Functional Use of Myoelectric and Cable-Driven Prostheses

PATRICIA DEBEAR, BS, OTR


Myoelectric prostheses have increased in popularity for upper-limb amputees in the last several years. At the Rehabilitation Institute recommending both the standard cable-driven and the myoelectric prostheses has become the standard procedure. To justify this approach as more than just a back-up system, long-term prosthetic use was studied.

One hundred ten upper-limb amputees were treated at the Rehabilitation Institute between January 1983 and July 1987. Fifty-one were fitted with myoelectric prostheses and 35 received both cable-driven and myoelectric prostheses.

Twenty-four patients (21 male and 3 female) who were fitted with both types of prostheses completed a survey which questioned which prosthesis they used for specific activities. The categories included work, school, self-care, social/personal, homemaking, outdoor chores, and recreation and hobbies. Six others did not qualify as long-term wearers and five could not be located.

Of the 24 respondents who were fitted with both types of prostheses, five reported that they used the myoelectric prosthesis exclusively. The other nineteen (79 percent of respondents) stated that they used the cable-driven prosthesis for at least one functional activity. Analysis by gender reveals different wear patterns. Two of the three female amputees use only the myoelectric prosthesis for all activities. In contrast, eighteen of the 21 male amputees (86 percent) claimed they used the cable-driven prosthesis for one or more functional tasks.

The study determined male amputees have a functional need for both prostheses for maximum success. Although the myoelectric prosthesis is used as the primary device, it is not a total means for the user to return to the previous lifestyle. It is, therefore, reasonable to recommend that both prostheses be prescribed during the initial training program.

The three female amputees used the cable-driven prosthesis only a third of the time. All three were those who requested and received both types of prostheses. Six other female amputees were not interested in having a body-powered prosthesis even as a spare appliance and therefore could not be included in this study. Prescribing both prostheses for female amputees has not become standard procedure. Instead, time should be spent during the training period exploring whether a functional need for both prostheses exists.