Disorders of the Knee

The knee is a modified hinge joint between the femur (thighbone) and the tibia (shin bone). The knee allows you to bend and straighten your leg. It also allows slight rotation of the lower leg when the knee is bent. Your hamstring muscles bend the knee, while your quadriceps muscles straighten the knee. Strong ligaments join your femur to your lower leg bones (tibia and fibula) and limit side-to-side movement, overextension, and overbending of the knee. The ligaments also limit sliding movement between the bones. Your knee also has two menisci (crescent-shaped disks of cartilage) to reduce friction and distribute the weight-bearing load evenly during walking or running. The knee joint is vulnerable to injury from the front or either side, as well as from overextension. Injury can affect the menisci or any of the ligaments, bursae, cartilage, bones, or tendons that form the knee. The knee is prone to a number of disorders and injuries because of its special design and because it bears weight and provides movement.

Torn Ligament
A torn ligament usually results from a severe twist or a forceful blow to the knee when the knee is bent and then straightened. It also can occur when the foot is placed firmly on the ground and the leg is straightened while the knee is twisted. Each ligament in the knee is subjected to tremendous stress and strain. Injuries to ligaments usually cause immediate pain that is present even at rest. The pain increases when the knee is bent or when weight is put on the knee. The joint also may be swollen and warm. There may be stiffness, and movement may be limited. You may hear or feel a “pop,” and your knee may give out when the ligament tears. Injury to a ligament on the side of the joint causes pain in that side of the knee. Injury to a ligament within the joint causes pain deep inside the knee.

Ligament injuries are first treated with RICE. You also must use some form of support (such as crutches or a cane) to avoid putting weight on the injured knee joint. In some cases a splint or a brace is needed for long-term immobilization of the joint. Nonsteroidal anti-inflammatory drugs such as aspirin or ibuprofen will help relieve pain and reduce inflammation. Arthroscopy (search arthroscopy for more info) often is needed to repair the ligament. Your knee joint may be unstable after this injury and may be more susceptible to recurring ligament or cartilage tears. Your doctor may recommend working with a physical therapist or an athletic trainer on exercises that will stabilize the ligaments and tendons and strengthen the leg muscles.

Torn Cartilage
Either meniscus in the knee can be torn during sharp, rapid, twisting motions. The incidence of this type of injury rises with age and participation in sports that require quick, reactive movements, such as basketball, downhill skiing, and soccer. Certain knee motions cause a popping sensation, sometimes accompanied by swelling, warmth, and instability in the joint. Treatment for torn cartilage is similar to treatment for a torn ligament. A torn meniscus is often repaired using arthroscopy.

Other Knee Disorders
Tendinitis can occur in the front of your knee below the patella (kneecap) or in the back of the knee at the popliteal tendon. As with ligament injury, tendinitis is treated with RICE and nonsteroidal antiinflammatory medication such as aspirin or ibuprofen. Rehabilitative exercise programs can begin when the swelling is gone. Because corticosteroid injections can rupture knee tendons, they are rarely, and very carefully, given. Surgical repair of a severely ruptured tendon may be necessary.

Bursitis of the knee commonly occurs on the inside of the knee and on the front of the kneecap. Treatment is similar to that for the ligament and tendon injuries described above. Osteoarthritis is a common cause of pain and inflammation in the knees. In severe cases, surgery to replace the damaged knee joints may be necessary