Arthritis and Other Joint Problems - Plica Syndrome
Introduction
Plica syndrome is the name given to irritation of a plica—a fold of tissue in the lining of the knee joint. Some doctors report that, for unknown reasons, women develop plica syndrome more often than men. Although the condition doesn't damage the knee, it can be a very painful nuisance. Diagnosing plica syndrome can be tricky, but treatment is simple.
Anatomy
As described in the Anatomy section of The Knee Joint, the lining of the knee joint (synovium) secretes a clear (synovial) fluid that lubricates the joint, helping the bones of the knee move easily. To further reduce friction between bones, the tissue of the synovium has extra folds of material called plicae. Normally, a plica is small and smooth. But if it becomes irritated, it grows red and thick, causing pain and inflammation.
There are 4 plicae in the knee, but only the one on the inner (medial) side seems to get irritated. The medial plica runs from the lower end of the kneecap (patella) along the inner side of the knee and attaches to the lower end of the upper leg bone (femur).
Causes
Plica problems can occur suddenly (acute) or over a long period of time (chronic). A sudden injury—falling or hitting your knee on the dashboard in an automobile accident—can cause the medial plica to swell and become painful. Later, scarring and thickening of the plica can develop, producing continuing symptoms.
Chronic plica problems develop when the medial plica is irritated by certain exercises that involve repeatedly bending and straightening the knee, such as biking or using a stair machine.
Symptoms
The most common symptom is pain. You may also feel a snapping or popping sensation when you bend your knee, or suffer tenderness on the inner side of your knee. Your knee may be unstable at times. If irritation is widespread, your whole knee may become swollen. If you're particularly thin, you may actually be able to feel a tender band of plica tissue under your skin.
Diagnosis
As discussed in the Diagnosis section of Arthritis and other Joint Problems, your doctor will take a history and do a physical exam to make the diagnosis. He'll ask you where it hurts and feel your knee to see if he can locate the tender band of tissue. Although x-rays and MRI scans can't detect damaged plica, these tests might be ordered to rule out other conditions.
Treatment
Nonsurgical measures can remedy most cases of plica syndrome. The primary goal is to reduce inflammation. To do this, you may have to give up such exercises as cycling and using a stair machine. Anti-inflammatory medications such as ibuprofen or aspirin may help. Ice packs or ice massage may also bring relief.
To restore your muscle balance, your doctor may also recommend exercises to strengthen your thigh muscle (quadriceps) and stretch the hamstrings at your knee.
If these nonsurgical treatments don't relieve your symptoms, you may need arthroscopic surgery to remove the irritated plica. For more information on this type of procedure, see the section on Arthroscopy. Since your knee can function just fine without the medial plica, expect a full recovery.
