Osteoporotic bone fragility. Detection by ultrasound transmission velocity.

We evaluated ultrasound transmission velocity at the patella as an indicator of osteoporotic fragility in 293 nonobese women. Osteoporosis was defined by atraumatic vertebral compression deformity. Ultrasound velocity averaged 1954 +/- 71 (+/- SD) m/s in premenopausal normal women and declined significantly with age after menopause, largely independently of age-related loss of spine bone mass. Postmenopausal osteoporotic women had lower velocities than normal women (-76 m/s). After allowing for slight differences in age between the groups, the difference (-54 m/s) was still significant. Women with velocities below 1825 m/s were about six times more likely to have one or more fractures than women with velocities about that level. By sensitivity-specificity analysis, ultrasound velocity discriminated between normal and osteoporotic women as well as direct measurement of spine bone mass. Ultrasound velocity measures both bone mass and a component of bone fragility distinct from decreased mass; it is a potentially valuable new tool for evaluating women for osteoporotic fragility.