Systematic review of the effect of 3D-printed exoskeleton on hand function rehabilitation in stroke patients

Abstract

OBJECTIVE: To systematically evaluate the clinical efficacy of different types of 3D-printed exoskeletons in hand function rehabilitation for stroke patients based on the International Classification of Functioning, Disability and Health framework. METHODS: A comprehensive search was conducted in PubMed, Cochrane Library, Web of Science, Embase, CNKI, and CBM databases for literature published between January 2015 and December 2024 on 3D-printed exoskeleton interventions for post-stroke hand function rehabilitation. Two researchers independently screened studies, extracted data, and assessed methodological quality following the PRISMA guidelines for systematic reviews. RESULTS: A total of 13 studies involving 62 stroke patients from the United States, China, the Netherlands, Italy, Singapore, and Turkey were finally included. Based on the Brunnstrom stages, exoskeletons were categorized into four types: assistive (Stage I), corrective (Stages II–III), training-oriented (Stages IV–VI), and compensatory (Stages IV–VI). Interventions were delivered via institution-based, home-based, or combined institution-home rehabilitation, with session durations ranging from 15 to 90 minutes, frequencies of 3 to 7 sessions per week, and durations of 5 to 8 weeks. Results showed that assistive exoskeletons improved fine hand use and self-care; corrective exoskeletons improved joint mobility, muscle tone, grip strength, and fine hand use; training-oriented exoskeletons improved joint mobility, upper limb muscle strength, and self-care; compensatory exoskeletons enhanced fine hand use and hand and arm use. CONCLUSION: Based on the ICF framework, evidence indicates that 3D-printed exoskeletons improve hand function, activity, and participation in stroke patients. It is recommended to select matching exoskeleton types according to Brunnstrom stages and develop individualized intervention plans to achieve optimal rehabilitation outcomes.

1. Introduction

According to the China Stroke Center Report 2022, the number of stroke patients aged over 40 in China reached 17.8 million in 2020, with approximately 2.2 million patients experiencing varying degrees of functional impairment [1]. Hand function rehabilitation has become a core challenge in post-stroke motor recovery, with 38% of patients exhibiting significant hand dysfunction at 3 months post-onset and 30%-66% not fully recovering by 6 months, severely impacting daily living and quality of life [2-3]. For hand rehabilitation, end-effector robots can improve proximal joint motor function but have notable limitations in distal joint movement and tactile feedback during object manipulation; clinical studies have confirmed their limited overall upper limb functional recovery [4-6]. In contrast, wearable exoskeletons are highly compatible with human anatomy, and through precise torque control can effectively promote muscle strength rebuilding, joint range of motion recovery, and motor coordination, while supporting high-intensity task-oriented training and significantly reducing therapist workload [7-8].

Traditional exoskeletons are limited by generalized design concepts, with standardized architectures that fail to adapt to individual hand structure differences or injury types, and are costly and poorly portable, failing to meet home rehabilitation needs [9-11]. In contrast, 3D printing technology, through the synergy of digital modeling and additive manufacturing, significantly enhances the adaptability of exoskeletons to patients' specific anatomical needs, offering customization, cost-effectiveness, and rapid prototyping capabilities [12-15].

Numerous systematic reviews have confirmed the positive effects of upper limb robot-assisted training on upper limb functional recovery in stroke patients [16-18]. However, the clinical application of 3D-printed exoskeletons for hand function rehabilitation still faces multiple challenges: heterogeneity in outcome assessment systems, lack of comparability across different functional assessment tools, making objective comparison of exoskeleton performance difficult; standardized treatment protocols have not been established, and optimal training intensity, frequency, and duration require large-scale clinical validation [19]. This study, based on the International Classification of Functioning, Disability and Health (ICF) framework, constructs a standardized assessment system [20], and uses the Brunnstrom recovery staging theory to build a matching model between functional recovery stages and exoskeleton types [21], systematically analyzing patients' differential responses to different types of exoskeleton interventions, aiming to provide a theoretical basis for individualized rehabilitation plans and promote the development of rehabilitation engineering towards universal accessibility and verifiable efficacy, thereby improving the quality of life for stroke patients.