Any device used to replace a body part, organ, or limb,
usually taking over all or part of its function. The most common
prosthetic device (and the only one that the vast majority of the
population are likely to need) is the
artificial denture ("false teeth" or a "false tooth"). More than 50 percent of the American population over the age of 50 have dentures of some sort, either complete or partial, or have has
teeth crowned.
The
design of
artificial limbs has been much improved in recent years. At one time an artificial leg was little better than the old-fashioned wooden leg; but the use of lightweight materials and
improvements in joint movement have now made it
possible for amputees to pass undetected in company. The most recent advance is the development of
artificial limbs that are
controlled by nerve impulses fed from the stump of the natural arm.
These prostheses look like
normal limbs, and their
internal power systems enable the user to pick up and manipulate objects.
A third common use of prostheses is in the treatment of arthritis. Replacement of the hip joint in cases of both rheumatoid arthritis and osteoarthritis is now commonplace, using stainless steel and plastic materials. As a result of the
success of this type of operation, surgeons have gone on to design elbow, knee, shoulder, and
finger joints that can be implanted to replace
joints in persons with
severe arthritis.
A
prosthesis that has gained much attention in recent
years is the artificial heart. It has been used as a total heart
replacement in a small
number of persons with severe, life-threatening, end-stage heart
disease who, because of
their age and other factors, are not good
candidate for heart transplants, and for those in need of a heart
transplant but for whom a donor heart is not yet available. So far the results have been so poor that many experts have condemned the procedure. It is
still considered experimental.
One of the most
common reasons for open-heart
surgery is the implantation of artificial heart valves in those whose valves are distorted or damaged from conditions such as
rheumatic heart disease.
Other prostheses in current use include acrylic lenses (to replace those affected by cataract) and artificial eyes (whose purpose is
entirely cosmetic). An artificial
larynx ("voice box") is
still under trial, and
attempts are being made to miniaturize an artificial
pancreas for use by diabetics. In the case of many complex internal organs, however, transplantation has so far proved more
practicable than the development of mechanical prostheses.