Definition of Injury, knee meniscus
< b>Injury, knee meniscus: Injury to one of the two crescent-shaped cartilage
pads between the two joints formed by the femur (the thigh bone) and the tibia (the
shin bone). Each meniscus acts as a smooth surface for the joint to move on.
The two menisci are easily injured by the force of rotating the knee while bearing
weight. A partial or total tear of a meniscus may occur when a person quickly twists
or rotates the upper leg while the foot stays still (for example, when dribbling
a basketball around an opponent or turning to hit a tennis ball). If the tear is
tiny, the meniscus stays connected to the front and back of the knee; if the tear
is large, the meniscus may be left hanging by a thread of cartilage. The seriousness
of a tear depends on its location and extent.
Generally, when people injure a meniscus, they feel some pain, particularly when
the knee is straightened. The pain may be mild, and the person may continue activity.
Severe pain may occur if a fragment of the meniscus catches between the femur and
tibia. Swelling may occur soon after injury if blood vessels are disrupted, or swelling
may occur several hours later if the joint fills with fluid produced by the joint
lining (synovium) as a result of inflammation. If the synovium is injured, it may
become inflamed and produce fluid to protect itself. This causes swelling of the
knee. Sometimes, an injury that occurred in the past but was not treated becomes
painful months or years later, particularly if the knee is injured a second time.
After any injury the knee may click, lock, or feel weak. Symptoms of meniscal injury
may disappear on their own but frequently, symptoms persist or return and require
treatment.
In addition to listening to the patient's description of the onset of pain and
swelling, the physician may perform a physical examination and take x rays of the
knee. The examination may include a test in which the doctor flexes (bends) the
leg then rotates the leg outward and inward while extending it. Pain or an audible
click suggests a meniscal tear. An MRI test may be recommended to confirm the diagnosis.
Occasionally, the doctor may use arthroscopy to help diagnose and treat a meniscal
tear.
If the tear is minor and the pain and other symptoms go away, the doctor may
recommend a muscle-strengthening program. Exercises for meniscal problems are best
performed with initial guidance from a doctor and physical therapist or exercise
therapist. The therapist will make sure that the patient does the exercises properly
and without risk of new or repeat injury. The following exercises after injury to
the meniscus are designed to build up the quadriceps and hamstring muscles and increase
flexibility and strength:
- Warming up the joint by riding a stationary bicycle, then straightening
and raising the leg (but avoiding straightening the leg too much).
- Extending the leg while sitting (a weight may be worn on the ankle for this
exercise).
- Raising the leg while lying on the stomach.
- Exercising in a pool, including walking as fast as possible in chest-deep
water, performing small flutter kicks while holding onto the side of the pool,
and raising each leg to 90 degrees in chest-deep water while pressing the back
against the side of the pool.
If the tear to a meniscus is more extensive, the doctor may perform either arthroscopic
surgery or open surgery" to see the extent of injury and to repair the tear. The
doctor can suture (sew) the meniscus back in place if the patient is relatively
young, the injury is in an area with a good blood supply, and the ligaments are
intact. Most young athletes are able to return to vigorous sports with meniscus-preserving
repair.
If the patient is elderly or the tear is in an area with a poor blood supply,
the doctor may cut off a small portion of the meniscus to even the surface. In some
cases, the doctor removes the entire meniscus. However, degenerative changes, such
as osteoarthritis, are more likely to develop in the knee if the meniscus is removed.
Medical researchers are currently investigating a procedure called an allograft,
in which the surgeon replaces the meniscus with one from a cadaver. A grafted meniscus
is fragile and may shrink and tear easily. Researchers have also attempted to replace
a meniscus with an artificial one, but the procedure is even less successful than
an allograft.
Recovery after surgery to repair a meniscus takes several weeks longer and post-operative
activity is slightly more restricted than when the meniscus is removed. Nevertheless,
putting weight on the joint actually fosters recovery. Regardless of the form of
surgery, rehabilitation usually includes walking, bending the legs, and doing exercises
that stretch and build up the leg muscles. The best results of treatment for meniscal
injury are obtained in people who do not show articular cartilage changes and who
have an intact anterior cruciate ligament.
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