0:00

Knee anatomy on MRI.

0:02

We're talking about the posterolateral corner.

0:05

Let's address the biomechanics and the anatomy of the posterolateral corner.

0:11

There are three main stabilizers

0:14

the lateral collateral ligament, which is a subset of the LCL complex,

0:18

also called the FCL, fibular collateral ligament.

0:22

The popliteus tendon with some very important attachments,

0:25

and the popliteal fibular ligament, which is one of those important attachments.

0:32

The popliteus is a myotendinous unit.

0:35

It consists of two bundles, a posterior bundle, which is taut in extension,

0:40

and an anterior bundle that is taut in flexion.

0:43

Now, most injuries to the popliteus involve the myotendinous junction.

0:47

And when they're isolated,

0:49

they're usually not treated surgically unless there's massive retraction.

0:53

And so these heal.

0:55

The popliteus may have a rare sesamoid bone

0:58

found in the tendon called the cyamella.

1:01

And I wouldn't mistake this

1:02

for the fabella, for the fabella has a different function.

1:06

As we'll see, it's inversely proportional in size to the arcuate ligament.

1:12

Now, there is a debate about the exact number of popliteal meniscal attachments,

1:18

and we're going to drill into those on MRI.

1:21

But probably the most important one is the posterosuperior fascicle.

1:27

The anteroinferior fascicles are also found and identified on sagittal MRI.

1:33

But in my experience, when the posterosuperior fascicle goes,

1:36

the meniscus can actually spin around or twirl and becomes unstable.

1:41

And the patient may report locking.

1:44

These attachments of the popliteus tendon,

1:47

which we'll outline, will form a floor and roof of the popliteus hiatus.

1:52

So I'm just going to draw a little bit here.

1:54

I'll change my color to orange.

1:57

So this would be your lateral meniscus.

1:59

And here's your popliteus tendon.

2:02

And then we're going to see, passing

2:04

through the popliteus tendon, in the region of the hiatus.

2:07

And maybe I'll make those a different color.

2:09

We'll see these attachments, superior attachment and the inferior attachment.

2:14

And they'll also be categorized as whether

2:17

they're lateral superior and inferior or more deep or medial superior and inferior.

2:23

So we're going to try and count about four

2:25

of them or follow them across from side to side.

2:28

In my experience, this one is more inconsistent and not as

2:33

critical to stabilization as the superior one.

2:36

Let's have a look on MRI.

The Posterolateral Corner: Biomechanics

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0:00

Knee anatomy on MRI.

0:02

We're talking about the posterolateral corner.

0:05

Let's address the biomechanics and the anatomy of the posterolateral corner.

0:11

There are three main stabilizers

0:14

the lateral collateral ligament, which is a subset of the LCL complex,

0:18

also called the FCL, fibular collateral ligament.

0:22

The popliteus tendon with some very important attachments,

0:25

and the popliteal fibular ligament, which is one of those important attachments.

0:32

The popliteus is a myotendinous unit.

0:35

It consists of two bundles, a posterior bundle, which is taut in extension,

0:40

and an anterior bundle that is taut in flexion.

0:43

Now, most injuries to the popliteus involve the myotendinous junction.

0:47

And when they're isolated,

0:49

they're usually not treated surgically unless there's massive retraction.

0:53

And so these heal.

0:55

The popliteus may have a rare sesamoid bone

0:58

found in the tendon called the cyamella.

1:01

And I wouldn't mistake this

1:02

for the fabella, for the fabella has a different function.

1:06

As we'll see, it's inversely proportional in size to the arcuate ligament.

1:12

Now, there is a debate about the exact number of popliteal meniscal attachments,

1:18

and we're going to drill into those on MRI.

1:21

But probably the most important one is the posterosuperior fascicle.

1:27

The anteroinferior fascicles are also found and identified on sagittal MRI.

1:33

But in my experience, when the posterosuperior fascicle goes,

1:36

the meniscus can actually spin around or twirl and becomes unstable.

1:41

And the patient may report locking.

1:44

These attachments of the popliteus tendon,

1:47

which we'll outline, will form a floor and roof of the popliteus hiatus.

1:52

So I'm just going to draw a little bit here.

1:54

I'll change my color to orange.

1:57

So this would be your lateral meniscus.

1:59

And here's your popliteus tendon.

2:02

And then we're going to see, passing

2:04

through the popliteus tendon, in the region of the hiatus.

2:07

And maybe I'll make those a different color.

2:09

We'll see these attachments, superior attachment and the inferior attachment.

2:14

And they'll also be categorized as whether

2:17

they're lateral superior and inferior or more deep or medial superior and inferior.

2:23

So we're going to try and count about four

2:25

of them or follow them across from side to side.

2:28

In my experience, this one is more inconsistent and not as

2:33

critical to stabilization as the superior one.

2:36

Let's have a look on MRI.

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: Biomechanics