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This is a child who had an injury more proximally in her arm,

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which resolved, but she continued to have pain

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more distally.

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And this is the X-ray on the left,

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and an MRI on the right.

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The MRI is a fat-suppressed fluid-sensitive sequence,

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meaning that anything that's fat is going to be dark,

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anything that's edema or fluid, it's going to be bright.

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What's striking on the plain radiograph is the amount of osteopenia that's present.

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How do you judge osteopenia?

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Well, look at the trabecular pattern.

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It's striking, right?

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You can almost count every individual trabecula.

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And look how it gets more dark

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or loosened as you go from the central metaphysis to the periphery

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involving the metaphysis, from the diaphysis to the metaphysis.

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And it's centered around joints.

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Here's the PIP joint, DIP joint, sort of extensive.

0:59

So this is called periarticular osteopenia,

1:02

meaning that the degree of osteopenia is

1:05

accentuated more so around joints.

1:08

So there's periarticular osteopenia here, here, here.

1:11

Basically, everywhere that you see it.

1:13

Another objective way of determining

1:15

whether it's osteopenia or not, is looking at the thickness of the cortex.

1:20

For example, you should be able to see the cortex on either side of

1:24

this proximal phalanx well-defined.

1:27

But here, I don't know where the cortex ends and the medullary cavity begins.

1:32

Final way, if you are able to

1:34

determine the cortex thickness,

1:36

for example, let's say we could see the cortical thickness

1:38

was from here to here.

1:40

Let's say that was the cortical thickness.

1:42

If you double this value, it would be something that went out to here.

1:49

That value should be at least half

1:53

the length or half the width of your medullary cavity.

1:57

And it's not clearly half that, is it?

1:59

Right.

1:59

So we know objectively, and even subjectively,

2:03

you have osteopenia.

2:04

Osteopenia is one of the hallmarks of this

2:07

condition, which is chronic regional pain syndrome.

2:11

It typically happens after some traumatic event

2:14

more proximately. On the MRI,

2:16

what are you going to see?

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You're going to see these patchy areas

2:20

of STIR signal hyperintensity, likely indicating edema.

2:26

Centered around the metaphysis,

2:27

you can see it over here, over here.

2:29

These are very well looked.

2:30

This is not artifact, this is actually

2:33

abnormal signal within the marrow.

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And oftentimes, the physis will get

2:39

a little wider, it'll get more accentuated, as you see over here.

2:42

But what you're really looking for is these,

2:45

are these areas of STIR bright signal in the marrow.

2:49

Sometimes, you can actually even have

2:51

atrophy of the skin, atrophy of the soft tissues,

2:54

so on and so forth, which is I think more difficult to appreciate on MRI.

2:59

So this is a great example of chronic regional pain syndrome.

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A very important thing to look for

3:07

when you can't find a reason for pain.