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 in a child with an irritable hip?

Design

Retrospective cohort study at a single US children's hospital with multivariable modelling to derive a prediction rule.

Patients

Children presenting with an acutely irritable hip who underwent joint aspiration or were diagnosed with transient synovitis.

Intervention

Four predictors: history of fever, non-weight-bearing, raised ESR and raised white cell count

Comparison

Final diagnosis of septic arthritis versus 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 single-centre derivation; later validation studies showed lower accuracy, and CRP (added by Caird et al.) was not included.

Impact on practice

The Kocher criteria are widely used in UK emergency and orthopaedic assessment of the irritable hip to decide on urgent aspiration, alongside CRP.