0:00

This 38-year-old man had a dislocation relocation event.

0:05

I've got before you a, a gradient

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echo image on the left, thin section.

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In the middle, a T2 fast spin echo

0:13

with excellent fat suppression.

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And on the right, a coronal PD spur.

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The patient has had a Hill-Sachs impaction injury.

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And this one is more lateral, and the lateral

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ones are less likely to have engagement with

0:29

the anterior glenoid as you've seen with our

0:31

discussion of on-track and off-track measurements.

0:34

Usually, the Hill-Sachs are right about here.

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This one is epicentered a little more laterally than

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usual, but they can occur anywhere from the apex out

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to about 24 millimeters laterally, but usually between

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2 and 5 millimeters off the apex of the humeral head.

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When we scroll our axial We are struck by

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the fact that the labrum, up high, is visible

0:58

and then disappears as we go down low.

1:00

And that violates one of our cardinal rules.

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Which is, when you go down, when you

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go low, the labrum comes up into play.

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It becomes darker, more triangular, more crisp,

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and bigger than the superior and posterior labrum.

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That is not happening here.

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What we see is a morass of signal intensities that

1:23

consist of capsule and fragmented labral tissue.

1:27

Now what is all this dark stuff that we see more medial?

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It is a combination of fractured, elevated

1:33

periosteum, and then within it, a large

1:36

chunk of labrum sitting underneath it.

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It's as if you took The labrum, which was here, and

1:44

you rolled it like this, like you would unroll a

1:47

can of sardines, and it has rolled underneath the

1:51

periosteum to sit beneath it and become stuck there.

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And sometimes it will scar there.

1:59

Now this is known as an anterior or anterior

2:02

inferior periosteal sleeve avulsion.

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Let's look at the coronal projection.

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Because we should see medialization of the

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labrum underneath the periosteum, and we do.

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Here's a piece of labrum.

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Here's another piece of labrum, more medial right

2:19

there, stuck underneath the elevated periosteum.

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This is not labrum.

2:24

This is hemorrhagic tissue.

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So we do have an anterior and inferior medialized

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labrum sitting underneath the periosteum.

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Let's pull down our coronal T1.

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I'm going to make it a little bigger for you.

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And make sure that we don't have a bony Bankart.

2:44

Our cortical integrity is preserved, even

2:46

though we don't see any labral tissue.

2:48

And why not?

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It's gray.

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It's swollen.

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It's buried in granulation tissue and

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blood and periosteal shards and fragments.

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So it is ghosted or disappeared on the T1-weighted image.

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You may also Determine the degree of depression

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and the character of the Hill-Sachs on the T1.

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And there is some debate about whether the water-weighted

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or fat-weighted images show the Hill-Sachs better.

3:13

I personally prefer the T1-weighted image.

3:16

The literature says the T2-weighted image may provide you

3:20

a better depiction of the cortical edge of the fracture.

3:24

Let's go over to that Hill-Sachs fracture for a

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minute, this osseous injury, and we can measure it.

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We can get a length out of it.

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I like to go to the level where it is broadest.

3:36

I usually go from ridge to ridge, although

3:38

some have advocated going from ridge to

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the medial border of the rotator cuff.

3:44

At any rate, these are similar measurements.

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This one measures just under 20 millimeters.

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And then we'd like to see that be

3:52

smaller than any other measurement.

3:55

Glenoid bone loss.

3:56

So let's go to the sagittal on Foss image.

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And here is our inverted pear.

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I'm going to draw on our inverted pear.

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I'm going to make a best-fit circle

4:07

of our inverted pear right there.

4:09

And there is no glenoid bone loss.

4:11

Everything's intact.

4:13

So the glenoid is preserved.

4:15

So we really don't have to worry about a scenario where we

4:20

have engagement and then subsequent repetitive bone loss.

4:24

And as a general rule of thumb, if this is 20 or 25

4:29

percent of the entire circumference of the humeral

4:32

head, but you've got preservation of the glenoid,

4:35

those patients usually do well with Bankart repair.

4:39

Occasionally, they'll need to be augmented if they

4:41

have very, very convoluted inferior axillary capsular

4:47

injuries, but most of the time, they'll be fine.

4:49

Isolated Bankart repair will do.

4:53

So in summary, this is a case of an ALPSA patient

4:56

has a moderate size, but pretty markedly depressed.

5:01

Hill-Sachs lesion measures about 20 millimeters.

5:04

There is no anterior glenoid bone loss and the

5:09

labrum is buried underneath the periosteum along

5:13

with shards of periosteum granulation tissue and

5:16

blood so that it is masked on the coronal image.

5:20

But seen very nicely on the T2-weighted image.

5:24

There it is right there.

5:25

There's a piece of labrum.

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There's more labrum buried underneath here,

5:28

and seen best probably in the axial GRE.

5:31

These are all shards of periosteum, and there is a large

5:35

fragment of labrum, medialized, as discussed previously.

5:40

The ALPS illusion.