Kocher score is a 0-4 point clinical rule. One point is assigned for each predictor present at initial assessment:

Predictor	Criterion	Points
Fever	History of temperature >=38.5 C	1
Weight-bearing	Inability to bear weight on the affected limb	1
ESR	Erythrocyte sedimentation rate >=40 mm/h	1
Serum WBC	White cell count >12 x 10^9/L	1

Total Kocher score = sum of points (0-4).

In the original derivation cohort, the estimated probability of septic arthritis at each score was:

Kocher score	Estimated probability of septic arthritis (derivation study)
0	<0.2%
1	3%
2	40%
3	93.1%
4	99.6%

Kocher Criteria for Septic Arthritis