This Kocher criteria for septic arthritis calculator provides a differential diagnosis between septic arthritis and transient synovitis in children with hip inflammation. There is more in depth information on the subject and the score interpretation below the form.

Non weight-bearing

Temp above 38.5°C / 101.3°F

ESR above 40mm/hr

WBC above 12,000 cells/mm3

How does this Kocher criteria for septic arthritis calculator work?

This is a health tool that aims to help orthopedics make a differentiate diagnosis between the probable non traumatic causes of joint infection in children with similar presentations, either septic arthritis or transient synovitis.

The Kocher criteria for septic arthritis calculator uses the original 4 criteria in the model, with yes or no answers as described below:

■ Non weight-bearing – this is one of the main suspicion signs of septic arthritis in children who experience a painful joint that they do not want to bear weight on that side.

■ Temperature above 38.5°C / 101.3°F – high fever or high temperature, a symptom of underlying condition with the likeliness of an infection.

■ ESR above 40 mm/hr – erythrocyte sedimentation rate or Westergren ESR, is the rate in which the red blood cells sediment in a set period of time, usually an hour. It is a commonly met hematology test aiming to measure inflammation.

■ WBC above 12,000 cells/mm3 – leucocytes as cells of the immune system are bound to be higher in infections and cases with sepsis present.

The only criticism given to the model is that it doesn’t perform well in the intermediate range with the patients still in need for further monitoring and intervention. However, it proved specific and efficient in extreme scores, confirming or eliminating the septic arthritis diagnosis.

Kocher criteria interpretation

There are four criterions to be answered to, each positive answer weighing 1 point out of the total possible score of 4 points. Either of them can be present and none excludes another one.

■ Scores of 0 indicate a very low risk of septic arthritis in the patient and the recommendation is that of close follow up.

■ Scores of 1 indicate a 3% intermediate risk of septic arthritis, while scores of 2 raise the risk as 40% in the patient and the recommendation is that of a radiology and orthopedics consultation for further intervention and hip aspiration.

■ Scores of 3 and 4 carry high risks of 93% and 99% respectively of septic arthritis being present with recommendation for hip aspiration in the OR, with likelihood of surgical drainage being necessary.

Septic arthritis in children and treatment

This condition is a surgical emergency and rapid measures need to be taken, such as surgical drainage in order to prevent any joint damage. The younger the child, the higher the risk of permanent disability in case of complications. This is similar to other conditions such as pulmonary croup, which target children and present more complications in young cases. Epidemiology states that incidence is 50% in cases under 2 years of age, with the hip joint involved in 35% of cases. In infants, SA usually occurs from propagation of close proximal femoral osteomyelitis.

The other diagnosis in patients presented with a limp associated or not with hip pain include transient synovitis, psoas abscess, other muscle abscess or osteomyelitis. 

Symptoms exhibited include the refusal to bear weight, walk or move the hip, fever and other systemic inflammation symptoms, localized swelling, tenderness and warmth. Other local signs include the hip resting in an unusual position of flexion, abduction and external rotation and experiencing severe pain at a range of movements.

Usually, the election treatment is with antibiotics intravenously administered, accompanied by bed rest. Fluid might also be drained from the affected joint during arthroscopy, an intervention performed by an orthopedic surgeon.

Hip aspiration is to be considered in most patients with at least one predictor in the Kocher criteria. High suspicions should go directly to orthopedics consultation and surgical therapy. Some cases also require hip arthrocentesis.

Complications that can appear include amongst others femoral head destruction, joint contracture, hip dislocation, gait abnormalities or osteonecrosis.


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

2) Kocher MS, Mandiga R, Zurakowski D, Barnewolt C, Kasser JR. (2004) 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; 86-A(8):1629-35.

3) Carpenter CR, Schuur JD, Everett WW, Pines JM. (2011) Evidence-based diagnostics: adult septic arthritis. Acad Emerg Med; 18(8):781-96.

06 Sep, 2015