0:00

So now, let's go back to the case.

0:04

Here's our axial,

0:05

and we now know something bad happened.

0:08

We got blood in the joint.

0:09

We already know we've got a fracture.

0:12

Something violent happened during the pivot shift.

0:16

There's a lot more information on here.

0:19

We can tell what's medial and what's lateral by

0:21

looking at the patella. There's the medial facet.

0:24

It. The cartilage is a little bit fatter.

0:27

It's usually a little shorter than the lateral

0:29

facet. So this would be lateral.

0:31

This would be medial.

0:32

And we get a quick glance at the MCL.

0:34

We get a quick glance at some of the lateral

0:36

collaterals. That's not the story today.

0:38

The story is the meniscus.

0:41

So let's have a look at the meniscus coronally.

0:45

First thing you ought to notice is the

0:48

lateral meniscus is too small.

0:51

I mean, normally,

0:52

the medial meniscus is bigger than the lateral

0:55

meniscus, or it's at least as visible.

0:58

We have a nice triangle on the medial side.

1:00

We can see the meniscus root.

1:03

We can even see the root attachment right there,

1:06

and it's lining up very nicely with the

1:08

edge of the femur and the tibia.

1:10

There is one of the attachments of the meniscus.

1:12

Let's blow it up a little bit.

1:14

Here's another attachment of the meniscus,

1:16

the so called coronary ligament attachment.

1:19

But on this side,

1:20

we already know that in this relatively young

1:23

person who's had a violent pivot shift,

1:24

that there's a meniscal problem.

1:28

We're missing our triangle.

1:30

So now we have to define the problem.

1:32

And as I'm defining it,

1:34

I recognize that there is another fracture

1:38

in the femoral terminal sulcus,

1:40

again illustrating the violence

1:42

of whatever happened.

1:43

We know that the ACL is going to be gone

1:46

with this constellation of fractures.

1:48

That's not why we're here.

1:50

There's less than a 7% chance the

1:53

ACL could still be intact.

1:55

But I am interested in where did the meniscus go?

1:59

Because this is about meniscus.

2:01

Did it go in? It's like belly buttons.

2:04

Is it an innie or an audi?

2:06

And I can't find it in.

2:08

I can't find a piece that got chopped off

2:10

and went in. I'm looking really hard.

2:12

In fact, I'm looking at that root.

2:14

We have a nice, clean root,

2:16

meniscus and root attachment, but over here,

2:19

not so much.

2:20

where is it? Oh, there's a root injury, all right,

2:24

the root ligament. Chop, chop.

2:27

The relationship of the meniscus to the root.

2:30

Chop, chop.

2:33

We have a root trauma, a root tear,

2:36

but we're not done yet because we

2:37

got to find this other piece.

2:38

We already know that this meniscus in this

2:41

younger person is floating outwards.

2:44

It's not lining up very nicely with the edge of

2:46

the tibby and the femur because it's

2:48

no longer properly anchored.

2:52

So, in a sense,

2:54

this meniscus is separated from the anchors

2:58

that keep it in the proper place.

3:00

And you got to remember,

3:01

this person's lying on their back.

3:04

They're not even weight bearing.

3:06

There are no hoop stresses.

3:08

So imagine what happens to this poor little

3:10

triangulated piece of cartilage when you stand up.

3:14

It's like toothpaste. Boom.

3:16

It goes out even further.

3:18

Let's take a look at the anterior horn.

3:20

Here's the anterior horn body junction.

3:22

There's the anterior horn.

3:23

There is the root attachment.

3:26

That includes a tether to the transverse meniscal

3:30

ligament of Winslow and a tether to this little

3:33

round structure here called the ligamentum

3:34

mucosum. Don't worry about that.

3:37

Let's go backwards. Now we're missing the body.

3:40

Keep going backwards.

3:42

And our posterior horn is way too small.

3:44

So let's look at the sagittal.

3:46

And here's our sagittal.

3:49

Let's work our way in from the body.

3:52

Here's the body of the meniscus all

3:56

the way out to the periphery.

3:57

And the back of the body should be tethered

4:02

to the popliteus tendon. Let's look at it.

