AN INEXPENSIVE AND ADAPTABLE PROSTHETIC WRIST IMPROVES DEXTERITY AND REDUCES COMPENSATORY MOVEMENTS.

Abstract

Many presently available prostheses lack a functional wrist. Here, we highlight the development of an inexpensive prosthetic wrist that can be adapted to work with various sockets and prostheses. Using this prosthetic wrist, we explore the functional and cognitive impact of using a prosthetic wrist to perform activities of daily living. We measured task performance, compensatory movements, and cognitive load while transradial amputees performed a Clothespin Relocation Task (CRT) using a prosthesis attached to the wrist controlled by surface electromyography (EMG). Three transradial amputees performed the task with and without EMG control of the wrist. In aggregate data, the success rate was significantly higher in the wrist condition (61% ± 9% mean, ± standard error) than in the no-wrist condition. Compensatory movements were also better; e.g., the maximum leftward bend at the hip was less in the wrist condition (18.9° ± 1.2°) than in the no-wrist condition (15.0° ± 1.4°). The addition of controlling a prosthetic wrist had no significant impact on cognitive load, as assessed by the NASA Task Load Index survey and the detection response time to a secondary task. This work suggests that using a prosthetic wrist may increase dexterity and reduce joint strain for amputees without requiring a significant increase in cognitive effort compared to that of EMG control of a hand alone. These results can guide future development and prescription of upper-limb prostheses.