Bone density is usually measured at the hip rather than the spine or wrist, which appears to be the most predictive of hip fracture. (Hip fractures are the most dangerous fractures, particularly in women older than sixty.) The BMD in the spine may also be measured. (Spinal BMD in older people however may be misleading. Bone density in this group may increase because of compression on the spinal bones from arthritic changes in the spine. Therefore, bone density measurements may be normal or even high, but the patient may actually be at risk for fracture.)
 | Click the icon to see an image of a hip fracture. |
Ultrasound. Ultrasound techniques measure bone density in the heels, fingers, and leg bones. In early studies, advanced ultrasound techniques, such as quantitative ultrasound (QUS), are promising for improving accuracy in predicting fractures when used with DEXA. Ultrasound itself is less expensive than DEXA and uses no radiation. Ultrasound bone tests are sometimes given at health fairs or other non-medical settings. It should be noted that these results typically vary widely from measurements of the hipbone and are not reliable when used alone.
Quantitative Computed Tomography. Quantitative computed tomography (QCT) scans, a form of CT scans, can provide highly detailed information about spinal density. Radiation doses from this technique are higher than the others. Whether QCT predicts fracture risk accurately is, however, unknown.
Determining Osteoporosis and the Risk for Fracture
Osteoporosis is diagnosed when bone density has decreased to the point where fractures will happen with mild stress, the so-called fracture threshold. This is determined by measuring bone density and comparing the results with the norm. However, low scores on bone density are not very accurate in determining fracture risk without consideration of other risk factors for fracture.
In general, doctors take the following steps to determine osteoporosis:
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