Understanding the variation of volumetric bone mineral density in the femur and tibia in a paediatric population

Childhood and adolescence are crucial time for bone mineral accumulation with 25 % of bone mineral density (BMD) being laid during puberty. BMD development during growth was found to be correlated with the development of osteoporosis later in life. Mapping the variation of BMD in a paediatric population is important to understand how BMD change with age and sex. Therefore, the aim of this study was to evaluate the variation of BMD in the long bones for a paediatric population. CT-scans of 333 children and adolescents aged from 4 to 18 years were used to reconstruct 657 femora and 652 tibiae. Volumetric meshing and material mapping was performed for all bones with a CT-calibration phantom. Volumetric BMD was calculated for each femur and tibia and analysed by regions of interest, femur and tibia proximal and distal epiphysis, shaft, femoral head, neck and greater trochanter. A statistically significant interaction between the effects of age and sex were found in all regions of the femur and tibia with a significant simple main effect associated with age between male and female and with sex at age 11 and 14. Correlation between vBMD and participants' age, height and weight were mostly found in the distal tibia and tibial shaft. Interestingly, the vBMD at the femoral head, neck and greater trochanter did not increase with age. This study is the first to report on the variation of vBMD with age and sex from children and adolescents aged from 4 to 18 years.