4:06

What do we mean by tethered?

4:08

We mean it should be attached.

4:11

There should be an attachment high and low,

4:14

a superior fascicle attachment and an inferior

4:17

fascicle attachment. Let's draw it for you,

4:21

because this is the other part of the story.

4:23

We've already established that the

4:27

media meniscus has those short,

4:28

stubby little attachments that

4:30

go all the way around.

4:32

You can see them a little better in the mid

4:35

coronal plane as the meniscofemoral ligament.

4:38

I'll draw them

4:40

for the medial side.

4:42

We're going to have a meniscofemoral ligament.

4:46

And I showed you the coronary ligament earlier

4:48

in the back. They're really short,

4:50

so we don't see them.

4:51

But now I'm going to get a little

4:52

bit thicker here, not too thick.

4:54

And I'm going to show you what the

4:57

lateral meniscus attachments look like.

4:59

You don't see those as well, coronally,

5:01

but you see them really well sagittally.

5:04

So here's the lateral meniscus,

5:07

and it has an upper fascicle and a lower fascicle,

5:13

and those fascicles are very important tethers.

5:17

If you lose one,

5:18

the meniscus can actually twist on itself,

5:22

and that can be a cause of locking

5:24

just one of these gone.

5:26

If they're both gone,

5:28

then the meniscus can start to displace or float.

5:33

So we should have an upper one.

5:35

We do, although it looks a little lax right there.

5:38

And we should have a lower one that goes straight

5:41

on back and perforates through the

5:43

popliteus tendon. We don't.

5:45

I'm going to race it so you can

5:46

see it a little better,

5:49

and I'm going to blow it up so you

5:50

can see it a little better.

5:54

Let's blow it up.

5:59

So that should go right on through as a straight

6:02

line. Here's the other piece of it right there.

6:04

It's missing in action.

6:07

It's still missing in action.

6:08

In fact, they're both missing in action.

6:11

There should be one going high and one going low.

6:13

To make matters more complicated,

6:16

we have an upper fascicle and a lower fascicle,

6:19

but we also have a group that's on the outside,

6:22

a lateral upper and lower group,

6:25

and a medial, more central upper, and lower group.

6:28

And they look a little bit different as you

6:30

go from the center to the periphery.

6:32

But that will be a story for another day.

6:35

That's kind of getting into master

6:36

level discussion. right now,

6:38

we're in a pretty advanced discussion,

6:40

but not quite master level yet.

6:42

But this patient has a true meniscocapsular

6:45

detachment. We are missing the lower attachment,

6:47

we are missing the upper attachment,

6:50

and we're also in a violent pivot shift situation.

6:57

Let's go over to the medial side and see what

6:59

that capsule looks like for a moment.

7:01

We said that when you have a violent pivot shift,

7:04

you get bleeding in the capsule.

7:05

There it is too thick.

7:07

But it's not a separation.

7:09

On the medial side, it's a sprain.

7:13

It's bleeding. It's an injury.

7:15

But on the lateral side,

7:16

we've got ligaments that have ruptured,

7:19

a meniscus that has displaced outward

7:22

because it's no longer tethered.

7:24

And just to be complete here is the awful

7:28

consequences of this pivot shift.

7:30

The ACl is gone. The PCl is swollen.

7:34

Here is our blood fluid level,

7:37

and the tibia is displaced anteriorly

7:40

relative to the femur,

7:41

both laterally and medially as

7:45

a sign of ACL deficiency,

7:46

so called passive anterior tibial translation.

7:51

So, in summary,

7:52

you've learned about two very important types of

7:56

vertically oriented tears. One not so bad,

7:59

the vertical longitudinal one, that could be bad,

8:02

the radial tear.

8:03

You've learned how to measure length and depth of

8:07

these tears. And you've also learned, to a degree,

8:11

we're not complete yet,

8:12

the meniscocapsular attachments

8:15

and what can happen to them.

8:16

And the sequela when you have a big time rupture,

8:20

the meniscus being displaced and floating out of

8:23

the joint and no longer providing

8:25

the proper support. Thank you.

8:27

Thank