Improving Active Range of Motion in the Arm After Stroke with a Body-Mounted Shoulder Exoskeleton

Arm use and arm function are inextricably linked; nonuse leads to a decline in fuctionality, while proper and consistent usage maintains functionality and can lead to further improvement. Many individuals with impairment are discharged from therapy with functional levels that are too low to promote self-use of arm and hand function at home. However, with gravitational support to the arm, some of these same individuals could experience immediate improvements in reachable workspace. To increase arm function and usage, we developed a custom wearable shoulder exoskeleton with variable levels of gravitational support and evaluated its effect on three participants with chronic impairment from stroke, measuring planar reach area during a single session (assisted vs unassisted). We also measured baseline arm use at home with wrist-mounted activity trackers to evaluate the amount of use vs. nonuse of the impaired limb during daily activities. With exoskeleton assistance, participants achieved average gains in planar reach area of 11%, 1.3%, and 14.2% in the transverse, sagittal, and frontal planes, respectively, relative to unimpaired function. Baseline unassisted arm usage was also measured by numerically integrated accelerometry activity counts which may offer a quantitative way to compare the difference in arm usage with and without provision of an assistive exoskeleton.