Home-based upper limb stroke rehabilitation mechatronics: challenges and opportunities

Abstract

Interest in home-based stroke rehabilitation mechatronics, which includes both robots and sensor mechanisms, has increased over the past 12 years. The COVID-19 pandemic has exacerbated the existing lack of access to rehabilitation for stroke survivors post-discharge. Home-based stroke rehabilitation devices could improve access to rehabilitation for stroke survivors, but the home environment presents unique challenges compared to clinics. The present study undertakes a scoping review of designs for at-home upper limb stroke rehabilitation mechatronic devices to identify important design principles and areas for improvement. Online databases were used to identify papers published 2010-2021 describing novel rehabilitation device designs, from which 59 publications were selected describing 38 unique designs. The devices were categorized and listed according to their target anatomy, possible therapy tasks, structure, and features. Twenty-two devices targeted proximal (shoulder and elbow) anatomy, 13 targeted distal (wrist and hand) anatomy, and three targeted the whole arm and hand. Devices with a greater number of actuators in the design were more expensive, with a small number of devices using a mix of actuated and unactuated degrees of freedom to target more complex anatomy while reducing the cost. Twenty-six of the device designs did not specify their target users' function or impairment, nor did they specify a target therapy activity, task, or exercise. Twenty-three of the devices were capable of reaching tasks, 6 of which included grasping capabilities. Compliant structures were the most common approach of including safety features in the design. Only three devices were designed to detect compensation, or undesirable posture, during therapy activities. Six of the 38 device designs mention consulting stakeholders during the design process, only two of which consulted patients specifically. Without stakeholder involvement, these designs risk being disconnected from user needs and rehabilitation best practices. Devices that combine actuated and unactuated degrees of freedom allow a greater variety and complexity of tasks while not significantly increasing their cost. Future home-based upper limb stroke rehabilitation mechatronic designs should provide information on patient posture during task execution, design with specific patient capabilities and needs in mind, and clearly link the features of the design to users' needs.

Keywords: Design methods; Physical patient–robot interaction; Rehabilitation robotics.

Fig. 1

Early in-clinic robotic rehabilitation devices: a a robotic exercise machine [10], Public Domain; b MIT-MANUS [11], licensed under CC-BY$-$2.0; c ARMin [12], licensed under CC-BY$-$2.0

Fig. 2

Examples of contextual factors in the design of an at-home rehabilitation robot, synthesized from [–38]. The Device Properties interact with the contextual factors to determine the user’s experience. While these factors also apply to in-clinic devices, the Personal and Environment factors are more impactful in the home setting compared to a controlled clinic

Fig. 3

The flow diagram of the study

Fig. 4

A histogram showing the frequency of publications on home-based rehabilitation mechatronic devices since 2010, colour-coded to distinguish between papers introducing novel devices (and the anatomy targeted by the device), and papers continuing the development of an earlier device. Devices targeting proximal anatomy (shoulder and elbow) are consistently represented across the time span, while devices targeting distal anatomy (wrist and hand) have increased in frequency in the past 6 years

Fig. 5

Examples of endpoint mechatronic devices: a Lu [44], edited, licensed under CC BY-NC-ND 3.0; b HomeRehab [60], licensed under CC BY 4.0; c BULReD [57], licensed under CC BY 4.0. Examples of joint-based devices: d SCRIPT [72], edited, licensed under CC BY 4.0; e eWrist [83], edited, licensed under CC BY 4.0

Fig. 6

A Venn diagram showing the variety of home-based upper limb rehabilitation devices, grouped according to the anatomy they target (proximal meaning shoulder and elbow, and distal meaning wrist and hand) and the interaction type with the patient (endpoint meaning interaction through a single point, and joint-based meaning interaction through multiple points on the body across joints). Devices that belong to multiple sets are placed on the borders. The device names correspond to the names and references in Table 1