Bilateral variation in calcaneal broadband ultrasound attenuation: part I

Potential benefits of marathon training on bone health as assessed by calcaneal broadband ultrasound attenuation

The purpose of this study was to determine calcaneal broadband ultrasound attenuation (BUA) of marathon race participants and compare this information with previously obtained normative data. BUA was assessed using the McCue CUBA clinical device in 217 male and 184 female runners, aged 20-93 yr, participating in the 2004 Flora London Marathon. The normative data included 267 men and 334 women, aged 20-80 yr. A significantly higher mean BUA (p<0.001) was observed for all the men (91.2 dB/MHz, standard deviation [SD] 18.2 dB/MHz) in the study compared to the women (81.6 dB/MHz, SD 17.0 dB/MHz) and for the marathon runners compared to the nonrunners (p<0.001) among men (97.2dB/MHz, SD 17.6 dB/MHz and 87.7 dB/MHz, SD 17.6 dB/MHz, respectively) and women (89.2dB/MHz, SD 14.2dB/MHz and 77.4dB/MHz, SD 17.0 dB/MHz, respectively). A significant decline in BUA with age was observed in all males and females, with the males starting from a higher baseline and with the rate of decline significantly ameliorated by marathon training (from -0.35 to -0.25 dB/MHz per year in men and -0.51 to -0.15 dB/MHz per year in women). This study provides observational evidence in support of the potential benefits of weight-bearing exercise, such as marathon training and running, on BUA of the calcaneus, an index of bone mineral density.

Contralateral differences in quantitative ultrasound of the heel: the importance of side in clinical practice

Quantitative ultrasound (QUS) of the heel is becoming increasingly popular for the assessment of skeletal status, although there appears to be a general lack of agreement regarding which side to measure. The purpose of the present study was to evaluate possible side differences (right versus left) in heel QUS within the general population, including children (10-15 years old, n=406), adults (26-33 years old, n=339), and elderly subjects (60-75 years old, n=455) of both genders (818 females and 382 males), and to examine the impact of these differences on prevalence estimates of osteoporosis and individual fracture risk assessment. All participants had both their heels measured twice with the Sahara device, which measures broadband ultrasound attenuation (BUA) and speed of sound (SOS) through the os calcis; a composite parameter, that is, quantitative ultrasound index (QUI) and an estimate of heel BMD (eBMD) were also derived. Significant side differences were detected for BUA and SOS (P<0.05), but not for QUI or eBMD. Contralateral differences were rather small in absolute terms, but were in the order of 12.6% for BUA, 0.72% for SOS, 7.9% for QUI, and 9.9% for eBMD, when expressed as percentage of the mean values for the two heels. Bilateral differences appeared to vary across age and gender. Significant correlations between QUS indices of the right and left heel were observed (r=0.75-0.85; P<0.001), which seemed to be stronger among the elderly and among male individuals. Prevalence rates of osteopenia and osteoporosis were not significantly different when estimated from eBMD T-scores for the one or the other foot (chi(2)=1.781, df=2, P=0.410). However, cross-classification analysis revealed that only 84% of the subjects classified into each risk category by the two calcanei were actually the same persons. In conclusion, results from the present study strongly suggest that QUS measurements of opposite heels may not be equivalent with respect to the evaluation of bone status and classification of individual fracture risk assessment, although the degree of discrepancy appears to be related to the primary outcome of interest.

Heritability of calcaneal quantitative ultrasound measures in healthy adults from the Fels Longitudinal Study

Quantitative ultrasound (QUS) measurements of bone have been reported to predict osteoporotic fracture risk in postmenopausal women and older men. Although many studies have examined the heritability of bone mineral density (BMD), few studies have estimated the heritability of calcaneal QUS phenotypes. In the present study, we examined the genetic regulation of calcaneal QUS parameters in individuals from nuclear and extended families. The study population includes 260 men and 295 women aged 18-91 years (mean+/-SD: 46+/-16 years) who belong to 111 pedigrees in the Fels Longitudinal Study. Three measures of calcaneal structure were collected from both the right and left heel using the Sahara bone sonometer. These measures included broadband ultrasound attenuation (BUA), speed of sound (SOS), and the quantitative ultrasound index (QUI). We used a variance components based maximum likelihood method to estimate the heritability of QUS parameters while simultaneously adjusting for covariate effects. Additionally, we used bivariate extensions of these methods to calculate additive genetic and random environmental correlations among QUS measures. All phenotypes demonstrated statistically significant heritabilities (P<0.0000001). Heritabilities in the right heel (h2+/-SE) were h2=0.59+/-0.10 for BUA, h2=0.73+/-0.09 for SOS, and h2=0.72+/-0.09 for QUI. Similarly, heritabilities for the left heel were h2=0.52+/-0.10, h2=0.75+/-0.10, and h2=0.70+/0.10, respectively. There was evidence for significant genetic and environmental correlations among these six QUS measures. Combinations of QUS measures in the right and left heel demonstrated genetic correlations of 0.94-0.99 and all were significantly different from one indicating at least a partially unique genetic architecture for each of these measures. This study demonstrates that QUS measures of the calcaneus among healthy men and women are heritable, and there are large shared additive genetic effects among all of the traits examined.

