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In the last vignette, I promised you

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the mechanism or the reasons behind why

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we get a fishtail deformity following

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a supracondylar fracture years ago.

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Okay, I'm going to draw on this

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and I'm going to show you exactly

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what happens and why this occurs.

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I'm going to draw my best rendition

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of a fishtail and see if you agree

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that this is what a fishtail is.

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So a fishtail will look something like this.

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It'll come down, it'll go

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like this, it'll go like this.

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And it'll go like this.

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Can you buy that as a fishtail?

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That's pretty good.

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Let's now outline our distal humerus.

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Can you see the resemblance?

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That's why this is called a fishtail deformity.

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Because of this divot, again, causes

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a fishtail-like appearance, okay?

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Now I'm going to try to draw in what the

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vascular supply is to that distal humerus.

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I'm going to do that in red.

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You've got tiny vessels

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that come in from each side.

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One's from here, one from here.

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And they send off little

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branches, like this, like this.

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Comes in through here, sends little

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branches, little branches, little branches.

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All like this.

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And here, those branches come

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across, and they try to meet.

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They don't do a great job.

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So it's right here, there is less

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vascularity than there is at the periphery.

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For example, I'm going to draw it a

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little bigger, so you can see that it's

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more vascularity at the periphery, and

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less vascularity at the central portion.

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So when you have a supracondylar

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fracture, where does that occur?

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It occurs right, okay, so when that happens,

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it may be close enough to damage this area.

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Very, very critical area.

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It's already vulnerable in the sense that

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you've got these two or multiple vessels

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that sort of perforate the area and already

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aren't really supplying it with a lot of

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vessels and a lot of nutrients to begin with.

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Now when you add in a fracture and cause damage

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to those tiny vessels, it can really predispose

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that person to avascular necrosis.

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But this doesn't happen for years down the line.

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It's probably happening

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slowly and slowly and slowly.

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That's how we finally see it.

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But it doesn't start hurting or have

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clinical manifestations until years later.

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So, a good orthopedic surgeon will say to his

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patient who's had a supracondylar fracture, even

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a lateral condylar fracture, any damage to the

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elbow that, hey, unlikely, but maybe years down

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the line, if you start having pain, there may be

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a problem and you'll have to come in and see me.

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So this is why a fishtail deformity

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can happen in really any type of elbow

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fracture, but most commonly associated

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with a supracondylar fracture.