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Fifteen-year-old boy who fell on an outstretched hand.

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This is a common mechanism, by the way, called a FOOSH

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mechanism, standing for falling on an outstretched hand.

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And he's a youngster, he's 15 years old.

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And young athletes who dislocate, who

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return to sports activities, have a very

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high likelihood of repeat dislocation.

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In fact, It's as high as 90 percent in some series.

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So, you've got to really analyze what type of

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abnormality you have to see what that risk is.

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Now, I'm scrolling three images.

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A fat suppressed water-weighted image on the left,

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a standard T2 on the right, and a T1 in the middle.

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So this is your bone sequence in the center, this

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is your sensitivity detection sequence, and we

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are not seeing anything that is Hill-Sachs like.

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Usually located in the posterior, superior

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aspect of the shoulder within 2 to 5

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millimeters of the 12 o'clock position.

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Sometimes goes down as far as about, say, 2 o'clock.

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Or, said another way, 10 or 11 o'clock.

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But let's keep going, shall we?

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Because sometimes you get the Hill

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Sachs lesions all the way in the back.

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And maybe we do.

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The best way to detect those is to

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look at the water-weighted image.

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There's a little bit of edema posteriorly.

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Could it be that this is a medialized Hill

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Sachs lesion, which is somewhat dreaded?

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For the Hill Sachs lesions that are more medial,

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with bigger defects and bigger depressions,

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and are broader, are more contentious.

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Nevertheless, let's make sure we don't have one.

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How should we do it?

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Let's pull down our sagittal.

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And, lo and behold, we do.

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We could have blown right by it.

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It's all the way in the back.

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So it's an atypical Hill-Sachs lesion probably

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related to the mechanism of the fall and the

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position of the hand when the child went down.

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And I say child at age 15, young man.

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Let's go back to our coronal projection.

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There are a few other signs that

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we have described in the past.

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Now most, most labral injuries occur from

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about the equator, what I'll call 3 o'clock

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position, or anteromedial, to 6 o'clock, inferior.

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And this one is at 6 o'clock.

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We're right in the middle, in the mid-coronal plane.

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We should never have linear high

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signal come all the way through.

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And what is this high signal doing here?

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When scapula, it usually means you've interrupted.

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Your medial capsule, or if it tracks all the way along the

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scapula medially, you gotta worry about a scapular fracture.

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That's not the case here.

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So we've got a labral ligamentous complex that is detached

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from the inferior bony glenoid cortex and periosteum.

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In the back, attached.

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In the front, not so much.

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On the humeral side, attached.

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On the glenoid side, not so much.

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See, it's a lot easier on the water-weighted

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image than on the T2, less water-weighted image.

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Let's take on our axial right in the center, shall we?

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Let's go up high.

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Up high, we see the superior glenohumeral ligament

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and the biceps, long head takeoff from the anchor.

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It takes off all the way from the back.

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Actually, here it is.

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I apologize.

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Right there.

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It takes off from the front.

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Now let's follow it down.

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Here's the MGHL, which is more linear.

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There's the labrum.

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There's a little space.

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And that should close down as we go past

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the equator of the humeral head ball.

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So let's keep going, shall we?

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And it's not closing down.

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And here's our ball.

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I'm gonna draw it for you.

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Best fit circle.

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Here's our circle.

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Right there.

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We get past here.

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We should see no more fissures, right?

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Let's see where we are.

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We're way past there.

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Our fissure is not only still present, it's getting bigger.

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Let's keep going, shall we?

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Still there, still there, still there, although

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there's a little periosteal attachment down low.

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Now the periosteum's off.

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Now it's on.

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Now it's off.

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Now it's on.

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Let's keep going down.

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And the tear is still present all the way down at

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the bottom, correlating with the axillary position.

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The tear is actually harder to see now.

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It's still here.

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Much easier to see in the coronal projection.

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So this is a classic or conventional soft

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bankart lesion, no bone involvement, no

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hyaline involvement, no joint involvement.

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This is the hallmark of the dislocation.

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Now, repeat dislocations in patients like this occur three

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times more frequently in young boys than in young girls.

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In contact sports, you can also get it

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from having the arm in the abduction.

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External rotation, position, and you

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take a shot to the back of the shoulder.

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But this one was a FOOSH mechanism of injury.

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A true Bankart lesion requires disruption of both the

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labrum, I'm going to draw the labrum in, of both the labrum

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and either the outside of the labrum or the periosteum.

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I'll make my lines a different color.

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How about orange?

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So disrupting all the way from deep to superficial,

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I'm The labrum, or going through the base of the

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labrum and out the periosteum, which this one did.

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Now some of you are wondering, what's a Perthes lesion?

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A Perthes lesion, first described in 1905, very

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similar to a Bankart lesion, has one major difference.

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Now let me use the same colors again so as not to

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confuse you, I'm going to go with orange for my labrum.

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So this is a good one to trace it on, because

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here we have a little bit of intact periosteum.

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Now you can see on other slices it was broken.

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Here's your labrum.

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You've got this little pouch right here.

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And filling in the pouch is mucoid inflammatory material.

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That may even expand this a little bit.

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So you may see a little bit of a pseudomass right there.

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So it's a type of partial tear.

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But there is still an area of periosteal

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attachment to the glenoid rim.

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In other words, the periosteal

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sleeve remains attached right there.

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That is what differentiates it.

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From a Bankart.

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And a Bankart, torn.

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Right through.

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So the periosteum is disrupted.

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Perthes lesions may be subtle in the axial projection.

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This is not one, but if you have to bring one forth, that's

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a good time to pull out your abduction external rotation.

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Let's just have a quick look for completion of our sagittal.

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We've already established that

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there's a subtle Hill Sachs abnormality.

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How does the pair of our glenoid look?

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Pretty good.

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How does our bone stock look?

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Pretty darn good.

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So in summary, classic Bankart lesion, the hallmark

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of single event collision dislocation, differentiated

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for your perusal enjoyment and educational interest

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from the Perthes lesion with periosteal sleeve.