0:00

Now let's assume we've got a patient with

0:02

instability, what, what are we looking for?

0:05

We're looking for the relationship of the humeral

0:08

head to the cup, the shape of the humeral head.

0:11

We're looking for depressions, and, and do not be confused

0:14

by this flattening of the posterior humerus that occurs

0:18

way far down from the apex or top of the humeral head.

0:23

This flattening is normal, and you're going to see a Hill

0:25

Sachs lesion up much higher, up around this area right here.

0:29

Usually close to the back or around the side slightly.

0:32

So this flattening is much lower and

0:35

usually seen close to the growth plate.

0:38

We're also going to look at the relationship of the humeral

0:40

head to the scapula and the scapular body and spine.

0:45

So if we draw a line right here along the spine, we want

0:47

to come out pretty close to the center of the humeral head.

0:51

So we want to make sure with the patient simply

0:53

with the act of lying down that the humeral head

0:55

isn't drooping back, giving us some distance here.

0:58

that we could measure, or lurching forward,

1:01

giving us some distance here from the

1:02

center of the head that we might measure.

1:05

We'll talk about those later, but you can eyeball

1:07

this very quickly and immediately glean whether the

1:10

humeral head is sagging backward or moving forward,

1:13

as it should not with the patient lying on their back.

1:18

The other thing you want to do is look at

1:19

how the technologist positioned the patient.

1:22

For instance, this patient over here on the right, actually

1:25

the same patient, got positioned in external rotation.

1:29

Okay.

1:29

And that was intentional.

1:31

But look at how much different the structures

1:34

look anteriorly when they're in external

1:36

rotation than when they're in a neutral position.

1:39

This is very important because in external rotation,

1:42

you're going to make the structures taut, and if you put

1:45

the patient's arm up in external rotation, this is known

1:48

as the Hebert position, you're going to make this taut,

1:51

but you can also pull away an occult lesion, a small

1:56

banker type lesion, or a Perthes lesion, which are sort

1:59

of mini lesions that occur in the labrum anteriorly and

2:03

bring them out when they otherwise might not be seen.

2:05

So pay attention to how the

2:07

technologist positions the patient.

2:09

This will also influence your diagnosis

2:11

in other portions of the shoulder.

2:14

Now as we scroll up and down, um, the superior

2:17

glenohumeral ligament is generally not a primary structure.

2:21

In patients with instability unless it's micro

2:24

instability or biceps pulley mechanism problem.

2:28

So if we're talking about patients that have had

2:30

collision injuries or, or single dislocations or

2:34

repetitive dislocations in one direction, we're

2:36

usually going to be most interested in the anterior

2:39

band of the IGHL and the labral ligamentous complex.

2:43

Now in the front, the labral ligamentous complex is, is

2:47

unique. In that the, the anterior capsule and anterior

2:51

inferior glenohumeral ligament comes off in a more

2:55

medialized fashion in the front than it does in the back.

2:59

In other words, it doesn't come off the tip of

3:01

this tissue right here, it comes off the base.

3:03

And sometimes, in a normal patient or in patients

3:06

with stripping, it may even medialize further

3:09

and fluid will track into this concavity.

3:13

Fortunately, that's not too common.

3:15

But it is seen more frequently.

3:18

That have to do large ranges of motion for

3:21

sport like javelin throwers and pitchers.

3:24

In the back, the capsule is also pretty

3:28

plastic looking, but this time, the apex of the

3:33

labrum is the site of takeoff of the capsule.

3:36

So here, apical takeoff in the front, not apical.

3:40

Medial to the apex, much, much different.

3:44

This apical takeoff, very consistent,

3:47

shoulder to shoulder, Patient to patient.

3:49

Now sometimes, if you're not paying attention,

3:51

you might think it's taking off over here.

3:54

Well, it's not.

3:55

What's really happening is, it's just distended.

3:58

It's redundant, because we filled up the joint

4:01

with fluid and gadolinium, and it's doing this.

4:04

Just looping around.

4:06

And you have to scroll to be able to see that.

4:08

And now when you scroll, you can actually see

4:10

down lower, it is taking off from the apex.

