Osteoporosis: The Primary Cause of Vertebral Fractures

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Osteoporosis is fairly common disease, and is especially common in postmenopausal women. In fact, it is estimated that approximately 25 percent of all postmenopausal women in the United States have had a vertebral compression fracture.¹

Osteoporosis also occurs in men, but is far more prevalent in women—approximately four times as many women have low bone mass, or osteoporosis, as men.

Osteoporosis causes bones to thin and become more brittle and weak. When the bones in the spine weaken they can break or cave in under normal pressure. The thinning bones can collapse during normal activity, leading to a spinal fracture. These compression fractures can cause a great deal of pain and can permanently alter the shape and strength of the spine.

The type of break in the spine that is typically caused by osteoporosis is called a compression fracture, usually defined as a vertebral bone in the spine that has decreased at least 15 to 20% in height due to fracture (as seen on an x-ray). These compression fractures can occur in vertebrae anywhere in the spine, but they tend to occur most commonly in the upper back (thoracic spine), particularly in the lower vertebrae of that section of the spine (e.g. T10, T11, T12). They rarely occur above the T7 level of the spine.

With a compression fracture caused by osteoporosis, the fracture usually occurs in the front of the vertebra, collapsing the bone in the front of the spine and leaving the back of the same bone unchanged. This results in a wedge shaped vertebra. Because the majority of damage is limited to the front of the vertebral column, the fracture is usually stable and rarely associated with any nerve or spinal cord damage.

Unlike many other conditions that can be treated before a serious complication develops, usually a fracture is the first sign that someone has osteoporosis. By the time a fracture occurs, the osteoporosis is usually advanced and the individual is then susceptible to more vertebral fractures.

Reference:

1. Melton LJ 3d. Epidemiology of spinal osteoporosis. Spine. 1997;22:2S-11S.

• Article written By:
• Scott Boden, MD

May 11, 2005

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