Plica Syndrome

Plica Syndrome (also known as Plica Knee, or Synovial Plica Syndrome) occurs when the plica (an extension of the protective synovial capsule of the knee) becomes irritated or inflamed. This inflammation is typically caused by the plica being caught on the femur, or pinched between the femur and the patella. The most common location of plica tissue is along the medial (inside) side of the knee. The plica can tether the patella to the femur, be located between the femur and patella, or be located along the femoral condyle. If the plicae tethers the patella to the femoral condyle, the symptoms may cause it to be mistaken for Patello-femoral Syndrome. Because of this similarity in symptoms, Plica Syndrome is frequently misdiagnosed as Patello-femoral Syndrome. Diagnosis is often complicated by the thin structures of plicae, fenestrated septum or unfenestrated septum all being too fine to resolve well even in MRI.

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The plica themselves are remnants of the fetal stage of development where the knee is divided into three compartments. The plica normally diminish in size during the second trimester of fetal development, as the three compartments develop into the synovial capsule. In adults, they normally exist as sleeves of tissue called synovial folds. The plica are usually harmless and unobtrusive; Plica Syndrome only occurs when the synovial capsule becomes irritated, which thickens the plica themselves (making them prone to irritation/inflammation, or being caught on the femur).

Treatment for Plica Syndrome should focus on decreasing the inflammation of the synovial capsule. First, the care provider may prescribe a non-steroidal anti-inflammatory medication. Therapeutic exercise and modalities may also be used to treat the plica. Iontophoresis and phonophoresis have been utilized successfully against inflammation of the plica and the synovial capsule. Rehabilitative exercises should begin when inflammation and pain have decreased.