What is plica syndrome?

The plica is a fold of joint lining (synovial tissue) that is a remnant of tissue from embryologic development. During embryologic development, bands of tissue divide the limbs into joints. These bands may persist into adulthood in up to 60% of people, although it infrequently causes symptoms. Several different band types may exist. These bands may become thickened and inflamed, causing varying symptoms.

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How does plica syndrome occur?

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.

What increases risk?

• Sports that require repeated, forceful straightening or bending of the knee (such as kicking and jumping)
• Repeated injuries to the knee
• Sports in which the knee may receive direct injury (volleyball, soccer, football) or that require prolonged kneeling

What are the symptoms of plica syndrome?

• 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)

How is plica syndrome diagnosed?

Plica syndrome is a diagnosis of exclusion. Pain over the medial (inside) of the knee, accompanied by clicking or snapping sensation, often indicates the possibility of an underlying symptomatic plica.

MRI is not particularly helpful at diagnosing this condition, particularly because the findings of plica bands is fairly ubiquitous. There is nothing remarkable about a plica band on an MRI that would confirm this as a diagnostic condition.

The definitive test for a plica is arthroscopic confirmation. At the time of arthroscopy (in which a small camera is inserted into the joint to visualize and facilitate treatment of a variety of conditions), a prominent fold of tissue is identified.· In addition, doctors look for evidence of abrasion in the vicinity of the plica, and, with motion, direct contact between the thickened plica band and the slightly worn joint surface, this confirms the diagnosis.

The diagnosis is further confirmed in the absence of any other knee pathology. For example, in a patient with a prominent plica band that has a medial meniscus tear, only a thorough history and physical exam pre-operatively, and attention to detail (looking for abrasion due to the band) at the time of arthroscopy, ensure that the plica is actually pathologic and responsible for symptoms.

Are there any special tests?

MRI is not helpful. Confirmation is via arthroscopy with appreciation of contact between a thickened fold and adjacent articular cartilage.

How is plica syndrome treated?

Non-operative treatment

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. Your physician may recommend an injection of cortisone to reduce the inflammation of the plica. Arch supports may also be recommended.

Operative treatment

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).

What are the complications of treatment?

Possible complications of non-operative treatment include:

• Persistent symptoms of pain and/or clicking

Possible complications of operative treatment include:

• Surgical complications not specifically associated with the knee joint, such as pain, bleeding (uncommon), infection (<1%), nerve injury (uncommon), stiffness, problems with anesthesia, and inability to return to previous level of pre-injury activity-level. 
• Complications specific to surgical treatment of this condition: pain in the area of the resection, stiffness, failure to improve. 

When can you return to your sport/activity?

Usually there is complete recovery with proper treatment.

How can plica syndrome be prevented?

• Proper padding can reduce direct injury to the fat pad.
• Allow complete recovery before returning to sports.