What is the management of septic arthritis?

Management of Septic Arthritis

Septic arthritis requires immediate joint drainage (surgical or arthroscopic) combined with IV vancomycin 15 mg/kg every 6 hours for empiric MRSA coverage, followed by culture-directed antibiotics for 3-4 weeks total duration. 1

Immediate Diagnostic and Therapeutic Steps

Joint Drainage - The Critical First Intervention

• Drainage of the joint space must always be performed immediately after obtaining cultures - this is non-negotiable and represents the cornerstone of treatment 1
• Surgical debridement with intraoperative cultures is preferred for surgical emergencies (patients with severe sepsis, symptoms >7 days, hip or shoulder involvement) 1, 2
• Arthroscopic drainage is highly effective and cures 91% of cases when combined with antibiotics, with only 4% requiring conversion to open surgery 3
• Repeated arthrocentesis alone has a 61% failure rate requiring eventual surgical drainage, with 5 of 6 patients with severe long-term sequelae having been treated by repeated puncture alone 2

Key Decision Point: Hip arthritis, shoulder arthritis, symptoms lasting >7 days, or severe sepsis mandate immediate surgical or arthroscopic drainage rather than repeated needle aspiration 2

Empiric Antibiotic Therapy - Start Immediately After Cultures

• IV vancomycin 15 mg/kg every 6 hours (or 30-60 mg/kg/day in 2-4 divided doses) is first-line empiric therapy for adults given MRSA prevalence of 42% in septic arthritis 1
• For children: vancomycin 15 mg/kg/dose IV every 6 hours (40 mg/kg/day in 4 divided doses), or clindamycin 10-13 mg/kg/dose IV every 6-8 hours if local clindamycin resistance is low 1
• Alternative empiric options if MRSA is less likely: linezolid 600 mg IV/PO every 12 hours, daptomycin 6 mg/kg IV daily, or teicoplanin 6-12 mg/kg IV every 12 hours for 3 doses then daily 1

Culture-Directed Definitive Therapy

Staphylococcus aureus (56% of cases) 2

• For MSSA: Switch to nafcillin/oxacillin 1-2 g IV every 4 hours, OR cefazolin 1 g IV every 8 hours, OR clindamycin 600 mg IV every 8 hours (if penicillin allergic) 1
• For MRSA: Continue vancomycin as primary therapy; strongly consider adding rifampin 600 mg PO daily or 300-450 mg PO twice daily for enhanced bone and biofilm penetration 1

Streptococcal Infections (18% of cases) 2

• Penicillin G 20-24 million units IV daily (continuous infusion or divided doses), OR ceftriaxone 1-2 g IV every 24 hours 1

Special Pathogen Considerations

• Children <4 years: Consider Kingella kingae as causative organism 1
• Sickle cell disease: Consider Salmonella species 1
• Polymicrobial infection: Dual antibiotic coverage is mandatory (e.g., linezolid for MRSA plus ciprofloxacin for Pseudomonas) 1

Treatment Duration and Route

Duration of Therapy

• Uncomplicated native joint septic arthritis: 3-4 weeks total duration 1
• Recent evidence suggests 2 weeks may be adequate after surgical drainage in select cases (predominantly small joints) 1
• Prosthetic joint infections with debridement and implant retention: 12 weeks is superior to 6 weeks 1
• Hip prosthesis with one-stage or two-stage exchange: 3 months total 1
• Knee prosthesis with one-stage or two-stage exchange: 6 months total 1
• Concomitant osteomyelitis (occurs in 30% of children): requires longer treatment 1

Transition to Oral Antibiotics

• Oral antibiotics are not inferior to IV therapy for most cases and can be switched after 2-4 days if the patient is clinically improving, afebrile, and tolerating oral intake 1, 4
• Oral options for MRSA (after initial IV therapy): linezolid 600 mg PO every 12 hours, TMP-SMX (trimethoprim 4 mg/kg/dose) PO every 8-12 hours plus rifampin 600 mg PO daily, or fusidic acid 500 mg PO every 8 hours plus rifampin 1

Monitoring Treatment Response

• Follow CRP and ESR to monitor treatment response 1
• Monitor vancomycin trough levels and adjust dosing to avoid toxicity 1
• Be vigilant for drug interactions and adverse effects, especially in elderly patients 1
• Synovial fluid WBC count ≥50,000 cells/mm³ is suggestive of septic arthritis at diagnosis 1

Critical Pitfalls to Avoid

• Never delay drainage waiting for culture results in surgical emergencies - immediate debridement with intraoperative cultures is required 1
• Do not rely on repeated arthrocentesis alone for hip or shoulder joints - these have high failure rates and poor outcomes 2
• Negative joint aspirate culture does not rule out infection; consider percutaneous bone biopsy if clinical suspicion remains high 1
• Do not use intra-articular corticosteroid injections during active infection 1
• For persistent or recurrent joint swelling after oral antibiotics, re-treat with another 4-week course of oral antibiotics or 2-4 weeks of IV ceftriaxone 1

Surgical Staging and Prognosis

• Stage I infection: only 5% need repeated arthroscopic irrigation 3
• Stage II infection: 52% need repeated arthroscopic irrigation 3
• Stage III infection: 75% need repeated arthroscopic irrigation, with 17% requiring open revision 3
• Medical treatment alone (arthrocentesis) has shorter hospital stays (21 vs 33 days) but higher failure rates (39.2% vs 30.4%) compared to surgical approach 5