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36-year-old woman playing the game of kickball,

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now experiencing locking and cannot extend her knee.

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Let's talk about locking for a minute.

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What do I think of when I think about locking?

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And the answer is, like anything else,

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it depends.

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No, I'm not a politician,

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but it depends on the age.

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You know, if it's a teenager.

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Most cases of teenager locking

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are not really locking.

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Their patella catches on the front of the knee.

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It's often because there's asymmetric growth and

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development of the medial and lateral musculature

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and the structures associated with them,

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the retinaculate, et cetera.

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That is a very common complaint.

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So in your mind,

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you have to really separate out pseudolocking

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catching from true locking,

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where somebody really is in this position

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and they can't get out of that position.

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I have seen true locking in patients with patellar

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disease that have massive spurs.

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I've seen it in individuals that have a painful

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flap where the pain restricts their movement.

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But I've especially seen it in

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fat pad impingement syndrome,

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where the fat pad is so large that they

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have difficulty flexing their leg.

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And that is a known entity, not just my own.

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But now let's go to the classic locking,

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where the patient is stuck in one position that is

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usually not a tumor, that is usually not pvns,

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even though mass effect can do that.

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Those are uncommon causes of locking.

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They're slow, they're progressive.

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Same thing is true of, say,

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a giant effusion with a cinovitis or a hematoma.

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They may not be able to bend and extend their

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knee. They may have decreased range of motion,

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but they typically don't have true locking.

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On the other hand,

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somebody that has a loose body or loose multiple

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loose bodies, true locking synovial metaplasia,

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especially synovial chondromatosis,

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where you have pebble or rock like

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structures that get in the way,

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those patients will have true locking.

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And the one that's,

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that's most important to see and diagnose

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acutely is a bucket handle tear,

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because with a bucket handle tear,

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you don't have a lot of time to operate on it.

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If you miss it and the patient walks

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on it for a month or two,

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they're going to macerate the bucket,

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and then you can't repair it.

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So you want to make that diagnosis early,

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often, and then get it to the or quickly.

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The younger the patient, the more important it is.

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In older patients,

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you may have to take out the

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bucket handle fragment.

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Now,

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there are other causes of locking that

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are less common, for instance,

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very severe conformity change of the

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femotibial articulation can do it.

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Chondro flaps on the weight bearing

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surface of the knee can do it.

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But the one that really should resonate in your

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head where you go into the case with locking,

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is rule out bucket handle tear.

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Now, one other caveat.

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Bucket handle tears go hand in hand like soup

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and sandwich, like vegemite and toast,

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with ACL deficient knees.

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So if you got an ACL deficient knee with locking,

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check for a bucket.

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If you got a bucket in an adult,

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check for ACL deficiency.

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We're going to do that right now.

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So we're talking about ACL deficiency.

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So let's go there first.

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The patient had surgery,

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and, you know, life's not perfect.

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Sometimes things don't last forever.

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This surgery was in 19, 92, 21 years ago.

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This ACL has done pretty well for 21 years.

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Look where it's placed.

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Time to get out my marker where should have been

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placed at a line drawn along the back of the femur

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that intersects with Blumenstadt's line.

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So the hole,

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the drill hole for the femoral end of the

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ACL could have been a little bit higher.

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Might have helped it last a little longer.

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The drill hole here in the tibia,

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about 2 cm from the middle of the PCL.

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But a lot more variability is allowed

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for this tibial entrance component.

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The size of the graft, the typical ACl,

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twelve to 14. Typical single bundled graft,

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bigger, 1516, sometimes even 17.

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You don't want to make them too big.

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If they're double bundled,

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you can see them up to 19 or 20.

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But our graph looks a little wispy,

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especially proximally.

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And then as we follow it down,

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this is a time when the T2 weighted image stands

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out, because we have some swelling distally,

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we want to damp down the swelling,

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and we want to raise up the low signal of the

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end of the graft if the graft is torn.

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In other words, we want to highlight the graft,

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and we have.

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And at the distal end of the graft,

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as it enters the tibial tunnel, there is,

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for the most part, a stump.

