Reactive arthritis

[Phloston]

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On joint aspiration, bacteria are not seen.

What would be seen?

 

[Old Style Nanny]

Nothing?

 

[Phloston]

I wasn't sure if you find immune complexes because it's a type-III HS rxn.

 

[Old Style Nanny]

I wasn't sure if you find immune complexes because it's a type-III HS rxn.

That's actually a possibility. Someone could clarify. Although in reality, joint aspiration is done only to make sure it is sterile and not septic arthritis.

 

[OveractiveBrain]

On joint aspiration, bacteria are not seen.

What would be seen?

20,000 polys, no organisms, no crystals

http://medicaleducationonline.s3-website-us-east-1.amazonaws.com/rheum/rheum1.html for an overview of joint disease. Free video

http://medicaleducationonline.s3-website-us-east-1.amazonaws.com/rheum/rheum5.html details of monoarticular disease. Free video

Both are designed for Step 2 / Shelves, but they might help put the content into context for you.

What you're looking for here is the difference between an inflammatory joint, an arthritic joint, and a septic joint.

Septic joint (mega-inflammatory joint):
- ****TON of polys (>50,000)
- bacteria

Inflammatory Joint (Reactive arthritis, for example, if there is an effusion that can be tapped)
- Lots of poly (>normal, <25,000
- No bacteria

Crystal joint (is technically an inflammatory joint, but there are crystals)
- Lots of polys (>normal, <25,000)
- No bacteria
- Crystals (gout vs pseudogout)

Arthritic joint
- No polys
- No bacteria
- No crystals
- probably should not have tapped in the first place....

Of course these numbers are not absolute. Of course there is variability on presentation. But what you're getting at is "there is a swollen joint that is hot, red, and tender. I know Im supposed to tap it, because FA tells me to tap all swollen joints... what do I expect to find if...?" And the clear cut cases the USMLE will give you on Step 1 and Step 2, are the things listed above. Hope that helps.