Kocher Criteria For Septic Arthritis

Diagnoses between septic arthritis and transient synovitis in pediatric patients with hip inflammation.

There is more information on the criteria used and on its interpretation, in the text below the calculator.

The Kocher criteria calculator helps with differential diagnosis between septic arthritis or transient synovitis, the two probable non-traumatic causes of joint infection in pediatric patients.

This is based on four criteria:

■ Non weight-bearing;

■ Temperature above 38.5°C / 101.3°F;

■ ESR above 40 mm/hr;

■ WBC above 12,000 cells/mm3.

For each positive criteria, 1 point is added to the total score (maximum obtainable is 4 points):

Score Septic arthritis risk
0 Very low risk / further monitoring
1 3% intermediate risk
2 40% risk / referral to radiology&orthopedics
3 93% risk / recommendation for hip aspiration
4 99% risk / recommendation for hip aspiration


Non weight-bearing


Temp above 38.5°C / 101.3°F


ESR above 40mm/hr


WBC above 12,000 cells/mm3

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Kocher criteria explained

This model helps differentiate between two non-traumatic joint infection conditions: septic arthritis or transient synovitis and determines the risk of SA in pediatric patients.

The four criteria used in the model are:

Kocher criteria Explanation
Non weight-bearing The pediatric patient does not want to bear weight on the side where they experience the painful joint. This is the main symptom of SA.
Temperature above 38.5°C / 101.3°F High fever is an indicator of an underlying infection.
ESR above 40 mm/hr The erythrocyte sedimentation rate or Westergren ESR represents the rate at which RBCs sediment and measures inflammation.
WBC above 12,000 cells/mm3 Increased leucocytes are another indicator of infection or sepsis.

Each positive answer to the four criteria weighs 1 point out of the total possible score of 4 points:

■ Scores of 0: very low risk of septic arthritis, however, recommendation of close follow up;

■ Scores of 1: 3% intermediate risk of septic arthritis;

■ Scores of 2: 40% risk of SA and recommendation for referral to radiology and orthopedics consultation for further intervention and hip aspiration;

■ Scores of 3 and 4: 93% respectively 99% very high risk of septic arthritis, indication of hip aspiration in the OR, with high likelihood of surgical drainage.

The main limitation of the model resides in the poor diagnosis performance for patients in the intermediate range, where further monitoring is required before intervention.

The Kocher criteria for septic arthritis has proved its specificity in diagnosing or ruling out SA for the extreme scores.


About the study

The original study was conducted by Kocher et al. on a cohort of patients evaluated at a major tertiary-care children's hospital between 1979 and 1996.

Diagnoses of true septic arthritis, presumed septic arthritis, and transient synovitis were taken in consideration.

A probability algorithm with four criteria for differentiation between septic arthritis and transient synovitis was constructed and tested.

Paediatric patients with SA differed significantly (p <0.05) from those with transient synovitis regarding the erythrocyte sedimentation rate, serum white blood-cell count and differential, weight-bearing status, temperature amongst other clinical parameters.

The validation study involved a population of pediatric patients who presented to a major children's hospital between 1997 and 2002 with the same indication of acutely irritable hip as those from the initial study.

The area under the receiver operating characteristic curve during the validation study was 0.86, compared with 0.96 in the original study.

The Kocher criteria was found to have a very good, diagnostic performance.


Septic arthritis in children

SA is a surgical emergency and rapid intervention is required to prevent or minimize joint damage. In younger children, there is a higher risk of permanent disability in case of complications.

Epidemiology states that incidence is 50% in children under 2 years of age, with the hip joint involved in 35% of cases. SA usually occurs from propagation of close proximal femoral osteomyelitis.

Differential diagnosis occurs with transient synovitis, osteomyelitis, psoas abscess or other muscle abscess.

The main symptoms include the refusal to bear weight and limited mobility of the hip along systemic or local signs of infection and inflammation (fever, localized swelling, tenderness and warmth).

In some cases, the child may rest the hip in an unusual position of flexion, abduction and external rotation and will avoid other movement because of pain.

In mild cases, treatment consists in intravenous antibiotic therapy and bed rest. Hip aspiration occurs in the rest of cases, where fluid is drained from the affected joint during arthroscopy, an intervention performed by an orthopedic surgeon.

Some of the possible SA complications are femoral head destruction, hip dislocation, joint contracture or gait abnormalities.


Original source

Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am. 1999; 81(12):1662-70.


Kocher MS, Mandiga R, Zurakowski D, Barnewolt C, Kasser JR. Validation of a clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children. J Bone Joint Surg Am. 2004; 86-A(8):1629-35.

Specialty: Rheumatology

System: Musculoskeletal

Objective: Diagnosis

Type: Calculator

No. Of Criteria: 4

Year Of Study: 1999

Article By: Denise Nedea

Published On: May 19, 2017

Last Checked: May 19, 2017

Next Review: May 19, 2023