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and previous noon conferences by creating a free account.

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Today we're honored to welcome Dr.

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Donald Resnick for a lecture entitled Tissue Delamination

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Pathological Unraveling of Tendons, ligaments,

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and Articular Cartilage.

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Dr. Resnick is a renowned lecturer and his list of awards

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and honors include twice awarded Aunt Mini's most effective

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radiology educator, 20 eighteens a CR gold medal

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for his lifetime achievements

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and an honorary doctorate from the University of Zurich.

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We're so thrilled he's here today

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to share his expertise with all of us.

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At the end of the lecture, please join him in a q

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and a session where he will address questions you may

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have on today's topic.

0:56

Please remember to use that q

0:58

and a feature to submit your questions so we can get to

1:00

as many as we can before our time is up.

1:02

With that, we're ready to begin today's lecture. Dr.

1:05

Resnick, please take it from here.

1:07

Uh, thank you very much.

1:09

It's a privilege for me to be back again to give one

1:12

of these noon conferences

1:14

and I've picked an interesting topic you've already heard.

1:17

It's gonna relate to tissue delamination

1:21

utilizing mainly MR Imaging.

1:24

Over the next 45 minutes

1:26

or so, we're gonna look at the way that certain tendons

1:30

and ligaments and particularly articular cartilage may fail

1:34

owing to the process of delamination.

1:38

Two general objectives that are listed here

1:41

to review the anatomic basis of tissue delamination.

1:45

And we're gonna emphasize the collagen architecture in

1:49

tendons and then in ligaments

1:51

and finally in articular cartilage.

1:54

And then knowing that collagen architecture,

1:58

we're gonna show you why there are certain particular

2:01

patterns of failure in which the term delamination

2:05

is appropriate.

2:08

If you go to a medical dictionary

2:10

or even an English dictionary

2:11

and you look up the word delamination, this is

2:14

what you will find.

2:16

It's a mode of failure in which a material fractures

2:19

or separates into two or more layers typically.

2:24

Then it relates to layered material.

2:27

Now those materials

2:28

that are layered may fail in a delaminated fashion shown

2:32

here, or they may fail in a non delaminated fashion.

2:37

Shown at the bottom of this slide

2:40

we're gonna emphasize today, delamination,

2:43

we can see this process

2:45

of failure in a lot of different things.

2:47

I'm illustrating three here on your left delamination

2:51

of cement in the middle, delamination of ceramic,

2:56

and on your right delamination of wood.

3:00

And while we're dealing with wood,

3:01

let me show you this example.

3:03

The way timber fails here is a cross section

3:07

of a wood log showing you two patterns of failure.

3:11

They have fancy names.

3:13

If you look at the pattern at the top called shake,

3:17

it's failure of timber related to delamination

3:21

along the growth rings of the wood.

3:24

If you look to the left, you'll see the word checking,

3:27

which is kind of anti delamination.

3:30

It's failure of timber related to cracks

3:33

that intersect though those growth rings.

3:36

And I was looking at this particular picture just this week

3:39

and I said, boy, it reminds me of something.

3:42

And what it reminds me of is the way

3:44

that the annulus fibrosis

3:46

of the intervertebral discs may fail.

3:49

We see fissures or clefts within the annular substance.

3:54

Some are delaminated. The word shake could actually be used.

3:58

And I illustrate that.

4:00

As you can see with one of those, the longer yellow arrow

4:04

and the other anti delamination, let's call it checking

4:08

of the annulus fibrosis failure at right angles

4:12

to the delaminated pattern of failure.

4:15

This looks very, very similar to me,

4:18

but we're not gonna deal with the intervertebral disc today.

4:21

We're gonna deal with these three particular substances.

4:25

We're gonna start with tendons.

4:27

Let's talk a little bit about the structure of tendons

4:31

emphasizing some of the collagen, uh,

4:34

of which they are composed and look at delamination.

4:39

Many years ago I came up with this particular drawing

4:42

to illustrate the simplest situation

4:45

of the muscle tendon bone unit.

4:49

Now I can tell you, and you'll hear this

4:52

directly a little later in this particular lecture,

4:55

this is simplistic

4:56

and doesn't in fact really account for

4:59

what we see in many different regions of the human body.

5:02

But let's go with this. In my drawing,

5:04

there is a single tendon entering a single muscle belly

5:10

at a proximal myo tendonous junction.

5:14

And we follow that over to the right

5:16

and we see a single exiting tendon at the distal myo

5:21

tendonous junction extending over further right

5:24

to attach to the bone.

5:26

That site of attachment, you know,

5:28

well perhaps you call it a footprint.

5:31

I know some of my colleagues call it a foot plate, others

5:35

fancy terminology and emphasis.

5:38

So this is what we learn

5:41

probably in medical school about a muscle tendon bone unit.

