A comparison of skeletal maturity and growth.

BACKGROUND

Somatic and bone development have each been studied in detail, but rarely in conjunction.

AIM

The aim of this study was to determine what somatic and bone development have in common and how they differ. A second aim was to check for a pubertal spurt in bone age (BA) and to quantify it in a similar way as has been done for height. The Preece-Baines model is used to fit longitudinal data for BA.

SUBJECTS AND METHODS

The data analysed are from the 1st Zurich Longitudinal Growth Study comprising 120 boys and 112 girls with almost complete data from birth to adulthood.

RESULTS

Variability of somatic milestones was reduced in terms of BA and there was an aftergrowth after reaching adult RUS score 1000. A strong increase in the RUS score was seen at a late stage of the pubertal spurt (PS). Somatic milestones correlated with the RUS score attained at these ages and more so at an early stage of the PS. A PS for BA was clearly identified with a location at 14.2 years for boys and 12.2 years for girls. Age of peak bone development correlated highly with age of peak velocity of somatic variables.

CONCLUSIONS

BA can be successfully modelled as a semi-quantitative entity. Bone development shows marked associations with somatic development, despite the fact that the latter reflects changes in size, while the former is essentially a maturity index and reflects changes in biochemical composition of tissues.