Septic arthritis

Background

• Most important diagnostic consideration in acute joint pain (can destroy joint in days)
• Knee most commonly involved in adults; hip most common in peds
• Most often seen in pts >65yr
• Gonococcal arthritis is commonest cause in adolescents and young adults

Clinical Features

• Fever
• Warm, red, painful, swollen joint
• Decreased range of motion to active and passive movement
• Gonococcal arthritis may have prodromal phase:
  • Migratory arthritis and tenosynovitis predominate before pain and swelling occurs

Diagnosis

• Arthrocentesis for synoval fluid

	Normal	Noninflammatory	Inflammatory	Septic
Clarity	Transparent	Transparent	Cloudy	Cloudy
Color	Clear	Yellow	Yellow	Yellow
WBC	<200	<200-2000	200-50,000	>25,000
PMN	<25%	<25%	>50%	>90%
Culture	Neg	Neg	Neg	>50% positive
Crystals	None	None	Multiple or none	None

DDx

1. Toxic synovitis
2. Abscess
3. Cellulitis
4. Primary rheumatologic disorder (i.e. vasculitis)
5. Iatrogenic
6. Reactive arthritis (post-infectious)

Work-Up

1. Arthrocentesis with synovial fluid analysis
   1. Synovial fluid culture only
2. CBC
3. ESR
   1. Sn 96% (with 30mm/h cut-off)
4. Blood Culture
5. Gonorrhea culture (urethral/cervical/pharyngeal/rectal)
6. Plain films (often normal but may show widening of joint space or evidence of osteomyelitis)
7. Ultrasound (can show joint effusion, extent of disease, and may help differentiate from other conditions)

Treatment

1. Joint drainage
2. Abx
   1. Gram stain can be used to guide treatment
      1. Gram+: vancomycin IV
      2. Gram- OR gonococcus suspected: Ceftriaxone IV
3. Consult ortho for joint irrigation in OR if joint aspirate is indicative of infection

Disposition

• Admit all to ortho

See Also

• Arthrocentesis
• Monoarticular Arthritis
• Septic Arthritis (Hip)
• Septic Arthritis (Peds)

Source

• Tintinalli