To study the functional, biomechanical, and cognitive impact of using a powered prosthetic wrist, researchers measured task performance, compensatory movements, and cognitive load while three people with transradial amputations performed a modified Clothespin Relocation Task. The participants used two myoelectric prostheses with and without the wrists: a commercial prosthesis with a built-in powered wrist, and a newly developed inexpensive prosthetic wrist for research purposes, called the Utah Wrist, that can be adapted to work with various sockets and prostheses.
Task failure rate decreased significantly, from 66 percent (± 12 percent) without the wrist to 39 percent (± 9 percent) with the Utah Wrist. The researchers found significant decreases when the participants used the myoelectric prostheses.
Compensatory forward leaning movements decreased from 24.2 degrees (± 2.5 degrees) without the wrist to 12.6 degrees (± 1 degree) with the Utah wrist, and from 23.6 degrees (± 7.6 degrees) to 15.3 degrees (± 7.2 degrees) with the commercial prosthesis with an integrated wrist.
Compensatory leftward bending movements decreased from 20.8 degrees (± 8.6 degrees) to 12.3 degrees (± 5.3 degrees), for the commercial with an integrated wrist.
“Importantly, simultaneous myoelectric control of either prosthetic wrist had no significant impact on cognitive load, as assessed by the NASA Task Load Index survey and a secondary detection response task,” the authors wrote.
They say that the work suggests that functional prosthetic wrists can improve dexterity and reduce compensation without significantly increasing cognitive effort.
The open-access study, “Electromyographically controlled prosthetic wrist improves dexterity and reduces compensatory movements without added cognitive load,” was published in Scientific Reports.
