Interactive Transcript
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Knee anatomy,
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cruciates the PCL on MRI.
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Let's return to the coronal projection for a moment to see where we are.
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We're down low at the insertion.
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There is the insertional footprint of the PCL.
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It's fairly broad.
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There is a medial bundle, a posteromedial
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and an anterolateral bundle.
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This patient does not have a very prominent meniscofemoral ligament
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of wrisberg, which is not uncommon seen in about 20% of individuals.
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Before we scroll the axial, which is probably my least favorite projection
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for the PCL, let's scroll the coronal for a moment.
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I want to show you one other thing.
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Look at the inferior fibers of the PCL.
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We've got our medial bundle and our lateral bundle.
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But these inferior fibers may sometimes separate out and produce
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some confusion for when they're really separate. This structure right here may be
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confused with a loose body or a bucket handle tear.
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Now let's scroll back and forth.
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The way to avoid this pitfall is to follow the fibers back up to the PCL.
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Separate.
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Together.
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Separate.
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Together.
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Now, let's turn our attention back to the axial.
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We're going to ride our PCL from posteroinferior to anterosuperior.
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We're below it, all bone.
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Now the insertion.
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And now let's ride it forward.
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Let's keep going.
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Here's the PCL, which is a more rounded, thicker structure in cross-section.
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The ACL, more linear.
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It's along the inner wall of the medial femoral condyle.
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And there is the very broad footprint of the PCL, which is complex and broken
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down into 16 zones or regions, which is far beyond what we want to discuss today.
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But do remember that the PCL is fatter, more round, more bulky than the ACL.
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And because of its configuration, in which the medial fibers and the lateral
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fibers may turn or twist or cross between each other, the PCL, when it tears is going
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to tear more often interstitially like this, and it'll blow up like a balloon.
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Whereas the ACL, which is more like
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a celery stalk configuration, more parallel, will often tear with a cut like this.
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Now, if the PCL is cut and separated, you have to be worried about a more serious
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catastrophic injury, including a knee dislocation or a complex pattern of knee
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injury, or potentially a fracture in the posterior aspect of the tibia.
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So different appearances of the tears, the PCL and ACL based on anatomy.
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Let's move on, shall we?
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