0:01

This interest in the acromion has led to a variety

0:04

of imaging methods that have been used to calculate

0:08

the shape, the size, the orientation of the acromion.

0:12

Uh, and this is done not just in the sagittal plane,

0:15

but is done in the coronal

0:17

and even in the axial plane as well.

0:21

The main classification system that we're familiar

0:24

with is was one provided by Big Liani and his associates.

0:28

And it, it indicates through three types of alteration,

0:34

the shape of the inferior surface of the acromion.

0:39

It can be flat type one, it can be a smooth curve type two,

0:43

or it can be what is described as hooked,

0:47

shown as type three.

0:49

Now, I would tell you a hooked acromion

0:52

can be developmental,

0:54

but it is much more not developmental.

0:58

It is acquired because of a subacromial and fiso fight.

1:03

I think it is very infrequent through development

1:06

to get a hooked acromium.

1:09

So these are enthesophytes and enthesophyte occurs

1:13

and an emphasis, an emphasis is a site of tendon ligament

1:17

or a capsular attachment to bone.

1:20

An in uh, phy grows through a complex process.

1:25

It may or may not contain marrow,

1:28

but the subacromial phy shown here generally does

1:33

contain marrow.

1:34

And you can see that nicely.

1:36

This is an acquired outgrowth with marrow present within it.

1:42

Now, if again, you are a believer, an external sub, uh,

1:47

or an external cause of impingement,

1:51

you're gonna love external subcoracoid impingement as well.

1:56

And you're gonna believe that any process

1:59

that narrows the subcoracoid space may lead to external

2:04

subcoracoid impingement.

2:06

Because of this, again, turning to the literature,

2:09

there have been a lot of articles addressing, well,

2:12

how can we as imagers identify narrowing of the space

2:17

between the coracoid process and the humerus?

2:23

And there are a number of, uh, values

2:26

that have been posted in the literature stenosis generally

2:30

as present, if you can find a value, a space

2:35

that is less than 5.5 millimeters in maximum

2:40

internal rotation of the humerus.

2:42

The point that I would make, okay,

2:44

you can see the normal values listed there.

2:47

That distance varies a lot according to the

2:51

position of the proximal humerus.

2:54

It will change in neutral external

2:56

and internal rotation. So I

2:58

Have found it not to be very reliable.

3:01

Clearly, if it gets down to six, 5.5

3:05

or less, I'm gonna wonder about it.

3:07

But rather than just that as a finding, I look

3:11

for other abnormalities such as a change in course

3:15

of the subscapularis tended, which may indeed

3:19

show a pressure effect as you can appreciate here,

3:23

and equally important I think are cyst

3:26

and irregularity present involving the broad

3:29

lesser tuberosity.

3:31

You add to that, of course, abnormalities

3:34

of the subscapularis tendon itself, which you can see here.

3:39

And because the upper fibers are a stabilizer,

3:42

you may see abnormalities of the adjacent biceps tendon,

3:46

including medial biceps displacement.

3:52

This particular phenomenon has been likened to a roller

3:57

ringer effect.

3:58

You can see what that looks like.

4:00

I'm showing it in motion here.

4:02

All right, that you see when you dry the clothes.

4:05

So that may be why it occurs.

4:08

And again, deep fiber failure

4:11

because of tough tensile undersurface Fiber.

4:14

Fiber failure is typical.

4:19

One of the other findings that I have found useful

4:22

is focal fluid involving a portion

4:26

of the subacromial subdeltoid Versace shown

4:29

by the arrows here,

4:30

and by my drawing in blue that is located near the tip

4:35

of the subcoracoid process.

4:38

It may be a fairly good sign, certainly not diagnostic

4:42

of external subc corticoid impingement.

4:47

Now, others would say, well,

4:48

maybe you should really get an idea perhaps with CT

4:53

of the shape of what is designated

4:57

the subcoracoid outlet.

5:00

Now, that is a space related to four points.

5:04

The sub glenoid tubercle, which I'm showing you here

5:06

with a yellow circle here.

5:09

The tips of the coracoid process, okay?

5:12

And acromion, which I'm showing you in blue here,

5:16

and the posterior aspect of the scapular spine.

5:20

And here are three potential shapes that you may get.

5:24

It's the third shape here

5:26

where there's an increased vertical distance,

5:29

as you can see from this particular point,

5:32

which is at the top of the glenoid

5:34

to the tip of the coracoid.

5:36

When that distance increases dramatically,

5:39

some people suggest it does, it is a positive sign

5:44

for external subcoracoid impingement.

5:49

Let's look at one form of internal impingement,

5:53

internal postal superior impingement.

5:55

I'm gonna talk more about this

5:57

Talk tomorrow when I talk about the throwing shoulder.

6:00

So once again, I'm giving you a drawing

6:02

that I made in PowerPoint.

6:04

Uh, those of you who do drawing in PowerPoint,

6:06

there's a limited number of shapes.

6:08

You're gonna see a lot of triangles and circles

6:10

and little bumps in my particular drawings,

6:13

but I, I like this simple but good.

6:16

This is a transverse section through the scapula

6:19

and proximal humerus.

6:21

Here's the glenoid.

6:22

I'm showing you in fact the anterior labrum

6:25

and the posterior labrum.

6:26

Here's the humeral head, lesser greater tuberosity,

6:29

bicy groove and bice subtenant.

6:31

Here's the in infraspinatus tendon attaching

6:35

to the posterior aspect of the greater tuberosity.

6:39

Okay? And so this is in neutral position.

6:43

Now, when you think about the baseball pitcher, look at me

6:46

and you go into abduction and external rotation.

6:49

If you're a good baseball pitcher, you better be able

6:52

to do this beyond what the normal person can do.

6:56

And I'll explain why that's important tomorrow.

6:58

But if you go into that position, there's a shift

7:02

in the relationship of that scapula and humeral head,

7:07

and this is what it looks like.

7:08

Everything rotates posteriorly.

7:10

So in that red circle that I've added,

7:14

everything gets crowded.

7:16

And what's in that red circle?

7:18

Well, you may have portions of the greater tuberosity.

7:21

You have the labrum,

7:22

certainly there you have the undersurface

7:25

of the in infraspinatus.

7:26

So those are the classic target sites for abnormalities

7:30

that occur with internal posterosuperior impingement.

7:36

So this is what it would look like.

7:37

This is in a, uh, Padres baseball pitcher.

7:40

They all look like this probably explaining their bad

7:43

record, except for the last couple of years.

7:46

This is an MR arthrogram that we've done.

7:48

This is the a bear. I'll talk more about that.

7:51

The A bear after the external rotated position.

7:55

Tomorrow we'll go into detail about that.

7:57

But in that position,

7:59

we can see contrast passing right here into portions

8:03

of the supraspinatus.

8:05

And it also involve the in infraspinatus tendon.

8:08

This, these are the articular sided fibers.

8:11

These are the bursal sided fibers.

8:13

They are relaxed in the a bear position,

8:15

which is terrific for us.

8:17

So you do see these delaminated tears.

8:21

You can see the cystic changes that occur

8:24

back here involving the greater tuberosity

8:26

and even the humeral head

8:28

and an arthogram, they often fill with contrast material.

8:32

And although not well sh shown here as an old image,

8:35

you can see abnormalities involving the

8:37

postal superior labrum.

8:39

I'll go again tomorrow into more detail about those.