Interactive Transcript
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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.
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