Bone's structural diversity in adult females is established before puberty.

INTRODUCTION: Bone must be rigid for leverage yet light for mobility. We studied how bone modeling and remodeling fashioned differences in bone size, shape, and mass during growth to achieve these properties in adulthood.
METHODS: We measured the structural features of a tibial cross-section using quantitative computed tomography and markers of remodeling in 258 10- to 13-yr-old girls during 2 yr and in 108 of their mothers.
RESULTS: Tibia total cross-sectional area and mass correlated between daughters and their mothers (r = 0.34 and 0.44, respectively, both P < 0.01). The location of a daughter's tibial total cross-sectional area, medullar area, and bone mass in the lower, middle, or upper part of the sample distribution was established before puberty and tracked during 2 yr (r = 0.84-0.94 first vs. last measurements' ranking). Tibial cross-sectional area correlated with medullar area (r = 0.69). Both areas correlated inversely with volumetric bone mineral density (r = -0.32 and -0.67, respectively; all P < 0.001), so larger cross-sections had a lower volumetric bone mineral density. The amount of bone deposited on the anterior and posterior periosteal surface during 2 yr was twice that deposited medially and laterally (P < 0.001), increasing strength more in the former than in the latter principal axis.
CONCLUSION: Differences in skeletal size, shape, and mass in adulthood are likely to be largely established before puberty. We infer that bone fragility in advanced age has its structural antecedents partly established in early life.