What Is Arthritis of the Knee?Arthritis of the knee is most often osteoarthritis, a degenerative disease where cartilage in the joint gradually wears away. In rheumatoid arthritis, which can also affect the knees, the joint becomes inflamed and cartilage may be destroyed. Arthritis not only affects joints, it may also affect supporting structures such as muscles, tendons, and ligaments.
Osteoarthritis may be caused by excess stress on the joint, such as from repeated injury, deformity, or if a person is overweight. It most often affects middle-aged and older people. A young person who develops osteoarthritis may have an inherited form of the disease or may have experienced continuous irritation from an unrepaired torn meniscus or other injury. Rheumatoid arthritis usually affects people at an earlier age than osteoarthritis.
What Are the Signs of Knee Arthritis and How Is It Diagnosed?A person who has arthritis of the knee may experience pain, swelling, and a decrease in knee motion. A common symptom is morning stiffness that lessens after moving around. Sometimes the knee joint locks or clicks when the knee is bent and straightened, but these signs may also occur in other knee disorders. The doctor may confirm the diagnosis by performing a physical examination and taking x rays, which typically show a loss of joint space. Blood tests may be helpful for diagnosing rheumatoid arthritis, but other tests may be needed as well. Analysis of fluid from the knee joint may be helpful in diagnosing some kinds of arthritis. The doctor may use arthroscopy to directly visualize damage to cartilage, tendons, and ligaments and to confirm a diagnosis, but arthroscopy is usually done only if a repair procedure is to be performed.
How Is Arthritis of the Knee Treated?Most often osteoarthritis of the knee is treated with analgesics (pain-reducing medicines), such as aspirin or acetaminophen (Tylenol), nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin, Nuprin, Advil), and exercises to restore joint movement and strengthen the knee. Losing excess weight can also help people with osteoarthritis. Rheumatoid arthritis of the knee may require a treatment plan that includes physical therapy and use of more powerful medications. In people with arthritis of the knee, a seriously damaged joint may need to be surgically replaced with an artificial one. (Note: A new procedure designed to stimulate the growth of cartilage using a patient's own cartilage cells is being used experimentally to repair cartilage injuries at the end of the femur at the knee. It is not a treatment for arthritis.)