0:00

Knee anatomy on MRI, posteromedial corner,

0:03

and a focus on the Posterior Oblique Ligament, or POL.

0:08

Now, the posteromedial corner and the POL provide active support during flexion.

0:15

And this is also further supported by the superficial portion of the deep

0:21

MCL, otherwise known as the tibial collateral ligament,

0:25

and the adjacent structure seen here in green, the POL immediately behind it.

0:31

Now, the POL is a restraint against a valgus stress.

0:36

It also supports both anterior

0:38

and posterior translation, and internal and external rotation.

0:42

Now, don't confuse the POL with something

0:46

that occurs back here, which we haven't really discussed yet, called the OPL.

0:51

The POL is the Posterior Oblique Ligament,

0:53

the OPL is the Oblique Popliteal Ligament,

0:57

and that is a primary restraint to knee hyperextension.

1:01

It's important in preventing something

1:03

called genu recurvatum, in other words, where the knee looks like it's kind

1:07

of bowed at the level of the knee joint itself.

1:13

So the POL is a support for translation and rotation,

1:17

and it's even more important when the knee

1:20

is PCL or Posterior Cruciate Ligament deficient.

1:24

After an isolated MCL injury,

1:26

the PCL may be an important secondary stabilizer for rotation and valgus stress.

1:34

I'd like to draw a little bit for a moment.

1:36

And this slide, I think, illustrates a somewhat triangular shape to the POL.

1:43

We don't have the triangle,

1:44

the back of the triangle down here because we just don't have enough room to draw.

1:48

But the fibers are actually running down,

1:50

and somewhat obliquely, and the triangle points

1:55

back towards the semimembranosus or towards the posterior aspect of the knee.

2:00

Whereas the second layer,

2:02

the middle layer of the MCL, also known as the deep layer

2:07

of the superficial MCL, also known as the tibial collateral ligament,

2:11

it runs more straight up and down.

2:13

Now, this is going to become relevant when I show you MRIs.

2:15

You're actually going to be able to see,

2:17

in the sagittal projection, the difference between this and this.

2:22

Now, this is going to communicate

2:24

with some fibers around the back over here, which form the OPL.

2:30

So it goes OPL in the back to POL,

2:34

transition into what we used to call the tibial collateral ligament or deep

2:38

layer of the superficial MCL, so called middle layer.

2:42

Now, there's some debate as to what layer the POL actually is.

2:48

As you're more forward at this interface,

2:51

many individuals consider the POL part of layer or middle layer number two.

2:57

But as you move further back, getting towards the OPL,

3:01

the oblique posterior ligament, most people consider that layer number three.

3:07

So there's a transition of the POL from layer two to layer three.

3:12

And this is the first time we're actually discussing this.

3:15

And the capsule at the back, and the POL, are virtually inseparable.

3:20

So it'll be hard to pick them out as two separate structures.

3:24

Another name, by the way, for the POL is the ligament of Winslow,

3:27

and most describe the origin to be near the adductor tubercle near the adductor magnus.

3:33

Although some have found it to be slightly distal and posterior to it.

3:38

Now, the distal end has three arms.

3:40

It has a capsular arm, which blends with the joint capsule and also blends

3:47

with the capsular arm of the semimembranosus.

3:49

It's got a central tibial arm, which courses right underneath

3:55

the anterior pars reflexa of the semimembranosus.

3:58

And then the main component is the distal superficial arm.

4:01

As we said, it has a somewhat triangular-shaped appearance.

4:05

So we're going to look at the POL on MRI,

4:08

and you're going to see it in its locations,

4:10

sagittally, if we get lucky, axially.

4:14

And remember, it sits immediately behind

4:17

the tibial collateral ligament, the deep portion of the superficial MCL,

4:21

or the middle layer of the MCL, this structure right here.

4:24

So if you find this, which is easy, right behind it is going to be the POL.

4:28

You're going to see it on MR.