Cartilage tears (tehrz) are the most common cause of leg pain in active people, both young and old. There are many causes of cartilage tears, many of which are related to the age of the person and their activity level. Cartilage, which is a white, gristle-like substance that covers the ends of bones where they come in contact with one another, is commonly torn in the knee when a person twists the area, resulting in swelling and pain. This injury is usually followed by stiffness that prevents you from completely straightening or bending your knee. In many cases, your knee may feel better with rest, but the symptoms are likely to return with any new physical activity. This type of injury may have a long-term effect on your knee if proper treatment isn't applied at the time of the injury. Unlike arthritis pain, which typically develops over many years, the symptoms of a degenerative tear (tehr) of the cartilage can be quick to develop in a person previously active and pain free. Arthroscopic (are-throw-SKAW-pik) surgery can be used to remove pieces of torn cartilage by making a tiny incision and viewing the joint with a small fiber-optic instrument. In some younger people, the cartilage can be sewn back together and removal of the cartilage is avoided. Symptoms of cartilage damage may be pain and tenderness, especially when bearing weight, locking of the joint, giving way of the knee, and in some cases, water on the knee. If you suffer from any of these symptoms, you many want to consult a physician.