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This is a companion to our PCL interstitial tear case.

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In fact, it's the same case,

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but emphasizing a critical teaching point,

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which is other injuries,

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for isolated PCLs are treated nonsurgically.

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So, what are the injuries that we're most concerned with,

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and which ones are we most likely to miss?

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And the answer is very simple,

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corner injuries.

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So, let's take a look at the corners very quickly.

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Here's our patient's interstitial PCL tear,

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which we affirm in the short axis projection

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with heavily water weighted imaging.

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Looking inside the PCL,

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seeing that both the medial bundle and the

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lateral bundle have well defined, etched,

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high signal intensity. Inside that,

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we're not volume averaging the sheath,

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but rather we have a tear that involves the fibers

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themselves. So, now that we've established that,

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let's go back to the posteromedial corner.

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Here's the medial meniscus,

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and in the posteromedial meniscus corner is

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this structure. We follow it forward.

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We run into the somewhat injured MCL.

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There's a tibial collateral ligament,

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the middle layer.

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The capsule is a little bit swollen.

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Now we go backwards to the posteromedial corner,

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where we are most concerned about a

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complementary injury to the PCL.

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We see the pol attaching very nicely to the

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superoposter corner of the medial meniscus.

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There it is, right there,

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that gray structure sweeping

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in in an oblique pattern.

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I'll even draw over it to highlight it for you.

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Right there. Now I'm going to take it away.

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Now I'm going to put it back.

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Put it back.

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Take it away. That's the pol,

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or a portion of the pol,

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the posterior oblique ligament of the knee.

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Now let's keep scrolling. We come forward again,

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and we see that there's been an MCL injury.

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Now,

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that could affect the management of PCL tears,

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but unless it's high grade, it usually does not.

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Let's look at the sagittal projection

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on the posteromedial side.

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There is the pol right there.

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I'm going to blow it up for you.

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There's the posterior oblique

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ligament of the knee,

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and there's a little bit of meniscocapsular

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junction injury. But there's no major rupture,

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for this would be one of our checkpoints

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for the posteromedial corner.

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So would the semimembranosus be a checkpoint

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for the posteromedial corner?

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Those would really be the main

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ones in this setting.

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Let's go over to the posterolateral corner,

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because if you tear the PCL and the posterolateral

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corner, you're going to get PLRI.

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Posterolateral recurrent instability syndrome.

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So let's check the posterolateral corner.

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And especially let's check the popliteofibular

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ligament. And it's there.

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It's a little bit stretched out from this fluid.

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That has come forth from a small microtubecular

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fracture, the posterolateral tibia,

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but it's present.

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And the meniscocapsular reflections

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are also present, specifically,

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the superior portion of the popliteus hiatus.

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The area of the arcuate, which is right here,

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is not swollen. So our posterolateral corner,

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a little bit stretched out, but otherwise okay.

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One other checkpoint.

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Want to make sure our fibular collateral ligament

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is intact so that we don't get PLRI,

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and our fibular collateral ligament is intact.

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Now, what if our posteromedial corner was gone.

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Along with a high grade injury of

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the medial collateral ligament?

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Then we might get anteromedial

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recurrent instability. Amri.

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so these are things that you think about

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with posterior cruciate ligament tears,

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making sure it's isolated to the pcl.

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The bulk of your mcl and post medial

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corner should be intact.

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Your fcl or fibular collateral ligament and your

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posterolateral corner should be intact.

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And in this case, one other caveat.

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let's take a look at our ACL.

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It's not perfect.

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Look up proximally.

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The fibers are a little bit disorganized right

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there. So there's a low grade proximal ACL injury.

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So a lot of little dings and dongs and

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nicks and knacks in this case,

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but one that would be managed conservatively.

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Let's move on to another one, shall we?