Total Knee Arthroplasty

Surgery to repair an injured or diseased knee joint is known as total knee replacement or total knee arthroplasty. During this procedure, an 8- to 12-inch incision is made in the front of the knee, the destroyed bone and cartilage in the knee joint are removed, and an artificial joint made of metal and plastic is implanted to restore the knee's normal function.

The knee joint is made up of three bones: the thigh bone, the shin bone, and the kneecap. These bones are covered by cartilage, which cushions the bones and allows them to move easily. Synovial fluid lubricates the cartilage and eliminates friction. Large ligaments connect the thigh bone to the shin bone. In a knee joint with osteoarthritis, the cartilage is worn away, leaving the bones to rub against each other when the knee is flexed. If the knee is affected by rheumatoid arthritis, there may be too much synovial fluid in the joint, leading to inflammation and cartilage damage. A knee injury can cause tears in the ligaments that hold the large bones together, damaging the articular cartilage. Any of these conditions can lead to disability, pain, and ultimately the need to replace the knee joint with an artificial joint.

Patients and their orthopedic surgeons decide together when a knee joint needs to be replaced. The classic symptoms of pain and stiffness when walking, climbing stairs, or even at rest signal the need for surgery when conservative treatment fails. Knee replacement surgery has become increasingly sophisticated since its development in the late 1960s. In addition, the design of and materials used for artificial knee joints have advanced considerably. In the vast majority of patients, surgery confers increased mobility and significant pain relief. If the patient adheres to standard guidelines for permitted activity, artificial knee joints should last 20 or more years.

Surgery Is the Next Step When Conservative Measures Fail

Knee replacement surgery is necessary when knee pain occurs during normal daily activities such as walking, climbing stairs, rising from a sitting position, or even resting. A sign that surgery may be needed is when an individual finds it difficult or impossible to bend the affected knee. Most people with knee pain and stiffness try conservative measures such as physical therapy, pain medication, corticosteroid injections to relieve inflammation and pain, avoidance of certain activities, or using a cane. When these methods no longer work, surgery is the next option.

About the Surgery

Knee replacement surgery can involve the entire knee joint (total knee replacement) or part of the joint (unicompartmental knee replacement). Some orthopedic surgeons perform a minimally invasive version of the classic knee replacement surgery, allowing faster healing, less pain, and less scar-tissue formation. This procedure requires a smaller incision and causes less trauma to the tendons in the knee joint.

Individuals most likely to require total knee replacement are those over age 65 who have significant osteoarthritis or rheumatoid arthritis of the knee or who have developed arthritis in the joint from a fractured-kneecap injury or torn ligaments. This type of knee surgery is best for older adults because younger people who are physically active can wear out the artificial joint quickly.

Risks and Complications

The most common risks of total knee replacement surgery are blood clots, bleeding, and infection. These risks are possible with every surgery, and steps are taken before and after the procedure to minimize them. If warning signs of these complications are noticed after discharge from the hospital, however, contact the doctor immediately. Signs to watch out for include increased pain, redness, or swelling in the knee, calf or ankle; chest pain; shortness of breath; and cough. Serious complications of knee replacement surgery are rare. The nerves in the knee joint could be injured and result in numbness, the knee joint could become infected, or the replacement joint could loosen or break after surgery.

Recovery and Healing

Total knee replacement surgery requires a hospital stay of 3 to 5 days, depending on the individual's physical condition upon entering the hospital. Blood thinners are prescribed to prevent blood clots, and medication is used to relieve pain. After discharge, physical therapy--some of which can be completed in a rehabilitation facility if needed--usually continues for a month or two. The patient is given strengthening exercises and instructions on how to perform activities so that the joint heals properly. Crutches or a walker may be required for several weeks after surgery, but most people can return to normal activities in 4 to 6 weeks. Some activities, such as running or high-impact sports, must be avoided permanently after total knee replacement surgery.