INFLUENCE OF ANTHROPOMETRIC PARAMETERS ON ULTRASOUND MEASUREMENTS OF OS CALCIS

Few data have been published concerning the influence of height, weigh t and body mass index (BMI) on broadband ultrasound attenuation (BUA), speed of sound (SOS) and Lunar ''stiffness'' index, and always in sma ll population samples. The first aim of the present cross-sectional st udy was to determine whether anthropometric factors have a significant influence on ultrasound measurements. The second objective was to est ablish whether these parameters have real effect on bone or whether th eir infuence is due only to measurement errors. We measured, in 271 he althy French women (mean age 77 +/- 11 years; range 31-97 years), the following parameters: age, height, weight, lean and fat body mass, hee l width, foot length, knee height and height of the external malleolus (HEM). Simple linear regression analyses between ultrasound and anthr opometric parameters were performed. Age, height and heel width were s ignificant predictors of SOS; age, height, weight, foot length, heel w idth, HEM, fat mass and lean mass were significant predictors of BUA; age, height, weight, heel width, HEM, fat mass and lean mass were sign ificant predictors of stiffness. In the multiple regression analysis, once the analysis had been adjusted :for age, only heel width was a si gnificant predictor for SOS (p = 0.0007), weight for BUA (p = 0.0001), and weight (p = 0.0001) and heel width (p = 0.004) for the stiffness index. Besides their statistical meaning, the regression coefficients have a more clinically relevant interpretation which is developed in t he text. These results confirm the influence of anthropometric factors on the ultrasonic parameter values, because BUA and SOS were in part dependent on heel width and weight. The influence of the position of t he transducer on the calcaneus should be taken into account to optimiz e the methods of measurement using ultrasound.