0:01

This is a 42-year-old woman who's got, uh, wrist pain.

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You're shown two images, a coronal T1 fat suppression

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image with IV contrast and a short axis or axial

0:15

T1 fat suppression image with contrast as well.

0:19

Let's look at the relationship of the

0:22

radius and ulna to compare their variants.

0:25

When the ulna is...Start over.

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9 00:00:33,520 --> 00:00:33,880 Ready.

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This is a 42-year-old woman with wrist pain.

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You're shown a coronal fat-suppressed

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T1 contrast-enhanced image, and the same sequence

0:46

used in the short axis or axial projection.

0:50

Now, as I scroll the coronal projection, there

0:53

are innumerable findings, but one that probably

0:55

strikes you right away is the relationship

0:57

of the distal ulna to the distal radius.

1:01

Now, if we were to perform an X-ray with the

1:04

strict variance position, we would do so with

1:07

the shoulder abducted 90 degrees, the elbow

1:09

flexed 90 degrees, the forearm neutral, and

1:12

the hand aligned with the forearm axis.

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You wouldn't have any flexion or extension of the hand.

1:19

It'd be neutral and it'd kind of be

1:20

at the side, almost with the thumb up.

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And this is the typical X-ray position

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that we acquire for assessing variance.

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And there should be an equidistant position

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of the ulna relative to the radius.

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In other words, the ulna should

1:34

be over here, not back here.

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So we would describe this as negative ulnar variance.

1:40

And this distance would be,

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say, 5, 6, 7, 8 millimeters.

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Now, normally when measured in the proper hand

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surgery, radiographic position, that variance or

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disparity between the distal margin of the radius

1:55

and ulna should be about a millimeter or less.

1:58

With hand clenching, the ulna juts forward.

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Now, it's kind of strange in men, the variability

2:06

of this distance is less than it is in women.

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As one ages, the variability of these two distances

2:15

Now, if the ulna were to project distally

2:18

to the free edge of the radius, we would

2:20

describe that as positive ulnar variance.

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Now in MRI, because we're not in the exact same

2:26

position that we use for measuring on X-ray, we

2:28

don't say positive variance or negative variance.

2:30

We say positive ulnar variance posture, or in

2:32

this case, negative ulnar variance posture.

2:36

And we look for the indirect sequelae,

2:38

or signs, of negative ulnar variance.

2:42

Which are, by the way, Kienböck's disease,

2:46

which is known as lunate necrosis.

2:48

The patient doesn't have it.

2:49

Let's scroll.

2:50

There is no necrosis or collapse.

2:53

Another potential complication would

2:55

be radioulnar impingement or abutment.

2:58

We start to get some undulation and

3:00

irregularity under inflammation in this area.

3:02

And you can see that there is some remodeling

3:05

occurring along the ulnar aspect of the radius.

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And then the third one, which is not very well

3:12

advertised, but is present in this case, is because

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the ulna is disparately proximal to the radius, it puts

3:20

a traction on the peripheral and dorsal attachments

3:24

of the TFCC, especially the attachments to the

3:28

styloid and to the extensor carpi ulnaris subsheath.

3:31

These areas become inflamed due to this traction.

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Because again, when the ulna is short, there

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is a taut pressure placed on these attachments.

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And that is what you're seeing here.

3:44

You're seeing diffuse inflammatory enhancement

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of the ulnar side of the capsule, of the

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dorsal radioulnar mechanism, and of the

3:53

extensor carpi ulnaris subsheath, right there.

3:57

Now let's look in the axial projection for a minute.

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This would be at the level of the TFCC.

4:01

This is the area of the volar radioulnar ligament.

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This is the area of the dorsal radioulnar ligament.

4:07

We don't see them properly, but what we

4:09

do see is a congruent relationship.

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Not too much dorsal floating, and not too much

4:15

palmar floating of the ulnar relative to the radius.

4:18

Why is that important?

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Because in people with negative ulnar

4:21

variance, you will get radial ulnar

4:24

incongruity in the anteroposterior direction.

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So you might have to perform neutral,

4:30

pronated, and supinated short axis views

4:34

to make sure that that is not happening.

4:36

And you can do that on CT.

4:40

So those are the three major sequelae

4:43

of negative ulnar variance posture.

4:44

Radial ulnar abutment or impingement,

4:47

we have some of that here.

4:48

Although not much inflammation, but some remodeling.

4:51

Kienböck's disease or lunate

4:53

necrosis, which we don't have.

4:55

And sprain, chronic strain of the ulnar capsule

4:59

and its attachments, which we absolutely do have

5:03

and are seen in the form of diffuse swelling.

5:06

Along the ulnar capsule, surrounding

5:08

the ulnomeniscus homolog, and involving

5:11

the extensor carpi ulnaris subsheath.

5:15

Subsequently, these patients often will evolve

5:18

into extensor carpi ulnaris disease with micro

5:23

instability and small tears, intrasubstance is

5:27

how they start, and eventually the ECU will split.

5:32

Now, one other caveat.

5:32

Anomalies play a big role in some

5:37

cases of negative ulnar variance.

5:39

You're all familiar with the Madelung

5:41

or reverse Madelung deformity, which can

5:43

produce positive or negative ulnar variance.

5:46

You can also get changes in variance from

5:48

fractures up by the elbow or by the wrist,

5:51

premature closure of the growth plates.

5:54

But another important variable that is associated with

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changes in variance, especially negative variance,

6:01

is an enlarged, irregular, or dysplastic styloid.

6:05

Perhaps that's the fourth thing on the

6:07

checklist that I should have added to

6:09

those big three that I initially gave you.

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And when there is negative ulnar variance, the styloid

6:14

tends to be rather large and dysplastic looking.

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And it may abut against the triquetrum,

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especially in ulnar deviation, and cause notching

6:25

or pseudocyst formation of the triquetrum.

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That is not the case here.

6:29

This is a normal notch.

6:31

It's well corticated, there's no edema of

6:33

the triquetrum, all the swelling is in the

6:35

proximal soft tissues, and it's related to

6:39

stretching and a taut appearance or a taut

6:43

mechanism of these attachments in patients who

6:46

are pronating and supinating and hand gripping.

6:50

So this concludes our discussion

6:51

of negative ulnar variance.

6:53

I've given you four main potential

6:56

sequelae of negative variance to look for.

6:59

Kienböck's disease, radial ulnar impingement,

7:03

inflammation or strain/sprain of

7:06

the peripheral and dorsal attachments,

7:08

and dysplasia of the ulnar styloid.