Ultrasound and densitometry of the calcaneus correlate with the failure loads of cadaveric femurs.

We assessed the bone mineral density (BMD) of 16 matched sets of cadaveric proximal femurs and feet using dual-energy x-ray absorptiometry (DXA). We also estimated the femoral neck length from the DXA scans. Quantitative ultrasound densitometry was used to measure the velocity of sound and broadband ultrasound attenuation (BUA) in the calcaneus of each foot. The proximal femurs were then tested to failure in a loading configuration designed to simulate a fall with impact to the greater trochanter. Femoral neck BMD and trochanteric BMD were strongly associated with the femoral failure load (r2 = 0.79 and 0.81, respectively; P < 0.001), whereas femoral neck length was modestly correlated with femoral failure load (r2 = 0.27, P = 0.04). Calcaneal BMD (r2 = 0.63, P < 0.001) and BUA (r2 = 0.51, P = 0.002) were also significantly associated with femoral failure load. Given the small sample size, we were unable to detect differences in the strength of the correlations between the independent parameters and femoral failure load. Using linear multiple regression analyses, the strongest predictor of femoral failure load was a combination of femoral neck BMD and femoral neck length (R2 = 0.85, P < 0.001). Thus, it appears that both femoral and calcaneal bone mineral properties may be useful for identifying those persons at greatest risk for hip fracture.