Prosthetics

Prosthetics is a branch of surgery that is involved in devising and fabricating a prosthesis for a missing or infirm body part. A prosthesis is an artificial part used to restore some amount of normal body function. The classic example of a prosthesis is a false leg or arm to replace one that has been amputated. A diseased heart valve can be removed and replaced by an artificial one.

Artificial body joints have been designed to replace diseased or impaired ones, especially those that have been damaged by osteoarthritis, the most common form of arthritis causing degeneration of the main body joints.

There are a wide range of prosthetic devices for different parts of the body and for internal and external use. Some prosthetic devices are used to improve a body function such as a hearing aid. Others, such as breast implants used after mastectomies, are mainly designed for cosmetic rather than functional purposes. Another example of a cosmetic prosthesis is a glass eye designed to replace an eye lost in surgery. Hip and knee replacements An artificial knee joint as used in replacement surgery (seen fitted to human bone samples). The replacement is made of plastic and consists of new contact surfaces, an artificial cartilage between the faces, and artificial tendons to limit flexion of the joint and prevent sideways movement. Photograph by Mike Devlin. National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission.

are examples of internal joint replacements with artificial parts.

Prosthodontics is a branch of dentistry that provides replacements of teeth and other related supportive dental structures. The two main types of replacements are either partial or complete dentures and crowns and bridges, which are placed over existing teeth.

Orthotics is a branch of medicine, allied to prosthetics, that designs devices, such as braces, to correct or control a bone deformity or other anatomical problem that interferes with the correct performance of a part of the body such as the leg, arm, or wrist.

Arthroplasty is a branch of surgical orthopedics in which artificial joints or parts of joints are used to replace joints in the hip, knee, finger, shoulder, and elbow.

Bionics is a field of science that combines mathematics, electronics, biochemistry, and biophysics with the study of living systems to develop innovations in both general and medical technology. It has been responsible for recent major developments in prosthetics. With the application of bionic principles, new prostheses have allowed amputees and those who are paralyzed to walk with feeling by using electronic neuromuscular stimulation. Microprocessors are able to transmit a voltage charge to muscles triggering a reflex response.

Replacing all or part of diseased or degenerated joints through the use of prosthetic joint parts provides the basis for a form of orthopedic surgery known as arthroplasty. Hip replacements were the first arthroplasty operations. They are still being performed with a high rate of success. Other routine joint replacement operations now also include knee joint replacement, finger joint replacement, and the replacement of the shoulder and elbow.

Heart valve implants and plastic surgery for the face or in smoothing wrinkles employ the use of silicone materials as well. The FDA continues to study other high-risk medical prostheses. These include inflatable penile implants, testicular implants, heart-bypass pumps, cranial stimulators, and saline-filled breast implants.