5:45

We learn also about the importance of tendons.

5:49

They connect muscles to bone and therefore they allow

5:52

and control joint motion.

5:56

Now let's look at a a little more detail here

5:58

and look at the collagen.

6:00

I'm showing you here a red tendon, I'm showing you here,

6:05

collagen fibers, they're the smallest unit.

6:07

They're in dark blue.

6:09

And here are the collagen bundles,

6:11

and I'm pointing out in this particular 3D like picture

6:16

that most of the collagen bundles

6:19

or fales are oriented along the long axis of attendant.

6:25

Now think about it, tensile force is applied to attendant.

6:29

The axis of that tensile force typically in most situations

6:34

is along the long axis of the tendon.

6:37

So these collagen fibers within their collagen bundles are

6:43

oriented ideally to resist the tensile force

6:46

applied to the tendon.

6:48

Here's my cross section

6:50

of the tendon showing you the collagen bundles in blue.

6:54

I'm showing you also now cellular connective tissue

6:59

between and among these collagen bundles.

7:02

Now let's do an experiment here is kind of a lateral drawing

7:07

of a tendon, again tendon in red.

7:10

I'm showing you two collagen bundles

7:14

and cellular tissue between them.

7:17

And in my experiment, I'm applying a tensile force

7:21

along the long axis of the tendon.

7:24

And what this picture is showing you is that as

7:27

that tensile force is applied, there is elongation

7:32

of the collagen bundles, but not to the same extent.

7:37

One bundle may elongate more than another,

7:41

and what that produces is something called

7:44

interfa movement.

7:47

Now you might think, in fact, if you have that movement,

7:49

there is friction in the connective tissue between

7:53

and among these collagen bundles.

7:56

Well, we're fortunate

7:58

because the human body provides us

8:00

with a lubricating factor.

8:02

It has a fancy name, it's called lubricant.

8:06

And because of that, that connective tissue

8:08

between the collagen bundles is lubricated

8:11

and hence the friction typically does not produce failure.

8:16

The pictures on your left are taken from a very nice article

8:19

now about, uh, 15, 16, 17 years ago,

8:23

showing you the lubricant stained brown

8:27

shown by arrows and arrow heads here.

8:30

And you can appreciate the collagen bundles located

8:34

on either side of these areas of luon.

8:38

Now, as we get older, a lot of bad things happen.

8:40

I know that well, not the worst of which is the loss

8:44

of luin.

8:46

And if in fact you lose luin,

8:49

friction will produce a particular pattern of failure

8:52

that spares the collagen bundles that is located

8:56

between and among them.

8:58

And shown in a picture on your left, that process of failure

9:03

represents tendon delamination.

9:06

So it is a collagen sparing process

9:10

as it relates to tendons.

9:13

Now to go further, let's look at some

9:15

of the terminology we applied to tendon abnormalities

9:19

that we see on Mr.

9:21

The first of these is the term full thickness.

9:24

A full thickness tear is a tear

9:26

that extends entirely from the superior

9:29

to the inferior surface medial to the lateral surface

9:33

or even obliquely.

9:35

Okay, so as this hair develops, all

9:38

of the collagen within the segment of the tear

9:42

is in fact disrupted.

9:46

We use the term split tear.

9:47

It is a full thickness tear,

9:50

but it is a delaminated tear

9:54

as classically described.

9:56

It proceeds in a horizontal or vertical direction,

9:59

and as it goes through the entire tendon,

10:03

it spares the collagen.

10:05

Now we see these split full thickness tears in many

10:08

different sites, but this most popular site is shown here

10:13

we see split tears, longitudinal delaminated, tears

10:17

of the peroneous brevis tendon.

10:19

I've labeled it PB on a transverse section

10:22

through the distal fibula.

10:24

And you can see a corresponding, uh, transverse

10:29

Mr image showing you

10:31

that the peroneous brevis tendon is split into two parts,

10:35

a split tear with the peroneous longest tendon labeled pl

10:40

located just behind it.

10:42

So a split tear is a full thickness delaminated

10:46

tear of a tendon.

10:48

Now here I'm showing you on your left some delaminated tears

10:52

and on your right non delaminated tears on your left.

10:57

The delaminated tears that I'm illustrating

11:00

actually are not disrupting, uh, the surface of the tendon.

11:04

But they may of course in involve at one or both surfaces.

11:09

On your right you can see

11:11

what a non delaminated tear might look like.

11:14

And you can see because of its shape,

11:16

and in this case its size,

11:19

collagen bundles will be disrupted.

11:21

Now one of the places

11:23

that we see delaminated tears will relate

11:26

to the rotator cuff,

11:28

and I show you a classic pattern here on an Mr arthrogram

11:32

of the Glen Humeral joint.

11:34

What we're looking at is a partial thickness

11:37

delaminated tear.

