ASSESSMENT OF THE STRENGTH OF THE PROXIMAL FEMUR IN-VITRO - RELATIONSHIP WITH ULTRASONIC MEASUREMENTS OF THE CALCANEUS

Matched pairs of the right proximal femur and right calcaneus were obt ained from 64 cadavers (28 female, 36 male), Ultrasonic velocity and b roadband ultrasonic attenuation were measured in the calcaneus using a laboratory ultrasound system, Bone mineral density (BMD) was measured at the calcaneus and at the trochanteric and neck regions of the femu r using dual-energy X-ray absorptiometry, Femoral strength was determi ned in a mechanical test simulating a fall onto the greater trochanter . Femoral BMD was more strongly correlated with femoral strength (r(2) = 0.71, 0.88 for neck BMD and trochanteric BMD, respectively) than we re any of the other predictive variables investigated (p < 0.05), Calc aneal ultrasonic measurements alone produced correlations with femoral strength of r(2) = 0.40-0.47, with no significant differences observe d in predictive ability between the various ultrasonic parameters, In multiple regression analysis, ultrasound was, in general, not a signif icant additional independent predictor of femoral strength when combin ed with either femoral or calcaneal BMD, and combining ultrasonic para meters did not improve the ability to predict femoral strength, Calcan eal width was found to be significantly correlated with both femoral s trength and femoral BMD, and this explained the slightly better correl ations with femoral strength found for those ultrasonic parameters whi ch were not effectively normalized for calcaneal width, In summary, ca lcaneal ultrasound did not significantly enhance the prediction of fem oral strength compared to femoral BMD measurements alone, Given the su bstantial differences between the in vitro and in vivo situations, thi s finding does not necessarily contradict emerging clinical data indic ating that ultrasound and BMD have comparable and independent predicti ve ability for hip fracture risk, Reasons for the apparent discrepancy are discussed, including the enhanced accuracy of DXA in vitro, Never theless, it is suggested that further fundamental investigations into the efficacy of current ultrasonic techniques are warranted. (C) 1997 by Elsevier Science Inc.