Objective: To examine whether ultrasound measurements of the calcaneus can help to identify subjects with a risk for non-vertebral fractures.
Design: Cross-sectional survey.
Setting: The suburb of Ommoord in Rotterdam, the Netherlands.
Methods: 1421 subjects (631 men, 790 women) underwent both ultrasound measurements of the calcaneus and bone mineral density measurement of the femoral neck by dual energy X-ray absorptiometry (DXA). At the calcaneus speed of sound (SOS in m/s) and broadband ultrasound attenuation (BUA in dB/MHz) were measured. In addition, all subjects were asked about fractures in the preceding 5 years. The frequency of non-vertebral fractures was examined per tertile of SOS and BUA. In addition, we examined whether there was a trend in the number of fractures per tertile of SOS or BUA, within tertiles of femoral neck bone mineral density.
Results: The measures of SOS, BUA and bone mineral density (DXA-measured) are comparable as predictors of fractures. Subjects with values of SOS, BUA or bone mineral density in the lowest tertiles were all found to report two to three times as many fractures as subjects with values for these variables in the highest tertiles. Within tertiles of bone mineral density, subjects with a low SOS reported more fractures than subjects with a high SOS. For BUA a similar but less pronounced pattern was visible. Nevertheless, the area under the receiver operating characteristic (ROC) curve was 0.63 for SOS and 0.64 for BUA, comparable to 0.62 for bone mineral density of the proximal femur. Combining ultrasound and bone mineral density measurements had limited effect on the area under the ROC curve (0.65).
Conclusions: Subjects with lower values of ultrasound parameters are at increasing risk of fracture, especially if low ultrasound values are accompanied by a lower bone mineral density. It remains to be seen whether ultrasound parameters are useful for screening.