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This is a 16-year-old young girl,

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3 00:00:02,600 --> 00:00:06,440 Dr. P here with a draining wound in the

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foot following a surgical procedure.

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And it looks like, in the long axis view,

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that they have tried to stabilize the C1 M2

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ligament, otherwise known as the Lisfranc ligament,

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9 00:00:19,359 --> 00:00:23,520 with this grafted ligament, and they often use

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resorbable anchors to assist in doing that.

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Now, one heinous aspect of this image is this

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high signal intensity on the T2-weighted image

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around the ligament and the anchor tract.

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Now you can get osteolysis as a reactive

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phenomenon to the material that is put in

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any graft, in any part of the body, and those

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osteolytic areas are usually not very wide.

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Now if they're left alone for a long

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period of time, sure you can get massive

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osteolysis, but it's usually pretty

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subtle at a few millimeters in width.

1:00

Here we actually have some fluid collecting

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around the anchor and the graft, and if we look

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at the sagittal T1 fat-weighted image,

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look at that bulky collection that

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has occurred around the anchor at

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the base of the second metatarsal.

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I mean, what is that doing there?

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And then as we examine it further, it's not fluid.

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So don't call that fluid, even though you're

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going to see it's high signal intensity.

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In fact, it's brighter than muscle.

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It's got to be something proteinaceous.

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And in a postoperative setting with a

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draining wound, you have to assume that

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this is an abscess with osteomyelitis.

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Now let's take down the short axis

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projections, and we'll do that three on one.

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Let's see if we can do that

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briskly and efficiently.

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And we've got the T1 on the left.

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We've got the fat suppression, proton density in

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the middle, and the T2 spin echo on the right.

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And you see an area of signal alteration

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that is completely, by the way, wiping out

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the signal intensity, erasing the

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signal intensity of the second metatarsal.

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There is edema on the heavily water-weighted

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image, which is one of the criteria that

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you need to at least introduce yourself

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to the diagnosis of osteomyelitis.

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You need wipeout or destruction

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of bone to make the diagnosis.

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Now here, it might not really apply

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because maybe this was a surgical defect.

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Maybe it's an osteomyelitic defect

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where you've lost the cortex there.

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So that makes it a little bit challenging.

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But then when we go over to the T2-weighted

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image and we do a little bit of scrolling,

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you've heard in other segments of our discussion

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that abscesses have this homogeneous, thin rim

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surrounding their outside.

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And that indeed is the case here as well.

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Look at this homogeneous thin rim.

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Now it tends to be thinner on non

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non peeled surface in the brain, but we're

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not in the brain, we're in the foot.

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Which is kind of the body's brain,

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because you really, really need

3:07

your foot for just about everything.

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And in the center of this abscess is an object,

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probably an anchor that's sitting in the object.

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But remember, I've told you before,

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you can get, even though abscesses are made

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of fluid, you can get low signal in the

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middle due to some of the neutrophils that

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accumulate there, the phagocytosis that

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occurs there, the peroxidases that are made,

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which are in themselves paramagnetic

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and can draw down the signal

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intensity on the water-weighted image.

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So this is a patient with an infected

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repair for a Lisfranc ligament injury.

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The patient has an abscess around

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her anchor and she's going to

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need to have that hardware removed.

3:55

Dr. P out.