0:00

I've got a magnified coronal projection on your left, water weighted,

0:05

an axial T2, also water weighted, but not as much so.

0:09

And a very magnified view of the posterolateral corner.

0:13

There's the lateral meniscus and fibular head, just to get you oriented.

0:16

Where should I start?

0:18

Well, perhaps the axial projection, where we see the medial limb,

0:22

the arcuate limb and the vertical lateral limb of the arcuate.

0:27

There are the two limbs.

0:29

Let's scroll.

0:30

They're barely visible. There's the lateral limb.

0:32

What happened to the medial limb?

0:34

It fused with the posterior capsule

0:37

which consists of the capsule and the OPL, which came from the medial side.

0:43

So medial limb, lateral limb.

0:45

What about the coronal projection?

0:47

We need to go to the apex of the patella to find them.

0:51

There's the medial limb with its arcuate

0:54

shape and the more vertical lateral limb is right there.

0:59

Let's draw over the medial limb for a minute.

1:02

l'll use my pen.

1:04

There is the origin of the medial limb coming from the tip of the head.

1:08

Now I'll take it away, and now I'll put it back.

1:12

Oh, that's tough.

1:14

Now, you have to scroll that a little bit to follow it,

1:16

and most of the time you can't follow it

1:18

because it merges pretty quickly with other structures.

1:21

Here's a little bit of the arcuate, too,

1:23

right there, this linear structure having an arcuate component to it.

1:27

And now in the sagittal projection,

1:29

if we cross-reference these structures, here's the medial limb.

1:34

There's the medial limb of the arcuate

1:35

in the sagittal projection, and then the lateral limb we cross reference.

1:39

And the lateral limb is kind of buried in all this tissue that includes some veins.

1:44

So it's a little harder to see.

1:45

It's a lot easier when there's an injury to identify the arcuate because these

1:50

little wispy structures that make up the arcuate membrane and ligament, will

1:55

retract and fold and get a little bit thicker, and be surrounded by fluid.

1:59

So it's almost as if you have a free arthrogram.

2:02

But the definitive medial limb is seen right here.

2:06

That is the medial limb.

2:07

And you can tell by cross-referencing from the axial to the sagittal.

2:13

And that's how thin it is.

The Posterolateral Corner: Arcuate and Fabellofibular Ligament on MRI

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0:00

I've got a magnified coronal projection on your left, water weighted,

0:05

an axial T2, also water weighted, but not as much so.

0:09

And a very magnified view of the posterolateral corner.

0:13

There's the lateral meniscus and fibular head, just to get you oriented.

0:16

Where should I start?

0:18

Well, perhaps the axial projection, where we see the medial limb,

0:22

the arcuate limb and the vertical lateral limb of the arcuate.

0:27

There are the two limbs.

0:29

Let's scroll.

0:30

They're barely visible. There's the lateral limb.

0:32

What happened to the medial limb?

0:34

It fused with the posterior capsule

0:37

which consists of the capsule and the OPL, which came from the medial side.

0:43

So medial limb, lateral limb.

0:45

What about the coronal projection?

0:47

We need to go to the apex of the patella to find them.

0:51

There's the medial limb with its arcuate

0:54

shape and the more vertical lateral limb is right there.

0:59

Let's draw over the medial limb for a minute.

1:02

l'll use my pen.

1:04

There is the origin of the medial limb coming from the tip of the head.

1:08

Now I'll take it away, and now I'll put it back.

1:12

Oh, that's tough.

1:14

Now, you have to scroll that a little bit to follow it,

1:16

and most of the time you can't follow it

1:18

because it merges pretty quickly with other structures.

1:21

Here's a little bit of the arcuate, too,

1:23

right there, this linear structure having an arcuate component to it.

1:27

And now in the sagittal projection,

1:29

if we cross-reference these structures, here's the medial limb.

1:34

There's the medial limb of the arcuate

1:35

in the sagittal projection, and then the lateral limb we cross reference.

1:39

And the lateral limb is kind of buried in all this tissue that includes some veins.

1:44

So it's a little harder to see.

1:45

It's a lot easier when there's an injury to identify the arcuate because these

1:50

little wispy structures that make up the arcuate membrane and ligament, will

1:55

retract and fold and get a little bit thicker, and be surrounded by fluid.

1:59

So it's almost as if you have a free arthrogram.

2:02

But the definitive medial limb is seen right here.

2:06

That is the medial limb.

2:07

And you can tell by cross-referencing from the axial to the sagittal.

2:13

And that's how thin it is.

Report

Description

Faculty

Stephen J Pomeranz, MD

Chief Medical Officer, ProScan Imaging. Founder, MRI Online

ProScan Imaging

Lesson

MRI Mastery Series: Knee Pre Course Activities

Lesson

Knee - Anatomy of the Supporting Structures

Lesson

Supporting Structure Anatomy: Focus on the Posterior Corners

Lesson

Case Review: Supporting Structure Injuries

Lesson

Meniscus MRI

Lesson

Pivot Shift Injuries and Meniscal Pathology

Lesson

More Meniscus Tears with Case Examples

Lesson

Applying What You've Learned

The Posterolateral Corner: Arcuate and Fabellofibular Ligament on MRI