The World Book Rush-Presbyterian St. Luke's Medical Center Medical Encyclopedia Osteoporosis Osteoporosis is a disorder in which both calcium salts and bone fabric are depleted. It is different from osteomalacia, in which only calcium is lost from the bone. Osteoporosis attacks bones containing a large percentage of trabecular bone, including the vertebral column, the hips, and the wrist. The bones affected by osteoporosis are more fragile and prone to fracture. There may also be a vague, generalized backache because the vertebrae, in becoming thinner, tend to compress the surrounding nerves.
Bones fracture more easily, causing acute pain.
Such severe pain is caused by a compression fracture of one of the vertebrae, commonly in the mid-spine. Other bones, such as the hip, may fracture more easily than usual in the elderly. The cause is not precisely known. After about the age of 30, the body normally loses bone mass at a slow rate. In women, this rate of bone loss accelerates significantly after menopause.