The medial plica is a structure that occurs normally in all knees. In some cases, however, it can be injured and become thickened. As a result it rubs on the medial (inner) condyle of the knee causing medial knee pain.
This condition can sometimes be difficult to diagnose when it is confused with a meniscal tear and when an MRI scan shows no such tear. Often a painful plica can be felt when the knee is examined in the clinic.
Trimming the knee plica arthroscopically (through key-hole surgery) can cure this condition.