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Joint Infections and Osteomyelitis

Ally Glover


  • If high concern for septic arthritis, engage Ortho before ID. Needs arthrocentesis ± wash out.
  • ESR/CRP are helpful but nonspecific in diagnosing bone/joint infections


  • Septic arthritis: erythema, effusion, limited ROM and pain with passive and active ROM
  • Osteomyelitis: often underlying a wound (diabetic foot ulcer, sacral decubitus ulcer) but may be hematogenous as well; probe to bone positivity is diagnostic for osteomyelitis


  • CBC (leukocytosis), ESR, CRP
  • Blood cultures
  • Imaging: start with X-ray → if radiograph is negative for osteo, cannot rule out, need to get MRI. Very helpful if it’s picked up on X-ray though due to specificity
  • Fluid studies & gram stain results from synovial fluid if concerned for septic arthritis: usually WBC > 20,000 cells/ microL


  • If pt is sick, don’t wait for culture data to start empiric antibiotics
    • Gram positives: empiric coverage with vancomycin until ID and sensitivities; MRSA nares being negative does not rule out MRSA skin/soft tissue infection
    • Gram negatives: empiric coverage with ceftriaxone or cefepime if concerned for Pseudomonas.
  • If concern for septic arthritis, consult Ortho, hold AC
  • If a pt has a foot wound with underlying osteomyelitis, talk to Podiatry/Ortho for deep tissue biopsy. If clinically stable, hold abx.
    • IR and CT/US guided procedures don’t really do bone biopsies, so talk to surgical specialty first
  • Osteomyelitis abx duration: usually 6 weeks, but can do PO antibiotics based on susceptibilities, ID follow up
  • Septic arthritis abx duration: usually 3-4 weeks

Additional information:

  • Septic arthritis mimic: gout / CPPD → obtain crystal analysis with synovial studies
  • Less common causes of septic arthritis: gonococcal, Lyme disease (order serologies if suspicion is high)