Posterolateral corner injury is damage or injury to the structures of the posterolateral corner. The structures of the posterolateral corner include the lateral collateral ligament, the popliteus tendon, and the popliteo-fibular ligament. Injuries to the posterolateral corner most often occur with athletic trauma, motor-vehicle accidents and falls. An isolated injury to the posterolateral corner is rare, but often occurs with injuries to the cruciate ligaments, the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL).