What is the treatment for infected patellar bursitis?

Treatment of Infected Patellar Bursitis

For infected patellar bursitis, treatment should include antibiotic therapy targeting Staphylococcus aureus (most common pathogen), surgical drainage or aspiration of the bursa, and supportive measures including rest, ice, and elevation. 1

Diagnosis

Before initiating treatment, confirm the diagnosis:

• Look for signs of infection: erythema, warmth, tenderness, fluctuance over the prepatellar area
• Distinguish from non-infectious causes (trauma, chronic microtrauma, inflammatory conditions)
• Obtain bursal fluid for:
  • Gram stain
  • Culture and sensitivity
  • Cell count (elevated WBC suggests infection)
  • Crystal analysis (to rule out gout)
  • Glucose measurement (lower than serum in infection)

Ultrasonography can help distinguish bursitis from cellulitis and identify fluid collections requiring drainage 1.

Treatment Algorithm

1. Initial Management

• Aspiration/Drainage:

  • Aspirate bursal fluid for diagnostic studies
  • For fluctuant collections or abscesses, complete drainage is essential
  • Consider incision and drainage for extensive abscesses or loculations

• Antibiotic Therapy:

  • Empiric therapy: Start antibiotics effective against S. aureus (responsible for 85% of cases) 2
  • First-line options:
    • Outpatient (mild-moderate): Oral antibiotics such as:
      • Cephalexin
      • Dicloxacillin
      • Trimethoprim-sulfamethoxazole (if MRSA suspected)
    • Inpatient (severe): IV antibiotics such as:
      • Vancomycin (if MRSA concern)
      • Cefazolin

• Duration of Therapy:

  • Short-course therapy (≤7 days) appears as effective as longer courses in non-immunocompromised patients 2
  • Immunocompromised patients may require longer courses due to higher risk of recurrence

2. Supportive Measures

• Rest and activity modification
• Ice application to reduce inflammation
• Elevation to minimize swelling
• Padding to protect the affected area
• NSAIDs for pain and inflammation

3. Monitoring and Follow-up

• Assess response to therapy within 48-72 hours
• Consider repeat aspiration if symptoms persist
• Adjust antibiotics based on culture and sensitivity results
• Continue antibiotics until resolution of infection signs

Special Considerations

• Immunocompromised patients: Higher risk of recurrence (5.6 times higher) 2; may require longer antibiotic courses and closer monitoring
• Recurrent cases: May require surgical bursectomy
• Chronic cases: Consider underlying causes (e.g., occupational kneeling) and address to prevent recurrence

Pitfalls to Avoid

• Failing to obtain cultures before starting antibiotics
• Inadequate drainage of purulent material
• Inappropriate antibiotic selection or insufficient duration
• Premature return to activities that may cause recurrence
• Using corticosteroid injections in infected bursae (can worsen infection)
• Treating uninfected bursitis with antibiotics

Evidence Strength

The recommendation for antibiotic therapy targeting S. aureus is strongly supported by evidence showing it causes 85% of infectious bursitis cases 2. The finding that short-course antibiotic therapy (≤7 days) is as effective as longer courses in non-immunocompromised patients is based on a retrospective study of 343 cases 2, providing moderate-quality evidence for this approach.