[Changes in bone volume and mineral density during aging in humans. In vitro study on 80 subjects]

The extent of bone loss was measured and compared at three characteristic skeletal sites: the humerus, iliac crest and vertebrum. The most important effect of ageing is the fall in bone volume: reduction of bone trabeculae, thinning of compact bone and increase in intracortical porosity. Between 40 and 80 years of age, women lose 42 percent of their vertebral spongy tissue, 29 percent of their iliac spongy tissue and 31 percent of humerus cortical bone. The mean degree of mineralization of bone tissue remains constant between 40 and 80 years of age. Cortical bone is mineralized to a greater extent than spongy bone: 1.20 g/cm3 versus 1.0 g/cm3. Bone loss from different skeletal sites varies; within a given bone-organ it varies from one point to another. The mineral content of the iliac crest differs from that of the vertebrum, but the change is parallel at these two sites.