The medial collateral ligament is the most commonly injured ligament in the knee. High-grade medial collateral injuries are associated with injuries to the posteromedial structures of the knee. Chronic medial-sided instability is rare due to the intrinsic capacity of the medial ligamentous structures to heal. However, when combined with anterior cruciate ligament deficiency, significant anterior, valgus, and rotatory laxity of the knee occurs. In this review, we discuss the important biomechanical, clinical, and surgical considerations in the management of chronic combined anterior cruciate ligament, medial, and posteromedial instability of the knee.