11:39

The articular surface of the supraspinatus tendon presumably

11:43

is in fact disrupted.

11:46

The uh, contrast material has entered the tendon.

11:50

And now we see this pattern of

11:53

delamination extending medially toward the myo tendon.

11:57

This junction, this is a classic pattern of failure

12:00

that we see in the rotator cuff tendons.

12:04

And for those of you who are doing, uh, Mr imaging

12:08

of the rotator cuff, you've seen pictures just like this.

12:13

When we deal with these del laminated tears

12:18

that extend medially, sometimes at the very end

12:22

of the delamination is a more dilated cyst like region.

12:27

We call it a sentinel cyst.

12:29

In this example, involvement of the subscapularis tendon,

12:34

a delaminated tear with a sentinel cyst.

12:39

I'm showing you now pictures of delaminated tendon tears,

12:43

partial thickness on your left,

12:45

full thickness on your right.

12:47

The full thickness tears on your right are split tears.

12:51

I'm showing you a vertical one

12:53

and a horizontal one with regard

12:55

to the partial thickness tears.

12:58

I'm showing you delaminated intrasubstance tears

13:01

and delaminated tears in which a surface of the collagen,

13:06

uh, of the tendon is disrupted.

13:09

Collagen sparing delaminated tears on your left,

13:14

uh, partial thickness

13:16

and collagen sparing full thickness tendon

13:20

tear on your right.

13:22

Now let's go into more detail about delaminated tears

13:26

of the rotator cuff tendons.

13:28

The pictures on your right taken from the literature,

13:32

the importance of diagnosing a delaminated tear.

13:35

When you look at the MR is it tells the orthopedic surgeon

13:39

this tear is a little bit more difficult to treat.

13:42

More extensive surgery may be required.

13:46

Typically, when you see delaminated tears,

13:50

the articular sided fibers here,

13:52

the deep layer are generally retracted more than the bursal

13:57

sided or superficial layer,

13:59

beautifully shown on the upper image on your right, right.

14:03

There's often a cellular lining to the area

14:07

of delamination that resembles a synovial memory.

14:13

Now we see delaminated tears in all types

14:16

of clinical situations.

14:18

One of the, uh, places we see it are in

14:20

our baseball pitchers.

14:22

We have a professional team, the San Diego Padres.

14:26

And if in fact you do arthrography on a baseball pitcher

14:31

who has shoulder pain,

14:33

you may in fact see a delaminated tear.

14:36

I'm showing you here an Mr Agram in the abducted

14:40

externally rotated position called Abe.

14:44

The contrast material within the joint is passing through

14:48

torn articular sided fibers,

14:51

and then is extending between the articular sided

14:54

and bursal sided fibers In a delaminated fashion,

14:59

Abe images are terrific

15:01

for picking up tendon delamination.

15:08

I'm now gonna talk briefly about

15:10

full thickness delaminated tears.

15:14

You'll see on your left two illustrations.

15:18

This is what a full thickness non

15:20

delaminated tear looks like.

15:22

There's uniform retraction of all of the torn tendon fibers.

15:28

Now let's look at the bottom.

15:30

This is what a full thickness delaminated tear looks like

15:34

with differential retraction of the torn fibers.

15:38

And as I've indicated in almost all cases,

15:41

it is the articular sided fibers that are retracted further

15:46

than the bursal sided fibers.

15:49

Here's a cadaver.

15:50

Years ago we injected latex into this glen humeral joint.

15:55

The latex extends

15:56

through the torn tendon filling the subacromial

16:00

subdeltoid bursa.

16:02

This is a delaminated tear full thickness

16:06

with the articular sided fibers retracted far more than

16:10

the bursal cited.

16:12

And here in an MR image, again, it's an old one,

16:16

not great resolution,

16:18

but look how it looks exactly like the cric section.

16:21

A delaminated full thickness tear with more retraction

16:25

of the articular sided than the bursal sided fibers.

16:30

This is what a partial thickness

16:33

delaminated tear would look like here,

16:36

the supraspinatus tendon on in the coronal plane,

16:39

the white arrow showing you the retracted articular sided

16:44

fibers, whereas the bursal sided fibers are intact.

16:48

And in the transverse or transaxle

16:51

or axial plane, whatever you call it,

16:53

here is the low signal reflecting the edge

16:58

of the retracted articular sided fibers.

17:03

Now, although we talk about tendon delamination shown here,

17:08

there is a particular pattern that I would also emphasize

17:12

where the delamination is between the capsule

17:15

and the tendon, and we see that

17:18

with the rotator cuff tendons here.

17:20

I just wanted to show you, as we look at a coronal section,

17:25

this is the superior capsule of the glen humeral joint.

17:30

This is the tendon here.

17:32

I mean, this is the muscle

17:33

and the tendon of the supraspinatus.

