A MIXED LONGITUDINAL STUDY ON SKELETAL MATURATION IN HEALTHY FINNISH CHILDREN AGED 1 TO 5 YEARS

In a mixed longitudinal "Model Child" study in Finland the bone specific rating system of Tanner et al. was employed for the assessment of skeletal age from hand-wrist X-rays. The presented study comprised age groups from 1 to 5 years. 36 boys and 49 girls were observed all each year up to age 5. The skeletal age determinations were made at each birthday. A total of 491 assessments were made in this series. Three observers rated each X-ray and the differences between them are detailed. About 25% of ratings differed by one stage; less than 1% by two stages. The means and standard deviations of the overall scores and of the corresponding skeletal ages according to the standards are presented for boys and girls in each group. Skeletal maturation in all the age groups of boys in our series appeared to be more advanced than in the standards, whereas girls were on the standard level. The question that the standards possibly are too low for Finnish boys calls for further study with a larger series of children. The annual increments and standard deviations of the overall score and the long bone and round bone scores are presented. The relatively wide ranges of dispersion of the round bone increments are an indication of the large variations in a normal series. A positive correlation was seen between the mother's height and the child's skeletal age. This reached a statistical significance when the children were of chronological age 1. The father's height, on the other hand, appeared not to be related to the child's skeletal maturation. Morbidity, consisting chiefly of recurring and/or severe infectious diseases, was not found to be associated with the child's bone age. Children with chronic diseases were not included in this series.