The plica is a fold of joint lining (synovial tissue) that is a remnant of tissue from embryological development. During embryological development, bands of tissue divide the limbs into joints. These bands may persist into adulthood in up to 60 percent of people, although it infrequently causes symptoms. Several different band types may exist. These bands may become thickened and inflamed, causing varying symptoms.
Trauma to the knee, either direct or with repetitive knee bending and straightening activity, causes thickening of the plica, and it loses its elasticity (becomes less stretchy). As a result, the plica pinches on the inner knee joint (medial femoral condyle) and inner patella. The pain is felt to be due to pinching or pulling of the plica band, which has many nerve endings.
Initial treatment consists of medications and ice to relieve pain and reduce inflammation, stretching and strengthening exercises (of the hamstrings and quadriceps), and modification of the activity that produces the symptoms. These may be carried out at home, although occasionally referral to a physical therapist or athletic trainer may be indicated. Occasionally your physician may recommend an injection of cortisone to reduce the inflammation of the plica. Arch supports may also be recommended. Surgery is not usually necessary; it is usually reserved for cases in which symptoms persist despite conservative treatment. Surgery to remove the plica is usually performed arthroscopically on an outpatient basis (you go home the same day).
Frequent Signs and Symptoms
- Pain in the front of the knee, often toward the inside of the knee, especially with kneeling, squatting, sitting for long periods, arising from a sitting position, or walking or running up or down stairs or hills
- Catching, locking, and clicking of the knee
- Pain and tenderness under the kneecap (patella)