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Condition/Disorder Synonyms

  • Plica syndrome

  • Pathologic plica/plicae

  • Synovial plica/plicae syndrome

ICD-9-CM Code

  • 727.83 Plica syndrome

ICD-10-CM Code

  • M67.50 Plica syndrome, unspecified knee

Preferred Practice Pattern1

  • 4E: Impaired Joint Mobility, Motor Function, Muscle Performance, and Range of Motion Associated With Localized Inflammation

Key Features


  • Plica is a shelf, fold, or pleat in the synovial membrane in the knee.

  • It is the result of incomplete or partial reabsorb during fetal development.

  • Plica can be inferior, medial, or superior to the patella.

  • Can vary in size (length or thickness) and clinical relevance.

  • Plica can be thickened and inflamed, usually following acute or chronic trauma.

  • The medial plica is most implicated.

  • Medial plica extends from anteromedial aspect of patella to the suprapatellar pouch

  • Suprapatellar plica separates the suprapatellar pouch from the knee joint

  • Infrapatellar plica, also termed ligamentum mucosum, runs from the infrapatellar fat pad to the intercondylar notch

Essentials of Diagnosis

  • Diagnosed primarily through symptoms and exclusion of other knee pathologies

  • Mechanism of injury can be either from chronic or acute trauma

    • Chronic: friction or rubbing over the femoral condyle

    • Acute: pinching under the patella

  • Found in concurrence with range of pathologies, both chronic and acute

    • Chronic: chondromalacia or patellofemoral pain syndrome

    • Acute: ACL or meniscus pathologies or contusion

  • Differential diagnosis from other knee pathologies that may warrant a more immediate surgical intervention is essential (meniscus tear)

  • Combination of tests/cluster of findings has been reported to have the strongest diagnostic value in terms of sensitivity (1.0) for diagnosis of medial plica syndrome.

General Considerations

  • Plica are normal unless thickened or inelastic from acute or chronic inflammation

  • Plica syndrome signs and symptoms mimic other knee pathologies

  • Full history of symptoms, medical history screening, and differential knee orthopedic examination will ensure appropriate diagnosis

  • History of anterior knee pain, pain primarily over medial femoral condyle, visible or palpable plica, and exclusion of other anteromedial knee pain.


  • Plica syndrome most commonly involves the medial plica2

  • Presence of a plica has been reported to range from 10% to > 50% in normal knees.

  • Has been found with much greater frequency in patients who have anterior knee pain.2

  • No delineation in incidence noted based on gender or age

  • Individuals with Japanese have the highest prevalence of synovial plica in the knee.

Clinical Findings

Signs and Symptoms

  • Insidious onset of knee pain

  • Pain or mechanical symptoms (clicking, catching, giving away) located in the anterior knee

  • Symptoms elicited with flexed positions of the knee; transitioning between flexion to extension

  • Pain and mechanical symptoms with stairs; squatting

  • Tender to palpation over the plica; swelling in plica

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