17:36

So be aware, when you look at the footprint,

17:39

it's not just a tendon footprint,

17:42

it is a capsular footprint,

17:44

which can occupy sometimes 30%

17:48

of the visualized footprint

17:49

that you're seeing on the mr image.

17:52

In the example at the bottom, you can appreciate

17:56

that there is in fact a torn capsule.

17:59

Okay? You can see it's attaching to the superior surface

18:03

of the glenoid.

18:05

Here is the tendon above it,

18:08

and you can see the failure with delamination is

18:11

between the capsule and the tendon shown in both

18:15

of these images.

18:17

So that's tendo capsular delamination,

18:21

and we see that same pattern at the footprint here.

18:26

Here is the footprint.

18:27

In a normal situation, we can see tendon,

18:31

but this is the superior capsule Here in a cadaver,

18:35

we can see failure that appears

18:37

to be located at the junction between the capsule

18:40

and the tendon illustrated here.

18:42

This was with Mr. Arthrography and Mr Biography.

18:47

Here is the delamination between the capsular fibers

18:51

and the tendon fibers.

18:54

Now finally, with regard to these tendons,

18:57

the term novel lesion.

19:00

Novel lesion is the term that's been described mainly

19:03

for the in infraspinatus tendon, but it can occur elsewhere.

19:07

So remember that first picture I showed you

19:10

that I said was simplistic

19:11

because you see, when you look at the anatomy

19:14

of the muscle tend bone unit, you will see a variety

19:18

of anatomic situations.

19:20

For example, you may have a single muscle belly

19:24

with two exiting tendons and perhaps failure of one.

19:28

Or you may have two muscle bellies with two exiting tendons

19:32

and failure of one.

19:34

You have to have enough vocabulary when you are reporting

19:39

tendon problems, particularly in the rotator cuff,

19:43

to let the orthopedic surgeon know exactly what's going on.

19:47

Things can get complicated

19:50

and this pattern of failure can often lead to delamination.

19:55

So let's look at that infraspinatus.

19:58

We're looking here at

20:02

a a cadaver picture showing you what has been suggested

20:07

as the anatomy of the infraspinatus muscle.

20:12

That's this part. Many people believe that here, I'm sorry,

20:16

here's the infraspinatus muscle.

20:18

Many people believe there are two parts to that muscle.

20:22

There is a larger angulated part shown here, known

20:27

as the oblique part that extends over

20:30

and attaches to the greater tuberosity.

20:34

And there is a smaller, more horizontal part,

20:37

the transverse part that extends over

20:40

and attaches perhaps to the myo tendonous junction

20:44

of the oblique part of the in infraspinatus.

20:48

And a pattern of failure that we may see is failure

20:53

of the tendon of the transverse part where it attaches

20:57

to the myo tendonous junction of the oblique part shown here

21:02

and shown here in this particular example with retraction

21:07

of the tendon of that transverse part, this

21:12

represents delamination.

21:14

Here's another example showing you the same thing.

21:17

A beautiful picture from Arad source web

21:19

clinic on your left.

21:21

This is a Del Delaminated novel lesion

21:26

of the in infraspinatus.

21:29

Now, the same thing can occur with a supraspinatus.

21:32

Here is my picture. Here's the humeral head.

21:35

You are, for example, the subacromial subdeltoid bursa.

21:39

You're looking down on the supraspinatus muscle.

21:43

You see a larger anterior muscle belly

21:46

with a long intramuscular tendon, somewhat delicate.

21:51

You see a posterior strap muscle

21:53

with a more terminal tendon,

21:55

and then they merge to attach to the greater tuberosity,

22:00

a delaminated pattern of failure

22:03

of the supraspinatus tendons.

22:06

We'll call a novel lesion shown here, full thickness partial

22:11

with tear involving the tendon of the anterior muscle,

22:15

but sparing the tendon

22:18

of the posterior muscle a delaminated tear.

22:23

Okay, we're done with our first structure.

22:25

We're gonna move now from tendons to ligaments.

22:31

Now the the morphology of a ligament is very, very similar

22:35

to that of a tendon.

22:37

The collagen fibers are indeed mainly

22:40

oriented along the long axis of a ligament

22:44

to absorb tensile force,

22:46

but they're slightly less oriented in a linear fashion.

22:50

So I'm gonna show string beans,

22:52

perhaps they illustrate that.

22:54

Now, when we look at failure of a ligament, various patterns

22:59

that we may see complete failure

23:03

would represent a pattern of failure.

23:05

Typically a transverse

23:07

or obliquely oriented defect in which all

23:10

of the collagen bundles within that ligament would fail.

23:14

I show you this complete tear in the mid portion

23:18

of the anterior cruciate ligament.

