0:02

Hello and welcome to Noon Conferences

0:04

hosted by MRI Online.

0:05

In response to the changes happening around the

0:07

world right now in the shutting down of in-person

0:09

events, we have decided to provide free daily

0:11

noon conferences to all radiologists worldwide.

0:13

Today, we're joined by Dr. Stephen J. Pomeranz.

0:15

He is the founder of MRI Online.

0:17

He's authored numerous medical textbooks in MRI,

0:20

including the MRI Total Body Atlas.

0:22

He is an avid conference lecturer.

0:24

Chairs fellowship training programs in a more and advanced imaging

0:26

and he is also the CEO

0:28

and medical director of ProScan Imaging.

0:29

Reminder, there will be time

0:31

at the end of this lecture for a Q&A session.

0:33

Please use the Q&A feature to ask all of your

0:35

questions, and we'll get to as many as we can before

0:37

our time is up. That being said,

0:39

thanks so much for joining us today.

0:40

Dr. Pomeranz, I will let you take it from here.

0:43

Today, we're going to be talking about menisci.

0:47

And my motto is, "Think it. Learn it. Apply it."

0:53

And that's what we're going to do.

0:56

Ashley has given you my faculty disclosures.

0:58

I have nothing else to disclose.

1:00

And we're going to get right to it.

1:03

One of your primary jobs as a radiologist and as a

1:07

musculoskeletal radiologist is to save the whales and

1:11

save the menisci. You need them.

1:13

In years past,

1:14

we indiscriminately resected small tears and

1:17

we're no longer going to go down that lane.

1:21

Let's talk about meniscus physiology and anatomy.

1:24

There is physiologic signal in a meniscus due to

1:27

diffusion from the joint towards the periphery that

1:31

does not communicate or approach the upper

1:33

lower or inner articular surface.

1:35

This is a given.

1:37

A tear is when one of the above is violated.

1:41

In other words, you have a signal that approaches one of these

1:43

surfaces and/or the meniscal shape is altered.

1:48

Here's a side or lateral view of the meniscus.

1:51

Gross specimen and reticulin staining

1:54

showing meniscal vascularity.

1:56

Here's the meniscus as a triangle.

1:58

The outer third of the meniscus,

2:00

particularly in young pediatric individuals,

2:03

is pretty well vascularized, and so tears in this region,

2:07

which are most commonly vertical,

2:09

will heal on their own in the majority of cases.

2:13

The meniscus has some very complex attachments.

2:16

The medial meniscus is less mobile than the lateral

2:19

meniscus. And it's firmly fixed to the joint capsule.

2:23

So, it is more prone to certain types of injuries.

2:26

There is a femoral meniscal attachment that is contiguous.

2:30

Comes in contact with and blends

2:31

with the deep portion of the medial collateral ligament,

2:35

known as the meniscofemoral ligament or MFL.

2:39

A lot on this covers a larger portion of the articular cartilage

2:42

compared with the medial meniscus.

2:44

About 80% vs. 60%,

2:47

although in discoid lateral meniscus, it's 100%.

2:51

The lateral meniscus is more mobile,

2:53

thus its lower propensity to be injured.

2:57

Lateral meniscal fibers do not directly attach

2:59

to the lateral collateral ligament as their

3:01

medial counterparts do attach to the MCL.

3:06

There's some variability in the meniscofemoral ligaments.

3:09

And most common and notable

3:11

is the anterior meniscofemoral ligament of humphrey.

3:15

Then there is the posterior meniscofemoral ligament

3:18

of Wrisberg, either or both of these come off the

3:22

posterior aspect of the lateral meniscus.

3:24

There is a transverse anterior

3:26

intermeniscal ligament of Winslow.

3:29

And there are various names and some

3:31

unnamed oblique intermeniscal ligaments

3:34

like the ligament of Barkow.

3:37

This diagram,

3:37

taken from the work of Stoller,

3:39

drawn by Salvador Beltran.

3:41

A beautiful diagram demonstrates some of these attachments,

3:46

including the anterior intermeniscal ligament

3:49

of Winslow, going from anterior horn to anterior horn.

3:53

And you can tell which side is which because the

3:56

lateral meniscus is more C-shaped,

3:57

the medial meniscus is more banana-shaped.

4:01

Here's the PCL, a posterior cruciate ligament.

4:03

In front, we have the meniscofemoral ligament

4:06

of Humphrey that we alluded to earlier.

4:08

Behind the PCL is the meniscofemoral ligament of Wrisberg,

4:11

and they are inversely proportional to one another

4:14

in terms of size.

4:16

But they both come off in the same general vicinity

4:19

in the posterolateral meniscus horn near the root.

4:24

There are root ligament attachments to the tibia

4:27

and tibial spines, both laterally and medially,

4:30

in the back and in the front.

4:32

And though not drawn,

4:34

there are intermeniscal ligaments

4:36

that may go from the posterior horn of one

4:38

to the anterior horn of the other

4:40

and these can be problematic.

4:41

The inner tip of the meniscus is not anchored.

4:45

It's freely floating like the wings

4:47

of a stingray or manta ray.

4:49

Whereas, the posterior periphery of the meniscus

4:52

is attached to the capsule more tight on the medial

4:56

side than on the lateral side.

5:00

Tearing of the meniscus roots have often been overlooked.

5:03

Only in the last decade have they been

5:05

recognized as an important cause of other pathology.

5:09

Tears of these roots result in untethering of the

5:13

meniscus and some loss of function and

5:15

alter biomechanics and kinematics.

5:18

The posteromedial meniscus root is the one that is most

5:21

associated with injury, and isolated injury at that,

5:26

and with that, the meniscus becomes untethered, begins

5:29

to extrude medially, and the patient ends up

5:31

with advanced osteoarthritis in later age.

5:36

We said that the meniscus is attached peripherally,

5:39

and here is an upper fascicle and a lower fascicle

5:42

of the lateral meniscus posterolateral corner,

5:46

and these are normal. We'll see later on that these can rapture.

5:49

But the inner portion of the meniscus is floppy,

5:52

it's not attached.

5:54

So, it can bend or be moved around

5:56

by synovial tissue and fluid.

5:59

This is known as meniscal flounce

6:01

as it was described by Zarins.

6:03

Some have proposed that people with hypermobile

6:05

meniscus tips are more prone to meniscal tears,

6:10

although that is the subject of debate.

6:12

Here's a patient that has sustained the valgus injury.

6:14

The amseal is torn, there's an impaction

6:16

injury on the lateral side.

6:17

But I'm showing it for the flounce.

6:20

There is some fluid and synovial thickening

6:23

that is bending and moving the meniscus around.

6:26

Bending it like Beckham.

6:27

Here's the sagittal projection again,

6:29

showing this phenomenon of hypermobility of the free

6:32

edge of the meniscus, known as Flounce,

6:35

not to be confused with a blunt-ended tip tear of

6:39

the meniscus, which is a look-alike.

6:41

There are three critical meniscal functions

6:44

and they are critical.

6:46

No more resecting these small, tiny little tears.

6:49

The menisci serves as stabilizers.

6:52

People that lose their menisci say that

6:54

"My knee feels like it's going to give away."

6:56

It reduces axial load hoop stress.

7:00

And it also improves the overall glide

7:03

and flexibility of the knee,

7:05

so that you have a bigger range of motion

7:07

when your meniscus is preserved.

7:11

Three critical rules.

7:14

No knee meniscus is uniformly black. None.

7:18

They all have water in them.

7:19

Most meniscal tears are not symptomatic

7:22

and are non-surgical.

7:24

The younger the individual,

7:26

the more relevant to clinical

7:27

management is the tear.

7:30

Incidental Meniscal Cleavage Tears

7:32

in the body of adults is extremely

7:35

common over age 60.

7:37

More than 50% of individuals will have them,

7:40

and they will be asymptomatic.

7:43

The meniscus is made up of extracellular matrix,

7:46

70% of which is water.

7:48

So you're going to see water in the meniscus.

7:51

They won't be bright like water,

7:53

it will be diffused water, as we'll see in a moment.

7:56

20% will be collagen.

7:59

And then, the remainder outside the extracellular

8:01

matrix are glycoproteins, proteoglycans,

8:04

and non-collagenous proteins.

8:06

So, what are the causes of meniscal signal?

8:09

Well, the most common cause is physiologic,

8:12

micro diffusion and fluid in the meniscus,

8:15

seen here in green.

8:17

Tears, of course.

8:19

Contusions in children and the outer third vascularity.

8:23

So common.

8:24

A tragic mistake is to intervene on a child for this.

8:29

Cyst.

8:30

Intrameniscal Tears.

8:31

Degeneration.

8:34

CPPD and even Gout,

8:35

and Meniscal Ossicles

8:38

So some of you are wondering how you distinguish some

8:40

of these things, and we're going to spend

8:41

some time talking about that.

8:44

But one of the hallmarks of a tear

8:47

is focality and inflammation.

8:50

Let's take a look at some normal meniscal signal.

8:53

If you squint and look very carefully and stare at this

8:56

T1 spin-echo image,

8:58

you can see

9:00

some gray signal intensity in this meniscus,

9:03

corresponding to the diagram,

9:05

showing this yellowish color in the meniscus,

9:08

which fades as you move into the inner third.

