What are the Kocher criteria?

1. history of fever
2. non-weight bearing
3. erythrocyte sedimentation rate (ESR) > 40
4. WBC > 12,000 per cubic millimeter

The more criteria met, the greater the chances of septic hip relative to a more benign cause of pediatric hip pain such as transient synovitis.

• 0/4 criteria = 0.2% chance of septic hip
  
• 1/4 = 3%
• 2/4 = 40%
• 3/4 = 93.1%
• 4/4 = 99.6%

Source

Kocher, M. MD et al. "Differentiating Between Septic Arthritis and Transient Synovitis of the Hip in Children: An Evidence-Based Clinical Prediction Algorithm" The Journal of Bone and Joint Surgery 81: 1662-70 (1999)