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Posteromedial corner injury in a 38-year-old man

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with left knee pain after an MVA in 2019.

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Suspect MCL tear or hemarthrosis.

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Let's get it cooking.

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So, let's start out.

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Let's be consistent.

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Let's start out with our axial,

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just as we did before.

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Should be in here somewhere.

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So right away,

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large effusion, distension anteriorly,

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some distension posteriorly.

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So at least a grade two,

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you could say moderate grade effusion.

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Moderate grade is a terrific grade.

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If it's mild, you're not too far off.

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If it's severe, you're not too far off.

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So if you're unsure, go moderate, go intermediate,

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and that's not critical.

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So, we'll say moderate effusion.

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That tells us, though, that something is wrong.

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Now, just as we did before,

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tilt it to the lateral side.

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The lateral facet is a little bit longer.

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This is lateral.

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The ACL, horrible.

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It looks like,

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as Muhammad Ali used to say,

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a balloon.

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Muhammad Ali said,

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"This is my balloon punch."

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He said, "This is my balloon punch.

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And your head is the balloon

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and my fist is the needle."

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Well, here's the balloon.

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That should be a linear black structure.

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PCL, okay.

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LCL, okay.

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Nice and black.

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MCL, pretty black.

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Not so bad.

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I think it's going to be all right.

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Maybe a little swollen anteriorly.

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I'm looking in the back to see if there's anything

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disruptive in the capsule.

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This looks a little bit irregular,

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but other than that, I'm pretty much done.

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This is an adult,

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patient's 38,

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so you can see the patella,

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a little bit different looking than the child.

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Certainly, not the kind of dysplasia we saw before.

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The lateral patellar facet,

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a little bit hypertrophic,

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which occurs as we age.

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Sometimes, it can get so hypertrophic that

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it gets locked on the lateral femur,

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and that's known as lateral pressure syndrome.

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This patient doesn't have it.

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So now,

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let's be consistent and do what we did before.

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Don't forget to check out the neurovascular

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bundle posteriorly.

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Let's scroll that just to be complete.

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The artery looks okay.

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And somebody has pointed to one of

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the posterior tendons right here,

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one of the pes anserinus tendons

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that has a little signal in it,

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right there.

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There's a little bit of fluid,

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likely a prolapsing gastrocnemius

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semimembranosus bursa.

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Here are the pes anserine tendons,

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the grassless sartorius and semitendinosus.

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And that takes us through the axial.

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Let's go to the water weighted images.

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Now, this time we have two different

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water weighted images.

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We have a proton density fat suppression

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and we have a coronal high resolution gradient echo.

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Some of you know it by the name MERGE/MEDIC,

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MFFE or ADAGE.

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This is an additive gradient echo sequence.

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What's it good for? Menisci.

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Let's scroll the heavily water weighted,

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fat-suppressed image.

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Great for menisci,

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great for cartilage,

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great for the articular surface.

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Not so good for bone.

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Terrific for bone on the right,

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on the viewer's right.

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I like to have a TE of around 35 to 45 for my

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proton density fat suppression.

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Along TR,

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I want uniform fat suppression.

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I want the bones to be black,

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and they are.

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The posterior aspect of the tibia, edematous.

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This time,

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the femoral terminal sulcus, anterolaterally,

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not edematous.

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So, not a pivot shift pattern.

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Weird pattern of bone injury.

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Anterior.

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Posterior.

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Slight depression.

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Something very weird happened.

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Perhaps it happened with a direct blow to

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the knee with some element of flexion.

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We already said our anterior cruciate ligament,

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not so good.

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Now, what I want you to get in the habit of doing

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is looking at your anterior cruciate ligament,

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and especially,

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up by the femoral end,

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looking for fiber disruption,

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because this is when they get tricky.

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In fact,

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I'll even bring down the T2.

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Let's bring it down.

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Let's see if we can see any fiber disruption

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because that's critical to the case.

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There's your PCL.

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There's your PCL.

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Let's keep looking.

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Right there.

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I think you can see it.

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The T2 is invaluable

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in the acute setting for this purpose.

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It's almost too swollen here to see,

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but it's right there.

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So, our anterior cruciate ligament

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proximally is ruptured.

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We've got an osteochondral injury

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of the anterior femur.

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Right there.

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See that very nicely on the water-weighted image.

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There it is on the T2, as well.

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Let's keep scrolling, shall we?

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Let's check out the menisci.

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This is a very meniscal-friendly sequence.

