What is the use of an infrapatellar plica?

Not Fully Known. The plica are remnants of tissue in the developing embrionic knee starting around 8 weeks. Some think that they act like eyelids and assist in lubrication of the joint. Generally asymptomatic, they may become inflammed after a direct blow to the knee, repetative sport activity, etc. Once inflammed, they can cause pain or irritate/damage surrounding tissues.