The mechanism for consolidation of bone mass in young men and women: A high resolution quantitative computed tomography study

The period between the end of linear growth and peak bone mass has been referred to as ‘consolidation’. We have found that in men and women peak bone mass at the radius and lumbar spine occurs in the middle of the third decade. The aim of this study was to better understand the changes in the bone compartments of the radius using high resolution peripheral quantitative computed tomography (HR-pQCT) and to relate these changes to bone turnover markers. We studied 113 healthy male and female volunteers ages 16–18 and 30–32.Wemeasured spine and hip BMD with DXA, and examined the distal radius with HR-pQCT (Xtreme CT, Scanco Medical). We analysed the HR-pQCT images with the standard software and also with extended cortical bone measures software. We also measured serum βCTX and PINP. Spine BMDwas higher at ages 30–32 than at ages 16–18 inmen andwomen. Hip BMDwas similar in both age groups. Radius cortical BMDwas higher at ages 30–32 than at ages 16–18 in men and women, due to lower porosity and higher tissue mineral density. Trabecular bone volume, BMD, number, thickness and separation did not differ between age groups. Cortical perimeter, endosteal perimeter and trabecular area were greater at ages 30–32 than at ages 16–18 inmen, but not inwomen. Serum βCTX and PINPwere lower at ages 30–32 than at ages 16–18 in men and women. These analyses demonstrate that cortical consolidation is due to an increase in mineralisation of bone tissue and a decrease in porosity. This consolidation is probably due to the decrease in bone turnover between the end of growth and peak bone mass. Also, there is evidence for periosteal apposition and endosteal resorption with increase in bone size in men. The trabecular compartment does not contribute to consolidation, and seems to have reached its mature state by the end of growth.