0:01

Okay, let's look at a 20 year old man

0:02

with recurrent dislocation.

0:06

He's got multidirectional instability preceding

0:10

a bout of acute traumatic instability.

0:16

People with multidirectional instability, laxity,

0:19

and repeated bouts of subluxation and dislocation

0:24

are frequently referred to as atraumatic

0:26

onset of multidirectional instability, or AMBRI.

0:29

And those patients As long as they don't come out

0:32

violently on a repetitive basis, can be treated

0:36

conservatively, and don't need major surgical procedures.

0:40

Whereas the traumatic unidirectional event, or traumatic

0:43

unidirectional instability, so called TUI, is a different

0:49

animal, but then you get the scenario where you get both.

0:52

The patient has multidirectional instability, Uh,

0:57

atraumatic, or they have traumatic multidirectional

0:59

instability, and then it becomes a repetitive process,

1:02

so called variants of AMBRI, and then on top of that you

1:05

substitute, or you include TUI, traumatic unidirectional

1:09

instability, or acute traumatic dislocation event.

1:13

That's what's happened here.

1:14

Patient dislocated a while ago, had

1:16

multidirectional instability for a while,

1:19

repeated bouts of subluxation, and then BAM, the

1:22

patient has a collision event, and they're out.

1:25

Let's look at what has happened.

1:27

On the far left, axial gradient echo image.

1:32

The Hillsax lesion is large.

1:35

Let's go ridge to ridge, or you could go

1:37

ridge to medial border of rotator cuff.

1:39

I personally find it easier just to find

1:42

the free edges of the ridge, measure it.

1:45

And this one is just a little over 20 millimeters.

1:49

Maybe 21, 22 millimeters.

1:52

Then we go over to our sagittal.

1:56

And we have made a best fit circle.

1:59

Instead of me hand drawing it,

2:00

I've let the computer draw it.

2:02

I've gotten the diameter of that best fit circle, big D.

2:06

I've multiplied that by 83.

2:13

bone loss, which was about 4 millimeters.

2:17

So, big D times 83 minus this little d right

2:21

here, came out to about 19 or 20 millimeters.

2:25

So I had about a 20 little over

2:27

20 millimeter Hill-Sachs lesion.

2:30

I've got a 19 to 20 millimeter, uh, calculation

2:34

for my glenoid bone loss and absolute values.

2:38

So using the on track off track anatomic

2:42

measurement technique, uh, we're kind

2:45

of borderline as to where we stand.

2:48

Now let me make a few other points.

2:51

Okay.

2:52

One thing we haven't talked about

2:55

is the height of the Hill-Sachs.

2:59

I get much more concerned when I have a Hill-Sachs

3:02

that goes above the 3 o'clock position or equator.

3:05

And this time I do.

3:07

And I should have a nice quartered circle.

3:09

I mean, where is my circle here, here, here, here, here?

3:13

I'm way up high.

3:15

So those patients are also at higher risk for repeated

3:21

dislocation when they're borderline off track, on track.

3:24

In other words, this measurement and the measurement I just

3:27

gave you were kind of equal, they're about 20 millimeters.

3:30

But when I have other factors, like a severe capsular

3:34

injury, and a very high extent of my glenoid bone loss

3:39

lesion, then I'm more apt to recommend or to support,

3:44

uh, other techniques for improving, uh, stability.

3:49

Now, there are other methods of measurement.

3:52

Another method would be to measure the radius.

3:55

Use the radius technique and see how much glenoid

3:58

bone loss we have, focusing mainly on the glenoid

4:02

bone loss and how much bone stock we really need.

4:05

So I would take a dot in the middle, and um, I

4:08

can make that dot with my, my little pen here.

4:12

So here's my dot right in the center of the glenoid.

4:15

Using a best fit circle, which I'm not going to draw again.

4:18

And then I take my radius to the back cortex.

4:21

And then I take my radius to the front cortex.

4:25

And normally those should be equal, right?

4:28

Because your dot should be right in the middle.

4:30

But it just so happens, That we have lost 20

4:34

percent of this length compared to that length.

4:37

That's just a simple way to explain it.

4:39

So when we say we've lost 20 percent of the

4:42

radius in the front compared to the back, we

4:45

then go to what's called the Knopfsinger table,

4:48

which you can Google and put on your desk.

4:50

And that would tell us that we have, in terms of

4:53

area, less than 10 to 5 percent overall area loss.

4:57

So that suggests that it's not so bad.

5:01

So you can see how you've got to kind of

5:03

put this together like you're baking a cake.

5:06

Because you know what?

5:07

That one I'm going to set aside.

5:08

And the reason I'm setting it

5:09

aside, my Hill-Sachs is really big.

5:12

My glenoid bone loss is really tall.

5:16

And my on track, off track, anatomic

5:19

measurements are virtually equal.

5:21

And then, now I'm going to look at the actual track.

5:24

of the humerus.

5:26

Look at that track.

5:27

Here's my depression, and I've told you

5:30

in the past that the track runs from

5:33

supralateral to inframedial, kind of like this.

