Mechanical contrivances adapted to reproduce the form, and as far as possible, the function, of a lost or absent member. The replacement of a missing body part by an artificial substitute is called prosthesis; the branch of surgery dealing with prosthesis is prosthetics.
Artificial limbs, in one form or other, have been in use from ancient times. In 1885 a specimen was discovered in a tomb at Capua, Italy, along with other relics dating from 300 BC. The celebrated artificial hand built in 1509 for the German knight Götz von Berlichingen (1480-1562), who was called Götz of the Iron Hand, weighed about 1.4 kg (3 lb) and had articulated fingers so constructed as to be able to grasp a sword or lance. The hand is in the Nuremberg Museum and is still in working order. Early in the 19th century a German prosthetist built a hand with fingers that could be flexed or extended without assistance and yet could still close to hold light objects, such as a pen, a handkerchief, or a hat. In 1851 a French prosthetist invented an artificial arm fitted with a wooden hand and attached to a leather socket that fitted the stump firmly. The fingers were half-closed, the thumb pivoted on a pin and could press firmly against the fingertips by a concealed, strong rubber band; the grasp of the thumb could be operated by a mechanism attached to the opposite shoulder. The same inventor devised a leg that reproduced a natural gait and lengthened the stride.
Before World War I, wood was universally considered the best substance for making artificial legs. Prosthetic devices made of leather reinforced with metal bands tended to lose their shape and were therefore unsatisfactory. Finally, the use of an aluminum alloy called Duraluminum, and later of fiber materials, made possible the manufacture of an artificial limb that was both lightweight and strong. Synthetic polymers now being introduced provide a skinlike covering for some forms of prosthesis.
Only in recent years, as a result of the needs arising out of the two world wars, has the manufacture of prosthetic devices developed into a science. Artificial legs with joints at knee and ankle can simulate a natural gait. The arm presents many more difficulties to the maker than the leg, and intricate mechanical devices make the use of metal imperative. Artificial arms are fitted with elbow joints and wrists capable of rotation. With the aid of springs controlled by shoulder movements, the hand can be manipulated, assuring a positive grip. Hip joint prostheses can provide virtually normal mobility for persons with damaged hip joints (see Hip).
To ensure maximum comfort for the wearer some prosthetic devices are now fitted immediately following amputation of the natural limb. A rigid plaster dressing is applied to the site, serving as a socket for the attachment of a temporary prosthetic device. More recently, use of a removable plaster dressing has reduced pain and infections while the prosthesis is being fitted. In certain severe cases permanent artificial arms are equipped with small battery-powered motors, which facilitate movement at the joints.
The design and development of prosthetic devices are coordinated by the Committee on Prosthetics Research and Development of the National Research Council. Special prosthetic training schools have been set up at several universities for the teaching of modern prosthetic concepts to physicians, surgeons, prosthetists, and physical and rehabilitation counselors. H.R.L.