Almost four million Americans use artificial limbs, the majority necessitated by amputation resulting from poor circulation caused by diabetes or atheroscleroses. Crude artificial limbs have been used since the earliest loss of an extremity; Greek historian Herodotus mentioned a wooden foot in 500 b.c.; a Roman mosaic depicts a peg-leg; and medieval knights had artificial limbs to improve their appearance. Today, prostheses rival natural limbs both in function and appearance.

The modern era of artificial limbs began with the famous French surgeon Ambroise Paré (1517-1590), a barber-surgeon who, in 1536, became a battlefield surgeon. After devising safer, more effective methods of amputation, Paré turned his attention to the design of artificial limbs, exercising great ingenuity and striving to simulate some degree of natural movement. An artificial leg pictured in Paré's Works of 1575 featured a movable knee joint controlled by...