23:22

A partial thickness tear would be a transversely

23:26

or obliquely oriented problem,

23:29

pathology within the ligament disrupting some

23:33

of the collagen bundles but not the others.

23:36

And I show you perhaps an example of that.

23:39

Here you can see a little bit

23:41

of high signal within the anterior cruciate ligament.

23:45

The third pattern of PA of failure is a delaminated tear.

23:50

And in common with a tendon, it is a pattern of failure

23:54

that spares the collagen bundles leading to areas

23:58

of high signal intensity here within the anterior cruciate

24:02

ligament between and among intact collagen bundles.

24:08

Now, as you look at that picture on the bottom right,

24:11

it should remind you of something.

24:13

It should remind you of an entity

24:15

that is well described in our literature that goes

24:19

by a variety of names, cystic degeneration

24:23

or mucinous degeneration.

24:25

It relates to mucinous change within the connective tissue

24:30

between the collagen bundles typically

24:33

of the anterior cruciate ligament.

24:36

So here is what it might look like

24:38

in a specimen sagittal section

24:41

through the anterior cruciate ligament.

24:44

It occurs with increased frequency, as with advancing age

24:49

On physical exam,

24:52

such a ligament generally is stable,

24:55

the knee will be stable, there may be pain,

24:59

often asymptomatic, but there may be pain.

25:01

And with regard to the ACL, that pain is typical

25:06

on terminal extension of the knee.

25:11

Now, one of the interesting aspects of the footprint

25:14

of the anterior cruciate ligament is it is intimate

25:17

with the anterior root ligament

25:20

of the lateral meniscus here from some cadavers we

25:23

studied a while ago.

25:25

Here you can see that these two footprints, that

25:29

of the ligament and of the lateral meniscus are intimate

25:32

and sometimes actually overlap each other.

25:35

So when in fact you have severe cystic degeneration

25:40

of the anterior cruciate ligament,

25:42

you may see similar abnormalities involving

25:46

the anterior root ligament of the lateral meniscus

25:50

and even the anterior horn.

25:51

Here's a beautiful example of

25:54

what cystic degeneration looks like

25:58

in the anterior cruciate ligament.

26:00

And here, abnormal anterior root ligament

26:04

of the lateral meniscus, cystic mucinous degeneration.

26:09

A condition we see in older people.

26:12

Now, there are names that have been applied to the uh,

26:16

image, the findings,

26:18

a celery stalk appearance shown in this example, a bag

26:23

of worms appearance shown in this example.

26:28

And with cystic degeneration

26:30

of the anterior cruciate ligament, intraosseous ous

26:35

ganglion cyst may develop less commonly in the femur,

26:39

more commonly in the tibia,

26:40

as shown in these three uh, or images.

26:43

And probably you know also that para cruciate

26:47

soft tissue ganglion cyst may also be seen

26:51

dominating posteriorly.

26:53

We see the same process in older people

26:56

involving other ligaments.

26:58

For example, here this is severe cystic

27:01

or mucinous degeneration of the posterior bruche ligament.

27:08

Now what happens when you see something like that

27:12

but the patient is younger?

27:14

Here I'm showing you images of a 26-year-old soccer player.

27:18

But let's say it's a 10-year-old

27:20

and you see something like this where there's some linear

27:23

altered signal areas of high signal, uh,

27:27

between the collagen fibers of the anterior crucet ligament.

27:32

If you're dealing with a child or adolescent

27:34

and you tell the mother, that's cystic degeneration,

27:37

I'm sure the parent will be upset.

27:40

This is something that you may see in active persons,

27:45

adolescents, young athletes,

27:47

and it relates to repetitive stress.

27:50

It's a pattern of delamination shown here between

27:55

intact collagen bundles.

27:58

Typically the patients have maybe mild pain, okay?

28:02

The knee is stable, the MR imaging findings

28:05

and any clinical manifestations will disappear

28:10

over a period of time.

28:11

We call this interstitial delamination when we see it in a

28:16

young person and we indicate it likely relates not

28:20

to a single traumatic event, but to repetitive stress.

28:26

Okay? We've now covered tendons and ligaments.

28:29

We now will address in the final part

28:32

of this particular lecture, something a bit more

28:36

complicated, delamination of articular cartilage.

28:41

So once again, we have to look at the structure, the anatomy

28:45

of articular cartilage, which in most areas

28:48

of the body is hylan cartilage, not fibro cartilage.

28:52

On your left, a histologic picture on right,

28:56

my 3D picture of what articular cartilage looks like.

29:02

So what we see here in this blue is the

29:06

noncalcified portion of articular cartilage.

29:10

We'll talk a little bit more about this in a moment

29:13

as we proceed downward.

29:16

Okay? We can see that there are certain zones,

29:19

and I'll also show you in a few minutes, cellular

29:22

rows within this particular portion of cartilage.