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Yes, there are a few fibers over here.

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They're pretty kinked,

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so there may be a few contiguous fibers that make

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it into the tunnel. Again, here they are.

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They're a little harder to define on the PD fat

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suppression, so I would call this a high grade,

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acl deficient graft. Now,

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why am I not calling it a full thickness graft?

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Because these fibers right here probably

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still do connect the ones in the back.

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Let's blow them up just in case you're

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doubting me, which I don't blame you.

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Right there.

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And also right there.

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So there are some still fibers there.

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But what about these fibers?

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Those fibers are blunted,

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and there's a little swelling in front,

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giving you a free complementary

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arthrographic effect.

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So we have a graft with nonisomeric,

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non ideal placement on the femoral end.

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We've got a high grade injury or insufficiency

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of the acl as it enters the tibial tunnel.

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Let's see if we have passive anterior

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tibial translation.

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Let's go to the sagittal T1 Tibia is

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a little bit in front of the femur.

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In fact, it's more than a little bit in front.

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How about on the lateral side?

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A little bit.

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So there is some anterior passive

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tibial translation,

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which suggests that there's acl deficiency.

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Now, by the way,

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one of the tunnels has filled in with fat,

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and that is expected to happen over

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a period of years or decades.

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So don't be alarmed at seeing this long,

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fatty columnar area inside the femoral conduct.

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Let's keep going, though.

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Remember we said that ACl deficient knees

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are associated with bucket handle tears,

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and this patient has locking.

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Now, could you get locking from an ACl alone?

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Yes, you could.

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If the ACl does something like this,

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the ACl comes up and then flips back over on

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itself and gets trapped in the front of the knee.

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You can lock. Is that common?

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It is not common.

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So, once again,

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I take you back to the premise that an

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ACL deficient knee warrants total

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commitment, passionate commitment,

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to excluding a bucket handle tear.

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And if that is riding on your brain,

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you're not going to miss it.

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Let's have a look, shall we?

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Here's our corotal,

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by the way. There's our little wispy ACL.

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It's not as thick as it should have been,

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and as it enters a tunnel, look at that kinked,

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attritional appearance. It's hanging on,

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as they say in the movies, by a very,

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very thin thread.

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And I dig that about the ACL and the coronal

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projection. But in the coronal projection,

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there's also two meniscae,

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and they are separated by a signal.

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Not on one slice, on another.

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And another. And another. And another.

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Now they're back together. Now they're apart.

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Now they're apart. Now they're apart.

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They're still apart. There's the gap still apart.

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Now back together.

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So this patient has this kind of bucket handle

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tear with a big hole in the middle.

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Right? Together in the front, apart, apart, apart,

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together in the back.

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To finally emphasize the ACL tear,

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let's have a look at the axial.

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It's a little more challenging,

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so find your lateral side.

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There's your lateral facet,

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and then follow your graft.

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The graph is a little bit thin

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in the axial projection,

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but look at how disorganized it is right here.

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Let's blow it up.

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That should be a tendon, right?

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That should be a thick tendon with parallel tendon

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fibrils. Oh, it's not. And then right there,

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it looks awfully sick.

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There's some pseudo tendinous material,

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but the rest of it inflammatory.

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Now, one last caveat before we get off this case,

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if possible,

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especially with difficult cases,

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please consider doing graph views.

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What's a graph view?

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A graph view is when you take your sagittal

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and you perform a paracoronal like this,

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and then you might take your coronal forward

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so that you follow it into the tunnel.

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You may then also produce a view that

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is perpendicular to the graft.

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So you would have a second view using a

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combination of T2 and maybe PD spur that goes

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perpendicular to the orientation of the graft.

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So it has an oblique or compound

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oblique character.

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And that way you're looking at the graft

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perpendicular as well as tangent.

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Those are ACL graph use.

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So, in summary,

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we have ACL graph failure after 21 years.

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Patient has an ACL deficient knee.

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The ACL deficiency led to a classic

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bucket handle tear.

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Patient also has some chondromalasia and other

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postsurgical findings. Let's move on, shall we?