Enhancing Motor Performance in Pediatric Cerebral Palsy: A Preliminary Study on Soft Knee Robotic

Crouch gait is a common pathology in individuals with cerebral palsy (CP), significantly affecting their daily activities. The soleus and gastrocnemius muscles in their shank are often too weak to generate sufficient force against body weight. Soft wearable robotics are compliant, lightweight, and portable. In this study, we aimed to address the gap in soft knee robotic systems for children with CP. This paper introduces the design of a textile-based knee actuator and a control system. It investigates the feasibility of this soft knee robotic system through a preliminary study involving two children with CP. The study includes 20 walking sessions to assess the system's performance.Methods: The actuator of the soft knee robot uses a PVC Nylon composite textile material. The actuator is worn on the back of the subject’s knee joint with a skin-friendly textile brace. The unilateral weight of the soft knee brace is only 0.2 kg. Two ground reaction sensors are placed on the forefoot and heel of the subject to detect gait events during the walking cycle. When the heel strikes the ground, the actuator inflates to assist knee joint extension until toe-off. The subjects participated in training twice a week, totaling 20 sessions over 10 weeks. Each session included 30 minutes of walking training with the soft knee robot.Results: Preliminary training results demonstrated the feasibility of the soft knee robot in improving crouch gait. The knee flexion angles of both subjects were reduced (Subject 1 from 20.56° to 1.9 ° and Subject 2 from 24.21°to 12.1°) during the mid-stance phase after 20 training sessions. The Modified Ashworth Scale (MAS) score of the paretic side knee joint reduced from 1+ to 0 and from 1+ to 1 respectively, indicating an improvement in muscle tone of the spastic knee joint. The subjects' gross motor function scale showed improvement.Conclusion: This work demonstrates the validation of the soft knee robot protocol for extension support in crouch gait with pneumatic and comfortable assistive torque. The pilot testing results indicate that the soft knee robotic system improves knee control and locomotor function during walking.