Combined models of ultrasound velocity and attenuation for predicting trabecular bone strength and mineral density

Three quantitative ultrasound parameters and their combinations were examined as possible predictors of the bone mineral density and compressive strength of human cancellous bone. Seventy-three trabecular bone cubes obtained from female cadaveric tibiae were measured by quantitative computed tomography. Measurements of the ultrasound velocity, ultrasound attenuation at 0.5 MHz and broad-band ultrasound attenuation were made in three orthogonal anatomical directions. The specimens were then tested to failure in compression, 38 in the anterior/posterior direction and 35 in the superior/inferior direction. The apparent density of all specimens was also found. Linear regressions showed that bone mineral density and strength were significantly correlated with each ultrasonic parameter in each direction (P < 0.05). Linear combinations of two ultrasound parameters were significantly better predictors than single parameters, although the optimum pair of parameters differed with direction. Three parameter models did not further improve predictability.