9:11

This is normal

9:13

fluid that lives in the meniscus that travels along

9:16

the radial fibers that are found inside the meniscus.

9:20

These are fibrocartilaginous structures that are

9:23

made mostly of collagen, that consist of a superficial thin

9:26

mesh-like layer, a deeper radial layer,

9:29

and a circumferential layer as well.

9:32

And the radial and circumferential layers,

9:34

the diffusion of fluid produces this,

9:36

and I'm going to show you

9:38

an even clearer example of it in a minute.

9:41

So, what to find is this normal meniscal signal,

9:44

which can be somewhat bright

9:46

on heavily water-weighted sequences.

9:49

It's in the outer third.

9:50

It fades as you go to the middle third,

9:53

it may communicate with the capsule,

9:55

but it never goes up and down.

9:56

It never goes to the superior surface.

9:58

It never goes to the inferior surface,

10:01

it is centric.

10:03

It is not as bright as hyaline cartilage.

10:05

It is not bright on the T2-weighted image,

10:08

and again, it doesn't surface

10:10

superiorly or inferiorly, or in the tip.

10:13

It doesn't go in the inner third and come out the tip.

10:16

This outer third area is vascularized

10:19

and is the zone of respect

10:21

where tears have a high likelihood to heal.

10:25

Here's a coronal projection showing you an ill-defined

10:29

area of increased signal intensity.

10:31

It's as if you are in Alice in Wonderland,

10:34

looking through the glass.

10:36

You can see little structures inside.

10:38

These are collagenous bands that are water-laden.

10:40

Here's some more water around them.

10:42

This is all normal.

10:44

It's fuzzy, it's ill-defined, and that surrounding

10:48

tissues are close to a normal.

10:50

The bone's normal. The cartilage is normal.

10:52

The shape of the meniscus is normal.

10:55

All features that help you decide you're

10:57

looking at normal.

10:58

Normal.

10:59

Normal.

11:00

Sagittal water-weighted image,

11:01

the signal slopes gently down.

11:03

It fades in the middle and inner third.

11:05

By the inner third, it's gone.

11:07

It's fuzzy.

11:08

It's not as bright as as hyaline cartilage.

11:10

It is window-framed all the way around the surrounding

11:14

tissues are coal stone normal.

11:16

This is normal

11:18

meniscal signal.

11:21

Contrast that with this.

11:23

Let's go back for a minute.

11:24

Fuzzy

11:25

sharp edge.

11:27

This is somebody who fell in a creek bank.

11:31

It's a tear.

11:32

Why is it a tear?

11:34

What makes it different than the last example?

11:36

First, the patient has pain right there,

11:39

a posteromedial pain.

11:41

Second, you see they had a bone injury.

11:44

So that helps you.

11:46

Third, it's a little bit swollen.

11:49

Fourth, it doesn't fade.

11:51

It's very focal and then comes to a sudden stop

11:54

instead of fading into the middle third.

11:57

It has a little bit of weird complexity to it.

11:59

The capsule is swollen.

12:01

So, this going to be a hidden tear.

12:03

But it is a tear,

12:04

by a virtue of all those features,

12:07

but especially the focality.

12:11

Now, not everything that produces intrameniscal

12:13

signals are tear, you already know that.

12:15

You know meniscal vascularity can do it.

12:17

Here is a scenario

12:18

where there is signal in the outer third.

12:21

Now, most tears that occur at the outer third are vertical.

12:24

This is horizontal signal.

12:26

And I don't mind if you have some signal

12:27

in the outer third.

12:28

But I do mind when the patient is very symptomatic

12:31

there, and they are.

12:32

I do mind when it's inordinately swollen.

12:35

Look at the superficial MCL bursa.

12:38

I do mind when there are erosions right

12:40

nearby in synovial hypertrophy.

12:43

This is a patient that has the MR manifestations,

12:46

horizontal signal that doesn't fade in the inner third,

12:49

comes to an abrupt hole,

12:51

with erosions,

12:52

with inflammation in the entity of CPPD.

12:55

Another cause of intrameniscal signal.

12:59

Here's a 16-year-old who had a football injury.

13:01

This is a meniscal ossicle or ossification

13:05

in the meniscus.

13:06

It was originally thought these are developmental,

13:08

but we now know that the majority of these occur as

13:12

a result of either a hematoma,

13:14

or sometimes a fragment of bone

13:16

may even get trapped in a torn meniscus

13:18

and the meniscus closes over on it.

13:20

So, the majority of these are acquired

13:23

as opposed to developmental in nature.

13:26

So now we come to a real tear.

13:29

Unlike the normal examples you saw,

13:32

this one is not window-framed.

13:34

There is no dark signal along the underbelly of it,

13:37

on the inferior tibial surface.

13:38

It's got these little fingerlets.

13:40

It's sitting on the surface of the tibia.

13:44

There's a little bit of swelling

13:45

in the posteromedial corner.

13:47

This is what we might refer to as an undersurface

13:50

scuff or rolled edge posteromedial meniscus body horn

13:54

junction or corner tear.

13:55

We'll ignore the intraosseous ganglion for now.

13:58

So now, what you can see,

14:00

we're working our way up the scale.

14:02

We've gone from some normal signals to some

14:05

inflammation, to some examples of intrameniscal tear.

14:11

And now, we have a clear-cut communicating tear

14:14

that's a lot bigger than our scuff

14:16

rolled edge undersurface tear.

14:17

That's a flap tear, it's obliquely oriented.

14:21

This one is not displaced in this position.

14:23

Here's a diagram of it.

14:26

This one involves the inner third, middle third,

14:28

and outer third.

14:29

It goes from the body to the posterior horn.

14:31

And in fact, went all the way to the root.

14:34

And it is key when you're looking at these tears to

14:36

evaluate them in thirds.

14:37

Inner third, middle third, outer third.

14:40

Here, the inner third is involved.

14:42

Here, the middle third is involved.

14:43

Here, the outer third is involved.

14:45

And this helps you decide whether a tear is

14:48

surgical or not.

14:49

A large non-displaced flap tear of

14:52

the medial meniscus.

14:52

Let's talk a little bit about technique.

14:55

What do we like?

14:57

On high field, I like proton density fat supression for detection,

15:00

along with the T1.

15:02

I always use a T1.

15:04

And some of the sequences you're familiar with

15:06

are PD FATSAT, PD SPIR, PD SPAIR, PD SPECIAL, and STIR.

15:12

On older high-field systems

15:13

and some low-field systems,

15:14

I like standard gradient echo and steady-state

15:17

free precession, including gradient recalled acquisition

15:20

in steady-state or GRASS,

15:21

true FISP, field echo, and on Hitachi scanners,

15:25

I love the SARGE,

15:27

which is a type of steady-state free precession.

15:30

For three-dimensional very high-resolution imaging

15:34

on newer high-field scanners, I like additive gradient

15:39

echo, which I can perform with one millimeter cuts

15:42

and reconstruct and look at the axial projection.

15:45

These go by the names of MERGE, MEDIC, M-FFE,

15:49

if you're Philips user, and ADAGE if you're a Hitachi user.

15:53

Here is an example of some of these sequences.

15:56

Here's a proton density fat-suppression,

15:59

heavily water-weighted image.

16:00

On an older system,

16:02

here is a gradient echo,

16:03

a GRASS sequence.

16:05

Pretty nice.

16:06

And it shows the meniscus tear

16:08

in a lovely way with a double meniscus sign anteriorly.

16:10

And here's another heavily water-weighted one,

16:13

the 3D 1 mm additive gradient echo or ADAGE

16:17

showing a large root-to-body meniscus tear.

16:20

These are the most favored nation status sequences

16:24

for meniscal detection, along with the T1.

16:27

Which ones do we no like?

16:29

We don't like the spoiled

16:31

gradient echo sequence that is made on

16:33

some of the older general electric scanners

16:36

because it makes the meniscus too grey

16:38

and too bright, and results in an overcall.

16:41

We don't like the T2 because it's under-sensitive.

16:44

It misses most tears that are scarred or have blood.

16:47

So if you rely on this, you will undercall.

16:50

And then, I don't personally like the proton density

16:53

non-fat suppression image because even though it shows

16:56

meniscal pathology well, it hides bone pathology.

17:00

Which I use frequently to decide on the relevance

17:04

and significance of my tears.

17:07

One special sequence that I rarely use is the radial,

17:11

where I am constantly rotating.

17:12

And perpendicular to the meniscus,

17:14

there is a tear right here.

17:16

But I'm showing it for the technique

17:17

rather than the tear itself.

17:20

This is a specialized view known as the radial series.

17:25

So, let's take a look at a tiny little tear.

17:27

Is that real? Is it flounce?

17:29

Is it volume averaging? Is it synovial tissue?

17:32

Oh, it's small.

17:33

Right at the tip of the posteromedial meniscus

17:36

in a 49-year-old man with pain,

17:38

swelling, and stiffness following an injury.

17:40

This is where the high-resolution images come into play.

17:43

In the axial projection, here is your medial meniscus

17:46

banana-shaped.

