Wearable Robotic Ankle Resistance Training Improves Neuromuscular Control and Walking Efficiency in Cerebral Palsy

Abstract

Cerebral palsy (CP) is characterized by deficits in motor function due to reduced neuromuscular control. We leveraged the guiding principles of motor learning theory to design a wearable robotic intervention intended to improve neuromuscular control of the ankle. The goal of this pilot clinical trial was to determine the response to four weeks of exoskeleton ankle resistance therapy (exo-therapy) in children with CP. Five children with CP (12-17 years, GMFCS I-II, four males and one female) were recruited for ten, 20-minute sessions of exo-therapy. Surface electromyography, three-dimensional kinematics, and metabolic data were collected at baseline and after training was complete. Changes in neural complexity (via muscle synergy analysis) and metabolic cost were compared to retrospective age- and GMFCS-matched controls who had undergone either single event multi-level orthopedic surgery (SEMLS) or selective dorsal rhizotomies (SDR). Participants displayed decreased co-contraction at the ankle (−29 ± 11%, p = 0.02) and a more typical plantar flexor activation profile (33 ± 13%, p = 0.01), and improvements in neuromuscular control led to a more mechanically-efficient gait pattern (58 ± 34%, p < 0.05) with a reduced metabolic cost of transport (−29 ± 15%, p = 0.02). There were significant increases in neural complexity (5 ± 3%, p = 0.03), where were significantly greater than those seen with SEMLS and SDR (p < 0.01 for both). Ankle exoskeleton resistance therapy shows promise for rapidly improving neuromuscular control for children with CP, and may serve as a meaningful rehabilitative complement to common surgical procedures.