What is the treatment for septic arthritis?

Treatment of Septic Arthritis

The treatment of septic arthritis requires immediate joint drainage or debridement combined with prompt initiation of empiric antibiotic therapy, followed by culture-guided antibiotics for 3-4 weeks. 1

Diagnostic Confirmation

Before initiating treatment, diagnostic confirmation is essential:

• Arthrocentesis is mandatory and should be performed before starting antibiotics 1
• Synovial fluid should be sent for:
  • Gram stain
  • Cell count with differential (WBC >50,000 cells/mm³ with >90% neutrophils is highly suggestive)
  • Aerobic and anaerobic cultures
  • Additional tests: leukocyte esterase and alpha-defensin 1

Treatment Algorithm

1. Joint Drainage

Joint drainage is essential and should be performed immediately. Options include:

• Surgical debridement
• Arthroscopic drainage and debridement
• Image-guided drainage (ultrasound or CT-guided) 1

2. Antibiotic Therapy

Initial Empiric Therapy

Start immediately after obtaining synovial fluid:

• For methicillin-resistant S. aureus (MRSA) coverage:

  • Vancomycin, linezolid, daptomycin, or TMP-SMX

• For methicillin-sensitive S. aureus (MSSA):

  • Nafcillin, oxacillin, or cefazolin 1

Targeted Therapy

• Adjust antibiotics based on culture and sensitivity results
• Oral antibiotics can be given in most cases as they are not inferior to intravenous therapy 2

Duration of Therapy

• Standard course: 3-4 weeks for uncomplicated septic arthritis 1
• Extended therapy required for:
  • Prosthetic joint infections
  • Concurrent osteomyelitis
  • Kingella kingae infections (6 weeks) 1
  • Fungal infections: fluconazole 400 mg daily for 6 weeks or an echinocandin for 2 weeks followed by fluconazole for at least 4 weeks 1

3. Special Considerations

Prosthetic Joint Infections

• Require specialized management
• Often need hardware removal or exchange
• Lower diagnostic threshold: intraarticular WBC >1,100/mm³ with neutrophil differential >64% 1
• Longer antibiotic courses

Concurrent Conditions

• Crystal arthropathy may coexist with septic arthritis
• Inflammatory arthropathy can complicate interpretation of serologic tests 1

Monitoring and Rehabilitation

• Track inflammatory markers (ESR, CRP) to assess treatment response
• Initial joint immobilization followed by early range of motion exercises 1
• Weekly repeat aspirations may be needed if first aspiration is negative but clinical suspicion remains high 1

Common Treatment Pitfalls to Avoid

1. Delaying joint drainage
2. Failing to obtain cultures before starting antibiotics
3. Missing concurrent osteomyelitis
4. Inadequate duration of antibiotics
5. Premature discontinuation of antibiotics based on clinical improvement alone without monitoring inflammatory markers 1

Prognosis

Septic arthritis carries significant morbidity and mortality:

• Poor functional outcomes occur in 24-33% of patients 3
• 90-day mortality rate is 7% in patients ≤79 years and 22-69% in patients >79 years 3
• Prompt diagnosis and treatment are essential to avoid irreversible joint destruction or death 4