The posteromedial corner of the knee is comprised of the structures between the posterior border of the superficial medial collateral ligament and the medial border of the posterior cruciate ligament. This includes the posterior oblique ligament, semimembranous tendon (SM), the oblique popliteal ligament and the posterior horn of the medial meniscus.
It is important to identify injuries of the PMC as, unlike isolated MCL injuries, they do not tend to heal without surgery. MRI images show altered signal intensity with T2 hyperintense signal in relation to the medial collateral ligament and posteromedial corner. There is edema and soft tissue thickening posterior to the medial collateral ligament.