0:01

Okay, let's take a real case of a dislocator and

0:04

examine the on-track, off-track characteristics.

0:07

Let's scroll axially.

0:08

We see a more narrow part of the hill-sachs

0:10

and a broader portion of the hill-sachs.

0:13

Let's measure it from its ridge, its bony ridge

0:16

right there, to as far as the eye can see where it,

0:20

where the ridge ends and it meets the rotator cuff.

0:24

This is a more medial portion of the cuff.

0:26

The cuff continues on more anterolaterally.

0:29

And that measurement is about 19 millimeters,

0:33

1.89 centimeters.

0:36

Now let's go over to our sagittal en face view

0:40

of the glenoid cup and see if I can master

0:44

making a circle that's about the right size.

0:49

It looks like it's about the right size.

0:52

Let's move the circle over.

0:59

That's a pretty good fit.

1:00

We want our dot to be right in the middle of the glenoid.

1:04

So now we're going to take the diameter of the rotator cuff.

1:09

So let's do that.

1:09

We'll call that big D.

1:12

So big D is all the way from here to here.

1:16

And we're getting a number of 2.

1:19

91 centimeters or 29 millimeters.

1:25

Now let's take that and multiply it by 0.83.

1:30

28 00:01:32,325 --> 00:01:33,075 And what do we get?

1:34

20, 24.

1:36

So we get 24 millimeters.

1:39

Then we're going to subtract from that.

1:41

Little d.

1:43

So what's little d?

1:44

Little d is the measurement of the bone loss.

1:49

We'll say it's from there to there,

1:51

because here's a big bone fragment.

1:54

Let's make it parallel to our circle.

1:59

And little d loss is 9 12, let's say 10 millimeters.

2:05

So 24 minus 10 is 14 millimeters.

2:11

So over here we've got almost 1.

2:14

9 centimeters, or 19 millimeters.

2:17

Over here we've got 14 millimeters, so the 19

2:21

millimeters is greater than the 14 millimeters.

2:24

Therefore, we have an off-track scenario.

2:28

Now, let's use a different technique.

2:32

Let's pull it down again, pull it down over here,

2:37

and I simply want to focus on the radius measurement

2:41

technique to see the amount of glenoid area bone loss.

2:47

So this time, I'm going to use my drawing tool,

2:51

and I'm going to make a Best fit circle again.

3:00

Then I'm going to put a dot in the middle of that circle.

3:04

And I'm going to get a radius going backwards.

3:07

And then a radius going forwards.

3:13

Now I'm going to see how much of that

3:16

radius going forwards is attenuated.

3:20

So let's take a look at that with a different color.

3:23

We'll make it a little thinner so we can see it.

3:26

Let's use light blue.

3:28

And from here all the way back to here, sorry.

3:32

There's light blue again.

3:33

From here, all the way back to here.

3:37

We've got almost 100 percent of the anterior radius.

3:41

Maybe it's a little less.

3:42

Maybe from here.

3:43

So we've got almost 100 percent of the radius.

3:46

Let's say 80 percent of the radius is

3:50

reduced in the front compared to the back.

3:52

Because they should be equal.

3:53

So an 80 percent radius reduction corresponds to to

3:59

a 38 percent area reduction in the best fit circle.

4:05

And we've said in other vignettes, that when you get above

4:08

a 25 percent area reduction, it is simply catastrophic,

4:15

or potentially catastrophic, and usually catastrophic.

4:20

So this patient has, Everything going against it.

4:24

They are off track, and they have

4:27

substantial glenoid bone loss.

4:30

So this is exactly the kind of patient who would

4:33

be a candidate for a latarjay bristo or a

4:36

latarjay procedure where you do a coracoid

4:39

transfer with the muscles and capsule over to

4:43

the anterior inferior glenoid as a bone block.

4:47

And you might also consider doing a humeral head

4:51

Remplissage, where you take the infraspinatus and bury

4:55

it in the humeral head defect along with the capsule.

4:59

And you might even have to augment that

5:01

with a piece of bone or bone block.

5:04

Those are methods you can use to calculate

5:08

the risk of recurrent dislocation.

5:11

And what procedure you should perform proactively.