Kocher criteria

Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm.

Kocher MS, Zurakowski D, Kasser JR. The Journal of bone and joint surgery. American volume 1999 · PMID 10608376 · doi:10.2106/00004623-199912000-00002

Question

Which clinical and laboratory features distinguish septic arthritis from transient synovitis of the hip in children?

Design

Retrospective single-centre cohort with multivariable analysis to derive a clinical prediction rule.

Patients

Children presenting to a US paediatric hospital with an acutely irritable hip.

Intervention

Four predictors: history of fever (>38.5 C), non-weight-bearing, ESR >40 mm/h, serum WCC >12 x10^9/L

Comparison

Final diagnosis of septic arthritis vs transient synovitis

Primary outcome

Predicted probability of septic arthritis by number of predictors present

Key result

The probability of septic arthritis rose steeply with the number of predictors present, being very high when all four were present and very low when none were.

Limitations

Retrospective derivation at a single tertiary centre; later validation studies found lower predictive performance, and CRP was not included.

Impact on practice

The classic decision aid for the irritable hip, taught universally; used alongside ultrasound and aspiration rather than as a stand-alone test.