Kocher Criteria for Septic Arthritis

The Kocher score was retrospectively derived by Kocher et al. in 1999 as a way to help clinicians differentiate between septic arthritis and transient tenosynovitis in pediatric patients with inflamed hips. The original study included 282 patients of which 82 were eventually diagnosed with septic arthritis based on joint fluid analysis. The most predictive four criteria were isolated retrospectively.

A subsequent validation study by Kocher et al. in 2004 maintained a strong utility for this decision tool, though with lower predictive probabilities. The validation demonstrated that the risk for septic arthritis was 2% for a score of 0, 9.5% for 1, 35% for 2, 72.8% for 3, and 93% for 4.

This remains a useful clinical decision tool for pediatric patients presenting with signs and symptoms of an irritated hip.

Variable & Associated Points

• Non-weight-bearing (Yes +1)
• History of measured temperature > 38.5 degrees Celsius (Yes +1)
• Serum ESR > 40 mm/hr (Yes +1)
• Serum WBC > 12,000 cells / mm3 (Yes +1)

Score: sum of points above

• Score 0 = < 0.2 % risk of septic arthritis
• Score 1 = 3% risk of septic arthritis
• Score 2 = 40% risk of septic arthritis
• Score 3 = 93% risk of septic arthritis
• Score 4 = 99.6% risk of septic arthritis