0:00

Now, let me just finish with a few other thoughts.

0:04

This is discoid lateral meniscus,

0:06

huge horizontal tear, mostly intrameniscal.

0:10

And yes,

0:11

there is a little radial component of the tear.

0:13

And in the next session,

0:15

we're going to talk about

0:16

the different types of tears.

0:18

But right now,

0:19

I just want you to get a feel overall

0:21

for how to address menisci,

0:23

and review a little more anatomy before we quit.

0:26

Some terms that you're going to hear us use

0:29

day in, day out, didactic, non-didactic for patients.

0:35

First, a term everybody uses.

0:37

Severe.

0:38

You say severe,

0:39

you mean you think this is horrible enough

0:43

to warrant an intervention?

0:46

Severe means something.

0:49

Another word,

0:51

incidental.

0:52

That means I see it.

0:54

I'd like other radiologists to know I saw it,

0:57

but that's all I care about.

0:58

It's unrelated, it can't be fixed.

1:02

It has nothing to do with the

1:03

patient's clinical syndrome.

1:05

Contralateral to the side of the patient's symptoms,

1:09

same thing,

1:10

means don't touch it.

1:12

Chronic

1:14

means it's been there a long time.

1:16

If you want to touch it, you're taking a risk.

1:19

Degenerative.

1:21

If you want to say degenerative,

1:22

there better be degeneration,

1:25

there better be DJD,

1:27

there better be flattening of the femur,

1:29

deformity of the tibia, chondromalatia.

1:33

If you have high signal in the outer third

1:35

of a 12-year-old, it's vascularity.

1:38

It's not degeneration, as we discussed.

1:41

Displacement.

1:43

Displacement means simply that.

1:45

One structure

1:47

is displaced relative to another.

1:49

It's a lead in for other descriptors.

1:52

So, let's talk about maybe one or two

1:55

of those descriptors.

1:57

Let's talk about displacement.

1:59

The menisci should line up

2:02

with the outer edge of the femur and the tibia

2:04

on both sides

2:05

in a healthy person lying on the back.

2:07

But what if they're lying on their back

2:09

and the meniscus starts to do something like this?

2:15

Meniscus starts to pooch out a little bit

2:17

like that.

2:18

Yeah, my lines are a little fat,

2:20

but that's okay.

2:21

Now, the patient didn't have trauma.

2:24

They're lying on their back.

2:26

They're not even standing up.

2:27

The hoop stresses that push the meniscus around

2:30

are not in play.

2:31

They're lying on their back

2:32

having a cup of coffee

2:33

while the MR is going on.

2:35

So, what's going on here?

2:38

From walking and from the change in shape

2:41

of the femur, and from running,

2:43

and from years and years of use and abuse

2:46

the attachments of the meniscus.

2:47

Perhaps, these attachments here,

2:50

the menisco tibial and femoral attachments,

2:53

or the root ligament attachments,

2:54

which I can show you.

2:56

Here they are.

2:57

Here's a root ligament attachment right there.

3:00

Let's put an arrow on it.

3:03

Right here.

3:04

There's the root ligament attachment.

3:05

These stretch out.

3:07

So I refer to this phenomenon,

3:09

personally, as pseudo extrusion.

3:11

Or you can say meniscocapsular laxity

3:14

due to the wear and tear of activities

3:16

of everyday living,

3:17

or if there's DJD,

3:18

associated with DJD.

3:21

When do I use the term meniscal extrusion?

3:24

When I define that one of those

3:26

attachments is actually torn,

3:29

or the meniscus has decided to take a trip,

3:32

south towards Georgia.

3:34

In other words,

3:34

it goes down along the tibial gutter here,

3:37

or it goes up in the parafemoral gutter,

3:40

then I use the term true meniscal extrusion.

3:45

Now, if you have a meniscus that is

3:48

ripped off and spit out,

3:49

or a meniscus that is ripped off and thrown

3:52

into the center of the joint,

3:53

that's true extrusion.

3:56

Or another synonym for that is

3:58

meniscocapsular separation.

4:02

Another term that is related to shape,

4:06

although I'm not going to get into shapes today.

4:08

That's for the next talk, is cleavage.

4:12

I picked that one out

4:14

because everybody knows what a cleavage is,

4:15

right?

4:15

It's a horizontal line.

