Structural changes of the femoral shaft with age measured by dual photon absorptiometry

During measurements of bone mineral content with dual photon absorptiometry the external and internal diameters of the femoral shaft were determined from the attenuation curves. Measurements on aluminium cylinders demonstrated a precision error on such determinations of 2-3%. Repeated determinations of the external and internal diameter on the femoral shaft in vivo showed an average difference between two measurements of 2.1 and 4.2%, respectively. Determinations on the femoral shaft in vivo of 101 normal women aged 20-90 years and 41 normal men aged 20-85 years showed that the external and internal diameter increased significantly with age in both women and men, but more pronouncedly in women. The cortical width and the density of the cortical bone, g/cm3, decreased significantly in women. In men neither the cortical width nor the bone density of the femoral shaft changed significantly with age.