Review Question - QID 212952

Given this current clinical presentation, she currently has 2 of 4 Kocher Criteria (leukocytosis and nonweightbearing status) which correlates with a 40% chance of infection, with staphylococcus aureus being the most common organism.

Differentiating pediatric septic hip arthritis from tenosynovitis is commonly encountered in practice. Timely diagnosis is paramount as a missed septic hip may have potentially disastrous results. Historically, multiple serologic, imaging, and physical findings were used to confirm the diagnosis. However, in 1999, the Kocher criteria showed that, of the multiple clinical variables, only 4 could reliably predict the presence of septic arthritis. These variables include the presence of fever of 38.5 degrees Celsius, refusal to bear weight on the affected extremity, an ESR above 40, and a peripheral white blood cell count above 12,000.

Kocher et al. published the seminal article proposing 4 separate diagnostic variables that, when combined, could predict the likelihood of infection. They reviewed a series of patients over 18 years and found that the presence of fever, inability to bear weight, elevated erythrocyte sedimentation rates, and elevated peripheral white blood cell counts were both independently and in combination predictive of infection.

Luhmann et al. retrospectively applied the Kocher criteria to confirmed cases of hip septic arthritis. They found this that when all 4 criteria are present, the predictive value was only 71% as compared to the original 99.6%. This poses the question about the universal generalizability of the Kocher criteria across differing institutions.

Figure A is a normal AP radiograph of the pelvis. Illustration A shows the predictive probability of the Kocher criteria variables from Kocher et al.

Incorrect Answers:
Answers 1, 2, 4, and 5: Only 2 of 4 Kocher criteria are present. Additionally, Neisseria gonorrhoeae is the most common organism in adolescents but not in the younger pediatric population, while Group A streptococcus is the most common organism following varicella infection and Group B strep infection is seen in neonates.