17:47

Lateral meniscus, C-shaped.

17:49

And right there,

17:50

right there,

17:52

there is your radial tear.

17:53

Let's see if my pen is working today.

17:55

It is. I'm going to draw right over it

17:57

so you can see it.

17:58

And now, I'm going to take it away.

18:00

Radial tears are a type of vertical tear that is

18:03

radially oriented to the arc of the meniscus.

18:05

There it is at low field. No less.

18:09

Let's take a look at the meniscus and

18:12

divide it up into thirds.

18:15

Well, first, when we look at the anterior horn,

18:17

body, and posterior horn, you could divide the meniscus

18:20

up that way into a third,

18:21

a third,

18:22

a third.

18:23

Same thing on the medial side as the lateral side.

18:25

But there's another way to divide it,

18:28

inner third, middle third, and outer third.

18:30

And I use them both.

18:31

And I use both as descriptors.

18:33

So whenever I have a tear,

18:35

I say whether it's in the anterior horn,

18:36

horn body junction, body posterior body horn junction,

18:40

or posterior horn.

18:41

And whether it is in the white-white zone, inner third,

18:44

red-white zone, middle third,

18:45

or red-red zone, outer third.

18:48

The outer third tears are usually vertical with pivot-shifts.

18:51

Living in the middle third, usually buckets.

18:55

Living in the inner third,

18:57

radials, flaps and parrot beaks live here.

19:01

There are three,

19:03

count of three basic tear shapes.

19:05

So don't get too discouraged,

19:07

vertical, horizontal, and complex.

19:09

Vertical, this includes the bucket.

19:13

Yup, that's a type of vertical tear.

19:15

The radial and the longitudinal vertical.

19:18

Horizontal tears.

19:19

These include traumatic and degenerative cleavage tears.

19:23

And then everything else, I lump into the complex.

19:26

Here's not all of them.

19:27

I'm not showing you a horizontal one.

19:29

But here's a few of them.

19:30

Here is the longitudinal vertical tear.

19:33

Parallel is the peripheral axis of the meniscus.

19:37

And here's another vertical tear.

19:39

This one comes from the inside out.

19:41

It's perpendicular to that one,

19:44

radial, vertical longitudinal.

19:47

Both vertical tears.

19:49

Now, if you take a vertical tear and you put it in the

19:52

middle of the meniscus, in the red-white zone, and then

19:56

it starts to widen, you get yourself a bucket-handle tear.

19:59

And here is an example of a flap tear.

20:02

Here is a baby flap tear with complex obliquity,

20:06

found in the anterolateral body horn junction,

20:08

called the parrot beak tear.

20:10

And here's a flap tear that has rotated posteriorly or

20:14

folded posteriorly,

20:15

the so-called folded displaced flap tear.

20:19

This is a very important thing to recognize

20:21

along with the bucket,

20:22

because these are surgical signs.

20:24

Here's a sagittal projection showing you

20:26

several folded flap tears.

20:28

Look at this one.

20:30

Folded backward, ripped off.

20:31

This one folded over on itself.

20:33

This one folded making a meniscal sandwich.

20:36

The folded flap tear,

20:38

usually going from anterior to posterior.

20:40

But it can fold in the opposite direction.

20:45

So, here's a vertical longitudinal tear.

20:46

You've already seen the vertical radial tear.

20:49

And in the vertical longitudinal tear,

20:50

it's usually in the outer third.

20:52

This one happens to be in the middle third.

20:53

It's got slight obliquity to it,

20:56

but you can see the analogy with the diagram

20:59

right here.

21:00

Most of these vertical longitudinal tears that occur

21:03

in the middle or outer third are left alone.

21:06

There's the radial tear.

21:08

Radial tear also vertical,

21:10

but this one going from the inside out.

21:12

We frequently pay attention to its gap,

21:14

how wide is it right there and we'll measure it.

21:16

How deep is it?

21:18

Not how deep is your love,

21:19

how deep is the tear?

21:21

It is said that tears over 8 mm in depth

21:23

should be operated on.

21:26

I am far more conservative than that,

21:28

even though I'm not making that decision.

21:30

Radial tears,

21:31

when they are near full depth,

21:33

usually have to be dealt with.

21:35

But not all the time,

21:36

the 8 mm rule is not hard and fast for depth.

21:39

But here we have the radial tear,

21:41

sagittal projection.

21:42

Normal meniscus.

21:44

Normal meniscus.

21:45

Defect.

21:46

Defect.

21:48

The rest of the meniscus.

21:50

The rest of the meniscus.

21:52

The radial tear seen as a defect

21:54

when you image it on en face.

21:56

If the tear was over here,

21:58

then you would see it in the coronal projection

22:00

as a defect.

22:02

A horizontal tear,

22:03

that one's easy,

22:04

self-explanatory.

22:06

Over 50% to 60% of all people over age 60 have this.

22:10

A horizontal cleavage tear of the

22:12

lateral meniscus body.

22:14

You don't operate on these.

22:16

They are so common.

22:17

They are frequently associated with osteoarthritis

22:20

and degenerative joint disease.

22:22

But sometimes, they can exist all by themselves

22:25

and still be asymptomatic.

22:28

Here's a radial tear.

22:29

But instead of being a small defect,

22:31

now you can analyze its shape.

22:33

It looks like a crab.

22:35

It's a complex radial tear.

22:37

So from walking on it,

22:39

it's getting mashed.

22:40

Here it is getting mashed.

22:42

So, complex radial would do very well on this one cut.

22:46

It's only in the inner third.

22:47

But on this next cut,

22:48

it's in the inner, middle, and outer third.

22:51

He's a 41-year-old man.

22:52

He's been symptomatic for some time with this tear.

22:55

And it's going to have to be, unfortunately, resected.

22:58

Which usually results in arthritis within six months,

23:01

but you have no choice.

23:03

Here's a complex tear.

23:06

Complex is easy.

23:07

It's anything that you can't simply

23:09

define as horizontal, vertical, or flap-like.

23:13

There, and even flap tears are considered complex.

23:16

But this one goes in many different directions.

23:18

It goes horizontal.

23:19

It goes vertical.

23:20

It goes up. It goes down.

23:22

And because of its size,

23:25

it has contributed to instability of the knee,

23:30

and eventually, that meniscus has pulled away

23:32

from its attachment posteromedially,

23:34

and we're starting to develop meniscal capsular detachment

23:37

from this complex tear.

23:40

Here's another type of complex tear.

23:42

This is a baby flap tear.

23:45

It's got a complex obliquity.

23:47

Let me see if I can draw it for you.

23:49

Here's a meniscus right here.

23:50

Let's see if I can make it 3D.

23:53

Here we go.

23:54

And this tear looks like the snout of a bird.

23:57

It can go this way.

23:58

It can go this way.

24:00

Not only is it curved,

24:01

when you look at it from the top as you dive into

24:03

the meniscus, it also has a curvature, as well.

24:06

Now when you image it,

24:07

you're going to see it, with successive cuts,

24:10

you're gonna see it march towards the

24:13

inside of the meniscus.

24:15

The so-called meniscal marching sign.

24:17

So, let's take a look.

24:18

There is a meniscus.

24:19

It's marching inward,

24:21

it's marching inward,

24:23

it's gone.

24:25

So when you see that, you know that your

24:26

tear has an obliquity to it.

24:30

These are thin tears that,

24:31

like the anterolateral body horn junction,

24:34

they're curved in multiple projections.

24:36

They look like the snout of a bird.

24:38

It's the parrot beak tear.

24:39

Here's another one.

24:41

This one perhaps doesn't show the

24:42

curves as well as I would like,

24:43

but it is in the typical anterolateral body horn junction.

24:46

There it is right there.

24:47

It looks just like a radial tear.

24:49

The axial projection,

24:50

you can see how it tapers.

24:51

Just like the snout of a parrot.

24:53

There it is right there.

24:55

Ooh, that's pretty.

24:56

Maybe a little more curve would

24:57

be nice, but I think you get the picture.

25:00

Meniscal Chronicity.

25:03

Unfortunately, as we age,

25:06

we get a little dehydrated.

25:08

Why do you think the salesperson

25:09

shows you pediatric MRI

25:11

when they're trying to sell you a scanner?

25:12

Because kids have more water.

25:14

The pictures are prettier.

25:16

Because you're measuring the amount

25:18

of protons in the body

25:19

when you make an MRI image.

25:21

When you're older, you dry out, and when you dry out,

25:24

things start to crack.

25:26

This is bad news.

25:27

And as they start to crack, they cleave.

25:30

This is very common for menisci.

25:33

And over time, the meniscus may macerate.

25:35

So, you're not going to go in and resect this.

25:38

The patient needs a joint replacement.

25:41

So, doesn't so much matter what you say as long

25:44

as you understand what you're doing,

25:46

that you don't force an unnecessary procedure.

25:49

There's...

25:49

Oh, wait.

25:50

We will describe it as degenerative joint disease.

25:53

We will Kellgren Lawrence grade it.

25:56

You can google this and learn the Kellgren Lawrence

25:58

grading system, which I urge all you young

26:01

radiologists to do since it's an important plain film

26:04

grading system and I apply it to MRI.

