0:00

Okay, this is a 17-year-old boy who's had

0:04

a known dislocation, and we're going

0:07

to attack this as an instability case.

0:12

And we're going to break down instability, as you know,

0:14

into single-event macro instability, repetitive micro,

0:21

or repetitive macro instability, in which somebody

0:24

repeatedly dislocates on top of a subtly unstable

0:28

shoulder, and then we've got patients that have pure micro

0:33

instability, that is frequently multidirectional.

0:37

Now, usually when there's been a collision event, it's

0:39

usually a unidirectional type of macro instability.

0:43

And when we say macro instability, we

0:45

mean dislocation, and/or locking.

0:49

And that dislocation can be proven by

0:52

an X-ray, a physical exam, or an MRI.

0:55

So let's start out briefly with the coronal projection,

0:58

because that's what most of you are going to put up first.

1:01

And once you see the coronal projection, and you see

1:04

something like this, even though it's not a flat-out

1:06

fracture, it's more of a micro-trabecular injury,

1:09

you don't see real depression, you don't see a

1:12

what I call a V-shaped hatchet sign, that is still a

1:17

very reliable sign that the patient has dislocated.

1:20

It's very hard to get a garden-variety

1:23

non-dislocation fracture over here.

1:25

Right?

1:26

You can't really get slammed from the top

1:28

because you've got the acromion in the way.

1:30

So there's not another mechanism for this to occur.

1:33

It's kind of like the pivot shift injuries of an ACL.

1:36

You know, once you have those, uh, first of all, they're

1:39

hard to get any other way, and second, once you have them,

1:43

the likelihood that your ACL has good integrity is very low.

1:47

How low?

1:49

5%, 3%, 1%, depends upon who you read.

1:52

The same thing is true here.

1:54

The chances of you having a normal

1:57

antero-infraoxillary space for the labral

2:01

ligamentous complex is close to zero.

2:05

Now that doesn't mean you have a bankruptcy.

2:06

You could have any one of a number of

2:07

lesions, including a capsular injury.

2:10

But there's going to be something wrong

2:12

down here automatically, and if you

2:14

don't read it, you're going to be wrong.

2:16

So the first thing we've established is that

2:18

there's a bone injury, what we call a Hill

2:20

Sachs equivalent, and it's close to the apex.

2:23

It's close to the 12 o'clock position on the humeral head.

2:26

And then drifts off with a little

2:28

bit of edema towards the side.

2:30

Now, it is true that the more violent, the more

2:33

depressed, and the broader the Hill Sachs, the more

2:37

violent the dislocation and the more likely you

2:39

are to have an anteroinferior higher grade lesion.

2:43

So you want to assess that Hill Sachs

2:45

for its severity, especially its length.

2:49

Now, how do we assess length?

2:51

We probably do it with circumference.

2:53

Now, please don't confuse this normal flattening

2:57

of the posterior humeral head with the Hill Sachs.

3:00

That's too low.

3:01

The Hill Sachs is up higher.

3:03

Here's our Hill Sachs here, and

3:05

here's our flattening down here.

3:10

So let's go up to our Hill Sachs, and let's

3:13

get the biggest area of Hill Sachs involvement.

3:16

And I would say that it's about here.

3:19

And if we wanted to, we could measure that.

3:21

We're not going to do it right now.

3:23

But we would give it a measurement, let's say,

3:25

12 millimeters, 15 millimeters, or whatever.

3:29

And, that would give us a rough idea, just in terms

3:32

of sheer magnitude, of the size of the Hill Sachs.

3:35

Now, the Hill Sachs lesions that I worry about

3:37

are the ones that are 20, 25 millimeters.

3:41

Or, I could take the circumference.

3:45

I could take this circumference, make a best fit circle.

3:48

And I'd say, okay, well that

3:49

amount of the circle was involved.

3:54

the circumference of the circle is involved.

3:56

Now what's the prevalence of a Hill-Sachs?

3:59

It actually increases from 25 percent in

4:02

first-time dislocators, to probably

4:06

80 to 90 percent in repeat dislocators.

4:10

Most people that dislocate have dislocated before.

4:13

Another caveat for Hill-Sachs lesions: they will

4:18

increase in size with increasing numbers of dislocations.

4:22

And eventually, they'll take on this,

4:24

more hatchet-like appearance.

4:27

So if you have a hatchet, the odds are

4:31

it's not a single dislocation event.

4:34

Now Hill-Sachs defects, by themselves, rarely

4:38

require surgical treatment, unless they're

4:40

large enough to cause severe injury,

4:42

mechanical symptoms, or there's a bipolar lesion.

