Injuries to the medial collateral ligament (MCL) and the posteromedial corner of knee are very common and can be isolated or combined with other ligamentous lesion. Posteromedial corner encompasses five medial structures posterior to the medial collateral ligament. Like posterolateral corner injuries, untreated or concurrent posteromedial corner (PMC) injuries resulting in rotatory instability place additional strain on anterior or posterior cruciate ligament reconstruction, which can ultimately contribute to graft failure and poor clinical outcomes. In some cases, the treatment of posteromedial corner injuries remains controversial. A thorough understanding of anatomy, biomechanics, physical examination, and imaging characteristics will aid the surgeon in the management of such injuries, with early results indicating that anatomic reconstruction can restore valgus stability and improve patient-related outcomes.