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Upper limb prostheses designed for partial functional (e.g., rotation, flexion) and/or cosmetic replacement of the distal portion of a limb at the wrist articulation, in which the radial component of the articulation is preserved. These prostheses are typically external or partially implantable devices that include a mechanism to provide rotational and flexion movements and locking positions at the distal end to the terminal device; they are usually attached at the proximal end with a socket that preserves pronation and supination. The prosthesis includes a terminal device (e.g., hand, hook) at the distal end; the use of a \'screwdriver\' type socket provides stability at the distal portion and transmits rotation. The prostheses may be mechanically operated (e.g., using cables and springs), electrically powered (e.g., using external motors and switches), or triggered by electrical signals produced by normal muscle contractions (i.e., myoelectric). Disarticulation wrist prostheses are available in a great variety of configurations and sizes; they are used mainly in patients who have congenital abnormalities or who suffered amputations due to illness (e.g., diabetes) or traumatic accidents.
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