4:45

In other words, you're missing part of the glenoid rim.

4:48

In other words, you've chopped it off and

4:50

you've got a bony fragment with medullary bone inside.

4:53

That is not the case here.

4:56

Larger lesions of the humeral head, though, even

4:59

though they may not be associated with recurrent

5:02

dislocation, they can be associated with a

5:05

sensation of catching, or clicking, or popping.

5:10

Another caveat.

5:11

The closer the Hill-Sachs lesion is to the top of the humeral

5:16

head, the more medial it is, and the closer it gets to the

5:18

articular surface, the more problematic it's going to be.

5:23

The more likely you are to get clicking and

5:26

the more likely you are to get dislocation.

5:31

So medialization of that Hill-Sachs,

5:34

let's take a look at it again.

5:35

It's right here at the 12 o'clock position, maybe 11:30.

5:37

So as it gets more and more in this

5:38

direction, it gets more problematic.

5:44

Hill-Sachs lesions are also more problematic

5:47

the more often the patient is in this position,

5:51

the abduction external rotation position.

5:54

If they don't get into this position that

5:56

often, it's not as big a problem.

6:01

So now let's have a look at our

6:03

anteroinferior aspect of a labrum.

6:07

Now we have said in some of our golden rules

6:09

in other vignettes that as we go from the top

6:12

to the bottom, the labrum should get big.

6:16

It should get bad.

6:18

In other words, it should get big and bad,

6:20

and black, and triangular, and smooth.

6:23

It should look something like this.

6:27

And it should definitely be

6:28

bigger than the posterior labrum.

6:30

And it should definitely be

6:31

bigger than the labrum at the top.

6:34

Let's go back up to the top.

6:35

There's a little weenie labrum, and

6:38

our labrum doesn't get much bigger.

6:40

It looks like a dark dot, with tissue running all the way

6:44

through it, crossing the labrum, and crossing this little

6:47

squiggle right here, which is the broken periosteum.

6:57

in a moment, the labrum for the most part, at least

7:00

anteriorly, doesn't medialize under the periosteum much.

7:05

For if it did, if it medialized, or tumbled underneath this

7:10

periosteum like this, here's the periosteum right there,

7:14

periosteum would be on top of it, I'll make a line for it.

7:19

Sorry, a little different color would be better.

7:23

Then you would have an Alps Elysian, an

7:26

Anterolabral Periosteal Sleeve Evulsion.

7:28

Now sometimes that can happen anteriorly,

7:31

sometimes that can happen in the axillary

7:33

area, sometimes it can happen in both.

7:36

So let's look at the axillary area.

7:39

So here's our axillary area, here's our labrum.

7:43

Our labrum has come off with the IGHL.

7:47

So our IGHL is attached to the humeral neck.

7:50

It's attached in the front.

7:52

It's attached in the axilla, and it's attached in the back.

7:56

If it wasn't attached, we would have

7:57

some variation of humeral ligament.

8:01

We don't have that.

8:02

But unfortunately, this part of the labral ligamentous

8:06

complex, labrum and ligament, have been yanked

8:10

off, hacked off, pulled off, the inferior labrum.

8:14

Is it medialized?

8:16

Yeah, a little bit.

8:17

Remember from one of our other vignettes, we said

8:20

that the axis of the labrum should be about like this.

8:27

that's relative to a vertical axis.

8:31

And indeed, this one is almost straight up

8:34

and down, and it's not in its proper position.

8:38

It's just slightly shifted towards the medial side.

8:41

Now another rule, another coronal rule, not applying

8:46

to the superior labrum, but the inferior labrum, is,

8:49

fissures, and dippity doos, and hyaline interposition.

8:53

And signals here should never cross over to the dark side.

8:57

What do I mean by that?

8:58

It should never go all the way through.

9:01

So they shouldn't go all the way through this way.

9:04

And this one does, right?

9:05

Right there.

9:05

White signal going all the way through.

9:07

So if you have a pure axillary labral

9:11

lesion, you shouldn't see this.

9:14

So, now we've established that we have a Hill-Sachs lesion.

9:18

That we have a labral ligamentous tear.

9:21

There's a little bit of medialization.

9:24

Perhaps it involves a little bit of the periosteum.

9:26

There's some fragmented periosteum.

9:29

There may be a little periosteum pulled off, it's a

9:30

little hard to tell, but there's not much medialization.

9:34

So, this would be appropriately called a giant Bankart.

9:38

Now in assessing, and this is basic stuff, we're

9:41

assessing the Hill-Sachs for its size and position,

9:45

we're assessing the Bankart for its position.

