Introduction
The skeleton acts as a rigid framework for the body by acting as a site for the attachment of muscles, protecting vital organs and by housing the bone marrow. Osteoporosis is a skeletal disease that is characterised by low bone density and deterioration of the bone tissue, which causes the bone to become more fragile and fracture much easier than normal. Regions of the skeleton can be replaced by bone remodelling, a process that involves the breakdown of old bone, which is reabsorbed by the body and then replaced by new bone. Under normal circumstances, the amount of old bone removed is balanced by the amount of new bone added. The main cause of osteoporosis is an imbalance in the remodelling process, where the amount of bone formed at certain sites is less than that which is reabsorbed or eroded.
Osteoporosis affects a large number of people 50 years and older, and is usually more common in women than men. The incidence of fracture rises steeply with age in both sexes, but occurs earlier in women than men. For example, the fracture rate in elderly women is twice that in men of the same age. Common osteoporotic fractures are of the spine and hip, but fractures of the forearm, wrist, humorous, tibia, ribs and pelvis also occur.