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So this is a 33-year-old woman with left, um, foot pain.

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Here's our long axis, T one, long axis PD fat suppressed.

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Um, here's a coronal, uh,

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or short axis, T two fat suppressed.

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And then let's pull up Thele T two fat suppressed.

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So scrolling through these images, we can see

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that there's intense bone marrow edema throughout the fifth

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metatarsal shaft.

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And along that same region we can see some periosteal edema.

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If we saw just the edema,

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we might call this a stress reaction,

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but on both the fluid sensitive images

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and the T one weighted images,

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we're seeing this non-displaced fracture line

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through the region of, uh, periosteal and marrow edema.

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If we look at the corresponding short axis images,

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we can see that there's some periosteal callus formation

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and cortical thickening.

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I really like the short axis images for evaluating the,

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the cortical thickness

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'cause you have, assuming

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that the other metatarsals are normal,

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some internal reference for how, um,

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thick the cortex should be.

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If this were normal, just keep in mind

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that these are usually sliced, um, to the,

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uh, uh, position

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of the foot in the scanner rather than along the axis

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of the metatarsals themselves.

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So you may have to do a little proximal in distal scrolling

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just to get a comparable level.

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So here we have again

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that periosteal callous formation, cortical thickening.

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Um, this was not a diagnostic dilemma.

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This is a metatarsal stress fracture.

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If you wanted to grade,

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you could use the fredrickson grading system that I think

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that was initially developed for tibial stress injuries,

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but has been applied elsewhere.

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So a grade one would be periosteal edema alone.

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Grade two would be periosteal

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and mar edema that you can see on

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the fluid sensitive images.

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If you had a grade three,

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you would see those same findings on

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your T one weighted images.

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And then a grade four would be if you have a stress fracture

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or if you have intracortical signal change.

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Um, I think the challenge with grading systems is

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what you do when they don't quite fit.

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There are times and I think you see just marrow edema

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without a lot of edema,

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and then you're kind of stuck wondering what you should do.

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And in those cases, I think it's best to be descriptive.

2:38

Um, there are other classification systems.

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There's the, uh, rent and griffis

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classification and the native systems.

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That's two other classification systems to memorize

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and I don't really have the brain capacity

2:49

for all of that memorization.

2:52

Um, as you know from, um, both Resnick, Dr.

2:56

Resnick's Bone and Joint Talk just

2:58

Earlier today and his earlier talk on Monday,

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there are two types of stress fractures.

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So this is the third time I'll repeat it for you.

3:07

You've got your fatigue fractures

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that are gonna result from your abnormal stress

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to normal bone and your insufficiency fractures

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that will result from normal stress on abnormal bone.

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So this case, remember this is a 33-year-old woman,

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otherwise healthy, we have no reason to think

3:26

that she has an underlying bone problem.

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So in this case, I think this is most likely

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a fatigue fracture.

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Um, metatarsal fatigue fractures are actually really common

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in athletes and people

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who were probably previously sedentary or less active

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and are starting a lot of activity for the first time.

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But usually the metatarsal fatigue fractures are gonna occur

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in your second and third metatarsals fractures

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of the lateral metatarsals are less common.

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Um, but there has been a reported association

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of these lateral metatarsal stress fractures in patients

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with Metatarsus Adductus.

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I believe Dr. Resnick was the senior author on

4:07

that paper in skeletal radiology.

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So he probably is familiar with that association.

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Um, this is obviously not a weight-bearing study,

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but if we look at the localizers, uh,

4:18

perhaps I can convince you that the axis

4:20

of the metatarsals is a little bit medially deviated

4:24

with respect to the axis of the lesser tarsals.

4:27

So perhaps this patient has this fifth metatarsal stress

4:31

fracture because I've got a bit

4:33

of metatarsus adductus putting some abnormal biomechanical

4:37

load on those lesser or those lateral metatarsals.