Hot Swollen Joint

Exam Cram

• Differentials of a hot swollen joint are septic arthritis, septic arthritis and septic arthritis

• Key investigation is a joint aspirate (and blood cultures) prior to giving antibiotics

• Medical emergency due to risk of joint destruction from septic arthritis

 Assessment

History

Examination

Investigations

• Joint Aspirate

  • • • Microscopy

      • 
        

• Blood cultures +/- wound cultures or MRSA swabs

• Joint XR: ?effusion ?calcification suggestive psueudogout

• FBC, EUC, LFTs, CRP: ?inflammation/ baseline bloods

• Calcium, urate: ?crystallarthropathy

Differentials

Management

• Analgesic ladder, elevate limb

• Treat underlying cause

Clinical Pearls

Urate levels in Acute Gout Flares

This is a source of contention as urate levels can be falsely normal in acute gout however it is my observation that they are usually taken and usually useful- but should be intepretted with caution!

Missing Septic Arthritis

As the night registrar, I was asked to see a 60M with ALD whom the nurses went happy. He was on ceftriaxone for pyrexia of unknown origin ?SBP ?HAP ?UTI and was midlly confused. He had some right shoulder pain on examination but I was told this was from previous operations. Overnight, we escalated to Tazocin and he appeared to improve. 

I followed up the notes, reading, a couple days later, the day team did an MRI of the right shoulder which showed septic arthritis. I reflected on how this diagnosis can be easily missed and in the future, to be cautious about information given, particularly overnight. 

References and Resources

Written in 2025