Septic Arthritis (General)

From WikEM
Jump to: navigation, search


  • Most important diagnostic consideration in acute joint pain (can destroy joint in days)
  • Knee most commonly involved in adults; hip most common in pediatric
  • Most often seen in patients >65yr
  • Most common causative organisms

Clinical Features

  • Fever
  • Warm, red, painful, swollen joint
  • Decreased range of motion to active and passive movement
  • Gonococcal arthritis
    • Urethritis/vaginitis may be absent
    • May have prodromal phase:
      • Migratory arthritis and tenosynovitis predominate before pain and swelling occurs
      • Macularpapular rash or pustules especially on hands/feet may proceed overt arthritis
  • Endocarditis should be considered in the presence of 2 or more affected joints

Differential Diagnosis

Monoarticular arthritis

Algorithm for Monoarticular arthralgia



  • Arthrocentesis with synovial fluid analysis
    • Synovial fluid culture only (not 100% sensitive)
  • CBC
  • ESR
    • Sn 94% (with 15mm/h cut-off)[1]
  • CRP
    • Sn 92% (with 20mg/L cut-off)
  • Blood Culture
  • Gonorrhea culture (urethral/cervical/pharyngeal/rectal)
  • Imaging
    • Helpful for excluding other diagnoses (e.g. trauma, osteo)
  • Immunocompromised
    • Consider mycobacterial or fungal arthritis
    • Leukemia history: predisposed to Aeromonas infections

Arthrocentesis of synoval fluid

Synovium Normal Noninflammatory Inflammatory Septic
Clarity Transparent Transparent Cloudy Cloudy
Color Clear Yellow Yellow Yellow
WBC <200 <200-2000 200-50,000

>1,100 (prosthetic joint)

>25,000; LR=2.9

>50,000; LR=7.7

>100,000; LR=28

PMN <25% <25% >50%

>64% (prosthetic joint)


Culture Neg Neg Neg >50% positive
Lactate <5.6 mmol/L <5.6 mmol/L <5.6 mmol/L >5.6 mmol/L
LDH <250 <250 <250 >250
Crystals None None Multiple or none None



  • Treatment based on diagnostic studies


For adults treatment should be divided into Gonococcal and Non-Gonococcal





  • Consult ortho for joint irrigation in OR if joint aspirate is indicative of infection


  • Admit all to ortho

See Also

External Links


  1. Hariharan, H, et al. Sensitivity of Erythrocyte Sedimentation Rate and C-reactive Protein for the Exclusion of Septic Arthritis in Emergency Department Patients. J of Emerg Med. 2010; 40(4):428–431.