Experimental Electronic Below-elbow Prosthesis in Our Clinic

Last ten years, functional artificial arms have been improved very much in the world, however, they have many difficulties for practical use. Electronic below-elbow prosthesis consists of control signal, transducer, amplifier, motor, battery, socket part, and terminal device. Attempts have been made to examine the muscle strain with a strain gauge in finger flexors and extensors of the forearm for electronic below-elbow prosthesis; two trial devices (Type III and IV). The control signal of Type III changes muscle strain into air-pressure, which is then changed into electric resistance by using a pressure gauge of carbonmembrane. The movement of the terminal device consists of flexion and extension of the metacarpophalangeal joints of the thumb, index and middle finger, using a micromotor powered by a rechargeable nickel-cadmium battery. The socket part made of plastic and double, be able to get supination and pronation of forearm. Type IV is an improved prosthesis compared to Type III, particularly in control signal for short stump and weakness of muscle strength of forearm. The control signal of Type IV changes the movement of chest into air-pressure or slide of two plate, which is then changed into electric resistance by a pressure gauge of carbonmembrane. The below-elbow amputees have used in the experiment with Type III and IV.