Development and clinical evaluation of a robotic hand orthosis to support functional recovery in persons after stroke
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2025
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Doctoral Thesis
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Abstract
Stroke is among the leading causes of adult, long-term disability in the world, with more than 100 million people living with its consequences. A persisting and functionally limiting outcome of stroke is impaired upper limb function, particularly of the hand, which severely hinders an individual’s abilities to perform activities of daily living (ADL). Despite conducting intensive conventional rehabilitation, only a fraction of survivors regain full upper limb function. Rehabilitation robotics has emerged as a promising solution to deliver the necessary dose to promote neuroplasticity, thereby facilitating recovery, without adding a significant burden on the healthcare system. Among these technologies, robotic hand orthoses (RHOs) are wearable devices that support functional grasping. They are unique solutions that provide a combination of either therapeutic or assistive support, depending on their context of use. However, many existing RHOs remain bulky, heavy, and impractical for widespread adoption in clinical applications.
This thesis addresses these challenges through the development and clinical evaluation of a fully wearable soft RHO, capable of supporting both assistance and therapy post-stroke. This work follows a user centered design (UCD) framework to ultimately maximize the functionality and usability of the device for the target users. The research is divided into five chapters, which
progress from understanding the user’s needs to ideating and prototyping a new technical solution, to finally clinically evaluating the new RHO in both supervised and unsupervised settings. The initial phase of this work involved complementing an existing set of design requirements for a functional and highly usable RHO. In a mixed-method focus group study with stroke survivors, this study revealed that end-users prioritize and value simplicity, intuitiveness, and effectiveness in a possible upper limb assistive technology (AT). These findings align with the broader clinical evidence presented in a perspective paper. In that work, recent clinical evidence on the utility of soft robotics for upper limb rehabilitation and assistance was compiled, based on over 37 studies involving 13 different devices. The paper outlines key recommendations for future development, with a focus on usability, design optimization, opportunities to scale, and also highlights the importance of acknowledging the contributions of softness in these devices.
After empathizing with the target users and defining the design requirements, the RELab tenoexo 2.0 was developed. The device is a soft, fully wearable RHO designed for stroke survivors with hand impairments to support their functional grasping abilities. The device addresses previously identified limitations in design from its predecessor, namely a lack of robustness and a highly complex assembly. The new design features a redesigned actuation system, with the motors now integrated into the hand module, along with a newly developed finger mechanism, all while maintaining a weight of below 270g. The development of this device resulted in a more suitable RHO for longer, more intensive use and clinical trials. Finally, the device was evaluated and validated in a two-phase clinical feasibility study, where participants first underwent three weeks of therapist-supervised, RHO-supported functional hand training in the clinic. Then, users brought the device home for two weeks of subsequent unsupervised, RHO-supported functional hand training at home. The feasibility was evaluated in terms of dose (time and repetition) and adherence to the at-home rehabilitation program.
Further, clinical outcome and usability were evaluated. Results demonstrated that the RHO can facilitate high-repetition training sessions, substantially surpassing conventional therapy, regardless of supervision level or location. Users had high adherence to the suggested usage at home (number of sessions and duration), and also rated the usability of the device and intervention highly. After the study, participants demonstrated significant improvements in their clinical outcome scores. Ultimately, this work demonstrates that the RHO can be successfully utilized as a rehabilitative tool for functional hand training across the continuum of care, supporting rehabilitation even outside of the clinic.
A subsequent sub-analysis of the device was performed to understand the secondary outcomes and additional uses beyond its role for functional hand training. Comparing users’ baseline scores with the immediate functional improvement the device provides, a suitability cutoff was defined for those most likely to benefit from using the device assistively to support their
ADL. Furthermore, analyzing the secondary outcomes of using the device, individuals had subjectively reduced compensatory strategies while wearing the RHO. Reductions in trunk flexion and shoulder abduction were seen when the RHO augmented grasping capacity and stabilized the user’s wrist. Finally, the translation of capacity to performance in daily life was analyzed as a measure of arm use. However, as seen in literature, no significant changes were seen in performance across the intervention, despite clinically meaningful improvements in capacity.
Overall, this thesis made substantial contributions to the design and evaluation of soft, robotic wearable devices by delivering a clinically validated, highly usable RHO tailored for persons after stroke. Through the device’s dual function for therapy or assistance, it blurs the boundary between technology and end users, thereby expanding the potential for use in-clinic or at
home. This work not only presents a robust design but also adds to the growing clinical evidence of soft wearable robotics. To date, the RELab tenoexo 2.0 is one of the few fully wearable, RHO devices evaluated in these contexts (in clinics and at home, supervised and unsupervised, for therapy and assistance). This work definitively demonstrates the integrability of RHOs into long-term rehabilitation strategies, supporting recovery and functional independence for persons after stroke.
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ETH Zurich
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hand exoskeleton; Stroke rehabilitation; neurorehabilitation; robotic hand orthosis
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03827 - Gassert, Roger / Gassert, Roger
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