Normative data for ultrasound measurement of the calcaneus within different female ethnic groups

The purpose of this study was to generate normative broadband ultrasound attenuation data for UK resident Indian-Asian, African-Caribbean and Chinese women, aged 20-80 years, using the McCue Cubaclinical II device. Additionally, comparisons were made against available Caucasian data previously collected by the authors. Exclusions were: use of hormone replacement therapy, corticosteroids or thyroxine for more than 6 months; menopause before the age of 45 years; oophrectomy; lactation within the preceding year; rheumatoid arthritis or a previous osteoporotic fracture. 977 women were recruited from various community centres, from a local GP surgery and from university colleges in the London area. Broadband ultrasound attenuation and velocity of sound were determined for the left and right os calces. Repeat measures on each side after re-positioning, to allow for anatomical variation, were averaged. Significance was set at a minimum level of 0.05. There were significant differences in non-dominant and dominant measures in all ethnic groups except African-Caribbean. For comparison purposes the means of the non-dominant measurements were plotted against age using a polynomial model to give the best data fit. No significant difference was found between non-dominant broadband ultrasound attenuation measurements for either Asian or Chinese when compared with the Caucasian sample populations. A significant difference in broadband ultrasound attenuation was found between African-Caribbean and Caucasian, with African-Caribbean between 10% (age group 20-30 years) and 29% (age group 70-80 years) higher. There was no significant difference in body mass index between Caucasian and Chinese groups, but significant differences were found between Caucasian and Asian, and between Caucasian and African-Caribbean groups.

Differences between the right and the left foot in calcaneal quantitative ultrasound measurements

A total of 621 women, aged 30-80 years, who were grouped according to having single (group 1) or duplicate measurements of their both calcanei with quantitative ultrasound (QUS) on the same day (group 2) or on a different day than the first measurement (group 3) were evaluated for differences between the right and left foot. Despite similar mean values of QUS indices on both sides, individual percentage differences were found varying from 7.3 to 9.5% in the quantitative ultrasound index (QUI), from 11.1 to 12.5% in broadband ultrasound attenuation (BUA), from 0.62 to 0.86% in speed of sound (SOS) and from 8.9 to 10.9% in estimated heel bone mineral density as measured using the Sahara Clinical Bone Sonometer in three groups of subjects. The percentage of subjects with a proportional difference exceeding the coefficient of variation of duplicate measurements of the same heel was the highest for BUA, varying from 63 to 76.7%, and ranged between 43.1 and 76.7% in other QUS indices. We conclude that there is a real inter-individual difference between the right and left foot in QUS parameters, whether measured once or twice or on different occasions. We recommend measuring both sides when using QUS to avoid misleading implications regarding a subject's bone status.

Bilateral variation in calcaneal broadband ultrasound attenuation. Part II: as measured by three bone densitometers employing ultrasound or X-ray

In previous study, we found a bilateral difference in broadband ultrasound attenuation (BUA) of the calcaneus, using the McCue Cubaclinical II device. The purpose of the present study was to determine whether a calcaneal bilateral difference (greater than that that would be expected from the coefficient of variation) was also found by other instruments and their technologies. Twenty-four subjects (ages 22-81) were each scanned by the same operator using three devices: the Cubaclinical (ultrasound [US], BUA), the Lunar Achilles plus (US, BUA and stiffness index), and the Pixi (dual X-ray absorptiometry, bone mineral density). To allow for the different variables used by the three devices, the following computation was applied to the data for comparison purposes (left - right) / (right). Analysis of variance showed no significant difference. We conclude that the three devices do not differ in their ability to detect a proportional difference between right and left calcanei. In an additional investigation, using the Cubaclinical, 23 subjects were scanned. The direction of the US wave between emitter and receiver transducers was reversed to determine the effect, if any, on bilateral BUA readings. In this case, the direction of the US wave was not influential.