ULTRASOUND MEASUREMENTS OF THE OS CALCIS - SIDE DIFFERENCES AND PREDICTION OF BONE-DENSITY IN 39 PERSONS

We measured the ultrasound Stiffness Index (SI) of the os calcis bilat erally with the Achilles Ultrasound Bone Densitometer in 30 women and 9 men, aged 53 (31-76) years. Lumbar spine BMD (percent of mean per ag e group) was measured with a DXA bone densitometer. Supplementary BMD measurements of the hip and the nondominant radius were made in 29 of the 39 persons; 11 of them had had a unilateral total hip arthroplasty (THA), the rest were healthy control subjects. SI values were in the range of 78-138 percent. Large individual differences between the righ t and the left os calcis were seen, even in healthy controls (CV 6.3 p ercent), although no differences between the means of the two sides we re found. The prediction of SI of one os calcis from that of the other was inaccurate (SEE 6 percent). The SI of the dominant os calcis corr elated significantly to the lumbar spine BMD, to the hip BMD and to th e nondominant radius BMD. In the group with unilateral THA the individ ual SI side-differences were larger (CV 8 percent; SEE 9 percent), but no systematic difference between the means of the operated and non-op erated sides was found. We conclude that there are large random indivi dual differences between the SI of the right and the left os calcis an d recommend measurement of both sides for classification of one indivi dual.