The largest joint in the body, the knee joint is formed where the lower part of the thighbone (femur) joins the upper part of the shinbone (tibia) and the kneecap (patella). Shock-absorbing cartilage covers the surfaces where these three bones touch.
In a standard total knee replacement, the damaged areas of the thighbone, shinbone and kneecap are removed and replaced with prostheses. The ends of the remaining bones are smoothed and reshaped to accommodate the prostheses. Pieces of the artificial knee are typically held in place with bone cement.
A knee replacement usually involves three to four days in the hospital. The recovery period depends on a patient's general health, age, and other factors, but many people can resume their normal activities four to eight weeks after surgery.
"While a knee replacement can dramatically improve the quality of life for a person with debilitating knee pain, it is major surgery," says Gerard Engh, M.D., director of knee research at Anderson Orthopaedic Research Institute in Alexandria, Va. "We usually recommend total knee replacements and partial knee replacements after other less invasive treatments have been attempted."
But most who opt for knee joint replacement are generally happy with the results. Ninety percent of those who have total knee replacement report fast pain relief, improved mobility, and better quality of life, according to a panel of independent experts. The panel was convened at a conference in December 2003 sponsored by the National Institutes of Health (NIH) and cosponsored by the FDA and other federal organizations.
The panel concluded that, overall, total knee replacement surgery is a safe, very successful, and relatively low-risk treatment for decreasing pain and increasing mobility in people who are not helped by nonsurgical treatments. Follow-up studies showed that revision surgery was needed in 10 percent of knee replacements after 10 years, and in 20 percent after 20 years, according to the panel.
"All You Need to Know About Joint Surgery," © 2002, Arthritis Foundation