Kocher Criteria for Septic Arthritis
Predicts probability of septic arthritis vs transient synovitis in children with acute hip pain. Validated by Caird et al. with CRP enhancement.
Score interpretation
Kocher 0–1: Low probability of septic arthritis (~3%). Transient synovitis likely.
→ Observation and analgesia (NSAIDs: ibuprofen 5–10 mg/kg TDS). Bed rest. Follow-up in 24–48 hours. Return if fever develops, condition worsens, or not improving within 1 week. Ultrasound hip for effusion if uncertain.
Kocher 2–3: Intermediate risk (~40–65%). Senior review and further investigation required.
→ Urgent paediatric orthopaedic review. Hip USS: if effusion present, joint aspiration under USS guidance (diagnostic + therapeutic). Send aspirate: MC&S, cell count, glucose, lactate. If WBC > 50,000/µL in aspirate: surgical washout. CRP, blood cultures, FBC, ESR. IV antibiotics after aspiration.
Kocher 4–5: High probability of septic arthritis (~99%). Surgical management indicated.
→ EMERGENCY orthopaedic referral. Urgent surgical washout and drainage of hip joint. IV antibiotics: flucloxacillin 50 mg/kg QDS (MRSA risk: vancomycin). Blood cultures × 2 before antibiotics. Staphylococcus aureus most common pathogen. Post-operative IV antibiotics for minimum 2 weeks then oral. Physiotherapy after drainage.
Interpretation bands for the Kocher Criteria. Apply clinical judgement and local guidance.
References
- Kocher MS et al. Differentiating between septic arthritis and transient synovitis of the hip in children. J Bone Joint Surg Am. 1999.
- Caird MS et al. Factors distinguishing septic arthritis from transient synovitis of the hip in children. A prospective study. J Bone Joint Surg Am. 2006.
Related
Curated clinical cross-links plus same-class fallbacks.
- Ibuprofen (Orthopaedic Musculoskeletal Pain) · NSAID — Non-selective COX Inhibitor
- Vancomycin (Orthopaedic Bone and Joint Infections) · Glycopeptide Antibiotic
- Teicoplanin (Orthopaedic Bone and Joint Infections) · Glycopeptide Antibiotic
- Paracetamol (Paediatric) · Analgesic / Antipyretic — First-Line Pain and Fever in Children
- Morphine (Paediatric) · Opioid Analgesic — Moderate to Severe Pain in Children
- Hydrocortisone (ICU — Stress Dosing) · Corticosteroid (ICU/Septic Shock)
- Infective Endocarditis · ESC 2023 Infective Endocarditis Guidelines; NICE NG41
- Eczema Herpeticum · BAD; NICE CKS
- Suspected Bacterial Meningitis (Adult) · NICE NG240 (2024); NICE NG143 (paeds)
- Clostridioides difficile Colitis · NICE NG199 (2021); IDSA/SHEA 2021
- Returning Traveller — Fever · NaTHNaC; PHE; ESCMID 2018
- Malaria — Diagnosis & Management · PHE 2016; WHO 2023
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.