0:00

Okay, we're talking about the six key components of the

0:04

rotator cuff complex: the supraspinatus,

0:07

the infraspinatus, the teres minor, the subscapularis,

0:10

the capsule, and the coracohumeral ligament.

0:13

We've shown you, in other vignettes, injuries of all of

0:17

them and how to assess them in different projections.

0:21

But I want to focus just for a moment on the

0:24

surrounding anatomy.

0:25

Specifically, I want to focus on the subacromial arch.

0:30

This case of a massive rotator cuff tear,

0:33

there is no supraspinatus.

0:36

There is massive retraction with the fibers seen medially,

0:40

was instigated, at least in part,

0:43

by this funny-looking acromion.

0:47

The acromion has been a subject of

0:52

much debate and much discussion.

0:57

There's even a categorization of the acromion called

1:00

the Bigliani subtypes of the acromion.

1:02

I hardly ever use that.

1:03

What I do use is the proper descriptors.

1:07

I'd like to see if the acromion is downsloping

1:10

in the coronal projection.

1:11

There is a sloping angle,

1:13

but that's a little bit beyond the discussion today.

1:15

How often do I use it? Never.

1:18

I rarely measure things,

1:20

but I do look at them.

1:22

So downsloping in the coronal projection is a little

1:25

different than downsloping in the sagittal projection,

1:28

but I pay attention to both.

1:30

Then there is the shape of the acromion.

1:33

Very often,

1:34

people that have anatomic impingement have an acromion

1:38

that has a little shelf on it, that looks a little

1:41

bit like the end of a telephone receiver.

1:43

You'll also hear this called a keel-like acromion

1:48

I often refer to it as a telephone receiver acromion.

1:53

Now, when you're younger,

1:55

the acromion plays a scant role in impingement,

1:59

unless you have a humeral head that won't stay down,

2:04

in other words,

2:05

it starts floating up when you pick your arm up.

2:08

In other words, there's microinstability.

2:10

The humeral head doesn't rotate

2:12

in the center of the cup.

2:14

And if you pick your arm up and the humeral head

2:16

goes up, what does it bump into? Your acromion.

2:19

As you get a little bit older, the acromion remodels,

2:24

and it becomes like this,

2:26

keel-like.

2:28

And now you've got a self-perpetuating prophecy.

2:33

The humeral head is up. The acromion is in the way.

2:37

The acromion further damages the rotator cuff.

2:40

The humeral head comes up higher, and eventually,

2:43

and unfortunately, they meet bone to bone.

2:48

There is another structure that participates in this

2:53

process, and that is the coracoacromial ligament.

2:58

The coracoacromial ligament comes off the acromion

3:02

and heads towards the coracoid.

3:04

Now, this patient's coracoacromial ligament

3:06

is not that well seen.

3:08

It's right here

3:11

and it's not that thick. It's a little bit thick,

3:14

but most of the time,

3:16

if you went to decide whether the ligament or the bone

3:20

is a bigger contributor to anatomic encroachment,

3:23

it's more often the ligament than the bone.

3:26

It's about 60-40, 70-30, but either one can do it,

3:31

and sometimes it is both. In this case,

3:35

it's more bony than it is ligamentous.

3:38

Let's take a quick look at the sagittal projection for a moment

3:42

and see what our acromion looks like

3:44

in the sagittal projection.

3:46

When we say that the acromion is downsloping,

3:49

here's what we mean.

3:52

Here's our humeral head,

3:54

not a very good drawing of it.

3:56

And if our acromion is tilted down from posterocraniad

4:02

to anterocaudad, it's positively downsloping.

4:07

If it's straight in line with the humeral head,

4:10

something like this, then it's neutral.

4:13

And if it's angled up, then it's negative slope.

4:17

We don't pay too much attention to that.

4:20

We are more interested in positive sloping,

4:23

but especially

4:25

whether the acromion has a hook

4:28

or a spur associated with it.

4:30

And it often looks quite different in the sagittal projection.

4:33

It often looks like it has a little snout,

4:36

and that snout is where the coracoacromial ligament attaches.

4:41

So you have a fat acromion that has a snout or a spur.

4:47

And if it's downsloping sagittally,

4:50

which this one really is not.

4:53

And in the coronal projection,

4:55

you have a kell-like or telephone receiver acromion,

4:57

which in this case it is.

5:00

And if you have a thick coracoacromial ligament,

5:03

which in this case it's a little bit thickened,

5:05

but not very much.

5:06

All of those components are part of the analysis of

5:10

impingement syndrome and contributors

5:12

to rotator cuff pathology.