Hybrid Myoelectric Prosthesis for Congenital Elbow Disarticulation
T. WALLEY WILLIAMS, III, MA**, SAMUEL POLSKY, CP,BRUCE GANS, MD, AND HOLLI GORDON, OTRHopkinton, Massachusetts
A quadrimembral congenital amputee, age 11, wears stubbies for ambulation. The child attends school in a powered wheelchair which provides extended reach. His upper limbs consist of a "flipper" that is permanently flexed on the left, his dominant side, and an elbow disarticulation on the right. The preliminary right prosthesis has a Surlyn socket made over Otto Bock spacers mounted on the plaster model. Careful attention to the interior shape of the socket has allowed the child to couple natural humeral rotation to the socket, albeit, not as securely as would be possible with an angulation osteotomy. Biceps closes the myoelectric hand and triceps opens it. Elbow function requires adult-size outside locking hinges. Wrist rotation will be added in the definitive prosthesis. Pronation will be spring driven and the Bowden cable will power supination when the elbow is locked. The wrist lock will be toggled on and off by a gentle push against the forearm. The wrist unit is supplied by Robin Aids.
**Liberty Mutual Research Center, 71 Frankland Road, Hopkinton, MA 01748