A 3D-printed passive exoskeleton for upper limb assistance in children with motor disorders: proof of concept through an electromyography-based assessment

Evaluation of a Game-Based Mechatronic Device for Rehabilitation of Hand-Arm Function in Children With Cerebral Palsy: Feasibility Randomized Controlled Trial

BACKGROUND

Children with neurodevelopmental disorders, such as cerebral palsy (CP), often experience motor impairments in manual dexterity, which hinder daily tasks and social interactions. Traditional rehabilitation methods require repetitive task practice, which can be difficult for children to sustain due to low engagement. Game-based rehabilitation devices and robots offer a promising alternative by combining therapy with digital play, improving motivation and compliance. However, many systems fail to incorporate actual object manipulation, which is essential for motor learning through sensory feedback. To address this limitation, a low-cost, easy-to-use robotic manipulandum device (RMD) was developed. The RMD enables real-time object manipulation during gameplay while providing assistive force, allowing the practice of a wide range of manual dexterity skills beyond gross reaching. This system offers an engaging and effective rehabilitation approach to enhance hand function in children with CP.

OBJECTIVE

This study aimed to provide evidence for the feasibility and therapeutic value of the RMD game-based exercise program for children with CP.

METHODS

In total, 34 children with CP, aged 4 to 10 years, were randomly assigned to the experimental group (XG) or the control group (CG). The XG received a computer game-based exercise program using the RMD, focusing on object manipulation tasks, while the CG received task-specific training similar to constraint-induced movement therapy. Both groups received their respective therapy programs 3 times per week for 8 weeks. Semistructured interviews with parents and children, along with qualitative analysis, were conducted to evaluate their experiences with the exercise program. The following outcome measures were used: (1) the Peabody Developmental Motor Scale-2 (PDMS-2) grasping and visual-motor integration subtests and (2) the computer game-based upper extremity (CUE) assessment of manual dexterity.

RESULTS

No dropouts occurred during the 8-week program. Both groups showed significant improvements in the PDMS-2 subtests (P<.001) and the CUE assessment of manual dexterity, including success rates (tennis ball: P=.001; cone: P<.001; medicine ball: P=.001; and peanut ball: P<.001) and movement errors (tennis ball: P=.01; cone: P<.001; medicine ball: P=.04; and peanut ball: P<.001). The XG outperformed the CG, showing greater improvements in PDMS-2 grasping (P=.002) and visual-motor integration (P=.01). In the CUE assessment, the XG demonstrated higher success rates (medicine ball: P=.001 and peanut ball: P=.02) and fewer movement errors (cone: P<.001). Parents reported an increase in the children's independence in daily tasks.

CONCLUSIONS

This study demonstrates the feasibility, acceptability, and positive outcomes of the RMD game-based exercise program for improving hand function in children with CP. The findings support further research and development of computer game-assisted rehabilitation technologies.

TRIAL REGISTRATION

Clinical Trials Registry - India CTRI/2021/07/034903; https://ctri.nic.in/Clinicaltrials/pmaindet2.php?EncHid=NTc4ODU.

Design, Development, and Functional Validation of a 3D-Printed Passive Upper Limb Exoskeleton

Motor disability in children is evident in diagnoses such as cerebral palsy, muscular dystrophy, multiple sclerosis, or spinal muscular atrophy, among others, due to altered movement and postural patterns. This becomes more evident as the child grows and can be treated with physical therapy. The effectiveness of early interventions in facilitating an improvement in daily life activities varies depending on the child's condition. In this context, the use of exoskeletons has emerged in recent years as a valuable resource for conducting more efficient therapy processes. This work describes the design (both structural and functional) and preliminary usability and functional validation of a 3D-printed passive upper limb exoskeleton. The goal is to provide clinicians with an efficient, low-cost device that is both easy to manufacture and assemble and, in a gamified environment, serves as an assistive device to physical therapy. The device features 5 degrees of freedom, enabling both a pro-gravity and an anti-gravity mode, controlled by a series of elastic bands. This gives rise to a dual operating mode, offering assistance or resistance to different arm, forearm, and shoulder-dependent movements. Usability validation conducted by exoskeleton users showed average results in all aspects rated above 3.8 out of 5, which implies levels of satisfaction between "quite satisfied" and "very satisfied". The analysis of metrics recorded during therapy, such as the Hand Path Ratio and Success Rate (capturing user movements using an inertial sensor in the gamified environment), as well as the range of motion, reveals quantifiable improvements which can be attributed to the use of the exoskeleton: the Hand Path Ratio tended to approach 1 throughout sessions in almost all the users, the Success Rate remained stable (as users consistently were capable of completing the assigned tasks), and the range of motion showed that all patients achieved improvements of more than 10 degrees in some of the tested movements). These functional validation processes involved the participation of 7 children with varying levels of upper limb neuro-motor impairments.

Evaluating the advantages of passive exoskeletons and recommendations for design improvements

Construction and manufacturing workers undertake physically laborious activities which put them at risk of developing serious musculoskeletal disorders (MSDs). In the EU, millions of workers are being affected by workplace-related MSDs, inflicting huge financial implications on the European economy. Besides that, increased health problems and financial losses, severe shortages of skilled labor also emerge. The work aims to create awareness and accelerate the adoption of exoskeletons among SMEs and construction workers to reduce MSDs. Large-scale manufacturers and automobile assemblers are more open to adopt exoskeletons, however, the use of exoskeletons in small and medium enterprises (SMEs) is still not recognized. This paper presents an experimental study demonstrating the advantages of different exoskeletons while performing workers' tasks. The study illustrates how the use of certain upper and lower body exoskeletons can reduce muscle effort. The muscle activity of the participants was measured using EMG sensors and was compared while performing designated tasks. It was found that up to 60% reduction in human effort can be achieved while performing the same tasks using exoskeletons. This can also help ill workers in rehabilitation and putting them back to work. The study concludes with pragmatic recommendations for future exoskeletons.