0:00

Okay,

0:00

our next example is going to focus on the

0:03

meniscal attachments and the roots.

0:05

It's going to be a child.

0:06

But let's start out blank screen

0:09

and draw our meniscus again.

0:13

When you're looking from the top down,

0:15

it can be a little difficult to see the roots.

0:17

They're kind of wispy.

0:18

They dive down towards the tibia.

0:21

So, you're going to have a posterior root,

0:25

you're going to have an anterior root.

0:26

You're also going to have an anchor.

0:28

Not in everybody, but in most people,

0:31

you're going to have an anchor in the front,

0:33

which is known as the transverse

0:35

meniscal ligament of Winslow

0:36

that goes from meniscus to meniscus,

0:39

to the other side.

0:40

And yes,

0:41

there is such a thing as a posterior

0:43

transverse ligament.

0:44

It occurs in about one in every 5000 individuals.

0:47

So, you're not going to see it very commonly.

0:49

We also said that on the medial side,

0:53

for the most part,

0:54

you're going to have short,

0:55

stubby little attachments to the capsule,

0:59

all the way around.

1:00

But they're pretty tight.

1:03

And because they're pretty tight,

1:05

when you tug on Superman's cape,

1:07

they're more likely to break.

1:09

So, meniscal capsular true separations

1:12

are more common on the medial

1:14

than the lateral side

1:15

because you just have less purchase,

1:17

you have less play.

1:20

We also said that the meniscus,

1:24

when you view it in cross section,

1:26

you can see in the mid coronal plane

1:29

a little better, these attachments.

1:31

They're a little bit longer

1:32

than they are in the front and the back.

1:35

And that's why most of the separations

1:37

don't occur in the mid coronal plane.

1:39

They occur where the attachments are shorter,

1:42

in the front or in the back,

1:44

mostly in the back.

1:45

So, when you look in the mid coronal plane

1:47

and let's say you've got the tibia underneath,

1:49

we'll make the tibia blue also.

1:51

And now, we'll draw the ligaments.

1:54

Let's take the ligaments in green.

1:56

You've got a meniscotibial ligament,

1:58

also known as the coronary ligament.

2:01

Again, best seen in the coronal plane,

2:03

and a longer

2:05

meniscofemoral ligament.

2:07

And that one would go up to the femur.

2:09

And I assume you can imagine the femur.

2:12

So, that's the stabilization of

2:15

the medial meniscus.

2:17

Now, tears of the medial meniscus root are not

2:22

uncommon in patients with a pivot shift.

2:26

That tear can hit part of the root

2:29

just like any other ligament.

2:31

It can go all the way through the root,

2:34

it can also go all the way through

2:37

the depth of the root into the screen

2:38

or all the way from anterior to posterior.

2:41

So you can,

2:43

if you have the resolution,

2:45

differentiate what is complete from front to back

2:49

and what is full thickness from top to bottom

2:52

or from proximal to distal.

2:55

Most of the time,

2:56

root tears are not the entire ligament.

3:01

You still have a little bit of ligament

3:02

tethering the meniscus,

3:04

and so it doesn't migrate all the way out

3:07

or start slipping because there's no attachment.

3:09

An equivalent to a root ligament injury,

3:13

as we've previously discussed,

3:14

would be as if you cleaved off

3:16

a whole segment of meniscus,

3:18

and now this portion of the meniscus migrates one way,

3:21

and this part stays over with the root.

3:25

Let's go over to the lateral meniscus.

3:29

The lateral meniscus is actually

3:32

a little more c-shaped.

3:34

I should have made the medial meniscus a little

3:36

more kind of banana shaped, but I didn't.

3:37

You'll have to forgive me.

3:39

The lateral meniscus is more c shaped,

3:43

and the attachment story with regard

3:45

to the root ligaments is the same.

3:48

So, I'm not going to redraw them for you.

3:51

You know,

3:51

you can imagine they're kind of little wispy ligaments

3:53

that go down towards the tibia.

3:56

But the major difference on the

3:58

lateral side is twofold.

4:01

We've got arising from the popliteus hiatus,

4:05

proximal, and on the lateral side,

4:08

the popliteus tendon.

4:10

So there's the popliteus tendon coming around,

4:13

and it's going to become the popliteus muscle.

4:17

Then we also have another ligament.

4:20

That ligament is known as the

4:23

ligament of Wrisberg.

4:25

The ligament of Wrisberg will come off the

4:28

posterior superior margin of the meniscus.

4:33

And then if we were looking coronally,

4:35

we're not right now.

4:36

Here, we're axially,

4:38

with the letter A.

4:39

But if we were to look coronal,

4:41

what would the Wrisberg ligament do?

4:43

It would do something like this.

4:47

It would come off the tip of the

4:49

lateral meniscus right here.

4:51

So, it would have an oblique course

4:53

from the lateral meniscus superomedially.

4:57

Now, that's a little hard to appreciate

4:59

in the axial projection,

5:01

but what you can appreciate is that the ligament

5:04

of Wrisberg is going to have

5:06

an interface between it

5:08

and the meniscus,

5:10

which I've drawn in green.

5:12

And if you look at that interface

5:15

in cross section...

5:17

Let's do that.

5:18

Let's make our meniscus blue again for consistency

5:22

and let's assume we have a sagittal

5:25

slice right here.

5:26

What might we see

5:29

at the interface of the Wrisberg ligament?

5:32

Well, we'd see the interface in green,

5:36

and then we'd have a little black structure,

5:39

which you might confuse as a piece of meniscus.

5:41

Well, it's not.

5:42

It's the ligament.

5:43

So, I'm going to color it yellow

5:46

because I like yellow,

5:48

but it's not really yellow on the image.

5:50

On the image,

5:51

it's going to be black because it's a ligament.

5:53

And that appearance, that angle,

5:56

that interface is going to persist for about

6:00

two slices, and then it goes away,

6:05

unless this area, which is weak,

6:09

propagates a tear,

6:11

which I'll make the tear in orange.

6:14

So if a tear comes off here,

6:16

now you've got something related to the

6:18

interface of the ligament of Wrisberg,

6:20

and we refer to these as

6:22

the series of Wrisberg rips.

6:25

But that's a story for another day.

6:28

I'm interested in the overall anchoring

6:31

of the meniscus and the roots.

6:33

So, let's get back to the popliteus tendon.

6:37

Let's look at a sagittal view at about

6:40

the mid posterior horn level.

6:44

So, let's draw our meniscus in blue

6:46

for consistency.

6:49

And behind it,

6:50

we have the popliteus tendon,

6:55

which then courses down.

6:57

It sends a small little fascicle to the fibular

7:01

head known as the popliteofibular ligament.

7:03

It sends one over to the tibia,

7:05

known as the popliteal tibial ligament,

7:07

and there are two posterior penetrating fascicles.

7:11

When you're close to the midline of the knee,

7:14

one of these fascicles is going to be

7:16

a little longer than the other.

7:18

And when you're out towards the periphery

7:20

of the knee, they change,

7:21

then the bottom one gets a little longer.

7:24

That's not so important, though.

7:26

You have an upper fascicle and a lower fascicle,

7:28

a set of ones near the midline

7:30

and a set of ones near the periphery.

7:32

So you have superolateral,

7:34

inferolateral,

7:35

superomedial,

7:36

inferomedial,

7:37

and they perforate the popliteus tendon,

7:40

and they serve as anchors for the lateral meniscus,

7:44

for when they're torn,

7:45

this meniscus is going to start floating that way.