0:00

This is a 12 year old girl with wrist pain.

0:04

On the image on the left is a dual echo

0:07

steady state, a gradient sequence, again

0:09

that's really good for marrow, differentiating

0:11

it from the cartilaginous physis.

0:13

And the image on the right

0:14

is a T1 weighted sequence.

0:16

Marrow is bright because it's fatty, physis

0:19

has a cartilaginous appearance, but we sort

0:22

of can't differentiate any more than that.

0:25

So what really stands out as

0:27

I look at this is how wide.

0:30

That physis is.

0:31

It's also present to a lesser extent,

0:34

uh, in the distal ulna physis.

0:36

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

0:51

Harris 1 injury to the physis.

0:54

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?

1:05

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.

1:14

It's a much wider surface area for

1:16

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.

1:25

In addition, typically as these kids get older,

1:28

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.

1:42

So again, that diminishes the amount of

1:44

loading that the ulna is going to face.

1:47

And finally, the positioning.

1:48

When they're doing these different

1:50

gymnast positions, it's sort of a.

1:52

Uh, dorsiflexed and, and in that position

1:54

it ends up affecting predominantly the

1:57

distal radius more so than the distal ulna.

2:00

So what's happening here?

2:02

If we looked at an x ray of

2:04

this child, what would we see?

2:05

We would see an area of, of, of

2:07

lucency in the distal radius, maybe

2:10

to a little bit of the distal ulna.

2:12

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

2:14

But look at the signal

2:15

characteristics over here.

2:17

Look at the signal here,

2:18

this versus this versus this.

2:23

It all has cartilage signal, right?

2:28

Look at this, this is uniformly gray,

2:30

cartilage here is uniformly gray.

2:31

So this is actually cartilage that

2:34

has invaginated into the metathesis.

2:37

Why does that happen?

2:39

Remember, from our earlier videos, what

2:42

did we say lives in the metathesis?

2:45

We've got vessels that come in,

2:50

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

2:53

just basically showing a macro of this.

2:56

Vessels comes in at loops.

2:59

And it releases stuff, right, into the

3:04

spongiosa, primary spongiosa of the metathesis.

3:09

That's what made that area very bright.

3:11

Remember that?

3:11

Because it's very vascular, it has a

3:13

lot of liquid, a lot of humeral factors.

3:17

If you remember, one of those humeral factors is

3:20

an apoptotic factor that tells cartilage to die.

3:24

That's what apoptosis is, programmed cell death.

3:27

So if you damage, let me get a little different

3:30

color here, if you damage these blood vessels,

3:34

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

3:35

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

3:36

much pressure, all that Salter-Harris injury,

3:39

you're damaging the very ends of these vessels.

3:42

If you damage those vessels, they can

3:43

no longer bring in those apoptotic

3:46

factors to tell the cartilage to die.

3:48

So since the cartilage can't

3:50

die, it just overgrows.

3:52

And how does it overgrow?

3:54

It overgrows into the metaphysis.

3:59

That's why you've got an area with

4:02

a widened cartilaginous component.

4:05

So this is cartilage that

4:06

hasn't been told to die yet.

4:09

Oftentimes, this will get much better with rest.

4:12

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.

4:20

You can cause disruption of the

4:22

physes, which will not heal.