AGE-RELATED-CHANGES IN CORTICAL AND CANCELLOUS VERTEBRAL BONE-DENSITYIN GIRLS - ASSESSMENT WITH QUANTITATIVE CT

OBJECTIVE. Bone mass increases during growth, but little information i s available about the changes in cortical and cancellous bone densitie s during skeletal development or their relative contributions to age-r elated increases in bone mass. Accordingly, separate measurements of c ancellous and cortical bone density were done at each stage of sexual development in white girls during childhood and adolescence. SUBJECTS AND METHODS. Quantitative CT was used to measure the densities of cort ical and cancellous bone of the lumbar spine in 96 healthy white girls 4-20 years old. The relationships among various anthropometric indexe s, pubertal status, and corresponding densities of cortical and cancel lous bone were then examined. RESULTS. Cortical bone density increased with age, and values were significantly correlated with the anthropom etric indexes of height (r=.61), weight (r=.62), body mass index (r=.6 1), and muscle volume (r=.58). In contrast, cancellous vertebral bone density increased only during the later stages of puberty. Moreover, c ancellous bone density in prepubertal girls was inversely related to a ge (r= -.27) as well as to both the volume (r= -.20) and the height (r = -.15) of the vertebral body. CONCLUSION. The results suggest that we ight bearing and/or mechanical stresses are important determinants of cortical bone density in the lumbar spine throughout growth, whereas c ancellous vertebral bone density is more strongly influenced by hormon al and/or metabolic factors associated with sexual development during late adolescence.