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Meniscus Tear & Pivot Shift Injuries 2

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Now, we said earlier that this vertical longitudinal

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tear is one type of up and down tear.

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There's another kind of up and down

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tear that we should talk about,

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and that is one that starts in the inner third,

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and instead of going

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up and down,

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that's parallel to the capsule.

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In other words, that's parallel to the capsule,

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which we'll imagine is here in red.

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That has some blood in it.

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It is perpendicular to the capsule,

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kind of like the spokes on a wheel,

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right.

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The spokes on the wheel are perpendicular

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to the outer part of this circle,

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kind of like the wheels on the bus

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go round and round. Right.

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So what does that look like?

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Well, here's the spoke on the wheel right here.

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It's coming right at you.

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It's coming at you.

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Sometimes it makes a little v.

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That's a radial tear,

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and that goes into the screen.

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That also goes up and down.

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It's just in a different axis.

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Now,

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we're interested in this tear because this

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tear can get a little bit nasty.

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Well, how come?

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Because it's in an area that doesn't heal.

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Remember, we have outer third, red red zone,

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middle third, red white zone, inner third,

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white white zone.

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The white white zone has no vascularity,

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doesn't heal.

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Okay, so we have a little tear there.

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When do we mess with it?

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When it's symptomatic. But what kind of symptoms?

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Pain, maybe not because pain alone,

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maybe it breaks off. Maybe it's scars.

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Maybe the pain goes away.

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But if it's pain and clicking or pain and locking

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or pain and progressive arthritis,

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then it has to be addressed.

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Now, in the orthopedic literature,

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they say that if the tear has a depth of greater

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than six to 8, are more likely to become unstable,

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to propagate,

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and even to lead to consequences like

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fragmentation, locking, and chondromylation.

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But I think we've gotten a little more liberal as

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time has gone on and less aggressive in trying to

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resect these tears because there's no sewing them.

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You just go in with a claw,

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and you just claw them out of there,

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which is kind of ugly.

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So what do we mean by depth?

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Depth is the measurement from here,

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the inner edge, to the outer edge.

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So depth goes this way.

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Remember,

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length is completely different for

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the longitudinal vertical tear.

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For the radial vertical tear,

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we're more interested in this character.

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Now,

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we also have gapping the side to side dimensions

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so the tears can get a little wide.

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And the more gap they are,

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the more troublesome they are.

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So depth is important.

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The measurement from here to here,

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greater than six to 8 mm,

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but also the side to side dimension,

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because gapping can lead to instability.

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Instability of what? Instability of the meniscus.

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So where might we see a problematic area of

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gapping back here, near the meniscus root.

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Remember, we have a posterior horn posture, third,

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a body middle third,

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an anterior horn anterior third.

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To keep it simple,

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we also have,

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in the deepest attachment of the meniscus,

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the meniscus root, in the back and in the front.

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And although we haven't drawn them in,

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there are ligaments.

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Don't confuse the meniscus root,

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which is meniscus,

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with the meniscus root ligament.

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You can tear the meniscus from its root,

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you can tear the ligament from the bone.

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Now, they both have the same consequence,

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but what happens if you have one of these

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radial tears and it keeps going back,

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to quote Chris Berman,

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and it keeps going back and boom,

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it goes to the outer surface.

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Now we got a problem, right?

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The meniscus isn't anchored to itself anymore.

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Doesn't matter where the ligament is still there.

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This is not attached to that.

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And so they spread apart,

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and the meniscus starts to float this way

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out of the edge of the femur and the tibia.

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And now you essentially have a meniscus

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that extrudes itself.

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So these very large radial root

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tears are problematic.

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The little ones, we leave all of those alone.

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We hardly ever touch the root.

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Radial tears that don't go all the way through,

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even the ones that almost go all the way through,

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we don't touch.

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But the ones that clearly go all the way from

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the inner third to the outer third,

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the meniscus is starting to gap and

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separate those we got to go after.

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So we've learned about two very important

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vertically oriented tears today.

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The one that's longitudinal and parallel to the

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outer portion of the meniscus and the one that's

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perpendicular to the outer arc of the meniscus,

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the one that's parallel,

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is less problematic because it's in the red,

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red zone.

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The one that is perpendicular is problematic.

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Now, if this radial tear were to arc,

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if it were to do something like, say this,

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we would call it a flap tear.

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See,

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radial tears are straighter

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if it were to arc and it were to get a little

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bit wider and a little bit longer.

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Now we're into a parrot beak tear,

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which happens to, like, the body horn junctions.

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Let's draw another meniscus for a moment,

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just so we can demonstrate one

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other thing for completeness.

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I realize my meniscus is a little bit thin here,

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but I think you can see it.

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Actually,

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I'm going to make it thicker because I know

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I'm going to get reprimanded if I don't.

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Let's make a thicker meniscus.

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Erase this one.

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Give you

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a little more visual

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stimulation here. Oh, wow,

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that's a really thick one.

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Yeah.

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This is for all of us out there

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that are over age 60.

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So here's a big, fat meniscus.

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Okay, now let's make it thinner.

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Let's make our line thinner,

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and let's change the color.

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And now let's assume we have a longitudinal

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tear and it's in the middle third.

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It would be a vertical longitudinal

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tear in the middle third.

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But if that vertical longitudinal tear starts to

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gap and get wider and wider and wider and wider,

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and all of a sudden this portion of

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the meniscus starts to go inwards.

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Now we have ourselves a bucket handle tear.

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So a bucket handle tear really starts

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out as a vertical tear,

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usually in the center of the meniscus,

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and that will be a story for another day.

Report

Description

Faculty

Stephen J Pomeranz, MD

Chief Medical Officer, ProScan Imaging. Founder, MRI Online

ProScan Imaging

Tags

Trauma

Musculoskeletal (MSK)

MRI

Knee

Acquired/Developmental

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