0:00

Continuing on from the diagrammatic

0:02

vignette we did before, let's look at a representative case on the MRI.

0:08

Now, this kid is a 4-year-old boy with elbow pain.

0:12

There's plenty of things wrong with this kid.

0:14

There's a large joint effusion over here.

0:17

You can see that here.

0:18

You can see that over here.

0:20

And over here. This is the axial image on the right.

0:23

This is the sort of a coronal image.

0:26

The patient wasn't able to completely

0:28

extend his elbow because he was in so much discomfort.

0:31

But this is the trochlear area right here.

0:35

This is the capitellar area.

0:36

We know this is the capitellar area because here's the radial head.

0:39

Radial head, capitulum, ulna, trochlea.

0:42

And you remember from the prior vignette, we said that the pre-ossification center,

0:48

one of the places that it loves to develop, and we can see routinely is in the trochlea.

0:53

And here it is, right over here.

0:55

This area. Very, very high signal.

0:57

Almost looks like, "a blister."

0:59

That is the pre-ossification center.

1:01

This is where bone will develop.

1:04

So if we took this kid, you know,

1:06

next year or a few months later, this is where you'd see bone developing.

1:11

What happened here?

1:12

Blood vessels that run in through here, they coalesced,

1:16

they brought in mineralization factors, apoptosic factors, other

1:23

factors that caused the cells, the hypertrophy, and also to die apoptosis,

1:31

leaving this sort of area of high signal, which will eventually form bone.

1:35

Let's see what that looks like on some other sequences.

1:38

Let's bring up a sagittal sequence just so you have an idea.

1:42

I'm going to zoom up just a little bit.

1:44

Again, you notice there's a big joint effusion.

1:46

Pay no attention to that.

1:46

There are other problems that this kid has.

1:48

But one of those problems is not this.

1:52

This is the pre-ossification center in the trochlea.