0:01

Sagittal arthrography.

0:03

Well, sagittal in general, I like either a T2

0:06

fast spin echo with or without fat suppression.

0:09

I prefer fat suppression, but I'm fine without it.

0:12

Or, in some cases, I might like a T1 sagittal,

0:16

especially if bony architecture is critical.

0:19

And bony architecture is critical in dislocations,

0:22

especially when you're looking at bipolar lesions.

0:25

What's a bipolar lesion?

0:27

A bipolar lesion is when you have a Hill Sachs.

0:29

And a banker.

0:31

And it doesn't have to be a bony banker, but it could be.

0:34

So let's talk about looking at the glenoid cup

0:37

in the sagittal projection arthrographically.

0:41

And it's the same as if it's non-arthrographic.

0:45

The normal glenoid is shaped a little bit like a pear.

0:50

Unless you lose, you know, a substantial

0:53

portion of the inferior glenoid.

0:54

In which case, some people call that an upside-down pear.

0:59

There's often a little thin area here called the bare area.

1:03

And what I like to do is make a

1:06

best-fit circle of my glenoid cup.

1:08

So here's my best-fit circle.

1:11

I'm gonna draw around the cortex as

1:12

steadily as I can and make my circle.

1:17

I got a nice little dot right here in the

1:19

center for the middle of my glenoid cup.

1:23

And now I'm going to examine Very simply,

1:28

the radius technique of the glenoid cup.

1:30

So how am I going to do that?

1:32

I'm going to take the radius from that central

1:33

point to the back, and I'm going to take that

1:38

radius from the central point to the front.

1:40

And they should be pretty equal.

1:42

Unless I've wiped out the anterior glenoid from repetitive

1:46

dislocation, I've ground it down, or I've fractured it.

1:51

If I fractured it, I should see a piece

1:54

of bone with marrow in it over here.

1:57

And I should have a very jagged, irregular signal over here.

2:01

As opposed to when it's ground down, where this interface

2:05

right here will be very smooth, and I won't see a fragment.

2:10

you could have it on an acute basis.

2:12

Now let's assume we have it on an acute basis.

2:14

We got a ragged, jagged area of glenoid bone loss.

2:18

So now, let's look at our radius measurement.

2:22

That is about 40 percent of that.

2:27

Pretty simple, right?

2:29

So, when you have 60 percent loss in the front,

2:34

You've got 25 percent of your entire glenoid area

2:38

affected according to the Knopfsinger Technique.

2:41

So, 50 to 60 percent of this front radius lost

2:45

compared to this back radius, that's bad.

2:49

That is a jumping-off point.

2:51

Now, if you have a bipolar lesion, you're going to also

2:55

be looking for a Hill Sachs in the sagittal projection.

2:58

We don't have one here, but it

3:00

would be superior or supralateral.

3:03

So, it would be somewhere around here.

3:06

Now, in the axial projection, you

3:07

can also look at Hill Sachs lesions.

3:09

So, let's pretend we have one.

3:11

Let's draw one in.

3:12

Let's say we've got a Hill Sachs lesion like this.

3:15

Oh, it's a big one.

3:16

It's a deep one.

3:17

I've colored it in blue.

3:20

Now, you could make an angle of it.

3:22

One of your colleagues was doing that for me earlier today.

3:24

So, let's say the angle is 90 degrees.

3:27

What is that?

3:28

Well, that's 25 percent of the entire circumference head.

3:35

What does that mean?

3:36

Well, if you don't have a bipolar lesion, in other words,

3:39

you don't have a bony banker, Those patients do okay.

3:43

When do they start not doing okay?

3:46

When this is about 40 percent or more.

3:50

So now this line goes out here.

3:52

Now we've got 40 percent of the entire

3:55

humeral head wiped out by a Hill Sachs lesion.

3:58

That's when, even by itself, without a bipolar lesion on

4:02

the glenoid side, you could potentially have a problem.

4:06

And when you have them both, 40 percent over here or

4:10

25 to 40%, you've got a big area of glenoid bone loss.

4:16

That measures out what we showed you before.

4:20

In other words, 60 percent of the anterior radius is gone.

4:26

That's a patient that's going to be a recurrent dislocator.

4:29

And you've got to have the sagittal projection

4:32

to make these measurements for the glenoid cup.

4:35

And you've got to have the axial projection to

4:37

make these measurements for the humeral head.

4:40

What else is going to be of interest?

4:43

In a dislocator.

4:45

Well, people that have dislocations,

4:46

they have collision lesions.

4:48

So I urge you to keep tracking the scapula inwards.

4:52

You may have to use some of these other projections.

4:54

If you see signal that is tracking along the scapula

4:58

immediately, especially in the back, odds are you

5:01

have sustained an unrecognized scapular fracture.

5:07

Look for clavicle fractures.

5:09

Look for glenoid fractures.

5:11

And also, look to see that fragments have not displaced.

5:16

Down into the anteroinferoaxillary region

5:19

and are encroaching on the brachial plexus.

5:22

Those are just some of the roles of the sagittal projection.

5:25

Look at the bands of the IGHL here.

5:28

There are multiple innumerable bands and senechii, all part

5:32

of the normal anatomy discussed in the anatomic section.

5:35

That's it for the sagittal projection.

5:37

If you want, you can move on to our summary overview.