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Here's the left hip of a 15-year-old

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with pain in the groin and aching

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sensation in the outer aspect of the hip.

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We've got some excellent variance here.

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On this gradient echo, let's draw our

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acetabulum, kind of a thick line here.

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There's the acetabular arc, and notice there's

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a little notch right here, which corresponds to

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this notch, which is the fusion or merger site

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of the triradiate cartilage, also known as the

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stellate lesion or stellate crease, actually.

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Thank you.

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And then we've got the

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femoral head underneath it.

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So we'll draw in the femoral head as an arc.

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And then we'll make our line a lot thinner.

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So we can see a little better.

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So let me do that for you.

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And then we'll change color.

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And we'll look at the hyaline cartilage.

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So you've got hyaline cartilage on one side.

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And that corresponds to this

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somewhat light area right here.

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Then you've got a thin, dark slit.

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That's the potential space or capsular space

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between the hyaline cartilage on the other side.

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Femur side, which I'm drawing right now.

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And I've left the space a lot wider

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than it is here, as this thin slit.

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So this is the potential capsular space,

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and that's where fluid would accumulate.

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Now, if you add the hyaline cartilage

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together at any point in the hip,

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it should add up in a young, healthy

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person to about three millimeters.

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Labrum, all the way out in the periphery,

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which I'll draw in a different color.

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The labrum kind of hangs off

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the free edge of the acetabulum.

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There is the labrum.

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And it makes like kind of a little

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dark line as you see it blending

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with the free edge of the capsule.

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And then right underneath it, right here,

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is some bright signal intensity that looks

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like it works its way up into the labrum.

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And that is the hyaline interposition, or

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the junction of hyaline cartilage with the

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fibrocartilage of the acetabular labrum.

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So just as we see here a transition

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of blue to orange, and we're going to

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take our blue transition, and we're

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going to extend it a little bit.

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The labrum and it looks like it goes up

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right in between the labrum and the bone,

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which is what you're seeing right here.

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Now, how do you know that's normal?

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Because it smoothly transitions right

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into the hyaline cartilage, and it doesn't

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enter the black triangle of the labrum.

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In other words, it doesn't

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violate this orange area or zone.

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Second, it has a very smooth undulating

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transition so that it makes an arc like this.

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As opposed to something that would

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be more jagged and irregular.

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And then even when it went up, it

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would be more jagged and irregular.

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So that's, that's all normal.

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And if we scroll the image a little bit, I think

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you'll get a better feel for this, this hyaline

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transition between labrum and hyaline cartilage.

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Between labrum and hyaline cartilage.

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And there, as we, as we go backwards, that

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space shuts down a little bit, it gets

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smaller, and as we go forward, we see the

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space again, and we still see it, but we don't

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see it extend all the way through the labrum.

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It's not associated with inflammation.

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There's no effusion.

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There's no chondromalacia.

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The labrum is triangular, and finally,

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that hyaline signal doesn't enter

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the black triangle of the labrum.

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So what is the aching pain from?

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Well, in a child, in a young person, uh,

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under age 21, and granted a 21-year-old is

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a young man, you really shouldn't see a high

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signal intensity between the capsule or the

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iliofemoral ligament and the underlying bone.

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And that increased signal intensity

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is consistent with capsular stripping.

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I'll allow maybe 2 millimeters of high signal

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down here, but I won't allow that high signal

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to go all the way up the acetabulum as we see

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more proximally.

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So this patient has capsular stripping

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as a very subtle manifestation

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or finding of their symptoms.

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Whereas the labrum itself is actually fine.

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An example of iliofemoral and capsular

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ligamentous stripping from the acetabulum.