Medial collateral ligament of the knee

Last revised by Dr Henry Knipe on 13 Sep 2021

The medial collateral ligament (MCL) of the knee is a flat, triangular band on its medial aspect that resists valgus forces. It forms part of the medial capsuloligamentous complex of the knee

The MCL measures 8-10 cm in length and has superficial and deep portions 4.

The superficial MCL, also known as a tibial collateral ligament or vertical component of the MCL, is part of the middle layer of the medial capsuloligamentous complex of the knee. Its proximal attachment is the posterosuperior aspect of the medial femoral epicondyle, anteroinferior to the adductor tubercle. Distally it has two insertion sites at the upper medial surface of the tibia 1-5:

  • anterior band of the semimembranosus tendon (principally a soft tissue attachment)
  • tibial periosteum posterior to the pes anserine attachment

The posterior aspect of the medial collateral ligament blends into the posterior oblique ligament and knee capsule.

The deep MCL, also known as the mid-third capsular ligament, is part of the deep layer of the medial capsuloligamentous complex of the knee, and is a thickening of the medial joint capsule, and is divided into meniscofemoral and meniscotibial ligaments 4,5

  • branches of the superior and inferior genicular arteries 5

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Cases and figures

  • Figure 1: knee ligaments (Gray's illustrations)
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  • Figure 2: knee ligaments (Gray's illustrations)
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  • Case 1: complete MCL tear
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  • Case 2: grade 2 MCL injury
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