Thread by @AdamJBrownMD

INFLAMMATORY ARTHRITIS

it's a word we throw around a lot

What does it mean? How can you tell the different causes from one another?

a🧵

#meded #rheumatology #rheumtwitter #arthritis @VuMedi

Inflammatory arthritis just refers to:

🌟immune cell (typically innate) invading the joint space
🌟 typically neutrophils are the 1st to the scene of the crime

Normal synovium has very few cells

if you tap a joint, and there is greater than 2,000 WBC, this is considered "inflammatory"

lots of things can do this:
🌟trauma-foreign body into a joint
🌟infection-septic joint
🌟crystals-gout or pseudogout
🌟autoimmune!

Trauma:

Usually this can be hinted at during the history and physical exam

Monoarticular-ie 1⃣ joint involved

Crystal and septic ruled out 1st‼️

You CAN'T tell one from the other based on history or exam

both:
🌟swelling/large effusion
🌟extremely painful
🌟WORSE with movement
🌟fevers
🌟elevated peripheral WBC

You have to tap to sort it out!

Septic Arthritis workup

synovial fluid typically very high WBC (often >50,000 cells) with neut predominant

BUT WBC can be lower especially if tapped early in infection

a lot of cases (dots) in fig below with < 50,000 WBC

Send for gram stain and cultures:

🌟70% + for gram ➕organisms
🌟45% + for gram ➖organisms

🌟Blood culture ➕ in 1/3 of cases

Speaking of WBC counts in synovium

Gout and Pseudogout can cause WBC >50,000

so that cutoff can't be relied on completely for the diagnosis of septic joint

What about autoimmune conditions? how do they present differently?

1⃣Joint pain typically BETTER with activity (which is pretty strange)

2⃣Joint pain TYPICALLY not as severe as septic or crystalline

3⃣Synovial fluid WBC typically in the 2,000-20,000 range

In autoimmune conditions patients typically say:

🌟morning is the worse part of the day
🌟"I have to get up and walk around" (you won't hear a patient with acute gout or septic joint say this)
🌟sitting for long periods (car rides, plane rides) make things much worse

Here is a quick video to summarize what I've talked about:

I mumble through parts of it, but I think the point gets across!

protect-us.mimecast.com/s/8p9ZCyP5KWU7…

References:
Ross JJ. Septic Arthritis of Native Joints. Infect Dis Clin North Am. 2017

Coutlakis PJ, et al. Another look at synovial fluid leukocytosis and infection. J Clin Rheumatol. 2002

References cont

Li SF, et al. Laboratory tests in adults with monoarticular arthritis: can they rule out a septic joint? Acad Emerg Med. 2004