Nailing the Septic Joints in the ED: A Swollen Situation

-Case-
A 67-year-old man with a history of diabetes and osteoarthritis presents with acute onset of right knee pain, swelling, and inability to bear weight. He denies trauma. The knee is warm, erythematous, and tender with a moderate effusion. Vitals reveal a low-grade fever. Are you thinking what we’re thinking?

-Evaluation-
A red, hot, swollen joint is septic arthritis until proven otherwise. This is a can’t-miss diagnosis, especially in high-risk patients like diabetics, immunocompromised individuals, and those with preexisting joint disease or recent joint procedures. And remember – the knee is the most commonly affected joint!

  • Common signs/symptoms: monoarticular joint pain, warmth, swelling, erythema, decreased ROM, inability to bear weight
  • Red flags: fever, chills, systemic signs of illness
  • Risk factors: diabetes, immunosuppression, joint prostheses, rheumatoid arthritis, IV drug use, recent joint instrumentation or surgery

Diagnostic Workup:

  • Joint aspiration is key!
    • WBC >50,000 with PMN predominance is highly suggestive
    • Send off a gram stain, culture, glucose, protein, and crystals (to rule out gout/pseudogout)
  • Blood cultures are positive in ~50% of cases
  • X-rays may show an effusion but are mainly to exclude fractures or other causes
  • Ultrasound can identify an effusion to guide arthrocentesis

Common Organisms:

  • Staphylococcus aureus (including MRSA) = most common overall
  • Streptococci species
  • Think Neisseria gonorrhoeae in young, sexually active patients

-Management-

  • Prompt empiric antibiotics after joint aspiration
    • Vancomycin + ceftriaxone is a solid combo
    • If concerned for gonorrhea: add coverage accordingly!
  • Orthopedic consult for washout vs admission
  • Analgesia and joint immobilization
  • Admission is needed for all cases

-Fast Facts-

  • Don’t delay antibiotics for imaging, but aspirate the joint before starting them if possible
  • Septic arthritis can rapidly destroy cartilage within days
  • Always rule out coexisting osteomyelitis in adjacent bone
  • Gonococcal arthritis may have migratory polyarthritis, rash, and tenosynovitis

Want to learn more? Read our in-depth study guide and listen to our podcast episode on this topic!

Cheers,

Tamir Zitelny, MD

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-References-

  1. Goldenberg DL. Septic arthritis. Lancet. 1998;351(9097):197-202. doi:10.1016/S0140-6736(97)09482-6
  2. Ross JJ. Septic arthritis. Infect Dis Clin North Am. 2017;31(2):203-218. doi:10.1016/j.idc.2017.01.003
  3. Shirtliff ME, Mader JT. Acute septic arthritis. Clin Microbiol Rev. 2002;15(4):527-544. doi:10.1128/CMR.15.4.527-544.2002
  4. Mathews CJ, Weston VC, Jones A, et al. Bacterial septic arthritis in adults. Lancet. 2010;375(9717):846-855. doi:10.1016/S0140-6736(09)61595-6
  5. Carpenter CR, Schuur JD, Everett WW, Pines JM. Evidence-based diagnostics: adult septic arthritis. Acad Emerg Med. 2011;18(8):781-796. doi:10.1111/j.1553-2712.2011.01121.x
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