Harnessing technique for myoelectric arm prosthesis (a technical note).

One of the most serious obstacles in the clinical implementation of myoelectric control arm prostheses is the interface with the amputee, particularly the high level or the bilateral amputee . The need with many systems to monitor reliably up to nine myoelectric signals from muscles as remote as the upper trapezius, pectoralis and latissmusdorsi requires complex harnessing techniques which to now have not been clinically practical . For laboratory testing, investigators have used tapes and cement to secure myoelectric signal (VIES) recording electrodes to the patient's skin . Difficulties in reaching areas on the back, in applying the electrodes at the exact same location with any system, and in donning the electrodes, makes this approach unacceptable to the patient, necessitating the development of a new type of harness. The design priorities guiding development of the new harness were as follows : (i) reliability of electrode contact with the skin, (ii) comfort in wearing the device for a prolonged period of time, (iii) cleanliness, and (iv) economy. A T-shirt was designed and fabricated to fit an above-elbow amputee subject . The material of choice was a two-way-stretchable Milliskina, a fabric similar to those used in leotards worn by athletes and dancers. The material (when the garment is properly designed and fitted to the subject) . tightly conforms to body contours as a "second skin" under all movement conditions . The fabric chosen does not demon-