29:26

At the very bottom in red, I'm showing you this plate

29:31

that is called a tide mark.

29:33

It is a histologic landmark.

29:36

You can see it beautifully here.

29:38

Below the tide mark is the

29:41

calcified cartilage shown in blue.

29:44

So the tide mark is at the junction of the noncalcified

29:49

and calcified cartilage.

29:51

Okay? You can kind of see that here.

29:53

Below that, a layer of compact bone.

29:57

And below that the subc chondral bone.

30:00

So that's the typical morphology of articular cartilage

30:05

and subc chondral bone.

30:06

We're gonna add to it.

30:08

Now, the collagen bundles, you can see at the very top

30:13

that there are layers of collagen, generally several.

30:18

This is known as the laminate SPLs

30:21

of the articular cartilage.

30:24

Below it, there are arcades of collagen described

30:27

by benninghoff, known by every orthopedic surgeon,

30:31

often designated the arcades of benninghoff.

30:35

And these extend downward from the superficial layers

30:38

of cartilage to the deep layers through, in fact,

30:42

the tide mark into the calcified cartilage,

30:45

and sometimes below that as well.

30:48

So if you've ever wondered how force applied to the surface

30:52

of articular cartilage reaches the subc chondral bone,

30:56

you can blame the arcades of benninghoff as the carrier

31:01

of that particular force.

31:04

Now, one other point I would make is that compact bone,

31:08

because I've seen a mistake made often by residents,

31:11

fellows, and even by radiologists themselves.

31:16

There are two types of compact bone in the human body.

31:20

The first of these well known to you is formed

31:23

by the periosteal membrane owing to the process

31:27

of intramembranous bone formation.

31:30

You see it on the surfaces of bone that is called cortex.

31:35

But the other area of compact bone,

31:37

as we're talking about here, occurs at the end of the bone

31:42

as the cartilage lays down that compact bone

31:45

through a different process known as endon

31:49

or endochondral bone formation.

31:52

So when you see a white line at the end

31:54

of the bone on a plain film

31:56

or ct, you should not be calling that cortex.

32:00

The proper term is a SubCal bone plate.

32:05

All right? That's a very important anatomic point.

32:08

I see the long-term cortex often applied to

32:12

that area, that white line that we see.

32:17

Now, here's the beautiful pictures taken from the literature

32:20

with electron microscopy showing you the laminate

32:24

splendid layer of collagen.

32:25

Then we can see the arcades forming

32:28

and deeper down, becoming more and more vertical.

32:32

This the collagen framework.

32:36

Now, when we talked about tendons and ligaments

32:40

and delamination, we use collagen

32:43

as our point of reference.

32:46

When we talk about articular cartilage based on the

32:50

literature, sometimes collagen is used

32:53

and sometimes something else.

32:55

Here I'm showing you the layers

32:57

and columns of collagen in articular cartilage.

33:01

But you see we have horizontal cellular rows as well,

33:06

and some people talk about separation

33:09

of cellular rows in articular cartilage as a pattern

33:13

of delamination.

33:15

So you end up with something like this.

33:17

I'm showing it on a pic, my picture on the right, different

33:22

patterns of failure that people have called delamination.

33:26

Let's look at them. Labeled number one

33:29

is failure in the mid portion of articular cartilage.

33:34

This is delamination.

33:36

If you're using horizontal cellular rows

33:40

as your point of reference.

33:43

Two A is showing you delamination

33:47

horizontal in nature occurring in the laminate Splendas.

33:51

We're using collagen as our point of reference.

33:55

Two B is a pattern of failure that occurs in the tide mark.

34:01

That is an area that is prone to failure with sheer forces.

34:05

So again, we're using collagen as our point of reference.

34:10

And two C is vertical

34:12

or vertical O blight failure, again, with reference

34:16

to collagen delamination, parallel

34:19

to the arcades of Benning law.

34:22

So two A, two B

34:23

and two C deamination related to collagen,

34:29

uh, architecture.

34:30

And number one, deamination related to cellular rose.

34:35

In my vocabulary with my terminology, I do not refer

34:39

to failure, uh, between cellular rose as deamination.

34:44

I'm a collagen fan.

34:46

And so when I talk about deamination, I'm talking about it

34:50

with reference to the collagen.

34:53

But let's look at some examples.

34:55

So if you're a fan of cellular rose,

34:58

this pattern would represent delamination

35:01

and perhaps I illustrated here as a horizontal

35:05

or like cleft,

35:06

and I show you what it looks like on these two MR images,

35:12

delamination only if you are using cellular rose

35:16

as your point of reference.

35:19

But if we go back to the collagen, this is horizontal

35:24

delamination occurring in the laminate.

35:27

Splendid right at the surface, it reminds me of failure

35:31

of roof shingles.

35:32

I've had that problem in my own house.

