0:01

I'm going to, uh, show you some examples

0:04

of macro instability

0:06

and, uh, I think about macro instability, I think with some

0:09

of the definitions that Dr.

0:11

Resnick gave, and I think about it as somebody

0:13

that either dislocates

0:15

or locks as opposed to micro instability.

0:19

Now, another way to come at the labrum,

0:22

and you've heard the term single lesion, double lesion,

0:26

triple lesion, and quadruple lesion is

0:29

to anatomically think about the labrum

0:32

as having the following structures

0:34

that help support the glenohumeral articulation.

0:36

You've got bone, you've got hylan cartilage,

0:40

you've got fibrocartilage, and then you've got capsule,

0:43

and you can add to that periosteum.

0:45

So there's actually five structures.

0:47

And when you're analyzing, especially if you're new

0:49

to this game, uh, when you're analyzing the labrum,

0:52

if you consciously make an effort to look at each

0:55

and every one of those,

0:57

the odds are you're not going to miss.

0:59

So here's a 15-year-old gal.

1:01

She's a volleyball player, uh,

1:04

but she didn't injure herself during the overhead motion.

1:07

She fell, uh, on an outstretched arm,

1:10

which is a common mechanism for macro instability.

1:13

And if you look at her axial, uh, gradient echo image,

1:17

first, you can see she's got an indentation,

1:21

not the normal indentation found,

1:23

lowered down in the humerus,

1:24

but a true traumatic indentation, uh,

1:27

that you can measure in the axial projection

1:29

and get a rough idea of the width of the hill sax.

1:33

This one measures about 1.15.

1:36

There are other methods that I'll show you in a few minutes

1:39

to, to make the measurement a little more interesting

1:41

and a little more accurate.

1:43

And you can see how the, the hills sax kind of comes down

1:46

from superolateral to infra medial, not dissimilar

1:51

to the direction of the track.

1:53

The glenoid track width that comes down.

1:56

Now, we said the glenoid track width in a normal individual

1:58

is gonna be, uh, about, um,

2:02

0.83 times the length of the glenoid cup,

2:05

which I'm gonna show you in a moment.

2:07

But the glenoid track width is gonna come down this way.

2:12

And then we're also going to have our hills sacks,

2:15

which may be engaging or non engaging.

2:18

Let's see if I can pick another color.

2:19

I don't know if I can, I think you got me hidden here.

2:23

Can I or can't I? Well, nevermind.

2:26

Um, our, if our hills sax is wider,

2:30

let's see what's happening here.

2:32

If our hill sac is wider than our glenoid track,

2:38

then chances are we're going to be off track

2:41

and have an engaging, uh, bipolar scenario, especially if

2:44

that occurs along the medial side.

2:46

And I'm gonna show this to you in subsequent cases.

2:49

Now, let's go back to the axial, um, which

2:53

in individuals

2:55

that have had a dislocation is the, the projection

2:59

For slap lesions. It's

3:00

the coronal plane for dislocations.

3:02

It's the axial plane,

3:03

and we see that the anterior labrum is separated

3:08

from the bony glenoid.

3:10

So we at least have a single lesion.

3:12

And then we look to see if we've got some periosteal injury.

3:14

And we do. So we, we have a double lesion.

3:18

So there's some periosteal insult, which there is typically

3:21

with a banked lesion.

3:22

We have fragments or shards of labrum that are displaced.

3:26

So this one's somewhat complex.

3:28

And then we would drill into some

3:30

of the other structures such

3:31

as the middle glenohumeral ligament,

3:32

the subscapularis anteriorly, as Dr.

3:36

Resnick described earlier, we'd look at the,

3:38

the circular concept of the shoulder

3:40

and make sure that everything's okay in in the back.

3:43

And usually when you have superior

3:45

and posterior lesions, they're often, uh, preexisting.

3:48

So we have a hill sax fracture with some depression

3:52

that you can measure and we'll measure

3:53

it here in a few moments.

3:55

We've got edema that supports

3:57

that this is a fresher type lesion

3:59

and we have an an mid to inferior quadrant, uh,

4:04

rather large fragmented, uh, soft anchored abnormality.

4:09

What do you consider the best plane

4:11

to measure a hill sax lesion?

4:13

I'm gonna let you answer. And do you measure the

4:15

depth of the lesion?

4:17

Um, I do measure the depth, uh, of the lesion.

4:20

Uh, I do it in the coronal projection,

4:23

but my favorite way

4:24

to measure the hill sacks is the one I gave you

4:27

where I have, um,

4:30

where I have an axial projection

4:32

and I perform a coronal projection

4:36

that is, I can even do it.

4:39

Whoops, what happened there?

4:44

I need, there we go. Thank you.

4:47

I can do it off the sagal as well.

4:49

I wanna have a coronal that is on Foss to the hill sacks.

4:53

Now there's no hill sacks here

4:54

because this is our ac joint separation case,

4:58

but I would draw a line.

5:00

Whoops. So I draw a line along the back assuming there was a

5:04

hills sacs here, um, parallel to that line.

5:07

So I have a, a para coronal view.

5:10

And then as you saw in my earlier coronal view,

5:12

I can see the hills sacks coming down, you know,

5:15

in the direction of where the glenoid track would be.

5:18

And I'm going to measure that. I'm gonna measure that width.

5:21

And that was the width I gave you earlier, that was about 13

5:24

to 15 millimeters.

5:26

So that's how I do it.

5:27

There's a more complex way to do it

5:29

that I think is a little bit beyond our discussion today.

5:32

And that is done with 3D CT with reformatting.