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In the previous vignette, I showed you infection abscess extending

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from the metaphysis of a long bone into the epiphysis.

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And I mentioned that this is something

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that you have to look out for in this age group.

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When I say this age group, I mean children less than about 18 months of age.

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Between birth and 18 months of age, you have communication between your

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epiphysis and metaphysis, across the physis.

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Like this.

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And what causes that communication?

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The communication is with blood vessels.

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So in the metaphysis, as you remember,

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you've got blood vessels that come up like this, sort of loop around and come back

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like this, loop around, come back, loop around, come back.

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I think you get the idea.

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Well, before the age of 18 months,

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these vessels also go in and feed the epiphyseal cartilage.

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The epiphyseal cartilage itself does have

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its own independent blood supply that comes in from the periphery,

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forming the secondary ossification center, or pre-ossification.

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But you also have added supply coming

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in from the metaphysis that crosses the physis and gets into the epiphysis.

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So what is that...

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What clinical relevance does that have?

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That means that before 18 months of age, remember we said that this area here,

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the blood flow is low because the blood has to come in, has to make a turn,

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it has to go through these little crevices and interstices, and it slows down.

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It slows down rich supplies.

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So things that are going into the blood can get stuck. Can get stuck right there.

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And what are those things that get stuck?

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Bloodborne infections and bloodborne tumors.

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Okay? So when that happens, if this area is infected or involved,

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it can use this pathway to extend into the epiphysis.

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That's why I say, if you see an infection or some process happening in the metaphysis

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in kids less than 18 months of age, pay very, pay very, very close attention,

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really scrutinize the epiphysis and the physis to make sure that process

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hasn't crossed the border to the other side.