Thanks to Brittany for this excellent Peds pearl.

A 4 year old boy presents with a fever and a one-day history of rapidly worsening limp at the LLE, now with complete refusal to bear weight or range the L hip.

You are concerned about a wide differential, but particularly about septic arthritis.

Labs are sent and are significant for:

WBC 14

ESR 41


Is there a decision rule that can help you risk stratify this patient?


Yes! This rule is helpful in both the positive and negative directions, and can help you decide which patients require arthrocentesis.

The Kocher Criteria for Pediatric Septic Hip

Kocher criteria for a child with a painful hip, suspected to have septic arthritis:
1) non-weight-bearing or refusal to bear weight, with support
2) sedimentation rate greater than 40 mm/hr
3) fever
4) WBC >12,000
The criteria have a high specificity with three or four criteria.
4/4 — 99%
3/4 — 93%
2/4 — 40%
1/4 —  3%
Zero criteria had a high sensitivity of 0.2-2%
Kocher etal. Validation of a Clinical Prediction Rule for the Differentiation Between Septic Arthritis and Transient Synovitis of the Hip in Children. The Journal of Bone and Joint Surgery (American) 86:1629-1635 (2004).