Lateral collateral ligament of the knee

Last revised by Henry Knipe on 09 Nov 2022

The lateral (fibular) collateral ligament (LCL) is on the lateral aspect of the knee and forms part of the posterolateral corner. It is a major knee stabilizer against varus forces 6.  The lateral aspect of the knee is divided into three layers and the LCL is part of the deep layer of the lateral aspect of the knee.

The LCL originates within an osseous depression slightly posterosuperior to the lateral femoral epicondyle and inserts onto the anterolateral fibular head 4,5. Its average length is ~50 mm and is more commonly cord-like than band-like 5,6.

Unlike the medial collateral ligament, it is not attached to the knee capsule or lateral meniscus and as such, is more flexible and less susceptible to injury 1

The popliteus tendon (through the popliteal hiatus), a bursa and the lateral inferior geniculate vessels and nerve run deep to the LCL. The iliotibial band is superficial to the LCL and attaches to Gerdy's tubercle 4,5.

  • biceps femoris muscular branch of the tibial nerve

  • branch from the common fibular nerve at the popliteal fossa

  • branch of the common fibular nerve at the head of the fibula 4,5

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Cases and figures

  • Figure 1: internal knee ligaments (Gray's illustrations)
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  • Figure 2: ligaments (Gray's illustrations)
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  • Case 1: lateral collateral ligament - normal
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