Abstract: An orthotic device attached to the external part of the body is adapted to provide support for the malfunctioning arm of a patient, said support offering a variety of stable arm positions in space in a manner essential for functional use of the forearm and hand. A plate attached to the body anchors an artificial ball and socket joint. The joint is actuated by a lockable rod which carries an adjustable elbow support or trough. Such structure provides the adequate range of motion and the needed accompanying stabilization of the arm in space, while said ball and socket joint replaces and/or augments the human shoulder joint. The device is worn by the patient inconspicuously under a garment, is useful either during mobility, while seated or when recumbent, and is applicable to human beings whose willful control of the shoulder joint is absent or decreased as the result of illness or injury.