Objective Osteoarthritis (OA) commonly occurs in the patellofemoral joint (PFJ) and knee pain in subjects with knee OA often emanates from the PFJ rather than the tibiofemoral joint (TFJ).Despite this,research into risk factors and mechanisms for PFJ OA is limited compared to that of the TFJ.Mediopatellar plica (MPP) is often observed in conjunction with patello-femoral structural damage and plica syndrome is a common cause of knee pain.However,it is largely unclear if MPP is an independent risk factor for structural PFJ damage or if MPP is an incidental finding of questionable relevance.