26:07

I usually describe menisci like this

26:09

as medial compartment failure

26:11

when they have OA, penetrating erosions,

26:14

no cartilage replaced by synovium,

26:17

and a macerated meniscus that is extruded medially.

26:20

So, my conclusion will read medial compartment failure

26:24

with failed medial meniscus

26:25

and extensive diffused chondromalacia,

26:29

with grade 3-4 delamination.

26:31

Meniscal Cysts.

26:33

These are actually pretty common.

26:36

The ones on the lateral side are smaller,

26:40

they are more anterior,

26:41

and they're more often painful.

26:44

The ones on the medial side

26:46

are more often posterior.

26:48

They are more often giant,

26:49

and they're more often painless.

26:51

This one happens to be small.

26:54

It's a child with open growth plates.

26:57

This case illustrates what I have

26:58

referred to over the years

27:00

as the meniscal arrow sign.

27:02

Those of you that understand the sport of wrestling,

27:04

especially our friends from Russia and

27:07

Iran where wrestling is a huge sport,

27:09

there's a lot of flexion of the leg that takes place.

27:12

So, there's a lot of what I call compressive axial load tears.

27:15

The meniscus develops

27:17

what I call a traumatic split.

27:19

And with that split, the diffusion event that

27:22

normally takes place becomes accelerated.

27:25

And that diffused synovial fluid gets loculated as a

27:30

small, peripheral, parameniscal cyst that comes

27:33

right smack dab out of the center.

27:37

The so-called meniscal arrow sign.

27:39

Right out of the tip of the arrow comes the tear,

27:42

and right at the tip is your small ball-like meniscal cyst.

27:48

Contrast that with this patient,

27:50

an adult, growth plates closed.

27:52

Now fifty years of age.

27:54

I call this the under-over sign.

27:57

Our tear comes right out of the center of the meniscus,

27:59

but not this lesion.

28:00

It comes from underneath the meniscus.

28:03

It's got pressure.

28:05

It's moving structures out of the way.

28:08

There's not a lot of joint fluid,

28:09

which makes a capsular synovial cyst unlikely.

28:12

There's no synovium.

28:14

It's loculated.

28:15

It's a ganglion pseudocyst.

28:19

Let's talk about meniscal instability.

28:25

Here are some signs that, taken together,

28:28

support the diagnosis of meniscal instability.

28:32

Each one by itself not necessarily, although

28:35

some are more important than others.

28:38

But here are the things I look at

28:39

to decide how aggressive

28:41

I'm going to be in my dictation:

28:43

length greater than 45 cm,

28:45

complex shape,

28:47

diminished volume or height,

28:50

displacement, extrusion, fragmentation,

28:54

folding like you saw earlier.

28:56

Inflammation,

28:58

swelling of the capsule,

28:59

swelling of the tear,

29:02

associated ligamentous laxity

29:04

makes smaller tears more relevant.

29:07

Is it trizonal?

29:08

Outer third, middle third, inner third.

29:11

Radial depth, as we said earlier.

29:12

Greater than 8 mm.

29:14

Is it gapped or widened?

29:17

Here's an example of an unstable tear

29:20

that has to be dealt with surgically.

29:23

The sign known as the comma sign.

29:25

The meniscus is extruding out and down.

29:28

There's your comma right,

29:29

there with a large complex flap tear

29:32

that is traveling with the meniscus as it should,

29:35

and associated inflammation.

29:38

So if you have a comma sign,

29:40

then you also have an apostrophe sign.

29:43

We look at this coronal water-weighted image

29:45

and we say, "Well, where's the meniscus?"

29:47

It's too small.

29:48

The most common cause of a small meniscus

29:50

is meniscectomy, but they've had no surgery.

29:54

Another common cause is inflammatory

29:57

autodigestion, as in, RRA.

29:59

Neither one exists here.

30:01

The meniscus has gone fishing out into the

30:04

parafemoral gutter as the meniscal apostrophe sign.

30:08

Another example of an unstable meniscus tear.

30:13

So, all of those features can be used to help you

30:17

make intelligent, cogent, thoughtful decisions about

30:22

how to word and discuss the case with your clinician.

30:25

Your job is to make the clinician look good.

30:28

What are the factors that determine

30:29

surgery besides those?

30:31

Patient Age.

30:32

Much more likely to operate on somebody 25 than 65.

30:36

Patient activity level.

30:38

Kind of sport are they doing.

30:40

Other symptoms on the same side as the tear.

30:44

It won't operate on a medial tear

30:45

when the symptoms are lateral.

30:47

They have locking.

30:48

Are there cysts?

30:50

Are there signs of instability

30:52

like we described in the prior slide?

30:55

One of the most important that you just simply

30:58

cannot miss, is a bucket handle tear in a youth,

31:03

and associated ligamentous pathology

31:06

Here's an example of a tear

31:07

in a young person that we would operate on.

31:09

Goes all the way from the root into the horn body junction.

31:14

It's thick.

31:15

There is extensive inflammation.

31:18

And on the sagittal T1,

31:20

it is complex and it is the locus

31:23

where the patient's symptoms are.

31:24

So cleaning this up

31:26

with a trimming and a sowing of the middle and outer third

31:29

is totally appropriate.

31:31

And you've already seen an example of a meniscus cyst

31:34

previously, so we're not going to talk about that again.

31:37

But here is an example of a patient with a small tear.

31:42

The posteromedial corner, right there, is swollen.

31:45

There's some horizontal signal in the meniscus

31:47

that's not that impressive.

31:49

As you go to the coronal adage,

31:51

which is a 3D 1.2 mm slice thickness,

31:55

and you see the signal,

31:57

and you say,

31:57

"Hm. That's a lot brighter than the lateral meniscus."

31:59

Well, normally,

32:00

the medial does have more signal

32:03

than the lateral meniscus because of the normal

32:06

valgus angulation of the knee.

32:07

But right there, it's going up to the superior surface.

32:11

It's going down to the inferior surface,

32:14

and you have evidence of ligamentous microinstability.

32:17

There's a pericruciate ganglion pseudocyst

32:21

that augments your diagnosis

32:23

and supports the notion that

32:26

you might have to intervene on this very small

32:28

tear in a young individual.

32:31

Buckets.

32:34

Well, one very clear-cut sign of a bucket,

32:36

seen in this 34-year-old with right knee pain and locking,

32:39

is the double PCL sign.

32:42

Another sign of a bucket handle tear

32:45

is a double meniscus sign.

32:50

But what is a bucket?

32:52

A bucket is a tear

32:55

that usually occurs in the middle third of the

32:58

meniscus, although it can occur in the outer third,

33:01

but it's a longitudinal vertical tear,

33:04

and then it starts to widen.

33:06

I have many cases of performance athletes that

33:10

start out with virtually

33:13

profound symptoms.

33:14

But in MRI, that is almost normal.

33:16

And all they have in the very beginning,

33:19

I can think of two hockey goalies where this has happened,

33:21

is the tiniest thin little sliver tear.

33:23

Right about here.

33:25

And then one day, as they're trying to do the split

33:28

to block a puck from going in the net,

33:30

they feel a pop, and they come in,

33:32

and now they've got this.

33:34

They've got a full-blown separation of this,

33:38

And the inner portion migrates inward.

33:41

Now, sometimes the front of this bucket,

33:44

here's the pitcher, here's the spout,

33:46

here's the handle of the bucket.

33:49

Sometimes the front part will come off.

33:52

So, it'll be free in the front.

33:53

Sometimes the back part will come off.

33:56

Sometimes both the front and the back will come off.

34:00

Let me change color

34:00

so you can see it a little better.

34:02

And then you have what we call

34:03

a bucket-free fragment.

34:05

Sometimes this inner piece will tuck up and squidge up

34:10

underneath the parrot meniscus, push it forward.

34:13

Sometimes this will break

34:14

and go over the top of the main meniscus.

34:17

Either one of these can create the double meniscus sign.

34:22

Here is an example.

34:24

You're right at the front here. You're right there.

34:26

So you're seeing free-edge meniscus.

34:29

That.

34:30

Defect.

34:31

That.

34:32

And then the rest of the fragment.

34:35

That.

34:36

Then you start to get into the heart of the tear.

34:39

Fragment.

34:40

Hole.

34:40

Fragment.

34:42

Fragment.

34:43

Hole.

34:43

Fragment.

34:44

Fragment with a flap tear in the rim.

34:47

So important because you've got to deal with that

34:49

if you're gonna sow it back together.

34:51

So you have to describe the rim.

34:52

How deep is the rim?

34:56

Rim torn itself.

34:58

And there is your fragment sitting underneath

35:00

the posterior cruciate ligament,

35:02

a bucket handle tear.

35:05

In the axial projection,

35:06

let's take a look at our bucket handle.

35:08

There's one part of the bucket.

35:10

There it is on the diagram.

35:11

Here's a big giant hole.

35:13

There's a big giant hole.

35:14

There is the inner portion of the bucket.

35:16

There is the inner portion of the bucket.

35:17

And there's volume averaging of the native meniscus

35:20

in the bucket.

