Comparison of radiogrammetrical metacarpal indices in children and reference data from the First Zurich Longitudinal Study

A number of radiogrammetrical metacarpal indices are in use, some of which have been adapted for children. The purpose of this study was to compare four known indices-bone mineral density (BMD), relative cortical area, Exton-Smith index, bending breaking resistance index-and the more recently defined pediatric bone index (PBI) according to the two criteria of minimum height dependence and minimum variability in children of equal bone age. A total of 3,121 left-hand radiographs from 231 healthy Caucasian children ranging in age from 3 to 19 years old were analysed using BoneXpertA (R), a programme for automatic analysis of hand radiographs and assessment of bone age. Dependence on height for chronological age or bone age and the mean relative standard deviation were lowest in the PBI for both genders pooled. The differences in height dependence were statistically significant and are shown to be clinically relevant. Reference data for PBI are presented. PBI may be a better indicator than BMD for bone health in children; however, verification in a clinical group is needed.