Kocher Criteria

Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. Derived the four predictors (non-weight-bearing, ESR ≥ 40 mm/h, fever > 38.5 °C, WBC > 12 ×10⁹/L) from a retrospective cohort of 282 children.

Kocher MS, Mandiga R, Zurakowski D, Barnewolt C, Kasser JR. Validation of a clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children. Prospective validation cohort; the predicted probabilities shown here (2%, 9.5%, 35%, 72.8%, 93% for 0–4 predictors) are from this study — the original 1999 cohort estimated higher probabilities at 3–4 predictors, and probabilities have varied further in later external validations.

The criteria were derived and validated before Kingella kingae was widely recognised as a cause of paediatric septic arthritis; Kingella-related cases can present with a normal or only mildly elevated ESR/CRP and a low score, so a low Kocher score does not exclude septic arthritis when clinical suspicion remains. Joint aspiration and orthopaedic consultation are appropriate whenever septic arthritis cannot be confidently excluded, regardless of the score.