Schuch, in collaboration with Michael Tompkins of N.C.-based Animated Prosthetics, is using the latest in computer technology to provide working arms and hands to patients without them. As director of Duke's prosthetics and orthotics department, he is proving that an oft-maligned prosthetic strategy - called myoelectrics- does indeed work well in the real world.
"The first myoelectric devices evolved in the late 1960s and the first reported use of myoelectrics in young children was in 1971 in Sweden," Schuch said. "By the '80s they had fallen out of favor - the experts said they were too expensive and that kids weren't using them. However, by the late '80s, we showed that if you start very early, the kids have great success with them."
In a myoelectric system, tiny electrodes in the prosthetic socket read the electrochemical signals on the surface of the skin when different muscles in the natural portion of the arm are moved. Patients soon learn that moving different muscles makes the arm and/or hand move a certain way.
Three new advances have led to the new system, which Duke has individually fitted for 10 patients to date: a programmable microcomputer in the prosthesis to control the movements of tiny motors, lithium batteries that are lighter and last longer, and a prosthesis configuration unit (PCU).
The PCU, which has a 5-inch screen about the size of a car television, acts as the system's brain and communicates with the prosthesis by telemetry. The device does not need to accompany the patient, and is used to fine-tune the on-board computer and to gather data.
"In the early days, we basically had two hand movements- open and close," Schuch said. "Now, with the advances in computer technology, the system can now control two motors, such the hand and wrist, or elbow and hand. We now have a choice of 15 different strategies to control or effect these movements. The system is sensitive enough that if a muscle is moved lightly, the prosthesis reacts one way; if the same muscle is moved stronger, the prosthesis reacts another way."
Three years ago, Schuch acquainted Jeffrey Wade with a conventional myoelectric prosthesis; this summer, at the age of 6, Jeffrey will try out the new computer-controlled myoelectric device in time for elementary school.
Reprinted with permission
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