Radiographic absorptiometry of the middle phalanx (digit II) in a Caucasian pediatric population: normative data

The availability of improved therapies for children with diseases affecting bone growth and/or metabolism has caused increased interest in bone mineral density (BMD) assessment. The purpose of this study was to determine normal values for phalangeal radiographic absorptiometry (RA) in a Caucasian pediatric population. Five hundred and seventy-two healthy Caucasian children and adolescents (aged 5-19 years) were enrolled in this study. For RA one posteroanterior exposure of the left hand and one lateral exposure of the left index finger were taken. All films were analyzed, yielding BMD (mg Al/mm3) values for two phalangeal sites: one at the proximal quarter of the phalangeal length (BMD25%) and the second at the midpoint of the phalangeal length (BMD50%). Also skeletal age (SA) was assessed, as data normalized for SA can be used in populations which show a dissociation between SA and calendar age. We found that the BMD25% was significantly higher in girls than in boys for the SA group 11-14 years. The BMD50% was significantly higher in girls than in boys for the SA group 11-15 years. Our data show that BMD25% remains fairly constant until the SA of 12.0 years in boys and 10.1 years in girls; after these skeletal ages BMD shows a sharp increase. The same applies to BMD50%, which remains fairly constant until the SA of 12.4 years in boys and 10.7 years in girls. In this paper we present normative data for RA in a pediatric population. These data normalized for skeletal age could be implemented in a clinical setting.