What is the definition or description of: plica?

Plica: Infolding synovial tissue within a joint. It is a normal finding. It may on occasion get pinched and swollen--becoming symptomatic.

Remnant tissue: A plica is a remnant band of tissue that is there after our knees form in the womb. Initially our knees are three different compartments and then as we form the tissues that separate those compartments go away. Any tissue that is left is called a plica. You can have one on the inside, outside or top of the knee. Usually they are flimsy, but sometimes they get thickened and cause pain later in life.