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Here, we have another great case,

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sort of continuing on the theme of physical

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injury and cartilage abnormality.

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This is a 10-year-old boy with an abnormal gait.

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So the mom brought this patient in because

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she said he was bow-legged, uh, meaning

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that there's too much space between his

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knees and they're sort of, the knees

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were pooching out from the midline.

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So the complaint is bow-leggedness.

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And this is a very, very classic case

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of a condition called Blount's disease.

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B-L-O-U-N-T-S.

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This is the left knee.

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The T1-weighted sequence is on the left.

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And the STIR sequence, or a fluid-sensitive

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fat-suppressed sequence, is on the right.

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And let's first of all look at the normal

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anatomy, which is the distal femoral condyle.

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You notice metaphysis, nice trilaminar

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appearance, or kind of trilaminar appearance.

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The DESS sequence for that, but

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you can see there's a difference.

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There's nice clear white and dark

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areas, uh, in the distal femur.

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On the lateral aspect of the tibia,

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we can also see that, but look what

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happens as we approach medially.

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There is too much signal here in the

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epiphysis, it's down-sloping, and there is

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basically an abrupt cutoff of your physis.

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Do you see that?

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And again, look at this.

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It almost reconstitutes even more

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medially, but then it takes a very

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weird abnormal course inferiorly.

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Almost like something is pounded down on this

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medial physis, and then caused it to depress.

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And what's happened there is there is now

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increased growth on this side, which is the

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lateral side, and not much growth on this side.

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And as you can imagine, this will cause a bow

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legged or widened appearance of your knees.

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Blount's disease typically is bilateral.

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So we actually imaged both sides.

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So this is the left knee.

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Let's bring up the right knee.

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Do you want to wait a sequence?

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That's a breast fluid-sensitive sequence.

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And let me reposition that so

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you can see all of it very well.

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Hand out.

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Right over here.

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Again, notice that there is

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basically no ossified epiphysis here.

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There's no hematopoietic marrow, there's no

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vessels going to that to stimulate it to ossify.

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There is disruption of that physis and there is

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downsloping and fragmentation that we notice.

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So, all those are key words.

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Downsloping of the medial physis,

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hypodevelopment of the medial

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epiphysis, okay, and fragmentation.

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And again, look how much bigger this side

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is on the lateral versus the medial side.

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Another thing that you may have noticed, look

2:57

at the size of this meniscus and compare it to

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the contralateral or the, or the lateral side.

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That's a hallmark feature of Blount's disease.

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The affected side, the medial

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meniscus is often hypertrophied.

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It's often bigger than on the

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lateral side, so look out for that.

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Who does this typically affect?

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It typically affects obese children.

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Uh.

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Um, usually African American or

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Scandinavian descent, because there's a

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high association with increased weight,

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biomechanics also plays a large role in

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the development of Blount's disease.