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.