35:21

Having trouble separating them,

35:22

but not now.

35:24

That's the native meniscus

35:26

That is the tear. So the tear is actually

35:29

the inner fragment has done this.

35:32

Sorry, the inner fragment has done this.

35:33

Let me use my drawing tool properly.

35:37

It's come in and it is this right here,

35:40

underneath the native meniscus.

35:41

Then here is the native meniscus right there.

35:45

And although not shown on this one cut,

35:47

the rest of the meniscus is in the

35:48

back with a very thin rim.

35:50

So the back part has detached or has a very thin pedicle

35:54

and it's shoved itself right underneath

35:56

the native meniscus, and now you can see it.

35:59

Let's see if I can take it away.

36:00

Ignore this red line right there.

36:02

There is your native meniscus.

36:04

There's your transverse meniscal ligament of Winslow.

36:06

And there is your displaced bucket that's stuck up

36:10

underneath the native meniscus.

36:13

Pseudo buckets.

36:15

Pseudo buckets include fragments of the ACL,

36:19

the menisco-femoral ligament of Humphrey

36:22

may have a large anterior footprint insertion,

36:26

maybe volume average.

36:27

There's a pseudo bucket bodies and volume averaging

36:30

of cordicated spurs.

36:32

Here's an example.

36:34

A series of coronals.

36:36

Lateral. There's the fibula, medial.

36:40

There, by the way, is the anterior Humphrey bundle,

36:43

right there,

36:44

which is sometimes confused with a bucket.

36:46

It's not.

36:47

But what's that?

36:49

And that?

36:50

And that?

36:53

And that?

36:53

Very reminiscent, wouldn't you say,

36:56

of our previously shown bucket

36:57

handle tear in this 51-one-year-old man

37:00

with pain and instability?

37:03

But the reason this is here is because the ACL is not there.

37:06

Here's the ACL, folded over on itself.

37:10

The ACL is being volume averaged as a potential

37:13

fragment in the notch of the knee.

37:16

And you see the buckling of the PCL

37:19

consistent with ACL-deficient knee.

37:23

Let's turn our attention now to something

37:25

that's a little bit challenging.

37:26

But that's why we're all here

37:28

in the middle of the day

37:29

to think, to learn, to apply.

37:34

Meniscus attachments include roots, rips, and ramps.

37:39

We're going to talk about anterior and posterior root injuries

37:43

and the anatomy of the roots, also medial

37:47

injuries to the meniscofemoral and tibial attachments,

37:50

known as the coronary ligament,

37:52

the meniscotibial attachment.

37:54

We'll talk about the posterolateral meniscal fascicles.

37:57

Remember, I showed you two very delicate normal ones earlier.

38:01

And then we'll show you posturomedial corner injuries

38:03

that involve the posterior oblique ligament

38:06

detachment of the meniscus.

38:08

And then finally, some anterolateral,

38:11

very challenging variations of the meniscus root

38:15

and its interdigitations.

38:17

Let's start out with what I think is the simplest,

38:19

the meniscal femoral and tibial attachments,

38:23

this one known as the coronary ligament.

38:26

There is also, not going to be shown today,

38:28

a meniscopatellar ligament anteriorly.

38:32

So, here's our meniscus.

38:33

It's a T2.

38:34

I don't like T2 imaging for menisci,

38:36

as stated earlier. But I do like it for ligaments.

38:39

And there is your meniscotibial coronary ligament.

38:45

It is squidged up, its crimped,

38:48

it's retracted, it's wavy.

38:51

You can see the tear right there,

38:53

a meniscotibial ligament tear.

38:58

Here's a meniscofemoral ligament tear.

39:00

Should have a nice firm attachment to the femur.

39:03

No, it doesn't.

39:05

See, it's off right there and right there.

39:10

And then as you get more anteriorly,

39:11

you get into the meniscopatellar ligament.

39:13

That's a 29-year-old who felt a pop

39:15

while working out.

39:16

Remember, the deep portion of the MCL

39:19

is contiguous with these meniscotibial

39:23

and femoral attachments.

39:24

Not so on the lateral side

39:27

where the LCL or fibular collateral

39:28

ligament is a structure onto itself.

39:32

Meniscal roots.

39:36

Let's start out with the anteromedial root.

39:38

The medial meniscus anterior root inserts along the tibial

39:40

eminence and tear to the ACL and contacts directly

39:44

the posterolateral bundle of the ACL.

39:48

It's the root with the largest insertion footprint

39:51

and it has a low injury incidence.

39:54

The medial meniscus root is often contiguous with

39:58

the intermeniscal ligament,

39:59

AKA the transverse meniscal ligament of Winslow.

40:03

And you saw that in the bucket handle tear shown earlier.

40:08

Posteromedial root.

40:10

It's the least mobile root.

40:13

A great deal of force is transmitted to the

40:16

posterior horn in ninety degrees of flexion.

40:20

Stress in flexion, combined with relative immobility

40:24

results in the highest incidence of root tears

40:26

in the posteromedial root.

40:29

Let's have a look.

40:31

Here's a young patient.

40:32

Although the growth plates are close.

40:34

Under age 20.

40:35

There's the lateral meniscus and the gorgeous root.

40:38

It fans out there,

40:39

the little root ligaments attaching there.

40:42

And they get a little thicker on subsequent slices.

40:46

There's no inflammation.

40:47

But on the opposite side, on the medial side,

40:50

the most common place to see a root tear,

40:51

the posteromedial root.

40:53

Chop-chop.

40:55

Somebody went in there with a butter knife and cut it.

40:57

It's blunt, there's nothing attaching it anymore.

41:00

It's squared off, it's no longer fanned,

41:04

and there's swelling around it.

41:06

What will happen next?

41:08

Nothing good.

41:09

It will start to untether,

41:11

start to displace as the patient stands

41:13

and runs and performs, and eventually it will extrude.

41:17

The patient will go on to premature osteoarthritis.

41:21

This particular type of tear is categorized

41:23

as a LaPrade 4.

41:25

We'll discuss that in a few moments.

41:28

Here's another...

41:29

Actually, the same patient.

41:30

Sagittal projection demonstrating

41:32

what I call the ghost meniscus.

41:34

You should not see the meniscus suddenly disappear.

41:37

It should gradually disappear.

41:38

So if I perform a series of sagittal slides like this,

41:42

the meniscus should get smaller and smaller,

41:45

but it shouldn't disappear all in one cut.

41:49

And that's what's happening here.

41:50

Let's take a look.

41:52

We see it.

41:53

Now you see it,

41:54

now you don't.

41:56

It should just get

41:58

a smaller triangular shape

42:00

as you go successively into the midline.

42:03

It's not.

42:04

Sudden disappearance of the meniscus,

42:06

a tip-off of a large full-depth root tear.

42:12

LaPrade and others have classified

42:14

five types of root tears.

42:17

I don't have any dreams of you

42:20

memorizing this at this time.

42:22

It's here as a reference,

42:24

but it's just showing you what's important.

42:26

Type 1 is the partial radial root tear

42:28

or any tear in the adjacent posterior

42:31

horn or body region closed by.

42:33

Type 2.

42:34

A complete radial root tear

42:36

of which there are three subtypes and they divide them

42:39

up into those that are right next to the root,

42:42

1-3 mm from the root,

42:43

3-6 mm from the root.

42:46

Here's an example of a 2A,

42:48

right at the root.

42:49

There it is right there in the expected place,

42:52

the posteromedial root.

42:54

They look similar, but different.

42:56

This one fans out, there is no white line.

42:59

There is a white line in the 69-year-old.

43:03

Now, interestingly, the patient's pain was lateral

43:06

rather than medial.

43:08

Here is another one.

43:10

This is one that demonstrates meniscal ghosting.

43:14

We look at the meniscus, it's getting smaller.

43:16

It's getting smaller.

43:17

And then suddenly, bam!

43:18

It's gone.

43:20

That's a tip-off that you're dealing with

43:21

the root tear. Here's another one.

43:24

This one is about 3-6 mm from the root tear.

43:27

There's the root.

43:27

There's the root ligament.

43:29

There's the tear, and there's the rest of the meniscus.

43:33

So what's important here with regard

43:34

to these LaPrade tears?

43:36

Where are they resigned?

43:37

How close are they to the root?

43:40

Do they involve the meniscus?

43:43

The meniscus and the ligament?

43:45

Just the ligament?

43:47

In terms of their depth,

43:49

when you're looking at the root,

43:50

let's look at the sagittal projection for a minute.

43:53

How deep are they?

43:54

Do they involve just the inner third,

43:57

the inner and middle third?

43:58

Or do they involve all three thirds?

44:01

And this improves your ability to use one of these

44:04

grading systems or to simply describe.

44:08

And if you're looking in the coronal projection

44:10

and you have a meniscus like this,

44:13

you have a big gap tear right here.

44:16

This is, in some ways,

44:17

a form frost of a bucket handle-like tear.

44:20

We would call that a LaPrade 3.

44:22

But again, I'm not here to have you memorize

44:24

a grading system,

44:25

simply to understand what's important.

44:27

Where it is relative to the root?

44:29

Are the ligaments involved?

