Synopsis
Recognise native-joint sepsis, aspirate before antibiotics when safe, drain infected synovium urgently and tailor systemic treatment to organism, host and adjacent bone involvement.
- Septic arthritis is infection within a native synovial joint and can destroy cartilage within days; treat the acutely hot restricted joint as infection until adequately assessed.
- First diagnostic priority in a stable patient is urgent synovial aspiration before antibiotics for cell count, Gram stain, culture and crystal analysis.
- Do not delay antibiotics for aspiration in sepsis or haemodynamic instability; take blood cultures and treat immediately.
Key red flags
Hypotension, confusion, tachypnoea or rising lactate indicates septic shock requiring immediate treatment.
Rapid onset of severe pain, swelling, warmth and markedly restricted active and passive movement is the classic native-joint presentation.
Investigation priorities
Obtain the most direct pre-treatment evidence of joint infection and alternative crystal disease.
Management branches
A new hot, swollen or severely restricted native joint has no better established diagnosis.
- Assess ABCDE and sepsis, document every involved joint, skin source, procedure, immune status, sexual exposure and endocarditis risk.
- Take blood cultures and aspirate the joint before antibiotics when the patient is stable and aspiration can occur immediately.
Key medicines
Empirical native-joint intravenous regimenGive the exact local age-, allergy-, renal- and MRSA-risk-adjusted intravenous native-joint combination immediately after blood and synovial cultures when feasible.
Flucloxacillin for susceptible staphylococciGive 2 g intravenously every four to six hours when directed for methicillin-susceptible Staphylococcus aureus, with exact interval selected by the local severe-infection protocol.