Septic Arthritis

Exam Cram

• Infection of a joint- 10% mortality risk per joint

• Bugs- 50% staph aureus, 25% beta haemolytic streph, Gonorrhea and Lyme disease rarer

• Presentation: hot, swollen, painful joint

• Key investigation: joint aspiration, shows raised WCC & grows organisms

• Management: IV flucloxacillin, IV Vancomycin (MRSA +ve)

Outline

Background 

Commonest source of septic joint:

• Adult- knee

• Child- hip

Complication of joint injections, 1/ 2000 

Diagnosis

Diagnostic criteria: fluid aspirate

• reasonable to start treatment after aspirate but before results if high clinical suspicion

History:

Examination:

• Hot, swollen, irritable joint

Ix

• Joint aspirate: gram stain +ve, raised neutrophils

• Raised CRP, neutrophils (serum)

• XR: soft tissue swelling

Differentials

Management

• IV Flucloxacillin

  1. IV Vancomycin if MRSA concerns

• Orthopaedics admission +/- joint washout

Deeper Dive

References

Page written in 2024.