0:00

We have about 35 more minutes

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and I do wanna cover a whole bunch of other things.

0:05

Let's see if we can do this.

0:07

We're gonna turn our attention to the meniscal roots,

0:11

something that I learned about late in life.

0:14

There are four of them.

0:15

We already talked, uh uh, about them. Okay.

0:18

You can see there two on the medial side, one

0:21

and two widely separated, two on the lateral side

0:25

that are much closer together.

0:28

Okay? It is suggested at the time of arthroscopy.

0:32

About 10% of the time you will find root ligament problems,

0:36

particularly the posterior horn.

0:39

The posterior root of the medial meniscus. All right?

0:42

That is the one that may be involved.

0:45

Most commonly, uh, the attachments

0:48

of these root ligaments are fairly broad.

0:50

They have central as well as supplementary fibers.

0:54

Medial meniscal root ligaments tend

0:56

to occur in a slightly older group

0:59

and associated with osteoarthrosis.

1:02

Lateral meniscal root ligaments are seen in younger persons

1:05

following injuries, often ACL injuries.

1:10

To give you an idea, these are some images

1:11

that we did in cadavers a long time ago.

1:15

This is the classic anterior root ligament

1:18

of the medial meniscus attaching

1:21

to the sloping anterior margin of the medial ti beo plateau.

1:25

Here you see the anterior root ligament

1:27

of the lateral meniscus, which is intimate

1:30

with the footprint of the anterior cruciate ligament,

1:34

and then the posterior root ligament

1:36

of the lateral meniscus.

1:37

Perhaps the most complicated, often with two attachments,

1:41

one to the lateral tubercle

1:42

and one to the medial tubercle

1:44

of the intercondylar eminence of the tibia.

1:48

The root ligament I'm gonna emphasize is the posterior root

1:51

ligament of the medial meniscus.

1:55

It is intimate with the footprint

1:57

of the posterior cruciate ligament, as I already suggested.

2:01

Here is the footprint of the root ligament, okay?

2:04

Just in front of the footprint

2:06

of the posterior cruciate ligament on sagittal images.

2:10

Here we can see in fact that root ligament attachment

2:14

as we go central to medial.

2:17

Here's the PCL footprint adjacent to it.

2:20

You can see that nicely in these specimens

2:24

and in the transverse plane.

2:26

Here is the PCL,

2:28

and here is the posterior root ligament

2:30

of the medial meniscus.

2:33

One further example. These are coronal images.

2:36

This the more posterior this slightly more anteriorly.

2:39

Here's the footprint of the PCL.

2:42

Here is the inner margin of the posterior horn

2:45

of the medial meniscus,

2:46

and right in front of that footprint we see the footprint

2:50

of the posterior root of the medial meniscus.

2:54

This is what a root ligament emulsion looks like,

2:57

producing a gap in that

2:58

Very important half image of the knee.

3:02

Mr. Examination, there is a classification system

3:06

that has been put forth by Lara,

3:08

or I'm not gonna go into detail about it.

3:11

Of these five types, the ones that I see most commonly

3:15

are the type one which are partial tears,

3:19

the type two which are complete tears at variable distances

3:24

from the precise footprint

3:27

of the posterior root ligament

3:29

and the number one, uh, third one, this one, which is a

3:33

bone avulsion at the attachment

3:36

of the posterior root ligament.

3:39

One of the interesting findings that has been suggested

3:43

that may tip you off

3:44

that the posterior root ligament is not doing well

3:47

is a pattern of branching altered marrow signal called the

3:51

spreading root side.

3:53

I think this likely reflects edema

3:56

or edema like changes and you'll see it.

3:58

This is what it looks like. I have an example of one here.

4:03

Here you can see some subtle edema in the tibia right at the

4:07

attachment site of the posterior root ligament,

4:10

which looks partially torn in this particular image.

4:14

Four months later, a higher grade partial tear is present.

4:19

So be aware of altered marrow signal in this region.

4:24

Another beautiful example of a high grade partial tear

4:28

in the region of the attachment

4:29

of the posterior root ligament.

4:32

And this one, a complete tear producing a gap

4:36

very similar to the radial tear that I showed you earlier,

4:40

involving the posterior horn.

4:42

Now, when you see this sort of failure, part

4:45

of the attachment of the medial meniscus,

4:47

that the tibia is no longer present,

4:50

so it should not surprise you.

4:52

When you look at the body of the medial meniscus,

4:55

you see a variety of abnormalities.

4:58

Typically, what you see is significant peripheral meniscal,

5:01

extrusion, bowing,

5:03

and sometimes thickening of the medial collateral ligament,

5:07

peri ligamentous edema, which you can appreciate here

5:11

and edema,

5:12

and sometimes insufficiency fractures involving the

5:16

subchondral bone in the medial tibial plateau.

5:21

Here is a case I may have shown you this

5:23

case, uh, yesterday.

5:25

Here is a problem involving the posterior root ligament

5:29

of the medial meniscus

5:31

with peripheral meniscal extrusion two months later.

5:34

The classic features of what originally was called sunk

5:40

a meniscul has been viewed as a normal finding

5:45

seen in certain animals, particularly large cats and

5:50

and the large dogs,

5:52

and particularly I think in the Bengal tiger.

5:55

So for a long time we

5:56

Were taught that if we saw an ossicle in a meniscus,

6:00

typically within the posterior horn of the medial meniscus,

6:04

it was generally a normal finding.

6:06

And it may be, but I would remind you

6:08

whenever you see an ossicle in

6:10

that location within the posterior horn

6:13

of the medial meniscus, you may be dealing

6:16

with a root ligament problem.

6:19

It may be an avulsion of bone

6:22

as shown probably in this case,

6:24

or it may be a root ligament, soft tissue avulsion

6:28

with secondary heterotopic ossification.

6:32

And similarly, a normal finding that we used to

6:36

describe was a meniscal fonce.

6:38

We saw it with standard arthrography.

6:40

When we would twist the knee,

6:42

we would saw this undulating inner margin,

6:45

particularly on the medial side,

6:47

and it was a meniscal fonce.

6:50

This can be physiologic,

6:51

but I've learned that when you see this, go back, look at

6:55

that most important half image for tears

6:58

of the posterior horn

7:00

or root ligament problems as shown here.

7:03

This allows the posterior horn

7:05

to translate anteriorly producing this undulating,

7:09

connective, uh, region, A meniscal France.