Ultrasound bone densitometry of os calcis in elderly Japanese women with hip fracture.

We evaluated 138 elderly patients (mean age 79 years) within 2 weeks after hip fracture (67 cervical and 71 trochanteric) using an Achilles ultrasound bone densitometer (Lunar Corporation, Madison, WI). The ultrasound variables of speed of sound (SOS in m/second), broadband ultrasound attenuation (BUA in dB/MHz), and stiffness (%) index were measured on the os calcis. Ultrasound densitometry also was done on 563 normal postmenopausal women to assess normal age changes. An elderly subgroup (n = 138) served as age-matched controls for the hip fracture group. Further subgroups of 33 patients and 33 controls were compared for lumbar spine and femoral neck BMD. There were no statistically significant differences between the hip fracture group and age-matched controls in height and weight, but each ultrasound variable was significantly lower for the hip fracture group (P < 0.0001). For the hip fracture group, SOS was 1470 +/- 19 m/second, BUA was 84.3 +/- 8.4 dB/MHz, and the stiffness index was 47.8 +/- 9.2%, whereas for the age-matched controls, SOS was 1486 +/- 27 m/second, BUA was 94.0 +/- 11.4 dB/MHz, and the stiffness index was 59.1 +/- 12.5%. There were no significant differences between cervical and trochanteric hip fracture groups. Logistic regression analysis showed that a change of the ultrasound values by 1 standard deviation (SD) changed the odds ratio for SOS, BUA, and stiffness index by 2.51, 3.24, and 3.60, respectively. Ultrasound variables, particularly stiffness, were good indicators of hip fracture risk.