DEVELOPMENT OF MASS, DENSITY, AND ESTIMATED MECHANICAL CHARACTERISTICS OF BONES IN CAUCASIAN FEMALES

Three hundred and thirty healthy Finnish girls and premenopausal women , aged 7-47 years, were examined to evaluate the natural development o f bone mineral mass and density from early childhood to menopause. Bon e mineral content (BMC, g) and areal density (BMD, g/cm(2)) were measu red from the spine (L2-L4), femoral neck, trochanter region of the fem ur, and distal radius using dual-energy X-ray absorptiometry (DXA). In addition, the bone mineral apparent density (BMAD, g/cm(3)) was asses sed from the above described skeletal sites, and the mechanical compet ence of the femoral neck was estimated. Special attention was paid to the timing of the peak values of these bone parameters as well as to t he evidence of premenopausal bone loss. The BMC, BMD, and BMAD of the spine, femoral neck, and trochanter region of the femur achieved peak values around the age of 20, and the bone loss seemed to start soon th ereafter. In contrast, the bone mass of the distal radius slightly inc reased between the ages of 20 and 47. In the femoral neck, the estimat ed bending strength achieved its peak value around the age of 20 and s howed a slight decrease during the following decades. The highest body weight and neck-length adjusted strength values of the femoral neck w ere, however, found in early childhood, with the values decreasing lin early thereafter. In conclusion, this study supports previous findings of rapid bone mineral accumulation in late adolescence, and occurrenc e of the peak bone mass and density around the age of 20. Premenopausa l bone loss seems to occur in the proximal femur and lumbar spine. Our observations of femur strength development imply that from childhood to menopause the mechanical strength of the femoral neck is well adjus ted to the biomechanical loading requirements of the body.