The knee joint is prone to injury, especially if you participate in activities in which you frequently start and stop, jump, run, change directions or twist. Cartilage covers the ends of the bones in your knee, and the pieces of cartilage between the bones are called meniscus. The cartilage cushions your joint as you move and prevents bones from rubbing together. Cartilage in your knee can tear if you suffer a direct blow or other trauma or if you forcefully twist your knee while playing. With age, cartilage wears away and can tear during everyday activities. If you notice signs or symptoms of a tear, see your physician for treatment so your injury does not become worse.
If your cartilage tears because of a blow to the knee or a sudden twist, you might hear a popping sound in your knee joint. Torn knee cartilage usually produces pain in the inner or outer part of the knee, not in the kneecap area. You might experience sharp pains and feel as if your knee is weak and unable to support you. Your knee joint may also catch or lock as you move. The American Academy of Orthopedic Surgeons states that if the tear is not severe, you may initially be able to keep playing or walking on it.
According to the Hospital for Special Surgery, torn cartilage in your knee can also cause the area to swell. This can happen right after the injury, usually within one to two hours, or it can take a day or two to appear. Your knee may also become stiff and you may find it is hard to bend or straighten. If you do not take steps to treat the injury, with time the swelling and stiffness can get progressively worse. If the tear is minor, it may heal on its own within a few weeks. In many cases, however, surgery is required.
If a knee tear is severe enough, your knee may temporarily lock in a certain position. Pieces of the cartilage can also break off and lodge in your joint, restricting movement. If the injury is not treated, your symptoms will return every time you are active. With time, you may have constant symptoms, even during routine daily activities. As the range of motion in your knee worsens, the surrounding muscles may become tight and weak, creating additional pain and stiffness. Some knees can remain locked for days at a time.