Diagnostic value of ultrasound analysis and bone densitometry as predictors of vertebral deformity in postmenopausal women

Bone fractures depend not only on bone density, but also on bone quality. Ultrasound (US) has been proposed as a technique for evaluating skeletal status. Speed of sound (SOS) and broadband ultrasound attenuation (BUA) are the US properties currently used to assess bone strength and fragility. In 304 postmenopausal women (age 58.8±5.5 years) we measured: bone mineral density (BMD) of the lumbar spine (by dual-energy X-ray absorptiometry), SOS, BUA and Stiffness in the os calcis (using an Achilles machine). In all subjects we performed lateral lumbar and thoracic radiographs. Morphometric parameters were derived by measuring the anterior, middle and posterior height of each vertebral body, to obtain a semiquantitative grading of vertebral fractures as follows: 0, no vertebral deformity; 1, any vertebral height reduced between 20% and 25%; 2, any vertebral height reduced between 25% and 40%; 3, any vertebral height reduced more than 40%. On the basis of the number and severity of vertebral deformities the women were divided into: group 1 (n=79), normal; group 2(n=80), mild; group 3 (n=85), moderate; and group 4 (n=60), severe. Mean values of SOS, BUA, Stiffness and BMD were significantly lower (p<0.001) in women with vertebral deformity than in normals. In the whole population SOS, BUA and Stiffness values were significantly correlated with BMD. SOS, BUA and Stiffness values were significantly decreased (p<0.001) with vertebral deformity, as was BMD. Receiver operating characteristic (ROC) curve analysis showed BMD to be slightly better than Stiffness in discriminating among groups. Logistic regression analysis showed that BMD, BUA, SOS and Stiffness were independent predictors of vertebral fracture risk. Ultrasound parameters were still significant independent predictors of vertebral fracture even after adjusting for BMD.