A Novel Clinical-Driven Design for Robotic Hand Rehabilitation: Combining Sensory Training, Effortless Setup, and Large Range of Motion in a Palmar Device.

Raphael Rätz,Laura Marchal-Crespo,René M. Müri,François Conti

doi:10.3389/fnbot.2021.748196

Abstract

Neurorehabilitation research suggests that not only high training intensity, but also somatosensory information plays a fundamental role in the recovery of stroke patients. Yet, there is currently a lack of easy-to-use robotic solutions for sensorimotor hand rehabilitation. We addressed this shortcoming by developing a novel clinical-driven robotic hand rehabilitation device, which is capable of fine haptic rendering, and that supports physiological full flexion/extension of the fingers while offering an effortless setup. Our palmar design, based on a parallelogram coupled to a principal revolute joint, introduces the following novelties: (1) While allowing for an effortless installation of the user's hand, it offers large range of motion of the fingers (full extension to 180° flexion). (2) The kinematic design ensures that all fingers are supported through the full range of motion and that the little finger does not lose contact with the finger support in extension. (3) We took into consideration that a handle is usually comfortably grasped such that its longitudinal axis runs obliquely from the metacarpophalangeal joint of the index finger to the base of the hypothenar eminence. (4) The fingertip path was optimized to guarantee physiologically correct finger movements for a large variety of hand sizes. Moreover, the device possesses a high mechanical transparency, which was achieved using a backdrivable cable transmission. The transparency was further improved with the implementation of friction and gravity compensation. In a test with six healthy participants, the root mean square of the human-robot interaction force was found to remain as low as 1.37 N in a dynamic task. With its clinical-driven design and easy-to-use setup, our robotic device for hand sensorimotor rehabilitation has the potential for high clinical acceptance, applicability and effectiveness.

Highlights

With about 17 million people worldwide that experience a stroke each year, stroke remains a major cause of disability (Feigin et al, 2014)
Clinical Requirements Prior to the novel device development, we conducted a survey with 33 clinical professionals from the University Hospital Bern, Switzerland and Reha Rheinfelden, Switzerland, to gather the clinical requirements for a robotic device targeting sensorymotor rehabilitation of the upper-limbs (Rätz et al, 2021)
We present PRIDE (Palmar RehabilitatIon DEvice), a novel device for sensorimotor hand rehabilitation based on clinical and anatomical requirements gathered from interviews and questionnaires with clinical personnel

Summary

Introduction

With about 17 million people worldwide that experience a stroke each year, stroke remains a major cause of disability (Feigin et al, 2014). Up to 75% of stroke survivors suffer from longterm arm and hand impairments (Lai et al, 2002), which leads to a severe impact on patients’ capability of performing activities of daily living and compromises their autonomy (Mercier et al, 2001; Hunter and Crome, 2002). Clinical evidence suggests that patients should embark in active (Lotze, 2003), long (Kwakkel et al, 2004; Nielsen et al, 2015), highintensity (Tollár et al, 2021), and repetitive functional taskspecific practice (French et al, 2016). Sensory training is highly recommended (Turville et al, 2019), as several studies have associated somatosensory impairment at baseline with poorer motor function and recovery after stroke (Meyer et al, 2014; Rowe et al, 2017). Most of the current therapies target primarily improving motor functions, neglecting the sensory aspects of neurorehabilitation (Bolognini et al, 2016; Gassert and Dietz, 2018; Handelzalts et al, 2021)

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