0:00

It's an MRI of the left knee and a 14-year-old,

0:03

which we described in a prior vignette,

0:06

as opposed to a lateral corner injury,

0:08

which is present,

0:10

and an ACL transection,

0:12

which one sees in the coronal projection,

0:14

which is present.

0:15

and the menisci are spared.

0:18

But there's so much more.

0:21

Let's focus on the medial side,

0:24

the media medial collateral ligament,

0:26

specifically the middle layer,

0:28

which used to be called the tibial collateral

0:30

ligament and in some circles still is,

0:33

is transected. Now, when it's folded on itself,

0:36

that's a potential problem.

0:38

May have to be repaired,

0:39

or if it folds into a torn capsule and gets stuck

0:43

in the knee, that might have to get repaired.

0:45

The patient also has a tear of the deep layer.

0:48

There's the meniscocapsular attachment,

0:50

which is floating freely.

0:52

Here's a piece of cortex that has been avulsed

0:56

as a sign of a capsuler injury.

0:58

But we're here to talk about the corners.

1:00

So if you follow,

1:03

especially on this oblique coronal image,

1:07

if you follow the tibial collateral

1:08

ligament from anterior,

1:11

where it is ruptured

1:14

to posterior, you're going to run into the pol.

1:19

So most of you may remember that

1:22

in the sagittal projection,

1:24

the tibial collateral ligament is vertical,

1:27

and the pol

1:30

can be found right behind it as kind of a

1:33

group of oblique triangulated fibers.

1:36

The pol is going to have three components.

1:38

It's going to have a more horizontally

1:40

oriented superior capsuler layer.

1:43

Then it's going to have a tibial bundle that goes

1:45

down like this. I'll make the tibial bundle blue.

1:50

Let's see if it'll take my blue.

1:52

I'll make the tibial bundle blue.

1:54

And that is actually the main bundle that goes

1:57

towards the tip of the postural superior

2:00

corner of the meniscus.

2:01

And then you have a distal superficial

2:04

arm that comes down this way.

2:05

And I should make that its own color.

2:07

Let's make that red.

2:09

So those are the major components of the pol

2:13

capsuler component in orange, superior arm,

2:16

the main arm, the central tibial arm,

2:19

which goes towards the upper angle of the

2:21

meniscus, and then the distal superficial arm.

2:25

Now let's take it away.

2:27

Let's go back to our coronal oblique.

2:30

So we're somewhat anterior.

2:31

We've got our ruptured middle layer of MCL.

2:35

We've got our ruptured deep capsuler layer of MCL.

2:39

Now let's go back. Once we get out of the MCl,

2:42

we should come into a similar looking

2:45

structure that's thinner the pol.

2:48

So it should be right there,

2:50

contiguous and attaching to the superior meniscus.

2:53

It's not, there's a big gap there.

2:56

This is all pol here.

2:58

In other words,

2:59

you're posterior to the tibial collateral

3:01

ligament. Tibial collateral pol,

3:04

torn pol torn pol from the suproposerior

3:10

angular tip of the medial meniscus.

3:13

Oh, that's gorgeous. But not for the patient.

3:16

Now let's go back to the sagittal projection for a

3:19

moment and look at our remaining structures

3:23

of the posteromedial corner.

3:25

The corner consists of the pol, the OPL,

3:28

the semimembranosus.

3:30

We've got a great look at the semimembranosus.

3:32

There's the anterior reflected arm,

3:34

one of the two major arms,

3:35

and the other arm is the deep direct arm,

3:38

which is a little bit deeper right there.

3:39

It's a little gray, so it has been strained.

3:42

So deep arm injury, not transected or retracted,

3:47

but sprained and swollen, reflected arm intact.

3:51

Other components,

3:53

the posteromedial meniscus and meniscal

3:55

capsuler attachment, swollen, injured.

3:58

So in this case,

4:00

we have a very complex pattern of injury

4:03

that included, let's set it aside,

4:05

the acl in the posterolateral corner,

4:07

but also a grade three medial collateral

4:11

ligament injury. And on top of that,

4:14

a posteromedial corner injury that affected mildly

4:18

the semimembranosus tendon but severely

4:21

affected the pol, or posterior,

4:24

oblique ligament of the knee.

4:27

Look at the blunting of the superior meniscus at

4:30

its corner, where the pol would normally be.

4:33

And finally,

4:33

the third component in is an injury

4:36

of the meniscocapsular reflection,

4:39

all of which contribute to stabilization

4:42

of the meniscus,

4:43

preventing it from subluxing when you

4:45

flex and extend the knee and.