35:35

Alright, this is what it looks like

35:37

with electron microscopy.

35:40

This is what it looks like with gross pathology.

35:43

This is what it looks like with histology

35:46

and the proper term, if you see that on Mr.

35:50

Is cartilage fibrillation, A surface phenomenon

35:54

with a feathery appearance, delamination

35:58

of the laminate Splendas.

36:01

This is delamination that is parallel

36:04

or somewhat parallel to the arcades of Bening Hall.

36:08

Here's what it looks like in a specimen.

36:10

This is the proximal tibia.

36:12

Here's what it looks like in a patella, as is this.

36:16

This particular pattern is cartilage fissuring vertical

36:21

or vertical Obi clefts extending downward from the surface

36:27

somewhat parallel to the arcades of Benning law.

36:32

That's my favorite area of fissuring that I see on EMR.

36:37

We call it the black line of death. Alright?

36:41

You can see here linear region

36:43

of low signal here in a specimen.

36:46

What that might look like.

36:48

Fissuring delamination using the arcades of benninghoff

36:53

as our point of reference.

36:56

Occasionally what you will see is delamination only

37:01

at the tide mark.

37:03

And in fact, this can be a problem

37:06

because when you look quickly at the mr,

37:08

you may not see much.

37:10

Here's an example. Eric Chang, one of my associates

37:13

provided it here at the time of injury.

37:17

Everything looks good.

37:18

Nine months later, a subtle cur linearal region

37:22

of abnormal signal in the trochlea, right

37:26

representing horizontal deamination at the Tide Mart,

37:31

separating calcified

37:33

and noncalcified cartilage, an area

37:37

that is in fact susceptible to shearer strain.

37:43

And then we see more extensive delamination here by drawing.

37:48

You can see failure at the surface, vertical delamination,

37:52

and then horizontal delamination at the tide mark.

37:56

Here we can see the disruption of the surface

37:59

and the delamination occurring at the tide mark separating

38:04

a large portion of the articular cartilage.

38:07

The arthroscopist will see this fairly easily

38:11

because there is in fact disruption of the surface.

38:17

Here's another example here.

38:19

We can see the point of surface disruption.

38:23

You can see the extensive deep chondral delamination

38:26

at the tide mark.

38:28

The separation of a large segment

38:30

of the articular cartilage.

38:32

Here again, the arthroscopist should be able

38:35

to see this pretty quickly because the surface is disrupted.

38:41

But this is the carpet lesion which can create problems

38:45

where the delamination is occurring just at the tide mark.

38:50

You can see here that the surface is slightly irregular

38:55

and maybe over here there is some disruption.

38:58

But in the region of this delamination,

39:00

the surface is not disrupted.

39:03

This is more difficult for the arthroscopist,

39:06

that's why it's called a carpet lesion.

39:09

But the good arthroscopy can look at it or probe it

39:13

and we'll see Findings are often called the wave sign

39:16

or bubble sign to indicate there's deep

39:19

chondral delamination.

39:22

A number of years ago, one of our uh,

39:25

fellows here at UCSD said, well,

39:27

that I think we can see the same pattern

39:29

of failure in a grapefruit.

39:31

And he showed me the grapefruit

39:33

and he lent me these particular images.

39:36

So if you saw something like this in your grapefruit,

39:40

that is delamination at the surface in layers as well

39:44

as extending down as as fissuring, right?

39:47

So that's grapefruit delamination with uh,

39:52

fibrillation and fissuring.

39:55

Alright? And then perhaps this which could be failure at the

39:59

tide mark of the grapefruit.

40:01

Okay? Again, a pattern of delamination.

40:05

Now, in, in reality, when you look at patterns of failure

40:10

of articular cartilage as viewed by Mr.

40:13

For example, in this case, you see some regions shown

40:17

by the orange arrow that obey the rules of delamination

40:22

using collagen as our point of reference.

40:25

And another region shown by the yellow arrow,

40:28

which is anti deamination if you're using collagen,

40:32

but is deamination if you're using cellular rose.

40:36

So in general, although cartilage failure varies,

40:41

it is painted on this background of the collagen.

40:45

But you may indeed have areas where the collagen is violated

40:49

as in this particular case.

40:52

To show you some examples of that, here are four

40:56

showing you pictures and my drawings at the bottom.

40:59

Number one is delamination of cellular rows

41:03

as well as collagen.

41:05

Column number two is delamination involving

41:09

just cellular rows.

41:12

Number three is delamination of collagen columns,

41:16

fissuring, as we've talked about.

41:18

And number four is deamination of collagen columns as well

41:22

as failure at the Tide Mart.

41:26

Okay? Different patterns of failure.

41:29

Now, to complete our story at the end of the bone

41:32

with delamination, there are certain situations

41:37

where the subc chondral bone is weak,

41:41

and then the pattern

41:42

of delamination may involve not only entire articular

41:46

cartilage, but portions of the sub chondral bone plate.