9:47

Um, let's talk a little bit about the variations

9:51

of a Bankart for a minute, and that leads me to

9:54

bringing up all the axials that I have at my disposal.

9:59

this one up, so we've got three of them.

10:03

Let's see if we can scroll them together

10:04

and get them all about the same size.

10:11

And now let's take a look at our Bankart lesion.

10:15

So, let's define a Bankart first.

10:19

So I'm gonna draw over my glenoid.

10:25

I'm gonna say this is my labrum, had it been here.

10:29

And I'm going to give it a little bit of

10:31

hyaline cartilage in blue for hyaline.

10:33

The hyaline can slip under here.

10:36

Sometimes it's a transition,

10:37

sometimes it's an abrupt transition.

10:40

It just stops and the labrum starts.

10:43

So for me to have a Bankart, I want to have a

10:48

tear that goes through and through the labrum.

10:53

So I'm going to use something like light purple.

10:55

I want it to go through and through

10:56

the labrum and out the other side.

11:00

Or, I want my Bankart lesion to go through and

11:03

through the labrum and then out the periosteum.

11:07

And by the way, I'll use the same color,

11:09

but the periosteum would be over here.

11:11

So I've either broken the periosteum or broken the labrum.

11:15

That is a classic soft Bankart.

11:20

Now, one caveat or pitfall.

11:23

It is not uncommon in people that have acute dislocations,

11:27

superimposed on chronic dislocations to have

11:30

the anterior aspect of the glenoid ground down.

11:35

So, in other words, what I mean by that

11:37

is, it's a little more rounded, like this.

11:41

Now, your immediate thought is,

11:43

okay, there must be a bony Bankart.

11:45

For there to be a bony Bankart, you

11:47

must see a fragment that has detached.

11:53

And we'll make it a little thicker

11:54

so we can see it a little better.

11:56

A fragment that's detached.

11:58

That is filled with bone marrow, or has some marrow in it.

12:03

Because you can simply grind this

12:05

down, and lose some glenoid bone stock.

12:09

And we're going to talk about the loss of that

12:11

glenoid bone stock in a separate vignette.

12:15

My goal here is to just illustrate a

12:18

simple Hill Sachs and a simple Bankart.

12:20

So we've defined a Bankart.

12:22

A Bankart is a through and through labral

12:24

tear, or a through and through tear that

12:26

involves the labrum, and the periosteum.

12:30

You'll see that there is an opportunity to subcategorize,

12:35

uh, Bankart lesions and lesions that stand in for Bankart

12:40

lesions and we're going to do that in separate vignettes.

12:42

And then we've talked about Hill Sachs and I'd

12:44

like to go back to the Hill Sachs for a minute.

12:46

We said size matters, depth matters, location matters.

12:51

Remember that Hill Sachs fractures are not always fractures.

12:56

They may be micro trabecular injuries.

12:58

They may be contusions.

13:00

They may be intramedullary and chondral bone, spongy

13:04

bone fractures, many of which you can't see on x-ray.

13:10

Now one last caveat, before we move on to another case.

13:15

And that is, what are the associated lesions around a soft Bankart?

13:22

And they include the following.

13:25

If you have involvement of the capsule, and

13:29

the capsule is detached from the labrum.

13:31

Now this capsule is injured.

13:33

It's a little bit irregular and rounded.

13:35

You can look at some of the other images nearby.

13:37

This is a gradient echo to the left, probably.

13:40

And another water-weighted image on the right.

13:43

When you look at the capsular tissues, if

13:45

they start to come undone, this one hasn't.

13:48

It's right on top of the labrum.

13:50

But if it starts to pull away from the labrum,

13:53

then you would say, "Okay, I've got a double lesion."

13:57

So if that pulled away from that, right now I

14:01

just have the labrum separated from the glenoid.

14:04

What if I had the periosteum stripped all the way off?

14:07

I do have a little periosteal stripping.

14:10

Then I would add to that and I'd say I have a triple lesion.

14:14

So, periosteum to labrum and glenoid.

14:18

Capsule to labrum.

14:20

Labrum to bone.

14:22

This is how I want you to think

14:23

about soft Bankart lesions.

14:26

And then finally, you're gonna make sure you don't have

14:30

glenoid bone loss as either remodeling from a current

14:34

dislocation or a flat-out fracture with fragments seen.

14:39

And by the way, if you have a

14:41

fragment, the fragment can resorb.

14:44

If you're not sure, if you're new, you're a resident, you're

14:47

a fellow, you're young, and you haven't done a lot of MRI,

14:51

don't be ashamed, get a CT, look for the bone fragment.