Upper extremity myoelectric prosthetics.

Myoelectric control of upper limb prostheses has proven to be an effective and efficient means of controlling prosthetic components. This means of control has been used extensively for over 30 years, during which time these systems have become reliable and durable in most situations. Myoelectric control, or any other prosthetic control scheme, should not be considered as the optimal control for arm prostheses, but rather as one of the several effective ways of producing desired function. Advanced clinical practice calls for a blending of all control schemes, as appropriate, to allow the prosthesis to serve the intentions of the user efficiently and with little mental effort. Technology continues to change, bringing with it new and sometimes better ways of fitting amputees. Microprocessors and programmable controllers have opened new and exciting avenues for improvement in function. New, and as of yet unidentified, electronic and mechanical advances are certainly on the horizon. There is much work to be done before upper limb prostheses rightfully are called arm replacements. But progress is occurring and advances are being made toward the goal of replacing the function and appearance of that marvelous tool, the human arm.

Successful voluntary grasp and release using the cookie crusher myoelectric hand in 2-year-olds.

We examined the ability of two 2-year-old children with limb deficiency to demonstrate grasp and release while using the cable-operated voluntary opening hook-hand and the externally powered single-site myoelectric Cookie Crusher system. The Cookie Crusher circuit is an electronic package that causes the prosthetic hand to open in response to muscle contraction and closes (as if crushing a cookie) when the muscle is relaxed. Both children were consistently good prosthetic wearers, beginning with their initial passive devices and progressing through their cable-operated hooks and hands. However, before they began to use the Cookie Crusher (Subject 1 at 25 months, Subject 2 at 30 months), neither had developed voluntary grasp or release in spite of 3 to 12 months' use of cable-operated voluntary opening prehensors. Both children developed a voluntary grasp and release for the first time within minutes of starting to use the Cookie Crusher. The more adept of the two children, a girl with a traumatic above-elbow amputation, showed prehensile function with the Cookie Crusher during play. The spontaneous use of the Cookie Crusher may be related to the predominance of associated reactions in young children. As children play bimanually, associated movements of the nondominant extremity often occur and, in the case of children with limb deficiencies fitted with Cookie Crusher prehensors, these associated reactions result in successful grasp and release. We will continue to follow the choice of effective control schemes in these children as they mature.