Triage: RIGHT KNEE PAIN THAT BEGAN LAST NIGHT, HX OF ARTHRITIS. NO FALL/INJURY.

History of Present Illness: This is a 50-ish-year-old female presents with approximately 12 hours of right knee pain without injury and with associated chills but no definite fever. She has also had nausea and vomiting for 1 day but no abdominal pain.  She uses ozempic and insulin for her diabetes. No recent infections or other complaints.

Vital Signs: T: 36.9 °C (Oral) HR: 77  RR: 16 BP: 134/67 SpO2: 99%

Physical Exam: Physical exam is normal except for a slightly warm slightly swollen left knee without erythema, though she is dark complected

Initial Diagnostic Testing:

  • CBC: Normal.  But CRP = 5 and ESR = 80
  • EKG and Troponin-i: normal
  • Chemistries: normal including LFT’s
  • Imaging: Knee x-ray shows an effusion 
  • Arthrocentesis: 35,000 WBC with 95% PMNs, no organisms, no crystals.

What is the most likely cause of the arthrocentesis findings?

  • A) Osteoarthritis
  • B) Septic joint
  • C) Gout
  • D) Lupus

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ANSWERS: What is the most likely cause of the pain?

  • A) Osteoarthritis – should not have >4,000 WBC
  • B) Septic joint – has to be assumed.  37% of septic joints have <50,000 WBC
  • C) Gout – possible but no crystals seen.  Patient denied h/o gout but chart review showed she possibly did have this.
  • D) Lupus – unlikely unless new

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CASE CONCLUSION: Cultures negative.  Patient improved completely after 48h of colchicine.  Lab asked to look harder for crystals and they found some on a second look recheck