The knees provide stable support for the body and allow the legs to bend and straighten. Both flexibility and stability are needed for standing and for motions like walking, running, crouching, jumping, and turning.
Several kinds of supporting and moving parts, including bones, cartilage, muscles, ligaments, and tendons, help the knees do their job. Any of these parts can be involved in pain or dysfunction.
Some knee problems result from injury, such as a direct blow or sudden movements that strain the knee beyond its normal range of movement. Other problems, such as osteoarthritis in the knee, result from wear and tear on its parts.
Arthritis of the knee is most often osteoarthritis. In this disease, the 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 can also affect supporting structures such as muscles, tendons, and ligaments.
Osteoarthritis may be caused by excess stress on the joint from deformity, repeated injury, or excess weight. 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 often affects people at an earlier age than osteoarthritis.
Most often osteoarthritis of the knee is treated with pain-reducing medicines, such as aspirin or acetaminophen (Tylenol*); nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin, Nuprin, Advil), and fosamax ( fosamax osteoporosis) and exercises to restore joint movement and strengthen the knee. Losing excess weight can also help people with osteoarthritis.