Cortical consolidation of the radius and tibia in young men and women.

CONTEXT: Bone size, geometry, density, and microarchitecture are important determinants of bone strength. By understanding how these properties change during skeletal development, we can better understand bone fragility.

OBJECTIVES

The aim of the study was to compare the geometry, microarchitecture, and strength of the radius and tibia in men and women at the end of adolescence and in young adulthood and to relate these properties to biochemical bone turnover markers and bone regulatory hormones.

DESIGN

We conducted a cross-sectional study of 116 healthy men and women ages 16-18 (n = 56) and 30-32 (n = 60) yr.

OUTCOME MEASURES: We used high-resolution peripheral quantitative computed tomography to measure bone size, geometry, and microarchitecture at the distal radius and tibia and micro-finite element modeling to estimate bone strength. We measured bone turnover markers (β C-terminal telopeptide of type I collagen and amino-terminal propeptide of type I procollagen) and hormones known to affect bone metabolism (estradiol, testosterone, IGF-I, and PTH).

RESULTS

Bone strength was greater in men than in women, and at the radius it was greater in men ages 30-32 yr than ages 16-18 yr. The gender difference was due to greater cortical perimeter, trabecular area, and trabecular density in men. The age difference was due to greater cortical thickness and cortical tissue mineral density and lower cortical porosity. IGF-I was related to two of these five key properties at the radius (cortical perimeter and cortical thickness). None of the hormones were predictors of density or structure at the tibia.

CONCLUSIONS

Cortical modeling of long bones continues beyond the end of adolescence. IGF-I may be a determinant of this process at the radius.