Cortical consolidation due to increased mineralization and endosteal contraction in young adult men: a five-year longitudinal study.

CONTEXT Peak bone mass is an important factor in the lifetime risk of developing osteoporosis. Large, longitudinal studies investigating the age of attainment of site-specific peak bone mass are lacking. OBJECTIVE AND MAIN OUTCOME MEASURES: The main outcome measures were to determine the site-specific development of peak bone mass in appendicular and axial skeletal sites and in the trabecular and cortical bone compartments, using both dual x-ray absorptiometry and peripheral computed tomography. DESIGN, SETTING, AND POPULATION In total, 833 men [aged 24.1 ± 0.6 yr (mean ± sd)] from the original population-based Gothenburg Osteoporosis and Obesity Determinants Study (n = 1068) were included in this follow-up examination at 61.2 ± 2.3 months. Areal bone mineral density (aBMD) was measured with dual x-ray absorptiometry, whereas cortical and trabecular volumetric bone mineral density and bone size were measured by peripheral computed tomography at baseline and at the 5-yr follow-up. RESULTS During the 5-yr study period, aBMD of the total body, lumbar spine, and radius increased by 3.4, 4.2, and 7.8%, respectively, whereas a decrease in aBMD of the total hip of 1.9% was observed (P < 0.0001). Increments of 2.1 and 0.7% were seen for cortical volumetric bone mineral density of the radius and tibia, respectively (P < 0.0001), whereas cortical thickness increased by 3.8% at the radius and 6.5% at the tibia due to diminished endosteal circumference (radius 2.3% and tibia 4.6%, P < 0.0001). CONCLUSION aBMD decreased at the hip but increased at the spine and radius, in which the increment was explained by continued mineralization and augmented cortical thickness due to endosteal contraction in men between ages 19 and 24 yr.