44:32

How deep is that root tear?

44:34

Because that affects how untethered

44:36

the knee is going to be.

44:37

Look at this one.

44:38

This one is right on the root. It's huge.

44:40

It's got a very large gap, never mind the grade.

44:43

It's got a very large gap.

44:46

We could see there is a continuation of it on the next slice.

44:49

The patient has developed chondromalacia.

44:52

The lateral compartment looks fine,

44:54

but the medial compartment looks awful.

44:56

There's osteoarthritis with spurs.

44:58

There's chondromalacia.

45:00

And look what's happened,

45:01

the root tear has become a closed flap.

45:05

And the rest of the meniscus?

45:07

The meniscus is now untethered; it's extruded.

45:10

There's no support, and the patient has developed

45:13

premature OA at age 56.

45:16

LaPrade 5, by the way, is an avulsion

45:19

fracture of the tibial plateau.

45:20

But the bottom line is how deep

45:22

relationship to the root,

45:24

relationship to the ligament.

45:27

Is there a closed extension?

45:28

Is the meniscus now untethered?

45:30

Is the meniscus extruded?

45:32

And if so, where?

45:35

The anterolateral attachment or root.

45:38

This one is pretty challenging.

45:41

It's the most challenging of all.

45:44

Look at this sagittal high-resolution T1 image,

45:47

and you would think this was a tear at first glance.

45:52

The posterior horn is pretty dark.

45:55

But what is all this heterogeneous signal

45:58

intensity in the anterior root?

46:01

Well, some of it, like that,

46:02

is synovial interdigitation.

46:05

Some of it...

46:06

This triangle right here represents the transverse

46:09

meniscal ligament of Winslow.

46:12

This horizontal gray signal right here represents an

46:16

interdigitation of the anterolateral root ligament,

46:20

which is quite long.

46:22

This is the anterolateral meniscosynovial recess.

46:26

So some of you, on this 0.6 mm thick image

46:29

are saying to yourselves,

46:31

"Well, how will I ever tell if there's a tear?"

46:34

Well, I'm going to give you a couple of clues

46:36

that will help you deal with this area,

46:39

and fortunately, it's an area that we often leave alone

46:43

and don't necessarily operate on.

46:45

It does better.

46:48

Then some of the other meniscal areas with a

46:51

conservative approach.

46:52

Let's take this 27-year-old man

46:54

with anterior and medial pain.

46:57

I highlighted anterior and medial for a reason.

47:00

It's worst over the last year. The injury is chronic.

47:03

What is causing the pain?

47:06

Look at that anterolateral root.

47:08

It's fuzzy.

47:10

Interdigitation of synovium.

47:13

Transverse meniscal ligament of Winslow right there,

47:16

more interdigitation.

47:17

Let's keep looking.

47:19

The next cut going towards the periphery,

47:22

vertical signal.

47:22

But we're still in very deep.

47:24

And what is all this?

47:26

It's synovitis in the midline.

47:28

It's a synovial reaction.

47:30

So, is this tear causing the pain?

47:33

Whatever is causing the pain is producing medial pain.

47:36

So it's more likely to be from this midline

47:39

near medial synovitis than it is the tear.

47:43

Let's take a look at this signal.

47:45

It persists for one more cut.

47:48

And then perhaps maybe for a fourth cut,

47:50

but it's not very deep.

47:52

So the truth of the matter is,

47:54

as you get out to the periphery, the thing is gone.

47:58

So when you're looking at the anterolateral meniscus,

48:01

if that vertical signal or complex signal that you're seeing

48:04

doesn't go out to the body,

48:08

I tend to dismiss it.

48:09

And how do I dismiss it?

48:11

I describe it as synovial interdigitation

48:15

anterolateral meniscus root injury

48:17

without displaced macromeniscus

48:21

or unstable macromeniscus tear.

48:23

Now, if it comes all the way out into the body

48:27

and the symptoms correspond,

48:29

I will approach it much differently.

48:31

So use a combination of the clinical and the

48:34

presence of a root injury that propagates

48:37

to make my decision.

48:40

The posterolateral attachments.

48:42

You already saw those two small little fascicles

48:45

that come off the posterior horn.

48:47

So here's the posterior horn of the lateral meniscus.

48:49

Here's an upper fascicle and a lower fascicle.

48:51

They're thin, they're dark, they're delicate,

48:54

and where are they?

48:55

They are gone.

48:57

There's not one over here.

48:59

There's certainly not one over here

49:00

where it's blunt-ended.

49:03

Again, blunt-ended.

49:05

These are typically seen in patients who have had a

49:07

pivot shift, frequently associated with vertical tears

49:12

or Wrisberg rips of the posterolateral meniscus.

49:16

An example of a fascicular detachment of the

49:19

lateral meniscus post superiorly

49:21

and inferiorly in a pivot shift.

49:24

The posteromedial attachments.

49:28

There are several small short unnamed

49:31

detachments to the posterocapsule.

49:33

There is one that's recognized called

49:35

the inferior meniscotibial ligament.

49:39

This is variably seen depending upon

49:41

the resolution of your imaging.

49:44

Also helping to stabilize the posteromedial corner

49:48

is the semimembranosus attachment and a tip of

49:53

ligament that attaches in the

49:54

posterosuperior quadrant called the POL

49:57

or Posterior Oblique Ligament of the knee.

50:00

So it gets a little complex.

50:02

Here's a child.

50:03

All those short unnamed detachments,

50:05

those are easy. They don't have a name.

50:07

All you need to do is look for swelling, synovitis, blood.

50:11

You have it all.

50:12

Swelling, synovitis and blood.

50:14

You also have a bone injury.

50:16

Where is your menisco inferior tibial ligament?

50:19

Right there.

50:20

And it's attenuator right there.

50:23

Over here, it's torn.

50:24

The inferior meniscotibial ligament is torn.

50:27

The meniscus is blowing out the back.

50:30

When the patient flexes their leg,

50:31

guess what's going to happen?

50:33

The meniscus is going to blow out the back and

50:35

they're gonna end up with premature

50:37

posterior arthritis.

50:38

This is called failure of the brake stop mechanism.

50:43

Here's an example of somebody that has another menisco

50:47

femoral menisco...

50:48

sorry, a posterior meniscocapsular injury.

50:51

This is one we missed about sixteen, fifteen years ago.

50:56

Clinician said, "Have another look at it."

50:58

This kid locks.

51:00

We had another look at it,

51:01

we missed it a 2nd time.

51:03

How humiliating.

51:05

But being humble is good.

51:07

There is the posterior inferior meniscotibial ligament.

51:11

We failed to recognize on one cut

51:13

that

51:15

the upper attachment, the POL attachment,

51:18

or the superior meniscocapsular attachment was gone.

51:22

So when the surgeon went in,

51:24

he could take the meniscus and rotate it on a pedicle.

51:27

That was the pedicle.

51:28

So we failed to recognize this upper attachment injury,

51:33

which was the only finding.

51:35

Now this one, not so difficult.

51:37

18-year-old man,

51:38

trauma while playing basketball,

51:40

difficulty walking.

51:42

Let's walk our way out from the midline

51:44

to the periphery.

51:47

Midline.

51:48

What's that?

51:50

Well, that is a fragment of meniscus and blood.

51:54

But there's your meniscus,

51:54

it should be lining up over here.

51:57

There's your meniscus, there's your tibial edge.

52:00

There's your meniscus, there's your tibial edge.

52:02

There's a hematoma.

52:04

There's your meniscus, there's your hematoma.

52:06

There's your tibial edge.

52:08

And again.

52:09

And again.

52:10

So, when you have greater than a centimeter of

52:12

displacement with a hematoma,

52:15

with a bone injury on successive three or four slices,

52:19

you've got meniscocapsular separation.

52:24

Let's talk about pivot-shift type tears.

52:27

The most common pivot shift type tear is the vertical

52:30

longitudinal tear, either medial or lateral.

52:33

Another very common type of pivot shift tear

52:36

with ACL is the Wrisberg rip tear.

52:40

Let's take a look at the normal ligament

52:42

of Wrisberg and its interface,

52:45

also known as the posterior meniscofemoral ligament.

52:49

So there's the lateral root.

52:52

That is not a fragment of meniscus.

52:54

That is the Wrisberg ligament.

52:58

If you go from the outside to the inside,

53:01

that ligament will move away from the meniscus.

53:04

If you go from the inside to the outside,

53:07

that will move towards the meniscus.

53:09

So that by slice number three of a 3 mm cut,

53:14

that interface right there is gone.

53:17

And it is, it's gone.

53:19

So, the normal Wrisberg interface will look something

53:22

like this, just to highlight it.

53:26

Like that.

53:28

And then this structure, which is the ligament,

53:31

as you go deeper and deeper into the knee,

53:33

will move away from the meniscus.

53:35

As you move to the periphery, closer to the body,

53:38

it will come towards the meniscus,

53:39

and by the time you're on cut three,

53:42

that interface will be gone.

53:45

Here is the posterior meniscofemoral ligament of Wrisberg,

53:50

going from inferolateral to superomedial.

53:55

Let's take a look at a Wrisberg rip.

53:57

So here's our lateral root.

