0:00

Before we get to our next case, I want

0:02

to briefly illustrate for you a point I

0:04

mentioned in one of the earlier vignettes.

0:08

I mentioned that the epiphysis has

0:10

blood vessels that run through it, okay?

0:13

So what does that mean as far as the

0:16

development of the epiphyseal cartilage?

0:19

So let's draw that epiphyseal

0:20

cartilage one more time.

0:23

Nice big cartilaginous epiphysis, okay?

0:27

Within this, we have coalescence

0:32

of blood vessels in their own

0:34

channels at various locations.

0:37

That's just for the sake of argument.

0:38

Let's take that.

0:40

Okay, the blood vessels

0:41

are running through this.

0:43

These blood vessels are not just blood vessels.

0:46

There are arterioles, venules,

0:50

lymphatics, connective tissue, all

0:53

bringing nutrients into the cartilage

0:55

and taking waste products away.

0:57

That's the function.

0:57

Okay.

0:58

One of the things that it brings in is

1:00

mineralization factors and apoptotic

1:03

factors, just like we saw in the metaphysis.

1:07

So, what does that do?

1:08

That readies the cartilaginous

1:11

portion to undergo ossification.

1:13

It tells it to become bone, okay?

1:15

So when that happens, there's the forming of

1:18

what's called a preossification center, okay?

1:23

That preossification center

1:24

happens around blood vessels.

1:26

And that preossification center is

1:29

going to look something like this.

1:31

And it's going to be very bright.

1:34

Because it's going to be fluid-rich.

1:35

It's going to be cartilage cell-rich.

1:38

That's very big cartilage cells

1:39

that have a lot of fluid in them.

1:41

Okay.

1:42

And it's going to look like a blister in

1:44

the cartilaginous center of the cartilage.

1:47

You don't see it all the time.

1:49

But it typically happens around

1:50

the knee, the femoral condyles.

1:52

It typically happens around the elbow,

1:54

around the trochlea of the elbow,

1:56

and that's what I want to show you.

1:58

This is a normal finding and it's

2:00

important not to call it cartilage

2:02

injury or an area of cartilage damage.

2:06

So now let's go on and take a look

2:07

at a case that represents this.