Thumb Stabilization and Assistance in a Robotic Hand Orthosis for Post-Stroke Hemiparesis

TL;DR

This paper introduces a dual-cable thumb stabilization method in a robotic hand orthosis for post-stroke hemiparesis, enhancing grasp stability and functional range of motion through passive and active assistance.

Contribution

It presents a novel dual-cable stabilization approach with passive and active thumb control, improving grasp stability and duration in stroke rehabilitation.

Findings

Both passive and active thumb versions improved grasp force.

Active thumb assistance enabled longer grasp durations.

The method shows promise for enhancing hand function post-stroke.

Abstract

We propose a dual-cable method of stabilizing the thumb in the context of a hand orthosis designed for individuals with upper extremity hemiparesis after stroke. This cable network adds opposition/reposition capabilities to the thumb, and increases the likelihood of forming a hand pose that can successfully manipulate objects. In addition to a passive-thumb version (where both cables are of fixed length), our approach also allows for a single-actuator active-thumb version (where the extension cable is actuated while the abductor remains passive), which allows a range of motion intended to facilitate creating and maintaining grasps. We performed experiments with five chronic stroke survivors consisting of unimanual resistive-pull tasks and bimanual twisting tasks with simulated real-world objects; these explored the effects of thumb assistance on grasp stability and functional range of motion. Our results show that both active- and passive-thumb versions achieved similar performance in terms of improving grasp force generation over a no-device baseline, but active thumb stabilization enabled users to maintain grasps for longer durations.