Plica: Pathologic or Not?

A fold that occurs within a joint is referred to as a plica synovialis. Three such plicae are seen with regularity within the human knee joint. These folds are normal structures that represent remnants of mesenchymal tissue and/or septa formed during embryonic development of the knee joint, and can be seen during arthroscopic inspection of the knee joint. Controversy exists within the orthopaedic community as to whether a plica can develop pathologic changes sufficient to cause disabling knee symptoms. The author defines the clinical syndrome, describes the arthroscopic appearance of pathologic plica, and outlines nonsurgical and surgical methods of management of this uncommon condition.