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Meniscus is a little bit bruised or contused.

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It's got some signal in it.

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Patient's 38,

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but nothing you would ever poke a hole

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in and try and sew.

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So, that's okay.

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Let's go over to the lateral side and check out

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the posterolateral corner.

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Pop fib ligament, fine.

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Arcuate, fine.

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Gastrocnemius, lateral head origin,

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fine.

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Let's go to the posteromedial corner.

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Not fine.

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Let's look at the most important structure

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in the posteromedial corner,

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the semimembranosus direct head.

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It is absent.

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It's over here.

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We pulled off the entire direct head.

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Now, there are other minor heads

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like the popliteal head

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and the pars reflexa.

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There's about five to six heads

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of the semimembranosus,

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well beyond the scope of what we want to achieve today.

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But the major direct head,

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which should be right here,

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an important stabilizer, gone.

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Which means all the lesser ones

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are probably gone, too.

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Look at the posterior capsule.

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It comes down, it stops.

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Should keep going.

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We're missing the whole undercarriage,

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the inferior aspect of the capsule.

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The capsule is composed of fibroelastic tissue and

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the oblique popliteal ligament, the OPL,

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that's torn.

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There are little short meniscocapsular attachments,

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like this one right here.

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The posterior meniscotibial ligament

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you saw earlier, that's torn.

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There is an attachment right here called the

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posterior oblique ligament of the knee,

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that should attach as a line.

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Right here.

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That's torn.

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So, this patient has a serious

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posteromedial corner tear.

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And the anterior cruciate ligament

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we already established is torn.

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So, this patient is at risk for having

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a complex knee instability syndrome.

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Let's keep looking.

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Let's look at the T1,

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see what kind of bone injury we might have.

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Probably nothing more than what

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we already described.

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We can certainly see the osteochondral injury much

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better on the water-weighted images than on the T1.

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Our posterior cruciate ligament is bathed or

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swathed in hemorrhage and inflammation,

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so it looks a little gray.

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We come over to the T2 It's nice and black.

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The posterior crucial ligament is intact.

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You can also check it out in the coronal projection.

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It's intact.

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But the anterior cruciate ligament, a huge,

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large blob of blood.

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There it is.

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Let's go back to our coronal gradient echo.

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Its strength is in the cartilage.

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Nice thick cartilage on the lateral side.

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She's 38. She's a pretty big lady.

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Thinning of the cartilage on the medial side.

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Some intra-substance closed signal.

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None of which rises to the level

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of a surgical meniscus tear.

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So, no traumatic or unstable meniscus tear.

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How about her conformity?

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How about her shape?

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Pretty good, but not perfect.

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What's abnormal about her shape?

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Excellent shape right here.

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She's getting a little spur.

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She's only 38.

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She's starting to get a little bit of arthritis.

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She's getting a little spur right there.

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She's only 38.

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She's starting to get a little bit of arthritis.

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Remodeling of the proximal tibia.

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These are things I pay attention to.

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Tib fib articulation, looking good.

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So, lateral compartment, fine.

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A little bit of early away.

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Medial compartment,

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a little bit of early OA

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and a little bit of cartilage thinning.

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No traumatic meniscus tear.

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Central compartment, ACL transection,

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subtle but definite.

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PCL intact.

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No central chondromalacia.

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Anterior compartment.

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There's our osteochondral injury right there.

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Osteochondral fracture.

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Traumatic fracture of the anterior femoral facet.

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Patella, spared.

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Extensor, spared.

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Posterior compartment, spared.

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That takes us through the entire case.

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There's our tib. fib. ligament again.

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So, this is a patient with a serious

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posteromedial corner injury.

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It was read as a high grade ACL sprain.

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It should have been read as a high grade ACL tear.

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If you wanted to call it a transection,

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I wouldn't object to that at all.

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This patient's getting an ACL repair.

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Actually,

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the person that read it called it a complete

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mid substance to proximal anterior

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cruciate ligament transection.

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A POL ligament sprain.

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Probably should have been a little stronger with that.

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They read the fractures.

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They read the high grade posteromedial corner injury,

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and they certainly read this.

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One of the most important findings

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not to be missed.

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Let me show it to you again one more time.

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The avulsion ripped away

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is the semimembranosus attachment.

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There's the stump of it right there.

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That should have inserted over here

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into the semimembranosus corner,

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the main posteromedial stabilizer,

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the posteromedial corner of the knee.