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Table 4 ROC analysis: Representation of different radiographic parameters and their ability to proof (100% sensitivity, 2nd column) or exclude (100% specificity, 3rd column) the presence of a normal foot at given upper or lower boundary values. The “threshold range” (4th column) describes the area of overlap of every parameter, where no clear definition of whether the measurement describes a normal foot or a flatfoot can be made. In the 5th and 6th column the number of feet that could be clearly classified as normal foot or flatfoot according to the upper and lower limits of the threshold ranges are shown

From: Is it possible to define reference values for radiographic parameters evaluating juvenile flatfoot deformity? A case-control study

Parameter Threshold value [°] for proof/exclusion of normal feet Threshold range [°] Number of feet classifiable according to threshold value
100% Sensitivity 100% Specificity Normal feet (n = 22) Flatfeet (n = 22)
Talocalcaneal angle (dorsoplantar-view) < 12.5 > 26.5 14 1 6
Talonavicular coverage > − 16 <− 28.5 12,5 9 18
Talo-first-metatarsal-base angle > − 7.5 <−17.5 10 9 18
Calcaneus-fifth-metatarsal angle > − 3.5 <−16.5 13 9 4
Talo-first-metatarsal angle (dorsoplantar-view) > − 1.5 <−12.5 11 7 12
Calcaneal-pitch angle > 21.5 < 10.5 11 9 7
Costa-Bartani angle < 124.5 > 141.5 17 10 11
Talo-first-metatarsal angle (lateral-view) > − 13.5 <−20 6,5 12 20
Talocalcaneal angle (lateral-view) < 47.5 > 69.5 22 2 2
Talometatarsal index > − 31 <−34 3 20 21
Talocalcaneal index < 66 > 88 22 7 5