According to a 2022 study, the Kocher criteria identify four factors that differentiate septic arthritis of the hip from transient synovitis:
• fever above 101.3ºF (38.5ºC)
• inability to bear weight
• serum white blood cell count above 12,000/mm3
• ESR of 40 mm/h or above
Kocher created the criteria in 1999, and the initial study found these four factors were 99.6% predictive of septic arthritis of the hip. Later research has not found the criteria as effective.
In 2006, researchers added a fifth criterion, with a level of CRP greater than 2 mg/dL being a strong risk factor for septic arthritis of the hip. The research found that all five factors could predict septic arthritis in 98% of cases.
The 2022 study found that the updated Kocher criteria effectively diagnose septic arthritis of the hip, with elevated CRP levels being the most significant risk factor.