MEASUREMENTS OF BROAD-BAND ULTRASONIC-ATTENUATION IN THE CALCANEUS IN PREMENOPAUSAL AND POSTMENOPAUSAL WOMEN

We report a study of broadband ultrasonic attenuation (BUA) in the calcaneus in 248 women. Measurements were performed with a Walker-Sonix UBA-575 ultrasonic bone analyser. The populations studied were 15 healthy young volunteers (group 1, mean age 26 years), 200 healthy pre- and postmenopausal women (group 2, mean age 53 years) and 33 osteoporotic women with vertebral crush fractures (group 3, mean age 66 years). Subjects in group 1 each had 10 repeated measurements of their right heel. Duplicate BUA measurements in the right heel were performed in 96 subjects and bilateral scans in a further 87 women in group 2. The remaining 17 subjects in group 2 and those in group 3 had a single scan of the right heel. All women in groups 2 and 3 had dual X-ray absorptiometry (DXA) scans of the lumbar spine and femoral neck. The precision study on the women in group 1 gave a root mean square (RMS) coefficient of variation (CV) of 4.2%. Individual CV results showed statistically significant differences (range 1.3%-7.6%). Duplicate scans in subjects in group 2 gave a RMS CV of 4.6% while the bilateral measurements showed no significant difference between the two heels. Linear regression analysis gave the following relationship between BUA and age: BUA = 87.1 - 0.76 (Age - 40) dB/MHz (r = -0.31, p<0.001, SEE = 14.0 dB/MHz). Multivariate regression analysis showed that, in addition to age, years since the menopause was also a significant factor in predicting BUA. In the first 5 years following the menopause BUA decreased by 2.5%/year, while in the next 5 years the decrease fell to 0.5%/year. The BUA measurements in the osteoporotic subjects in group 3 gave a mean T-score of -2.1 compared with 66 premenopausal normal women and a mean Z-score of -1.0 compared with 27 age-matched elderly normal women in group 2. In comparison the lumbar spine DXA measurements for the same women gave a mean T-score of -3.2 and a mean Z-score of -1.8. DXA therefore gave substantially better discrimination between osteoporotic and normal subjects than the BUA measurements.