The Posteromedial Corner Anatomy on MRI
HIDEInteractive Transcript
0:00
Knee anatomy on MRI.
0:01
Here is an MRI, sagittal or lateral, T1 fat weighted.
0:06
In the middle, sagittal or lateral, water weighted.
0:10
And on the right, coronal AP type projection, also water weighted.
0:16
We're focused on the corner, the posteromedial corner, which has five
0:21
main structures. The posterior oblique ligament, which is discussed on its own
0:26
but we can see a component of it, the capsular component,
0:28
right here along the posterosuperior aspect of the medial meniscus.
0:33
We can scroll it a little bit and we see
0:35
it right there, and perhaps right there, as a linear pointed structure.
0:41
Then we've got the OPL,
0:43
which we can't really separate from the posterior capsule.
0:46
But there it is, right there.
0:48
So the capsule and the OPL are seen as one, not as two distinct structures.
0:53
And the OPL is the oblique popliteal ligament.
0:57
Now, we've got the semimembranosus.
1:00
The semimembranosus, a dynamic stabilizer
1:04
and an anterior reflected portion of it is called the pars reflexa.
1:08
Then the semimembranosus continues
1:10
on down as the direct component of the semimembranosus.
1:15
There are actually five components,
1:16
a capsular, an inferior, a dista,l and then the two major ones, which I've just shown
1:21
you, the anterior pars reflexa and the distal... Sorry, and the direct...
1:26
and the direct component.
1:28
You can also see the direct component of the semimembranosus in the coronal.
1:31
It's this big, fat, dark blob.
1:34
It almost appears to wrap around the tubercle of the tibia.
1:40
Now, another structure that is seen
1:42
in this projection is the POL or posterior oblique ligament of the knee.
1:47
How do we find that?
1:48
Find your middle layer of MCL, also known as the deep portion
1:53
of the superficial MCL, layer number two or middle layer.
1:58
And then follow that posterior,
2:00
and that will turn into, it will become the POL.
2:05
So you're in POL right now.
2:07
You see the posterosuperior aspect of the meniscus and the POL, fused.
2:12
I'll make it a little lighter for you.
2:14
Then the POL is going to wrap around behind that meniscus and it's going to be
2:18
continuous with the posterior capsule and the OPL, the oblique popliteal ligament.
2:25
So you've seen several structures of the posteromedial corner.
2:29
You've seen the POL, you've seen the semimembranosus and two
2:33
components, the anterior pars reflexa and the continuation of the direct head.
2:40
Two other very important components are
2:42
the posteromedial meniscus itself and its capsular attachment, which is seen here as
2:48
these fuzzy areas of gray signal intensity on PD spur and on the T1 fat image.
2:56
Let's move on to another vignette, shall we?
Stephen J Pomeranz, MD
Chief Medical Officer, ProScan Imaging. Founder, MRI Online
ProScan Imaging
© 2024 Medality. All Rights Reserved.