What is arthroplasty?

Quick Answer
The replacement of joints—hips, fingers, knees, shoulders, or elbows—by metal or plastic prostheses
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Indications and Procedures

Joints become painful when the cartilage between them, which keeps bone from pressing on bone, deteriorates, a process called osteoarthritis. The joints can become sufficiently painful, particularly among the elderly, to indicate more than the analgesic treatment that most people suffering from painful joints initially try.

Arthroplasty, surgery undertaken to replace deteriorating joints, may be performed on the fingers, shoulders, and elbows. The most common sites of such surgery, however, are the hips and knees. Most patients requiring hip or knee replacements are over the age of fifty, but arthroplasty may be indicated for younger people who have suffered trauma. Specialists in sports medicine frequently prescribe arthroplasty, which is typically performed by orthopedic surgeons.

The hip is a ball-and-socket joint. When people walk, the top of the femur slides into the acetabulum. Cartilage normally covers both bones where they meet, permitting smooth, painless contact between them. When this cartilage deteriorates, bones rub against each other, causing pain and restriction in movement that is best relieved by hip replacement surgery.

A similar situation can afflict the knee. Using an arthroscope or endoscope, an orthopedist makes a small incision in the knee and inserts a narrow illuminated tube with a camera attached into the affected site to examine it. If this examination reveals worn bone and cartilage, then a knee replacement, in which the knee joint is replaced with metal and plastic substitutes, is indicated.

Typically, hip and knee replacements are performed on patients under general anesthetic, although a local anesthetic, either spinal or epidural, is sometimes used. In most cases, general anesthetic is preferred because patients must remain completely still during this surgery and general anesthetic causes temporary paralysis.

In hip surgery, an incision, varying in length from 2 to 12 inches, is made over the back of the hip. Tissue and muscles are cut or pushed aside to expose the hip joint. The femur and acetabulum are separated. A declivity made in the acetabulum accommodates the replacement cup and allows for the insertion of a plastic-lined metal shell. The ball atop the femur is removed and replaced with a metal ball attached to a metal stem, usually made of titanium, that is inserted into the femoral canal. The two parts are then cemented into place, making them adhere to the bone. Damaged muscles and tendons are repaired before the incision is closed with staples or sutures.

In knee surgery, a long incision is made in the front of the knee and the patella is removed to make the joint accessible. Holes are drilled into the lower femur to affix the metal replacement. Holes are also drilled in the upper tibia to anchor a plastic plate. The back part of the patella is excised to create a flat surface into which holes are drilled to receive a plastic button. The prosthesis is then secured with cement, and the incision closed, usually with sutures or staples.

Uses and Complications

Arthroplasty is used to relieve pain and restore mobility in patients who are reasonable surgical risks. Many have been disabled by their conditions. Because many such patients are elderly, extensive preoperative evaluation is necessary. Conditions such as diabetes mellitus, hypertension, heart or lung disease, and anemia increase the surgical risk. Open lesions increase the risk of infection.

Nerve damage can result from cutting muscles and tendons during surgery. Blood clots can form in the lungs or legs of patients undergoing arthroplasty, and this risk may continue for two months following surgery. Blood thinners are usually administered postoperatively.

Physical therapy, essential following arthroplasty, usually begins two or three days after the surgery and continues for eight weeks. Most patients are completely ambulatory within six weeks postoperatively.

Perspective and Prospects

As life expectancy increases, incidence of joint problems is increasing exponentially. In the early twentieth century, many people who lived beyond their sixties were immobilized by chronic arthritis, osteoporosis, and painful joints. When an elderly person suffered a broken hip, it often marked the beginning of a physical decline with a fatal outcome.

Medical advances made during World War II had a profound effect on treating many physical problems that, although experienced in combat by relatively young people, required treatment that was soon used in dealing with the joint problems of the elderly. Hip and knee surgery were once more disabling than they currently are. Hip surgery now requires incisions as small as one inch long, although four-inch incisions are more common and ten-inch incisions are used by some surgeons.

Although arthroplasty usually involves a hospital stay of two to four days, it is likely that soon such surgery will become an outpatient procedure. The use of titanium in prostheses has extended the effectiveness of such surgery, with these devices currently expected to last for about two decades.

Bibliography

An, Yuehuei H., ed. Orthopaedic Issues in Osteoporosis. Boca Raton, Fla.: CRC Press, 2003.

Doherty, Gerard M., ed. Current Surgical Diagnosis and Treatment. 13th ed. New York: Lange Medical Books/McGraw-Hill, 2009.

Kellicker, Patricia Griffin. "Hip Replacement." Health Library, May 6, 2013.

"Knee Replacement." Health Library, May 3, 2013.

Morris, Peter J., and William C. Wood, eds. Oxford Textbook of Surgery. 2d ed. New York: Oxford University Press, 2000.

Rose, Eric A. The Columbia Presbyterian Guide to Surgery. New York: St. Martin’s Griffin, 2001.

Rothrock, Jane C., ed. Alexander’s Care of the Patient in Surgery. 14th ed. St. Louis, Mo.: Mosby/Elsevier, 2010.

"Total Knee Replacement." American Academy of Orthopaedic Surgeons, December 2011.