Posteromedial corner of knee

The posteromedial corner of the knee is a complex anatomical region located between the posterior margin of the superficial medial collateral ligament (sMCL) and the medial border of the posterior cruciate ligament (PCL).The principal structures comprising the posteromedial corner include:

• Posterior oblique ligament (POL): Originates from the adductor tubercle and fans out posteriorly, blending with the posteromedial capsule and semimembranosus expansions. It is a key stabilizer against anteromedial rotatory instability.

• Oblique popliteal ligament

• Distal semimembranosus complex (Semimembranosus tendon and expansions): The tendon inserts on the posteromedial tibia and sends expansions to the posterior capsule, oblique popliteal ligament, and medial meniscus, dynamically stabilizing the posteromedial corner and mobilizing the posterior horn of the medial meniscus during flexion.

• Meniscocapsular and meniscotibial ligaments: These structures anchor the posterior horn of the medial meniscus to the tibia and capsule, resisting extrusion and contributing to meniscal stability.

• Posterior third of medial meniscus

This region is frequently involved in multiligamentous knee injuries, and disruption can result in anteromedial rotatory instability and compromise cruciate ligament reconstructions. Recognition of the nuanced anatomy is essential for accurate diagnosis and surgical planning.