Why to Use
Differentiating between SA and TS of the hip in children can be difficult. The Kocher criteria can be used to quickly identify subsets of patients who need urgent orthopedic consultation and those who can be observed.
When to Use
The Kocher criteria can be applied to all pediatric patients with an acutely irritable hip for whom SA and TS are in the differential diagnosis.
Abbreviations: CBC, complete blood cell; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; SA, septic arthritis; TS, transient synovitis.
Calvin Hwang, MD
Patients who meet none of the Kocher criteria can potentially be discharged; those who meet all 4 of the criteria require urgent orthopedic consultation for washout. Patients who meet some but not all of the Kocher criteria (1-3 predictors) may require hip arthrocentesis.
Diagnostic hip aspiration should be considered when there is a clinical concern for septic arthritis along with the presence of at least 1 predictor. If there is high clinical suspicion for SA, orthopedic consultation should not be delayed. Observation and/or discharge with close follow-up should be considered for well-appearing patients when there is low clinical suspicion for SA and no predictors are present.
In 1999, Kocher et al published a retrospective chart review of 282 patients who had been evaluated between 1979 and 1996 for an acutely irritable hip, and for whom the differential diagnosis included TS and SA. SA was diagnosed by a positive joint fluid culture or by a white blood cell (WBC) count in the joint fluid of ≥ 50,000 cells/mcL. Eighty-two patients were diagnosed with SA, while 86 were diagnosed with TS (defined as a WBC count of < 50,000 cells/mcL, with a negative joint fluid culture and resolution of symptoms without antimicrobial therapy).
The study identified 4 independent multivariate predictors for differentiation between SA and TS: (1) history of fever; (2) non–weight-bearing; (3) ESR > 40 mm/hr; and (4) serum WBC count > 12,000 cells/mcL. The probabilities for SA based on the number of predictors were as follows: 0 predictors = < 0.2%; 1 predictor = 3%; 2 predictors = 40%; 3 predictors = 93.1%; and 4 predictors = 99.6%.
In a 2004 study, Kocher et al prospectively applied the criteria to patients with an acutely irritable hip who had presented to a major tertiary-care children's hospital between 1997 and 2002. The cohort included 213 consecutive patients, 51 of whom whom were diagnosed with SA and 103 with TS. In this study, the probabilities for SA based on the number of predictors were as follows: 0 predictors = 2%; 1 predictor = 9.5%; 2 predictors = 35%; 3 predictors = 72.8%; and 4 predictors = 93%.
Other authors have retrospectively applied the Kocher criteria to their study populations. Luhmann et al (2004) found that having all 4 predictors yielded a probability for SA of just 59%, but they did not publish the rate of SA found when no predictors were present. Sultan et al (2010) retrospectively applied the Kocher criteria and found a predicted probability for SA of 59.9% when all 4 predictors were present, although the study was limited by having only 5 patients with SA, and no cases of SA in a patient with no predictors present.
Mininder S. Kocher, MD, MPH
Prakriti Gill, MD; Jennifer E. Sanders, MD
Richard M. Cantor, MD, FAAP, FACEP; Susan Fraymovich, DO
December 2, 2019
December 2, 2022
4 AMA PRA Category 1 Credits™, 4 ACEP Category I Credits, 4 AAP Prescribed Credits, 4 AOA Category 2-A or 2-B Credits. Specialty CME Credits: Included as part of the 4 credits, this CME activity is eligible for 4 Infectious Disease CME and 0.5 Pharmacology CME credits.