4:13

It's just being pushed or flattened up towards the back.

4:17

So you don't want to confuse that

4:18

with posterior capsular stripping.

4:21

Now let's go over here to the, to the right hand side.

4:24

You see this little divot right here, which is normal.

4:28

This is the labral ligamentous complex

4:30

that is just being shoved away slightly.

4:32

There's a normal little notch that exists

4:35

here when the joint is fully distended between

4:38

it and the base of the hyaline cartilage.

4:41

And sometimes, there's a little hyaline

4:44

interposition right here, that may look like fluid.

4:47

And that's what you're seeing here.

4:48

You're seeing fluid, a little bit of hyaline

4:50

interposition that is highlighted by the

4:53

contrast resolution of this particular image.

4:56

And you see that too over here.

4:58

Now, this time with the shoulder, in external

5:01

rotation, we are making the anterior IGHL very taut.

5:07

And we're opening up this recess right here.

5:09

This is not a tear.

5:10

It's nice and smooth and round.

5:12

We refer to this as the anterior inferior recess.

5:16

When we look at the labral ligamentous

5:17

complex, it's absolutely contiguous with and

5:21

smooth with the adjacent hyaline cartilage.

5:24

You can also, once again, see that little

5:25

pitfall in the back that we discussed

5:27

earlier, regarding the posterior capsule.

5:31

Now the other thing you want to do is you want to

5:32

look at the attachments in the axial projection of the

5:37

capsular tissues and the GHL stabilizers on the humerus.

5:41

We do that best in the coronal projection,

5:43

but we should also use the axial projection,

5:46

especially for the MGHL and subscapularis.

5:50

The MGHL, not as important a stabilizer as the

5:54

IGHL, and in fact, it's variable in its course.

5:57

It may be oblique, it may be horizontal, it may be

5:59

perforated, it may have accessory fascicles associated

6:03

with it, but this is a nice way to look at the

6:05

insertion sites on the lesser tuberosity of the MGHL.

6:09

And here the MGHL does get lost.

6:12

Behind the subscapularis, here you can

6:14

see it a little better, right there.

6:16

Inserting on the middle facet of the lesser tuberosity.

6:20

Then we also want to look at the insertion

6:22

of the IGHL, especially the anterior band.

6:26

And there it is, very nicely, tightly

6:27

inserting on the humeral neck.

6:30

And when it's detached, we refer to this

6:32

as a haggle lesion or humeral ligament.

6:35

The same thing is true in the back.

6:37

And as we go down, we see the posterior band of the IGHL.

6:41

We go over to this other image here and we

6:43

go all the way down and we often ignore it.

6:46

But there's the axillary band of the IGHL and we're

6:49

gonna highlight these in the coronal projection.

6:53

So another, another important take home message here

6:56

is the relationship of the Hyland cartilage to the

7:00

fibrocartilage or the fibrocartilage like tissue.

7:04

The fibrocartilage like tissue is a little darker.

7:08

It's pretty smooth.

7:09

It is hypertrophied with the IGHL

7:12

in throwing or overhead athletes.

7:14

So it can get pretty big.

7:16

And it transitions to hyaline cartilage, which is a

7:19

little bit brighter, and slithers up underneath it.

7:22

It's right here.

7:24

Right there.

7:25

That's hyaline cartilage.

7:26

Sometimes that hyaline cartilage may get even a

7:29

little deeper, called that hyaline interposition.

7:32

And that may be confused with various

7:35

low-grade types of labral pathology.

7:38

The interposition is not quite as prominent underneath

7:42

the fibrocartilage in the back as it is in the front.

7:47

So those are some of the basic

7:49

take-home points for looking at the axial

7:52

projection in patients with potential instability.

7:55

And I remind you one more time, one of the first things

7:57

you ought to do is look at how the humeral head is centered

8:00

relative to the glenoid cup, the shape of the glenoid

8:03

cup, the smoothness of the cup, and the hyaline cartilage

8:07

of the humerus, because that's going to tell you a lot.

8:09

Immediately, before you even start picking

8:12

apart these glenohumeral ligaments and the

8:14

associated labral structures and pathology.

8:17

Let's move on, shall we?