Calcaneal ultrasound attenuation in an elderly population: measurement position and relationships with body size and past fractures.

This study demonstrates, the relationship between past fracture, body size and broadband ultrasound attenuation (BUA) and investigates two sites of BUA measurement in a representative elderly population of men and women (n = 2106). We measured BUA at a fixed position and at a consistent anatomic position within the calcaneus. We found fixed BUA was less closely correlated with stature and age than anatomic BUA. Both correlations were substantially weaker in men than in women. Mean BUA was significantly lower in women with a past fracture compared with nonfracturers (fixed BUA 63.3 vs 69.4 dB/MHz, p = 0.0004; anatomic BUA 77.6 vs 81.7 dB/MHz, p = 0.013). However, in women, the fixed BUA was better than the anatomic BUA at discriminating between fracturers and nonfracturers (OR 1.38/SD (95% CI 1.12-1.68) and OR 1.22/SD (0.99-1.52), respectively) when adjusted for body size and age. There was no significant difference in either BUA in men with or without a past fracture. In conclusion, currently the fixed position for BUA measurement is preferable and, whilst we have demonstrated that it is possible to locate an anatomically consistent point in the calcaneus, the position chosen by this study did not provide a measurement with more discriminatory capability than the fixed position. In women, BUA behaves similarly to bone mineral density in relation to stature and in its strength of association with past fracture, while the lack of association in men may reflect differing contributions by bone strength to fracture risk in the sexes.