Complex knee specialist Robert LaPrade MD, PhD. discusses how to read an MRI of a PLC injury. The posterolateral corner of the knee is comprised of three main stabilizers; the fibular collateral ligament, the popliteus tendon and the popliteofibular ligament.

We start off with a coronal view of a right knee. As we start to course down the first things we see is edema on both the anterior aspect of the medial femoral condyle and the anterior aspect of the medial tibial plateau. This is a common secondary sign of a posterolateral corner injury. Bone bruising on the medial side of the knee is also common in these injuries.

We can see a disruption of the meniscal tibial portion of the lateral meniscus. As you move deeper you can see the biceps femoris is peeled off the fibular head. You can also see disruption of the popliteofibular ligament.

We can also see the fibular collateral ligament with a rippled appearance consistent with a complete tear and in this case has been torn off the fibula as well as the biceps femoris being torn off. We also see the disruption of the femoral attachment site of the popliteus tendon on the femur. We can also see some injury to the posterior horn of the lateral meniscus.

We will now look at the sagittal images on the medial side of the knee. As we move deeper we can see complete disruption of the ACL and the PCL. The posterior capsule looks disrupted.

In the axial view we can see a lot of edema and the bone bruise patterns. We can also see the disruption of the fibular collateral ligament and the popliteus tendon off the femur.

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