Get a Group Membership for your Organization. Free Trial
Pricing
Free TrialLogin

Hyaline Cartilage Anatomy

HIDE
PrevNext

0:00

Okay, let us take a look crudely

0:03

with a cartoon diagram of what the hyaline cartilage at birth looks like

0:08

and then we'll talk about some of the development.

0:10

We have a nice blank screen here.

0:11

I'm going to use a blue color just so you have an idea of what cartilage is.

0:17

And typically, I think of cartilages as being blue.

0:20

Let's just draw a nice big area here.

0:22

So think of this as the end of the long bone.

0:25

This is the epiphysis.

0:26

The metaphysis would be somewhere over here

0:28

and the diaphysis would be somewhere down here.

0:30

So right now we're concentrating on this part, which is the epiphysis.

0:36

I'm going to just call it EPI. Okay?

0:38

So when you're first born,

0:40

it's basically just a bunch of cells, bunch of cartilage cells.

0:49

They're very tightly packed.

0:51

And there are actually three components to this epiphysis.

0:55

There's what's called the articular

0:57

cartilage, which is at the surface. We're going to call that A for articular.

1:00

There is the majority, which is going to be

1:05

sort of in the center here, and that's called the epiphyseal cartilage.

1:11

The whole thing is the epiphysis and the majority is called epiphyseal cartilage.

1:15

And there's an area close to here,

1:18

the metaphysis, that's going to be the physeal cartilage.

1:23

And there's different composition of each section.

1:25

And actually, it depends on what the chemical and cellular

1:31

composition is to call this the articular, epiphyseal and physeal cartilage.

1:36

Let's talk now a little bit about the articular cartilage.

1:39

The articular cartilage, as I said, is the outermost layer of the epiphysis.

1:44

It contains three major things.

1:48

One, it's called aggrecan,

1:49

that's not very important.

1:51

Two, it has type 2 collagen.

1:53

And three, the most important thing, is it has a lot, a lot, a lot of water.

1:58

It's about 70% water by volume.

2:01

That's why on T2-weighted images and STIR images, the articular cartilage

2:06

looks very, very bright because of all the water that's unbound.

2:09

Okay? So, major thing to realize is it has a lot of H2O in the articular cartilage.

2:17

The articular cartilage also has several zones from the outside to the inside.

2:21

We're not going to worry so much about that.

2:23

The really important thing is the very

2:25

inner zone, which is calcified, and that often looks a little dark in MRI.

2:29

And I'll show you that as we go through these images.

2:31

The second thing I want to concentrate

2:33

on is the epiphyseal cartilage, which is this big area over here.

2:38

This is all epiphyseal cartilage.

2:40

In that epiphyseal cartilage, you've got chondrocytes, collagen,

2:43

glycosaminoglycans, and also has lots of water.

2:47

But the water in here, H2O in here,

2:52

are often bound to molecules, very tightly bound to molecules.

2:58

Because the water is tightly bound,

3:00

it's going to have a different signal characteristic

3:02

on MRI. It's often going to look a little darker, actually a lot darker

3:06

on the fluid sensitive sequences such as T2 or STIR.

3:09

Okay?

3:10

And you've got vessels coursing through there that actually we're going to talk

3:14

about how that contributes to

3:15

contribution to forming a bone later on.

3:19

And finally, the physeal cartilage,

3:21

which is this area over here next to the physis.

3:24

It's about 75% volume of cells.

3:27

So you think because there's so many cells there, it's going to be not so much water.

3:31

But the cells here are actually very big

3:34

and the intracellular component has a lot of water.

3:39

So that also an MRI is going to look very, very bright.

3:43

As a review, articular cartilage is going to be

3:45

bright, physeal cartilage is going to be bright,

3:49

and the epiphyseal cartilage, which is the majority here, is going to be very dark.

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

X-Ray (Plain Films)

Pediatrics

Non-infectious Inflammatory

Musculoskeletal (MSK)

Metabolic

MRI

Idiopathic

Congenital

Acquired/Developmental

© 2024 MRI Online. All Rights Reserved.

Contact UsTerms of UsePrivacy Policy