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Basic Knee Meniscal Descriptors

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Now, let me just finish with a few other thoughts.

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This is discoid lateral meniscus,

0:06

huge horizontal tear, mostly intrameniscal.

0:10

And yes,

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there is a little radial component of the tear.

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And in the next session,

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we're going to talk about

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the different types of tears.

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But right now,

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I just want you to get a feel overall

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for how to address menisci,

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and review a little more anatomy before we quit.

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Some terms that you're going to hear us use

0:29

day in, day out, didactic, non-didactic for patients.

0:35

First, a term everybody uses.

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Severe.

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You say severe,

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you mean you think this is horrible enough

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to warrant an intervention?

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Severe means something.

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Another word,

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incidental.

0:52

That means I see it.

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I'd like other radiologists to know I saw it,

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but that's all I care about.

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It's unrelated, it can't be fixed.

1:02

It has nothing to do with the

1:03

patient's clinical syndrome.

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Contralateral to the side of the patient's symptoms,

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same thing,

1:10

means don't touch it.

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Chronic

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means it's been there a long time.

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If you want to touch it, you're taking a risk.

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Degenerative.

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If you want to say degenerative,

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there better be degeneration,

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there better be DJD,

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there better be flattening of the femur,

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deformity of the tibia, chondromalatia.

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If you have high signal in the outer third

1:35

of a 12-year-old, it's vascularity.

1:38

It's not degeneration, as we discussed.

1:41

Displacement.

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Displacement means simply that.

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One structure

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is displaced relative to another.

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It's a lead in for other descriptors.

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So, let's talk about maybe one or two

1:55

of those descriptors.

1:57

Let's talk about displacement.

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The menisci should line up

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with the outer edge of the femur and the tibia

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on both sides

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in a healthy person lying on the back.

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But what if they're lying on their back

2:09

and the meniscus starts to do something like this?

2:15

Meniscus starts to pooch out a little bit

2:17

like that.

2:18

Yeah, my lines are a little fat,

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but that's okay.

2:21

Now, the patient didn't have trauma.

2:24

They're lying on their back.

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They're not even standing up.

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The hoop stresses that push the meniscus around

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are not in play.

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They're lying on their back

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having a cup of coffee

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while the MR is going on.

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So, what's going on here?

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From walking and from the change in shape

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of the femur, and from running,

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and from years and years of use and abuse

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the attachments of the meniscus.

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Perhaps, these attachments here,

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the menisco tibial and femoral attachments,

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or the root ligament attachments,

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which I can show you.

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Here they are.

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Here's a root ligament attachment right there.

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Let's put an arrow on it.

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Right here.

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There's the root ligament attachment.

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These stretch out.

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So I refer to this phenomenon,

3:09

personally, as pseudo extrusion.

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Or you can say meniscocapsular laxity

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due to the wear and tear of activities

3:16

of everyday living,

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or if there's DJD,

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associated with DJD.

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When do I use the term meniscal extrusion?

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When I define that one of those

3:26

attachments is actually torn,

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or the meniscus has decided to take a trip,

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south towards Georgia.

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In other words,

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it goes down along the tibial gutter here,

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or it goes up in the parafemoral gutter,

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then I use the term true meniscal extrusion.

3:45

Now, if you have a meniscus that is

3:48

ripped off and spit out,

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or a meniscus that is ripped off and thrown

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into the center of the joint,

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that's true extrusion.

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Or another synonym for that is

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meniscocapsular separation.

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Another term that is related to shape,

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although I'm not going to get into shapes today.

4:08

That's for the next talk, is cleavage.

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I picked that one out

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because everybody knows what a cleavage is,

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right?

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It's a horizontal line.

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So, if I see a nice horizontal line

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and it's not a 20-year-old,

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and I have DJD,

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cleavage is the lead in to tell you

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this is going to be a chronic tear

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that everybody has when they're 60 years old.

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Chronic, cleavage, trizonal, body tear,

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everybody's got that.

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Don't touch those tears.

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So, cleavage can be a word used to downplay.

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Finally,

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the last thing I want to emphasize is

4:49

the concept of meniscal failure.

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What does failure mean?

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Failure means the meniscus

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isn't doing its job anymore.

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All day long,

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failure after failure, after failure.

5:02

We see here at PSI,

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people that are too heavy.

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The meniscus just couldn't hold up for 50 years

5:09

under the onslaught of 280 pounds.

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And the meniscus gradually pseudo extrudes

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and displaces and displaces, and displaces,

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and it no longer supports the joint.

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And then, the joint develops arthritis,

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and the bones misshapen,

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and that pushes it out even further,

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and you're not even doing a standing MRI.

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That is one type of failure.

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Another type of failure is the meniscus auto digests.

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There's not much left of it.

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In that case, too,

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it is not supporting the knee.

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Now, if you have a small meniscus,

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you've got to go through,

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and we will go through this,

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the important laundry list of causes

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for why the meniscus is small.

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The most common cause,

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far and away, is resection.

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Another important cause is an old tear

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with a piece that got digested,

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maybe an old bucket handle tear that got missed.

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Another important cause is simple

6:07

autodigestion from arthritis.

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Yes, arthritis,

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especially rheumatoid, will,

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with its enzymes,

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destroy and dissolve the meniscus,

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just like you can normally destroy and dissolve

6:19

an extruded disc herniation in your back.

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Yes, your body can take it away.

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Another cause of a very small meniscus is

6:31

one that has fragmented and separated,

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not a classic bucket handle tear, but again,

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one that has broken up into innumerable pieces.

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And finally,

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another cause of a small meniscus

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is pseudo extrusion,

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where you're through the part of it

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that is just very thin.

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In other words,

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the whole meniscus is shifted

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and you think it's small,

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but when you look at the coronal,

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you see the fat part,

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but the fat part isn't where it's supposed to be.

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It's pseudo extruded out into the

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medial aspect of the knee.

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So, go through your appropriate checklist

7:04

of small menisci.

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Yes, there is such a thing

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as congenital absence of the meniscus.

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It's usually posterolateral,

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It's extremely rare.

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I've seen about five of them in my entire life,

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which is pretty long, so it's not a common thing.

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So that concludes our initial discussion

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of menisci for today.

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When we come back and review menisci

7:27

in our next session,

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we're going to talk about meniscal anatomy.

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We're going to go through all the roots.

7:33

This is obviously a meniscal cleavage tear

7:35

in our discoid meniscus.

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We're going to talk about all the root ligaments,

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all the individual attachments,

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the variations of the menisci,

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the dysplasias of the menisci,

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and we're going to show the individual

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meniscal tear shapes,

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and we're going to drill again and again

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into meniscal extrusion,

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pseudo extrusion,

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failure,

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severity,

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unstable versus stable menisci,

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displacement,

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nondisplacement,

8:00

full-thickness tears,

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partial thickness tears,

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chronic tears,

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acute tears,

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atraumatic, a very important word,

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versus traumatic,

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means you probably should fix it.

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Atraumatic,

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probably you shouldn't fix it.

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Cleavage in other shapes, incidental,

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non incidental.

8:18

Thanks.

8:18

Back to you shortly.

Report

Description

Faculty

Stephen J Pomeranz, MD

Chief Medical Officer, ProScan Imaging. Founder, MRI Online

ProScan Imaging

Tags

Trauma

Syndromes

Non-infectious Inflammatory

Musculoskeletal (MSK)

MRI

Knee

Idiopathic

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