Although the hipbones and the vertebrae (bones of the spine) provide the best measurements of bone loss, osteoporosis occurs in all bones. The osteoblasts and osteoclasts are most active in the bones of the body’s central region—that is, bones of the hip and vertebrae— and the long bones of the arms and legs. The skull bone is very rarely affected by osteoporosis. Fractures of the hip and vertebrae are also the most common fractures.
Because all bones can be affected by osteoporosis, clinicians usually recommend that individuals with weakened bones, like those caused by osteoporosis and osteopenia, avoid playing certain sports or engaging in certain activities that will increase the likelihood of falls which, of course, increase the risk of fractures of any bones, but particularly the hip. Every bone has a soft inner portion known as the bone marrow as well as an outer portion made up of trabecular bone (connective spongy bone tissue) and cortical bone (the hard outer shell). Trabecular bone makes up the softer inner shell of all bones and is present in higher amounts in the hip, vertebrae, wrists, and ends of the long bones. The central and long bones have more trabecular bone than the other smaller bones in the body.
Trabecular bone, which comprises about 20% of the body’s bone, provides strength and integrity, produces blood products, and provides the surface used for mineral exchange, such as phosphorus and calcium. Bone marrow is found in the spaces between trabecular bone. Cortical bone makes up the hard outer shell of bone and is critical for bone strength. Trabecular and cortical bone.In primary osteoporosis, women lose 5% to 10% of cortical bone and 20% to 30% of trabecular bone during the rapid bone loss occurring in the 4 to 8 years following menopause. In contrast, men and women (after the faster postmenopausal bone loss) experience a slower rate of bone loss as a result of aging. Occurring slowly over many years, this type of bone loss accounts for about a 20% to 25% loss of both cortical and trabecular bone. Thus, women are at risk for much greater bone loss than men.