Posteromedial Corner Knee Injuries: Diagnosis, Management, and Outcomes

* The posteromedial corner of the knee comprises the superficial medial collateral ligament (MCL), deep MCL, posterior oblique ligament, oblique popliteal ligament, and posterior horn of the medial meniscus. The main medial knee structure is the superficial MCL. * Injuries to the medial knee are the most common knee ligament injuries. A comprehensive history and physical examination are key to the diagnosis of a posteromedial corner injury. Patients often present with swelling and pain over the medial joint line after an injury involving a valgus and external rotation force. The valgus stress and anteromedial drawer tests can aid the clinician in deciphering whether an isolated medial structure was injured or if a complete posteromedial corner injury is likely. * Valgus stress radiographs can be utilized to quantify the amount of medial joint gapping. A side-to-side difference in gapping of 3.2 mm is consistent with an isolated superficial MCL tear, and a side-to-side difference of ≥9.8 mm is consistent with a complete posteromedial corner injury. Magnetic resonance imaging is also a useful tool in the detection of medial-sided injuries and has been reported to have an 87% accuracy. * Although a large number of medial knee injuries can be treated nonoperatively, complete posteromedial corner injuries may require surgical treatment to restore joint stability and biomechanics. There is heterogeneity between techniques with regard to the type of graft, the tibial and femoral tunnel position, and the tensioning protocol. Anatomic techniques have been reported to better restore knee kinematics and function.