0:01

Okay, this is a 17-year-old young man that

0:04

has had a history of a shoulder dislocation.

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I've got up for you an axial T1-weighted non-contrast

0:12

image and a coronal arthrogram with gadolinium,

0:18

dilute gadolinium, placed into the shoulder joint.

0:21

If we start with the coronal, the finding is rather subtle.

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And normally you'll see a little

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bit of undulation in the glenoid.

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There's normally a little notch here called the

0:34

notch of Oskar and you may see some thinning of

0:37

cartilage here called the bare area of the glenoid.

0:40

But the fact that we have this undulation that's so

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isolated down low in a 17-year-old, that's bothersome.

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So let's go over to the cross-referenced image here.

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And this is at the same level.

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When you look really carefully, and we'll scroll a

0:58

couple slices, this is the main slice right there.

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There is a focal defect at the glenoid base, right

1:08

at the site of hyaline cartilage and where it ends.

1:13

To compound matters, the tissues in

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front of it are tumefactive looking.

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They're mass-like looking.

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They're gray and intermediate signal.

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So perhaps there's some inflammatory tissue,

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or scar tissue, or reparative tissue.

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It really isn't clear yet what's happening.

1:30

Now there is an entity called a

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glom, a glenolabral ovoid mass.

1:35

And that, that is when you have a

1:37

detached labrum that migrates superiorly.

1:39

And frequently it takes capsule with it.

1:42

to produce a, a piece of labrum that, uh, is sitting

1:46

there with some swirling capsular tissue around it and

1:50

some inflammation to create a, a somewhat circular or

1:53

oval mass in the mid to upper quadrant of the shoulder.

1:57

But here we're in the lower quadrant.

1:59

And so I think it's time to pull

2:00

out, uh, our axial arthrogram.

2:03

Now I personally don't do arthrograms

2:05

very frequently in the shoulder.

2:07

Only when I have, uh, an instability situation or

2:11

some other clinical situation that is very concrete

2:15

with a strong history and I have not found the answer.

2:18

And that results maybe in one out of a hundred

2:22

really needing an arthrogram or even less.

2:25

My number one indication for doing the

2:27

arthrogram is the clinician wants it.

2:29

And it's too fatiguing to make that argument not to do it.

2:32

So I just do it.

2:34

Uh, but, but for the most part, I try not to.

2:37

And as I build trust with my clinicians over time, and

2:41

they, they learn that the answers we're giving are correct,

2:44

more and more they, They stopped requesting the arthrogram.

2:47

But this one has one.

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And this is a patient that's had a dislocation.

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And it's interesting.

2:54

What we were seeing as a tumefactive area of

2:58

intermediate signal on T1, let's bring it back

3:01

for a moment, really distends out very nicely.

3:05

So what you were looking at was collapsed

3:08

glenohumeral ligamentous tissue.

3:11

And maybe it distends a little too much.

3:13

You know, maybe there is plastic deformation

3:16

of the capsule that has led to, or is a

3:20

result of this patient's prior dislocation.

3:23

Now, not affecting the labrum, but right at

3:26

its base, involving the hyaline cartilage.

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See, this is hyaline cartilage in gray right here.

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Dressed in gray.

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Dressed in black is the cortex, and

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subcortical bone that's a little sclerotic.

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Let me make that even a little bigger for you.

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So there's your hyaline cartilage, and there is your

3:46

glenoid articulation rim divot, or guard lesion.

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Now, if this lesion had decided to partially enter,

3:55

the anterior labrum, then we would convert it to

3:59

a GLAD lesion, a glenolabral articular disruption.

4:03

Guard lesions can occur in dislocations or in

4:08

minor injuries, whereas GLAD lesions tend to

4:11

occur more exclusively in, in minor lesions.

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And as you know, type Bankart lesions.

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Those occur in flat out dislocations, and

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they are discussed in another vignette.

4:25

The Perthes lesion, which is discussed in another

4:27

vignette, is a tear in which we have a partial rim tear.

4:32

But it does not interrupt the periosteum.

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So the periosteum stays intact and attached.

4:37

And within that tear, we get accumulation of

4:40

some inflammatory material within the labrum.

4:43

Let's see if my colors will work here.

4:44

They do.

4:46

And you may see it puff up, but it

4:47

stops right where the periosteum begins.

4:50

And this Perthes lesion can occur as a result of an

4:54

acute injury or a subacute repetitive microtrauma.

4:59

So this is an example of the guard lesion.

5:03

Let's look at the, sorry, let's look at the

5:06

coronal projection and the sagittal projection

5:09

to see if we have anything even remotely

5:11

resembling a Hill-Sachs lesion, and we do.

5:14

So this corroborates our diagnosis of a former dislocation.

5:20

Now this is a little bit, uh, more apical than I

5:24

would expect in the 12 o'clock position, and maybe

5:27

this isn't related to the dislocation, but this

5:29

certainly is in a classic or typical location.

5:33

Supralateral, about 5 millimeters

5:36

off the apex of the humeral head.

5:38

It is a Hill-Sachs equivalent type lesion, and it

5:41

corroborates and supports our diagnosis of a guard

5:45

lesion with plastic deformation of the capsule as a

5:49

result of a prior dislocation in a 17-year-old boy.

5:53

Let's move on, shall we?