Study: Upper-limb Prosthesis Users Rely Heavily on Intact Limb

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People who use myoelectric arm and hand prostheses still rely heavily on their unaffected side, researchers from the University of Salford, England, have found. Adults without amputations demonstrated reliance on both upper limbs.

In the open-access study, published in July in Scientific Reports, researchers used electronic sensors to observe daily activities for one week among 20 people (14 men and six women) who had unilateral transradial amputations and used a single degree of freedom myoelectric prosthesis. Prosthesis users ranged from 18 to 75 years old and included 11 people with congenital limb loss; six of the remaining nine had amputations on their dominant side. The research team identified the participants' dominant and non-dominant sides and calculated the balance of activity across both limbs.

Accelerometers were placed on the wrists of the prosthetic and intact hands to measure continuous activity for seven days. Results were compared against a similar group of 20 people (nine men and 11 women, 23 to 61 years old) without amputations. Though researchers found all the prosthesis users showed an increased reliance on their intact hand compared to people without limb differences, they found that those who had used a prosthesis for a longer time did not rely as heavily on the intact hand.

Researchers also considered how long people wore their prosthesis daily but concluded that there was no relationship between the length of time and how much they relied on the intact hand. Researchers also invited participants into the lab to study how well the prosthesis users performed on a pick and place task. The researchers found no relationship between measures of task performance with either the amount of time a prosthesis was worn, or the degree of reliance on the intact arm.

"While further work is needed, our new technique allows clinicians and researchers to understand for the first time how people with prosthetic limbs actually use them in their day-to-day lives. This technique may eventually lead to better ways of supporting people who have been given prosthetic limbs," said Laurence Kenney, PhD, professor of rehabilitation technologies at the university, and research team leader.

Editor's note: This story was adapted from materials provided by the University of Salford.