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A little bit about imaging.

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Now all of you listening, who do knee Mr know that the two,

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there are two classic findings

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that have been emphasized in our literature

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that may indicate a meniscal tear.

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And I've listed them in numbered them one and two.

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And I'll tell you at the outset, one of these is a terrific

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criterion for a meniscal tear.

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And one in my view is not so good.

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In fact, it's almost terrible. So let's look.

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First, we all recognize

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that a normal meniscus typically is well defined triangular

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with a sharp tip, okay?

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An abnormality of meniscal contour could be a truncated

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meniscus and irregular meniscus.

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Something that is not triangular and well defined.

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An abnormality of meniscal signal classically is a linear

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or curve linear region.

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Region of intermediate

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or occasionally high signal

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that violates the surface of a meniscus.

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And when we talk about the surface of the meniscus,

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we're talking about the top, the bottom and the tip,

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and not the peripheral area,

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the meniscal capsular region of the meniscus.

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So one of these is terrific, one of these is not very good.

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The terrific one in my view is an abnormality

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of meniscal contour.

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If there is an abnormality of meniscal contour

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and you can eliminate the previous occurrence

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of meniscal surgery,

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that is an extremely reliable feature of a meniscal tear.

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So as the fellows listening know,

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whenever I have a MR exam of a knee,

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the first thing I'm gonna look for is evidence

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of prior meniscal surgery.

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Well, it's nice of course, if in fact that's indicated

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on the request slip, but it may not be indicated or worse.

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In fact, it's indicated and there was no meniscal surgery.

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So I looked for changes

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and there were a variety of changes that you can see

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typically scarring involving the soft tissues

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and hoffa's fat pad.

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And as most surgeons are right-handed,

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that scarring dominates in the anter medial rather than the

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anterolateral aspect owing to the cutting instruments

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that are placed within the knee at the time

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of our arthroscopy, rarely,

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and we'll talk more about this later when we talk about the

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cruciate ligament, there may be a cyclops lesion.

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You don't have to have ACL surgery

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or ACL reconstruction to get a cyclops lesion.

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Or you may see thickening

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and sometimes edema even along the course

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of the ligamentum mucosa,

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which is the inferior pica of the knee.

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All right? So those are features that I look for.

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And indeed there's another

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Feature that has been emphasized in the literature,

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and that is fibrosis occurring in the

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anterior interval of the knee.

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This is the anterior interval of the knee.

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And if there is extensive, extensive fibrosis there,

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particularly in its deep portion, this can lead

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to pain located anteriorly, particularly on extension

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of the knee, and may even lead to a contra, a contracture

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without the ability to fully extend the knee.

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So I will comment on that particular pattern.

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Now let's go to the second criterion,

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which is an abnormality of meniscal signal.

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We all know that early on when Mr came along

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and we used it to assess the knee, we, we came up

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with a grading system described in multiple articles in the

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literature, and these were the three grades

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that were introduced.

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A normal meniscus has either none

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or very minimal signal within it, okay?

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So you can see that here.

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That is a little bit of signal, it can be normal.

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And when you deal with a more extensive signal,

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grade two signal, often there is mucinous

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or OID change within the meniscus.

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And the finding of a meniscal tear,

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as I already commented on, was the fact

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that you had signal intermediate or high violating the top

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or as shown here, the bottom or the tip of the meniscus.

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Now, that would seem to be useful,

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but indeed in practice this can be very difficult.

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Looking at the top,

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and I'm using here some meniscal windows, you can see

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what appears to be in a linear

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signal not reaching the surface of the meniscus.

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Whereas you look at the bottom

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and you can see in fact that

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that signal is reaching the surface.

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So you would interpret this as no tear.

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You might interpret this as a tear,

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or the difference is just a pixel or two.

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All right? And that's why this is not sometimes useful.

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And indeed what I found through the years is in order the,

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the fellows will kind of lean forward, press their nose

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on the computer screen,

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or not quite that close to the computer screen, trying

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to turn that final pixel bright

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so they can call it a meniscal tear.

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You don't wanna look like this when you're studying the

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MR images, all right?

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That is not what you want to do.

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And worse, they'll change the windowing

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and come up with something like this

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where it looks like they it,

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the signal is violating the surface.

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No, when you look at these meniscus with MR imaging,

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you want to sit comfortably.

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You sit back because the abnormalities in signal

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reaching the meniscal surface should be evidence.

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Not that should have to get close to the image,

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But should be evident at a distance from the image.

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And indeed, my view is if you're not certain, it is better

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to under call than over call the presence

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of a meniscal tear.

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Because indeed, if the pain continues,

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the patient can always come back.

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All right? Here I'm showing you images at the time

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of the initial presentation

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where the signal does not reach the surface of the meniscus.

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And five months later, where there is

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abnormal signal reaching the surface,

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and indeed the more helpful finding abnormal morphology

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of the meniscus to kind of counteract the problem

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of trying to judge whether

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or not the meniscus signal reaches the

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surface of the meniscus.

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Arthur Smith and his associates introduced a two slice touch

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rule suggesting that in fact, an abnormal signal

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that contacted the meniscal surface

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on at least two MR images and one

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or more imaging planes increased the predictive value.

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Here you can see what they found for the presence

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of meniscal tears.

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So if you do have signal violating the surface

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of the meniscus,

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it's always good if you see it in more than one image,

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and hopefully in more than one imaging player.