41:51

And when I think of that particular situation,

41:55

two diagnoses come to mind on your left is osteonecrosis.

42:00

As you know, we often see fractures in the necrotic bone,

42:04

the crescent sign,

42:06

but those fractures may extend up into the SubCal bone plate

42:11

and into the articular cartilage.

42:14

So in fact, what you may see is delamination

42:17

of the entire cartilage

42:19

and portions of the SubCal bone plate shown on the left.

42:24

The other disorder, one

42:26

of my favorites is hyperparathyroidism.

42:29

I learned about it I think in my first week

42:31

of radiology residency,

42:34

subperiosteal resorption, which is important.

42:37

You see that particularly in the phalanges of the hand

42:40

and in the terminal cuffs, uh,

42:43

you may see some subtle abnormalities,

42:45

but you see in primary

42:47

or secondary hyperthyroidism,

42:50

there is also sub tenderness resorption,

42:54

sub ligamentous resorption, subfascial resorption,

42:58

and subc chondral resorption.

43:01

So the subc chondral bone may be weakened

43:05

and with minor injury, particularly in patients

43:08

with chronic renal disease

43:11

and secondary hyperparathyroidism, delamination

43:15

of the entire articular cartilage

43:17

and portions of the subcon bone plate may be seen

43:22

as in the example I'm showing you on the right.

43:26

So what we tried to do is talk about tissue delamination.

43:31

I think we have completed the story,

43:34

but I hope I have been able

43:36

to accomplish in this particular lecture is

43:38

to fill these two objectives.

43:41

We've reviewed the anatomic basis of tissue delamination

43:46

stressing the importance of collagen

43:49

and in my view, using collagen as our point of reference

43:53

to indicate the delamination patterns of failure

43:57

that we can see in tendons, in ligaments,

44:01

and in articular cartilage.

44:04

And with that, I appreciate, uh, your, uh, listening

44:09

to this lecture, and I'll be glad to try

44:12

to answer any particular questions that you might have.

44:19

Okay, let's see what we have here.

44:23

Articular surface tear looks the same as a partial

44:28

delamination tear,

44:30

and I'm not entirely sure what that question means.

44:34

So I I'm not gonna be able to answer that.

44:37

The next one is when to call an ACL sprain.

44:41

Well, I tried to show you patterns of failure

44:44

of the anterior cruciate ligament.

44:47

Um, I think the only thing

44:50

that you should remember is that in young people

44:54

you may get, uh, ligament delamination.

44:58

It is a sprain,

44:59

but it relates not to a single episode of, uh, injury,

45:03

but to repetitive stress.

45:05

And then why does cell restore extend

45:09

into the anterior root?

45:10

And I tried to show you there that it relates mainly

45:15

to the fact of the intimacy of the footprint

45:18

of the anterior cruciate ligament

45:21

and the anterior root ligament of the lateral meniscus.

45:26

There's another question here.

45:29

Um, let's see,

45:33

in some the anterior cruciate ligament is

45:36

normally splayed distally.

45:39

How you do you distinguish this from deamination?

45:43

Uh, it doesn't bother me that the bottom

45:45

of the anterior crusade ligament may be slightly wider.

45:49

I still think you can see collagen bundles without evidence

45:53

of high signal between and among them, a number.

45:57

Another one are, are all interstitial tears

46:00

of tendons, delamination?

46:03

Not all. Some are obliquely oriented,

46:06

but many of them in fact are, uh, patterns

46:09

of tendon delamination.

46:12

Another question, when describing a tendon tear,

46:15

what are the required areas

46:17

in your description of the injury?

46:20

Well, we talk about thickness,

46:22

whether a tear is partial thickness or full thickness,

46:27

and we talk about width, whether the tear involves just part

46:32

of the width or the entire width of the, uh, tendon.

46:37

And I rarely use the word complete

46:40

to describe a tendon tear,

46:42

but if I did, it would indicate it is full thickness

46:46

and full width in its extent.

46:50

And then ACL sprain is not the core.

46:54

I'm, I'm not sure I understand that.

46:56

So, uh, if that person wants to email me,

47:00

maybe I could try to figure out

47:01

what he means by that question.

47:03

Uh, my email is d

47:05

resnick@ucsd.edu.

47:10

And with that said, I think I am finished.

47:14

Uh, and, uh, hopefully, uh, I've answered some

47:17

of the questions you might have with regard to the use

47:21

of the word delamination.

47:23

Thank you all. Thank

47:24

You Dr. Resnick for

47:25

being here and for giving

47:26

another wonderful lecture.

47:28

We really appreciate it.

47:30

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47:32

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47:35

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47:37

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47:41

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47:43

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47:45

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47:48

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47:50

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