4:17

So, if I see a nice horizontal line

4:20

and it's not a 20-year-old,

4:22

and I have DJD,

4:24

cleavage is the lead in to tell you

4:27

this is going to be a chronic tear

4:28

that everybody has when they're 60 years old.

4:31

Chronic, cleavage, trizonal, body tear,

4:34

everybody's got that.

4:36

Don't touch those tears.

4:38

So, cleavage can be a word used to downplay.

4:45

Finally,

4:46

the last thing I want to emphasize is

4:49

the concept of meniscal failure.

4:52

What does failure mean?

4:54

Failure means the meniscus

4:55

isn't doing its job anymore.

4:58

All day long,

4:59

failure after failure, after failure.

5:02

We see here at PSI,

5:04

people that are too heavy.

5:05

The meniscus just couldn't hold up for 50 years

5:09

under the onslaught of 280 pounds.

5:12

And the meniscus gradually pseudo extrudes

5:15

and displaces and displaces, and displaces,

5:17

and it no longer supports the joint.

5:19

And then, the joint develops arthritis,

5:22

and the bones misshapen,

5:24

and that pushes it out even further,

5:26

and you're not even doing a standing MRI.

5:28

That is one type of failure.

5:30

Another type of failure is the meniscus auto digests.

5:34

There's not much left of it.

5:37

In that case, too,

5:39

it is not supporting the knee.

5:41

Now, if you have a small meniscus,

5:43

you've got to go through,

5:44

and we will go through this,

5:46

the important laundry list of causes

5:49

for why the meniscus is small.

5:51

The most common cause,

5:52

far and away, is resection.

5:56

Another important cause is an old tear

5:59

with a piece that got digested,

6:02

maybe an old bucket handle tear that got missed.

6:05

Another important cause is simple

6:07

autodigestion from arthritis.

6:09

Yes, arthritis,

6:10

especially rheumatoid, will,

6:12

with its enzymes,

6:14

destroy and dissolve the meniscus,

6:16

just like you can normally destroy and dissolve

6:19

an extruded disc herniation in your back.

6:21

Yes, your body can take it away.

6:24

Another cause of a very small meniscus is

6:31

one that has fragmented and separated,

6:35

not a classic bucket handle tear, but again,

6:37

one that has broken up into innumerable pieces.

6:41

And finally,

6:42

another cause of a small meniscus

6:44

is pseudo extrusion,

6:45

where you're through the part of it

6:47

that is just very thin.

6:48

In other words,

6:49

the whole meniscus is shifted

6:50

and you think it's small,

6:52

but when you look at the coronal,

6:53

you see the fat part,

6:54

but the fat part isn't where it's supposed to be.

6:57

It's pseudo extruded out into the

6:59

medial aspect of the knee.

7:01

So, go through your appropriate checklist

7:04

of small menisci.

7:05

Yes, there is such a thing

7:06

as congenital absence of the meniscus.

7:08

It's usually posterolateral,

7:10

It's extremely rare.

7:12

I've seen about five of them in my entire life,

7:14

which is pretty long, so it's not a common thing.

7:19

So that concludes our initial discussion

7:22

of menisci for today.

7:24

When we come back and review menisci

7:27

in our next session,

7:29

we're going to talk about meniscal anatomy.

7:31

We're going to go through all the roots.

7:33

This is obviously a meniscal cleavage tear

7:35

in our discoid meniscus.

7:36

We're going to talk about all the root ligaments,

7:38

all the individual attachments,

7:41

the variations of the menisci,

7:43

the dysplasias of the menisci,

7:45

and we're going to show the individual

7:46

meniscal tear shapes,

7:48

and we're going to drill again and again

7:49

into meniscal extrusion,

7:51

pseudo extrusion,

7:53

failure,

7:54

severity,

7:55

unstable versus stable menisci,

7:58

displacement,

7:59

nondisplacement,

8:00

full-thickness tears,

8:02

partial thickness tears,

8:03

chronic tears,

8:04

acute tears,

8:05

atraumatic, a very important word,

8:07

versus traumatic,

8:09

means you probably should fix it.

8:11

Atraumatic,

8:12

probably you shouldn't fix it.

8:14

Cleavage in other shapes, incidental,

8:16

non incidental.

8:18

Thanks.

8:18

Back to you shortly.