What is the treatment for septic arthritis?

Treatment of Septic Arthritis

Septic arthritis requires immediate surgical debridement combined with IV vancomycin as first-line antibiotic therapy, followed by culture-directed treatment for 3-4 weeks in uncomplicated cases. 1

Immediate Management Algorithm

Step 1: Recognize the Emergency

• Septic arthritis is an orthopedic emergency—bacterial proliferation rapidly destroys cartilage and causes permanent joint dysfunction 1, 2
• Mortality ranges from 2-15% overall, with 90-day mortality reaching 7% in patients ≤79 years and 22-69% in those >79 years 3, 4
• Poor functional outcomes (amputation, arthrodesis, severe deterioration) occur in 24-33% of patients 3

Step 2: Obtain Diagnostic Samples BEFORE Antibiotics

• Perform joint aspiration immediately in non-emergency presentations 1
• Synovial fluid WBC ≥50,000 cells/mm³ is highly suggestive of septic arthritis 1, 2
• Culture is positive in approximately 80% of non-gonococcal cases 1, 2
• For surgical emergencies (severe sepsis, rapidly progressive joint destruction), proceed directly to surgical debridement with intraoperative cultures rather than waiting for aspiration results 1

Step 3: Surgical Intervention

Drainage of the joint space must always be performed—this is non-negotiable. 1

• Surgical debridement with arthrotomy, irrigation, and drainage is the standard approach 1, 2
• Medical treatment (arthrocentesis alone) may be as effective as surgery for select cases with shorter hospital stays (12 days shorter) and better functional outcomes, but 30% ultimately require surgery 3, 5
• The choice between medical vs. surgical approach depends on:
  • Hip joints: Surgery preferred (medical failure rate 37.5% vs. surgical 52.9%) 5
  • Knee joints: Medical approach may be attempted first (medical failure rate 39.5% vs. surgical 17.2%) 5
  • Age and male sex are risk factors for medical treatment failure 5

Antibiotic Therapy

Empiric Treatment (Start Immediately After Cultures)

Adults:

• IV vancomycin 15 mg/kg every 6 hours (or 30-60 mg/kg/day in 2-4 divided doses) is first-line empiric therapy 1
• This covers MRSA, which is increasingly common in septic arthritis 1, 6
• Alternative empiric options if MRSA 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

Children:

• IV vancomycin 15 mg/kg/dose every 6 hours (40 mg/kg/day in 4 divided doses) 1
• Alternative: clindamycin 10-13 mg/kg/dose IV every 6-8 hours if local clindamycin resistance is low 1, 2
• Consider Kingella kingae in children <4 years 1, 2

Culture-Directed Therapy (Switch When Results Available)

MRSA (confirmed):

• Continue vancomycin as primary therapy 1
• Consider adding rifampin 600 mg daily or 300-450 mg twice daily for enhanced bone and biofilm penetration 1, 2
• Monitor vancomycin trough levels to avoid toxicity 1

MSSA (methicillin-sensitive S. aureus):

• Switch to nafcillin or oxacillin 1-2 g IV every 4 hours 1
• Alternative: cefazolin 1 g IV every 8 hours 1
• If penicillin allergic: clindamycin 600 mg IV every 8 hours 1

Streptococcal infections:

• Penicillin G 20-24 million units IV daily (continuous or divided) 1
• Alternative: ceftriaxone 1-2 g IV every 24 hours 1

Polymicrobial infections:

• Dual antibiotic coverage is mandatory (e.g., linezolid for MRSA plus ciprofloxacin for Pseudomonas) 1, 2

Transition to Oral Therapy

Oral antibiotics are not inferior to IV therapy for most cases of septic arthritis. 1, 6

• Switch to oral after 2-4 days if patient is clinically improving, afebrile, and tolerating oral intake 1
• Oral options for MRSA (after initial IV): linezolid 600 mg PO every 12 hours, TMP-SMX (trimethoprim 4 mg/kg/dose) every 8-12 hours plus rifampin 600 mg daily, or fusidic acid 500 mg every 8 hours plus rifampin 1

Duration of Treatment

Uncomplicated bacterial arthritis:

• 3-4 weeks total duration is standard 1, 2, 6
• Recent evidence suggests 2 weeks may be adequate after surgical drainage in select cases (predominantly small joints) 1

Prosthetic joint infections:

• 12 weeks is superior to 6 weeks for debridement with implant retention 1, 2
• Hip prostheses (one-stage or two-stage exchange): 3 months total 1
• Knee prostheses (one-stage or two-stage exchange): 6 months total 1
• If device cannot be removed: chronic suppression with appropriate antibiotics 2

Concomitant osteomyelitis:

• Occurs in up to 30% of children with septic arthritis 1, 2
• Requires longer treatment duration 1, 2

Candida septic arthritis:

• Fluconazole 400 mg daily for 6 weeks OR echinocandin for 2 weeks followed by fluconazole 400 mg daily for at least 4 weeks 2
• All patients require dilated retinal examination within first week to exclude endophthalmitis 2

Special Pathogen Considerations

• Sickle cell disease patients: Consider Salmonella species 1, 2
• Gonococcal arthritis: Requires specific consideration based on history and risk factors 6, 7
• Lyme arthritis (Borrelia burgdorferi): Consider based on geographic exposure 6

Management of Persistent Symptoms After Treatment

If joint swelling recurs or persists after completing antibiotics:

• Repeat joint aspiration to differentiate infection from sterile inflammation 8
• Re-treatment with another 4-week course of oral antibiotics OR 2-4 weeks of IV ceftriaxone 1, 2, 8
• Arthroscopic synovectomy may reduce inflammation duration in cases with significant pain or functional limitation 1, 2, 8

If synovial fluid PCR is negative and infection excluded:

• NSAIDs as first-line symptomatic treatment 1, 8
• Intra-articular corticosteroids only after infection definitively excluded 1, 8
• DMARDs (methotrexate, hydroxychloroquine, sulfasalazine) for severe persistent symptoms 8
• Biologic DMARDs (anti-IL-6R or TNF-α inhibitors) for refractory cases 8

Critical Pitfalls to Avoid

• Never assume negative cultures exclude infection—consider percutaneous bone biopsy if clinical suspicion remains high 1, 2, 8
• Never give intra-articular corticosteroids during active infection—this worsens outcomes 1, 8
• Do not delay treatment—permanent morbidity and mortality increase with diagnostic delays 6, 7
• Monitor for drug interactions and adverse effects, especially in elderly patients 1
• Recognize that synovial thickening may represent concurrent osteomyelitis requiring longer treatment 8
• Follow CRP and ESR to monitor treatment response 1, 8