54:00

There our Wrisberg.

54:00

It's a little tiny one this time.

54:02

There's the Wrisberg.

54:04

Here's cut number three,

54:06

and it should now be gone.

54:09

That ligament should be moving towards the meniscus.

54:12

This interface should fade away. It is persisting

54:14

and it's getting bigger,

54:16

and bigger,

54:17

and bigger and changing direction.

54:22

The tear begins at this weakened

54:24

interface between Wrisberg and the meniscus

54:28

and then propagates into the body,

54:30

the Wrisberg rip of ACL deficient knees.

54:35

Ramp lesions.

54:37

The anterior cruciate ligament is the guardian

54:39

of the posteromedial meniscus corner.

54:42

So when you pivot shift, bad things happened here.

54:47

What is a ramp lesion?

54:49

It's a meniscosynovial meniscocapsular

54:53

or peripheral meniscal injury.

54:58

Ramp lesions have been graded.

55:00

Here's a normal meniscosynovial interface.

55:04

There's the meniscus,

55:06

there's the meniscotibial ligament,

55:08

which is usually hidden from the clinicians view

55:11

and it's nice and tight.

55:14

Here is the earliest form of ramp lesion where you tear

55:17

the capsule and/or the synovium outside the meniscus.

55:21

This bleeds.

55:23

In a type II,

55:25

partial tear, outer third of the meniscus, upper surface.

55:27

Type III,

55:29

inferior surface,

55:30

and the meniscotibial ligament

55:32

may be it's ruptured.

55:33

Type IV,

55:35

all the way through.

55:36

Type V,

55:37

a double tear.

55:39

This has been overlooked for so long,

55:42

pivot shift, posterior medial, tibial impaction injury.

55:46

Here's what a pivot shift looks like.

55:48

Right? Tibia goes forward,

55:50

femur goes back, stretchy injury

55:53

capsule tears, fills with blood,

55:56

where's your posterior meniscotibial ligament?

55:58

It's gone.

55:59

There's blood in the capsule,

56:01

but there's no tears in the interstitium

56:04

or body of the meniscus,

56:06

a ramp 1.

56:09

Here's a ramp 4,

56:11

and ramp 4 goes all the way from

56:12

the upper surface to the lower surface,

56:14

and this time, not in the capsule,

56:15

although the capsule is bloody.

56:18

The capsule is injured,

56:19

but there's also a vertical through-and-through

56:22

tear in the outer third of the meniscus.

56:24

A ramp 4 and a ramp 5 is a double tear.

56:27

Blood and gore.

56:30

Diffuse swelling in the posteromedial capsule reflection

56:33

with not one tear,

56:34

but a second tear involving the meniscus

56:37

from the violence of the pivot shift.

56:40

Meniscus Dysplasia.

56:43

Most common form of dysplasia is

56:45

discoid lateral meniscus.

56:47

Lateral to medial ratio is 100 to 1.

56:51

Every patient with the discoid meniscus has

56:53

some form of tibial or femoral dysplasia.

56:57

One of the most common dysplasia is

56:58

hypoplasia of the lateral tibial spine.

57:02

They can get fibular head overgrowth.

57:05

They can get small aneurysms of geniculate vessels,

57:08

absence of the ligament of Wrisberg.

57:11

Common symptomatically is knee locking,

57:14

intra and extra-meniscal cysts are quite common.

57:18

Any signal in a discoid meniscus

57:20

that is not in the outer third

57:22

should be deemed an intrameniscal tear

57:24

to approve otherwise.

57:26

That rule works 100% of the time.

57:31

Now, this meniscus is going all the way in.

57:34

It's covering this hypoplastic tibial spine.

57:37

And on every single coronal cut,

57:40

the meniscus has a long tongue.

57:43

It never tapers into a triangle.

57:47

So it covers 100% of the tibial surface.

57:51

It may be flat, or in this case convex upward

57:54

when you look at it arthroscopically,

57:56

which produces quite a problem

57:58

in terms of knee biomechanics.

58:02

Here's another one.

58:02

Different patient.

58:04

Sagittal view showing discoid lateral meniscus.

58:09

Their signal, not just in the outer third, but it's cyst.

58:12

There's a perimeniscal cyst.

58:14

There is a continuation of that cyst

58:16

all the way into the middle and inner third.

58:18

This one unfortunately had to be resected.

58:22

And on the table,

58:23

it just flopped into two pieces.

58:26

It was already like a cleaving amoeba.

58:30

Any signal that is in the middle or inner third

58:32

should be deemed a tear until proven otherwise.

58:34

Any cystic signal in a discoid meniscus

58:37

should be deemed a tear until proven otherwise.

58:40

50% of all discoid menisci will have an intrameniscal tear.

58:44

It's darn common.

58:46

And dysplasias are frequently overlooked.

58:49

Here's another one.

58:50

Let's have a look. This is medial.

58:53

Our medial meniscus is tapering into

58:55

a nice little triangle, ain't it?

58:57

Here's our triangle.

58:59

But not on the lateral side,

59:01

it just keeps going and going,

59:03

and going, and going, and covers the entire tibia.

59:07

How about the medial femoral condyle?

59:09

It's slightly narrow.

59:11

It should be bigger than the...

59:13

The lateral femoral condyle

59:14

should be bigger than the medial femoral condyle

59:16

in terms of medial-lateral dimension,

59:18

it's not, it's hypoplastic.

59:21

The tibial spine is hypoplastic.

59:24

The patient had a large fibular head, not shown,

59:28

and has another anomaly, an intermeniscal ligament

59:33

that goes to the base of the ACL,

59:36

dysplasia.

59:36

When you see a discoid meniscus,

59:38

hunt for other signs of dysplasia.

59:41

Here is yet another one.

59:43

Medial meniscus, it becomes a triangle.

59:45

Hooray!

59:47

But on the lateral side,

59:48

it just keeps on going.

59:51

And again,

59:52

we have the most common anomaly:

59:54

hypoplasia of the lateral tibial spine.

59:57

And now, look at the slope.

59:59

Look at the dysplasia of the lateral tibia.

60:02

You've seen plenty of tibias in your lifetime already.

60:06

They don't look like that.

60:07

Sloping so steeply from superomedial to inferolateral

60:12

without the usual concavity that you'd like to have.

60:15

You want to see something

60:16

that looks a little bit more like this

60:18

rather than have this flat appearance.

60:20

And also look at the hypoplasia of the femur

60:23

in association with this discoid meniscus.

60:26

That one was Wrisberg deficient, by the way.

60:28

And here is another sign of a discoid meniscus.

60:31

In the sagittal projection,

60:32

you want to see as you go in,

60:34

the meniscus separate into two bowties.

60:37

Sorry, two triangles.

60:39

One in the back,

60:40

and one in the front.

60:42

But in this case, we have a bowtie.

60:45

And the bowtie just simply

60:47

never comes off the tuxedo.

60:49

Bowtie. Bowtie. Bowtie. Bowtie.

60:52

Discoid lateral meniscus.

60:55

So, in summary.

60:59

One of your most important jobs

61:01

is to make a cogent, thoughtful determination of

61:04

whether that meniscal tear is unstable

61:07

and needs intervention, attention,

61:10

or whether you can protect that patient by using

61:13

crafty words like chronic, incidental, small, minuscule

61:18

contralateral to the side

61:20

of the patient's clinical syndrome.

61:21

Save the whales,

61:23

save the menisci.

61:25

Understanding when tears are potentially unstable

61:29

was a focus of this talk.

61:31

Understanding when tears

61:32

may be surgical was included in this talk.

61:36

We also discussed root injuries,

61:40

ramps, and Wrisbergs.

61:42

The latter two, associated with ACL-deficient knees.

61:46

And we gave you some basic classification systems

61:49

for assessing root abnormalities.

61:52

We finished with some variants,

61:54

pitfalls, and dysplasia, like,

61:56

dysplasias like the discoid lateral meniscus.

61:59

At this point,

62:00

I want to thank you all.

62:02

I'll take any questions that you have.

62:03

You can either post your questions by text or chat.

62:09

Perfect.

62:09

Dr. P, I do see a couple of questions

62:11

in the Q&A feature for you.

62:13

You can open that up.

62:15

And just while you're opening that up,

62:16

I just want to say thank you everyone for joining today.

62:18

If you enjoy learning from Dr. Pomeranz,

62:20

please join MRI Online today for access

62:22

to many more courses by him.

62:25

Okay,

62:26

so the first question is how can you diagnose the

62:28

subgroup of discoid menisci,

62:31

such as the incomplete type,

62:33

or the type with Wrisberg's absence?

62:37

So, you have to know how to

62:38

look for the ligament of Wrisberg.

62:40

So you need to go to the posterolateral corner

62:42

and see if there is a Wrisberg deficiency.

62:45

If there is a Wrisberg deficiency,

62:47

then there may be a big Humphrey.

62:49

If there is neither Wrisberg nor Humphrey;

62:50

that is a form of dysplasia.

62:53

And the other thing I do is look at

62:55

the architecture of the bone.

62:56

In a partial discoid meniscus,

62:58

the bone is still going to be dysplastic.

