Improving crouch gait in children with CP through error augmentation

Children with cerebral palsy (CP) commonly exhibit pathologic gait patterns. Crouch gait, which is characterized by excessive stance phase knee flexion and may be accompanied by other deficits at the hip and/or ankle, is a common and debilitating gait disorder in children with CP. Left untreated or inadequately addressed, children with crouch gait will experience progressive gait deterioration, leading to a loss of ambulation in a large portion of adolescents with CP. While crouch gait is one of the most frequently observed gait deviations in children with CP, current intervention approaches including surgical and non-surgical have not been optimized to effectively address these key gait deficits in many children with CP. Specifically, surgical interventions, which typically target the hamstrings, remain the dominant interventions but outcomes are variable across different studies. Similarly, muscle strengthening programs have been developed to improve crouch gait, but studies showed inconsistent outcomes. Hamstrings botulinum toxin injections have been shown to modestly improve knee kinematics 2 weeks post injection, but the effects mostly disappeared by ~12 weeks, leading to a repeated injections of botulinum toxin during growth. Robotic assistance has been used to improve crouch gait in children with CP, although the effect was not retained after the removal of the assistance force. Thus, there is a clear need for the development of new interventions for improving crouch gait in children with CP, which requires a thorough examination of the motor learning mechanisms of the interventions. The overall objective of this study is to determine whether the application of a targeted resistance torque to the knee joint during overground walking will induce improvements in crouch gait in children with CP. Our central hypothesis is that increasing errors by applying a targeted perturbation torque to the knee joint during overground walking will facilitate motor learning and induce improvement in crouch gait in children with CP. Specifically, in Aim 1, we will determine the effect of error size on motor learning to improve crouch gait in children with CP. We expect to see a greater improvement in crouch gait in children with CP after applying a targeted resistance torque to the knee joint during the swing phase of gait in comparison to assistance torque during walking. In Aim 2, we will determine the effect of error variability on motor learning to improve crouch gait in children with CP. We expect to see a longer retention of improved crouch gait in children with CP after applying a varied resistance torque to the knee joint in comparison to a constant resistance torque during overground walking. Results from this study are expected to demonstrate the effect of error size and error variability on the motor learning of improved crouch gait in children with CP. The results of this study are expected to have an important positive impact by providing a strong justification for the development of an effective intervention for improving crouch gait in children with CP that is more effective than the best physical interventions currently available.