Interactive Transcript
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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
0:09
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
0:22
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,
0:34
uh, in the distal ulna physis.
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The proximal, the distal radial physis, I think,
0:39
is a lot more conspicuous than the distal ulna.
0:42
But this is severe enough that it
0:43
has gone on to affect the ulna also.
0:46
This is a case of a gymnast's wrist.
0:49
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,
0:56
are doing handstands, uh, uh, and they're
0:58
putting a lot of weight, uh, on the wrist.
1:02
So why does it affect the distal
1:03
radius more so than the distal ulna?
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In fact, distal ulna typically isn't involved.
1:08
It's only involved in the very late stages.
1:11
Because look at the surface
1:12
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.
1:18
So much of the weight as they're doing
1:20
handstand is borne by the radius.
1:23
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
1:32
ulna has not reached the height of the radius.
1:36
So not only is there less surface area, it's not
1:39
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.
1:52
Uh, dorsiflexed and, and in that position
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it ends up affecting predominantly the
1:57
distal radius more so than the distal ulna.
2:00
So what's happening here?
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If we looked at an x ray of
2:04
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.
2:14
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?
2:28
Look at this, this is uniformly gray,
2:30
cartilage here is uniformly gray.
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So this is actually cartilage that
2:34
has invaginated into the metathesis.
2:37
Why does that happen?
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Remember, from our earlier videos, what
2:42
did we say lives in the metathesis?
2:45
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.
2:59
And it releases stuff, right, into the
3:04
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
3:20
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
3:43
no longer bring in those apoptotic
3:46
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.
3:59
That's why you've got an area with
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a widened cartilaginous component.
4:05
So this is cartilage that
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hasn't been told to die yet.
4:09
Oftentimes, this will get much better with rest.
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Uh, it doesn't need intervention, but if it's
4:14
severe enough and the child still continues to
4:17
do the activities, you can form a physeal bar.
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You can cause disruption of the
4:22
physes, which will not heal.
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