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Gymnast’s Wrist

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This is a 12 year old girl with wrist pain.

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On the image on the left is a dual echo

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steady state, a gradient sequence, again

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that's really good for marrow, differentiating

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it from the cartilaginous physis.

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And the image on the right

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is a T1 weighted sequence.

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Marrow is bright because it's fatty, physis

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has a cartilaginous appearance, but we sort

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of can't differentiate any more than that.

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So what really stands out as

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I look at this is how wide.

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That physis is.

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It's also present to a lesser extent,

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uh, in the distal ulna physis.

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The proximal, the distal radial physis, I think,

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is a lot more conspicuous than the distal ulna.

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But this is severe enough that it

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has gone on to affect the ulna also.

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This is a case of a gymnast's wrist.

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This is a chronic Salter

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Harris 1 injury to the physis.

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So these gymnasts, as you can imagine,

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are doing handstands, uh, uh, and they're

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putting a lot of weight, uh, on the wrist.

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So why does it affect the distal

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radius more so than the distal ulna?

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In fact, distal ulna typically isn't involved.

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It's only involved in the very late stages.

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Because look at the surface

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area that you have over here.

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It's a much wider surface area for

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the radius than there is for the ulna.

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So much of the weight as they're doing

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handstand is borne by the radius.

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Okay, not so much by the ulna.

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In addition, typically as these kids get older,

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the ages at which they're susceptible, often the

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ulna has not reached the height of the radius.

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So not only is there less surface area, it's not

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quite up to the same level as the distal radius.

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So again, that diminishes the amount of

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loading that the ulna is going to face.

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And finally, the positioning.

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When they're doing these different

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gymnast positions, it's sort of a.

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Uh, dorsiflexed and, and in that position

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it ends up affecting predominantly the

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distal radius more so than the distal ulna.

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So what's happening here?

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If we looked at an x ray of

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this child, what would we see?

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We would see an area of, of, of

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lucency in the distal radius, maybe

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to a little bit of the distal ulna.

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And that'll look like a sort of a fracture.

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But look at the signal

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characteristics over here.

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Look at the signal here,

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this versus this versus this.

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It all has cartilage signal, right?

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Look at this, this is uniformly gray,

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cartilage here is uniformly gray.

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So this is actually cartilage that

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has invaginated into the metathesis.

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Why does that happen?

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Remember, from our earlier videos, what

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did we say lives in the metathesis?

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We've got vessels that come in,

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a form of the loop, and I'm also, I'm

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just basically showing a macro of this.

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Vessels comes in at loops.

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And it releases stuff, right, into the

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spongiosa, primary spongiosa of the metathesis.

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That's what made that area very bright.

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Remember that?

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Because it's very vascular, it has a

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lot of liquid, a lot of humeral factors.

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If you remember, one of those humeral factors is

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an apoptotic factor that tells cartilage to die.

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That's what apoptosis is, programmed cell death.

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So if you damage, let me get a little different

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color here, if you damage these blood vessels,

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and that's what you're doing when you're,

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when you're a gymnast, you're putting so

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much pressure, all that Salter-Harris injury,

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you're damaging the very ends of these vessels.

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If you damage those vessels, they can

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no longer bring in those apoptotic

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factors to tell the cartilage to die.

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So since the cartilage can't

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die, it just overgrows.

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And how does it overgrow?

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It overgrows into the metaphysis.

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That's why you've got an area with

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a widened cartilaginous component.

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So this is cartilage that

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hasn't been told to die yet.

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Oftentimes, this will get much better with rest.

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Uh, it doesn't need intervention, but if it's

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severe enough and the child still continues to

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do the activities, you can form a physeal bar.

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You can cause disruption of the

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physes, which will not heal.

Report

Faculty

Mahesh Thapa, MD, MEd, FAAP

Division Chief of Musculoskeletal Imaging, and Director of Diagnostic Imaging Professor

Seattle Children's & University of Washington

Tags

Trauma

Pediatrics

Non-infectious Inflammatory

Musculoskeletal (MSK)

MRI

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