5:38

Let's see what our track looks like.

5:40

And that's exactly what it's doing, isn't it?

5:43

It's going from supralateral to inframedial.

5:45

That is a typical humeral glenoid bone track.

5:49

Now you might ask yourself, Why are the Hill-Sachs lesions

5:54

so much more consistent than the glenoid lesions?

5:58

They're much more variable, and they're, they're honestly

6:01

the bone lesions in the glenoid, not the soft tissue ones.

6:05

But the bone lesions are less

6:06

frequent than the humeral lesions.

6:09

But aren't they both bone?

6:11

Why, why, why don't you get them with the same frequency?

6:14

And the answer is simple.

6:18

Softer bone.

6:20

Whereas on the glenoid side, first of all it's

6:22

pointed, So it has the potential of just ramming

6:25

right into the humerus and secondly, it's harder bone.

6:30

There's more corticated bone there and less spongy bone.

6:34

So this is softer, explaining why the Hill-Sachs

6:37

lesions are more frequent, deeper, and more prominent.

6:42

Oh, we're not done yet.

6:43

We'd like to be done, but let's bring down our other axial.

6:48

And I'm going to blow that one up just so we

6:50

have some size and symmetry and some beauty.

6:55

Wow.

6:55

Look at that.

6:56

Hill-Sachs.

6:56

This is a PD spur and this is a gradient echo.

7:00

They're very similar looking.

7:02

One is great for bone.

7:03

The other not let's get them about the same size.

7:08

That's one big, deep Hill-Sachs.

7:10

Easy to get the length once again.

7:14

And let's scroll and focus on the labrum.

7:18

So let's go up high where we have a more

7:20

decent looking, um, Labral ligament is complex.

7:23

Here's our superior glenohumeral ligament.

7:25

There's our rotator interval.

7:28

And now let's work our way down, where by

7:30

rule of law, that we have established, yes,

7:33

we are the law, we're the sheriff in town.

7:36

We're coming down, down, we see the MGHL, the

7:39

subscapularis, and our labrum, by law, should be

7:42

getting bigger, and blacker, and more triangular.

7:45

And what's happening to it?

7:48

It's turning into a wiener dog.

7:50

It's disappearing.

7:52

It's getting smaller and smaller and smaller.

7:55

Now, is it over here, medialized, like an absolution?

7:59

No, it's not.

8:00

Where did it go?

8:02

It could be autodigested.

8:04

Well, that would take some time.

8:07

But he is a repeated dislocator.

8:09

So that's a possibility.

8:11

Another possibility is it's just simply pulverized

8:15

into morass of edematous, bloody tissue.

8:20

Yes, the labrum can become edematous,

8:22

so let's keep looking at it.

8:25

And while we're at it, let's look

8:28

at the surrounding capsular tissue.

8:31

And here are some shards of labrum, these little

8:33

black structures right there, and that's our capsule.

8:37

Now typically, our labrum should look something like this.

8:40

Here's our glenoid, here's our labrum, and

8:44

then our capsule should have some linearity,

8:46

some consistent linearity touching the labrum.

8:50

That's our capsule right there.

8:52

It's a, a fluffy ball.

8:55

It's not linear.

8:56

So the capsule and the pulverized labrum are no more.

9:02

They're separated.

9:04

They're distorted.

9:05

But that's not all.

9:07

Let's take a look at our periosteum.

9:09

We have periosteal bleeding.

9:11

We have periosteal separation or detachment.

9:15

So we have a ligamentous to shards of labrum injury.

9:22

We have a labrum to bony injury, and we have

9:26

a periosteal injury to labral injury with

9:29

periosteal separation, a so-called triple lesion.

9:35

So this is an example of somebody that is

9:37

borderline on track, off track, but more likely

9:41

off track, Given the height of the glenoid lesion.

9:44

We've given you two methods for measurement.

9:47

Absolute measurements.

9:49

We've shown you how to measure

9:50

the radius of glenoid bone loss.

9:53

And translate that into the Knopfsinger scale.

9:56

Which you might put on your table while you're reading out.

9:59

And we've shown you the nasty, heinous,

10:02

triple lesion that this patient has sustained.

10:08

Oh no, we're not done.

10:11

This is a muscular young boy, young man.

10:14

He's not a boy, he's a young man.

10:16

And he's got lots of muscles, which means he weight lifts.

10:20

And when they weight lift, what do they do?

10:21

They do this.

10:22

And they do this.

10:24

So they can look good from the front.

10:27

Well, that's not a good idea unless you

10:30

try and look good from the back too.

10:32

You want to be balanced.

10:34

So it's important physiologically as well as aesthetically.

10:38

And here's our axial, and what's

10:39

going on in our posterior labrum?

10:42

We've got a tiny little lesion

10:44

that works its way out the back.

10:47

And you might call this a reverse Perthes lesion.

10:51

If it's really small, sometimes

10:53

we'll use the term Kim's lesion.

10:56

So this is a repetitive micro

10:58

instability lesion from weightlifting.

11:00

And that is the final finding in this case.