DISCRIMINATIVE CAPACITY OF CALCANEAL ULTRASOUND COMPARED TO BONE DENSITOMETRY IN YOUNG WOMEN 398

Abstract

Quantitative ultrasound (QUS) is an inexpensive and radiation-free method of assessing bone status that appears to be comparable to bone densitometry in predicting fracture risk in postmenopausal women. The purpose of the present study was to determine the discriminative capacity of QUS in a young healthy population by comparing QUS measurements of the calcaneus to bone mineral density (BMD) at several sites in women exposed to either high-impact loading(gymnastics) or regular weight-bearing activity. We studied 19 collegiate gymnasts (GYM) and 23 controls (CON) matched for age (GYM 19.2±1.2, CON 19.9±1.6 yr) and body weight (GYM 56.7±3.7, CON 57.7±7.8 kg). QUS parameters of the calcaneus (broadband ultrasound attenuation, BUA, bone velocity, BV, speed of sound, SOS) were measured by a Walker Sonix UBA 575+. BMD (g/cm2) of the lumbar spine, hip (femoral neck, trochanter, Ward's triangle) and whole body was assessed by DXA (Hologic, 1000/W). Gymnasts trained for 20±6 hrs per week compared to 5±3 hrs for CON (p < 0.001; Student's t-test) and had a higher (p < 0.02) bone-free lean mass and lower (p < 0.001)% body fat. Regional and whole body BMD of GYM was greater than CON (p < 0.001), with the difference being 7-28%. Average QUS parameters of the right and left calcaneus were also higher (p< 0.001) in the gymnasts: BUA, GYM 114±17 vs. CON 94±18 db/MHz; BV, GYM 1178±74 vs. CON 1674±49 m/s; SOS, 1524±8 vs. 1511±6 m/s. BUA, BV and SOS were significantly (p < 0.001) correlated to each bone site with r = 0.54 - 0.79. These results indicate that QUS parameters of the calcaneus discriminate between young women engaged in either high-impact or regular weight-bearing activity as does regional and whole body bone densitometry, although the magnitude of difference was considerably less for SOS.