The medial plica syndrome of the knee – Narrative review of the literature

Abstract

Synovial plicae are physiological tissue found in the knee joint. They are formed in the fetal period as remnants of synovial cavities that are not absorbed in the process of apoptosis. Depending on the location of the plica, medicine distinguishes several types of plicae - suprapatellar, infrapatellar, medial and the lateral one. Based on the shape and size of the fold, the types are divided into subtypes. In the knee joint, the most common is medial plica, which extends from the area of the articular muscle or the vastus medialis oblique muscle, which runs parallel to the medial femoral condyle and patella.

Medial plica syndrome (MPS) is the medical term for the development of sympthoms caused by a pathological synovial fold. A significant factor in the pathophysiology of medial plica syndrome is the stage of inflammation, occurring either in the direct injury mechanism of plica (e.g. torsional mechanism) or as a consequence of cumulative overload changes. Typical clinical symptoms of a patient with MPS include: dull pain in the antero-medial apspect of the knee, associated with repeated knee flexion movement with possible clicking or locking signs. Clinical provocation tests were described (Mediopatellar Plica Test, Hughston Fold Test, Stutter Test) to confirm the diagnosis. It is crucial to exclude the presence of other knee joint diseases.

Imaging including ultrasound and MRI may be useful in differential diagnosis but confirmation of the presence of the plica is not sufficient to make a diagnosis. Conservative treatment can be effective and it is based on NSAIDs administration, activity modification, kinesiotherapy and physical therapy. In the case of ineffective conservative treatment, arthroscopic surgery is considered. Usually larger folds in the MPS require surgical intervention.