Of the scores of technologies that appear to have enormous potential with respect to medical applications, one of the most promising is the use of bionic implants. Some such implants are already widely used and are well known to the general public; the pacemaker, used to regulate the beating of the heart, was one of the first bionic devices to be commonly used. Perhaps the most publicized bionic devices in recent times are the increasingly sophisticated artificial limbs that have received a great deal of attention in the press because of their impact on the lives of soldiers who have lost arms and legs in the fighting in the Middle East.