63:00

Do I have a funny slope of the tibia?

63:03

Do I have a hypoplastic femoral condyle?

63:05

And I still look to see...

63:08

hopefully, you can still see the screen.

63:09

I still look to see.

63:10

If the meniscus is too long.

63:11

Now, some types of discoid menisci,

63:14

they go all the way in.

63:15

But they're very, very thin in the inner third,

63:17

so you have to look very carefully.

63:19

And some will go,

63:21

you know, more than 80% of the way in,

63:23

but not 100% of the way in.

63:25

Some discoid menisci are actually perforated;

63:27

have little holes in them.

63:29

So you have to familiarize yourself with

63:30

these variations and understand

63:33

what is too deep. And the only way to do that

63:35

is to look at enough MRs.

63:37

But anything more than 80% coverage of the tibia,

63:41

always abnormal from outside to inside.

63:44

So that 80% rule may help you.

63:46

Is there a clinical significance of meniscal flounce?

63:50

Most important significance is not to confuse

63:52

it with a radial or small parrot beak tear.

63:56

A 2nd important aspect of flounce is some have said

64:01

that patients with hypermobile flouncy menisci are more

64:05

likely to have meniscal tears, although

64:07

this is debated.

64:10

What's the best way to diagnose traumatic tear

64:12

in a 60-year-old versus a degenerative type tear.

64:16

Well, first, degenerative tears are almost always cleavage

64:21

or narrow flap tears.

64:22

They're almost always horizontal in their orientation.

64:25

People with degenerative tears should have DJD.

64:29

They should have either osteoarthritis with spurs,

64:32

chondromalacia, remodeling, partial extrusion.

64:36

In a traumatic tear,

64:38

you want to see inflammation.

64:39

You want to see the tear too thick.

64:41

You want to see swelling of the surrounding capsule.

64:44

You might want to see some displacement,

64:46

some twisting,

64:47

some extrusion, a comma sign,

64:49

an apostrophe sign.

64:51

So all those features that we were discussing

64:53

earlier as they relate to surgery and instability

64:57

you would use to diagnose a traumatic tear

65:00

in a 60-year-old.

65:02

It is pretty easy to diagnose the degenerative tear

65:04

due to the presence of degenerative joint disease,

65:07

the absence of swelling and remodeling of the bone.

65:12

Which is the optimal interslice distance and gap?

65:16

The optimal interslice distance and gap

65:19

is the one that's right for you.

65:21

So there is no answer to that.

65:24

I read low-field MRI's with 4 mm slice thickness all the time.

65:29

If the pulsing sequence is exquisite like the SARGE

65:32

on the old 0.3 Hitachi,

65:35

then I have no problem doing 4 mm cuts.

65:38

On the other hand,

65:38

if my contrast resolution isn't quite as good

65:41

as I would like, I certainly prefer having something

65:44

that is 3 mm or less.

65:47

As far as gap goes,

65:49

I usually go gapless when I can.

65:51

If I'm doing a 3D image,

65:53

I use a 50% overlap.

65:54

But there's nothing wrong at low field with going

65:57

3 gap one or 4 gap one,

65:59

as long as you have the proper contrast resolution.

66:02

Which means you've got to know your scanner,

66:04

then you've got to know which sequences work,

66:07

and I gave you a list of those and which ones do not.

66:10

How successful are surgeons

66:12

at detecting intrameniscal tears?

66:15

Not very successful at all.

66:18

That is one of the reasons why MRI's can be so valuable.

66:22

Fortunately, most intrameniscal tears are

66:25

not symptomatic, but they are more symptomatic

66:28

in people that are more active.

66:30

So, the intrameniscal signal becomes

66:32

a lot more relevant when you're dealing with a 20-year-old

66:35

than when you're dealing with a 65-year-old.

66:39

But that's where MR has great importance, and

66:41

this is especially true in discoid menisci.

66:44

We are trying to let that meniscus right itself out.

66:47

You know, there's nothing you can do.

66:49

You know, meniscal transplantation

66:50

has not had tremendous success,

66:53

so you basically live with that discoid meniscus

66:55

as long as you can,

66:56

but once you start to see cystic degeneration

66:59

of that discord meniscus,

67:01

you know the end is near; if the child or person or

67:04

young person has pain,

67:05

then it's time to take that meniscus out

67:07

and you're stuck in a difficult situation.

67:10

Can we differentiate between prior and current

67:13

injuries to the menisci?

67:15

Well, you can.

67:18

I think part of it is combining history,

67:20

the location of the pain, new onset pain,

67:24

and I always...

67:25

I don't read knees without history.

67:28

If I don't have a history,

67:29

I'm on the telephone asking for the history.

67:32

My colleagues are on the telephone

67:34

asking for the history.

67:35

I am also looking at the degree of swelling.

67:38

A prior injury, going to be less swollen.

67:41

A prior injury, unlikely to have bone edema.

67:44

A prior injury, unlikely to have a chondral flap.

67:47

So I look at all the surrounding tissues to make my

67:50

decision in concert with the correlation of the

67:53

patient's clinical syndrome to decide

67:55

if it's relevant to a recent trauma.

67:59

How different ghost symptoms dramatic and postoperative?

68:04

I don't quite understand this,

68:06

but let me talk about the postoperative

68:07

meniscus for a minute

68:09

because I think that's the question.

68:10

So, when you...

68:13

when you resect the meniscus and didn't

68:15

get into this just due to time,

68:17

and I will do a postoperative meniscus talk for

68:19

you separately at some time in the future,

68:22

the resection is usually a trim.

68:24

So they trim out the inner third of the meniscus.

68:26

And now the meniscus is very truncated

68:30

and that interface right there is very smooth.

68:33

Now over time, the meniscus will usually remodel.

68:36

It becomes a little more curved and rounded.

68:38

So it looks like that.

68:40

Now, I don't mind if I have a small meniscus

68:44

like that and has some signal in it.

68:46

That's okay.

68:48

What will I do with that?

68:49

I'll call that chronic conversion type

68:51

signal in the meniscus remnant.

68:53

If the meniscus is so small that the

68:56

only treatment is resection,

68:58

I always read it conservatively.

69:01

Now let's talk about resection again,

69:05

and let's assume we had a large flap tear.

69:09

They go in and they trim, and they trim,

69:11

and they trim and they say,

69:12

"Okay, we're going to stop right here."

69:15

Why are we stopping right here?

69:16

Because the meniscus

69:17

is getting a little more vascular.

69:18

And I don't want to take this young person's

69:20

entire meniscus out. So they stop.

69:23

And what are they left with? They are left with this?

69:25

They are left with this converted signal, this stable

69:29

outer to middle third signal

69:30

that has been cut right to there.

69:33

So when I have a postoperative meniscus,

69:36

and I see a remnant that's less than 8 mm in depth.

69:40

And I have some horizontal or oblique

69:42

signal in the outer remnant,

69:44

and the remnant is not twisted. It's not extruded.

69:47

It's not displaced.

69:49

There's no comma sign.

69:50

There's no apostrophe sign.

69:52

There's no other signs of acute trauma,

69:54

I'm going to call it postoperative

69:56

meniscal conversion signal.

69:58

And I hardly ever perform MR arthrography to analyze

70:03

this signal intensity in a small remnant

70:06

with sequences most reliable for tear,

70:09

the sequence that is heavily water-weighted.

70:13

So on your scanner, that could be

70:15

proton density STIR , SPIR, SPARE,

70:18

special, and so on.

70:20

Another very water-sensitive

70:22

sequence is the water-weighted gradient echo.

70:26

On older scanners,

70:27

field-echo, gradient recalled echo, steady-state imaging,

70:31

also known as GRASS imaging.

70:33

On some of the newest scanners,

70:35

additive gradient echo known as MEDIC,

70:38

MFFE, ADAGE, MERGE, and others.

70:43

Any plain extra pointers to meniscal injury.

70:46

Well, sure.

70:49

If you got a segond sign, you've...

70:52

injured the lateral capsule,

70:53

you've had a traumatic various insult.

70:56

If you have a reverse segond sign,

70:58

a flake fracture on the medial side,

71:00

you've had a valgus injury.

71:02

If you've got an arcuate sign or you've raptured,

71:04

or fractured the fibular head, then you've got a

71:07

posterolateral corner injury.

71:09

All of those have association with meniscal pathology.

71:13

So, there are enumerable

71:16

but rather profound plain film signs that a meniscal

71:19

injury is likely to be present in concert

71:22

with the ligamentous insult.

71:26

Okay, I think that was our last question.

71:29

I appreciate your attention.

71:30

Thanks to the MRI Online team for having me.

71:33

Have a great day.

71:34

Perfect.

71:35

To bring us close on,

71:36

thank you, Dr. Pomeranz, for your time today,

71:38

and thanks to all of you for

71:39

participating in this Noon Conference.

71:40

A reminder that it will be made available on demand at

71:43

www.mrionline.com,

71:44

in addition to all previous Noon Conferences.

71:46

Be sure to join us on Monday for a lecture

71:49

on imaging of the adrenal glands.

71:51

You can register for that

71:52

the same way you registered for this.

71:53

Thank you and I have a wonderful day.