint extension are associated with gait inefficiency in adolescents with CP. Age is a significant factor influencing associations between ankle, knee, and hip joint kinematics and gait efficiency. Therapeutic interventions should investigate ways to increase knee and hip joint extension in adolescents with CP.