Torn Meniscus
Introduction
A frequently injured part of the knee, the meniscus is often damaged along with the anterior cruciate ligament and, on occasion, with the posterior cruciate ligament. The usual cause of the injury varies with a person's age. For example, in people under 30 the damage is typically the result of playing sports. Someone over 40 is more likely to suffer a meniscal injury due to normal aging or underlying disease.
Anatomy
There are two menisci in each knee: One on the outside (lateral) and one on the inside (medial). As discussed in the Anatomy section of The Knee Joint, the menisci protect the area where the upper (femur) and lower (tibia) leg bones meet at the knee joint. Although cartilage covers the ends of both the femur and tibia, the menisci provide extra "padding." They serve as shock absorbers, preventing any one area of the cartilage surface from bearing the full brunt of the forces of motion.
A meniscus can tear in several ways. A small flap of the inner rim may tear, or the entire inner rim may rip. In damage associated with aging (degenerative tears), a portion of the meniscus is frayed in several places.
CausesBecause the meniscus is strong and elastic in people under 30, a forceful twisting injury (such as one that might occur while playing sports) or severe trauma (such as getting hit on the side of the knee) is usually required to damage it. As we age, however, the meniscus gets soft and is more easily torn. Degenerative tears in patients 40 and older can be caused by a minor event or none at all. They are sometimes triggered by something as simple as squatting down to pick up a spoon from the floor. They are often the result of osteoarthritis. |
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Symptoms
A torn meniscus is usually signaled by a sharp pain on the inside or outside of the knee, where the menisci are located. Some people, though, feel pain in the whole knee. If a torn piece of meniscus gets caught in the hinge portion of the knee, your knee may "lock," so that you can't completely straighten it. The knee may also swell and eventually become stiff and tight.
Diagnosis
As discussed in the Diagnosis section of Arthritis and other Joint Problems, a history and physical exam will help your doctor make the diagnosis. He'll feel your knee to determine where it hurts, check to see whether it "locks" and find out whether it "clicks" or "pops" when you move it. Although an x-ray can ensure that you don't have a broken bone, it won't show a meniscal tear. For that, an MRI is needed.
Treatment
You'll need to give the knee plenty of rest. Ice applied 2 or 3 times a day for 15 to 20 minutes may decrease pain and swelling. Compressing the knee with a bandage or brace can also limit swelling. A warm wash cloth or heating pad on a low setting may relieve stiffness.
You may need to use crutches for several days to keep weight off your knee. Put your weight on your arms and hands rather than your armpits and bend your elbows. Keep your injured leg off the floor by bending your knee. Move both crutches forward. Then swing your uninjured foot between the crutches, landing heel first.
To help your knee heal, your doctor will probably advise that you avoid squatting, turning your knee, and walking on uneven ground. Try to sleep with your legs straight out. Your doctor may also have you start an exercise program to strengthen your thigh (quadriceps) muscle and the muscles behind your knee.
If your symptoms continue or your knee is locked and can't straighten on its own, you'll need arthroscopic surgery. For a description of the procedure, see the section on Arthroscopy . If the tear can't be repaired (which is typically the case with degenerative tears), the doctor can still relieve your symptoms by removing the torn part of the meniscus.
To restore motion and strengthen the knee muscles after surgery, your doctor may recommend exercises.
Illustration by: Calhoon, Borman, Mueller
