Is BMD sufficient to explain different fracture rates in Sweden and Turkey?

Osteoporosis and consequent fractures have become an important health problem all over the World. However, there are quite different fracture rates among different populations. In this study, our aim was to obtain the bone mineral density (BMD) values at calcaneus in a healthy Turkish population and compare them with Swedish population data. BMD was measured at the calcaneus using a dual X-ray and laser Calscan (Demetech AB, Stockholm, Sweden) bone densitometer. The total number of subjects was 951 consisting of 639 women and 312 men and age ranged from 15 to 79 yr. Mean BMD value for healthy young women (20-39 yr old) was 0.411+/-0.058 g/cm2 and for healthy young men was 0.504+/-0.068 g/cm2. BMD values tended to decrease with age in both genders. In comparison between the Turkish and Swedish population data, the Turkish population has about 1 standard deviation lower BMD values than the Swedish population in both genders, for all ages. Considering that Swedes have high fracture rates and Turks have the lowest fracture rates in Europe, the opposite difference in BMD values in the calcaneus seems interesting. Further research is needed to explain the difference in fracture rates among different populations.

Pediatric reference data for bone mineral density in the calcaneus for healthy children 2, 4, and 7 years of age by dual-energy x-ray absorptiometry and laser.

Dual-energy X-ray absorptiometry and laser (DXL) Calscan measures bone mineral density (BMD) in the calcaneus. In the present study, the DXL Calscan device has been modified for use in pediatric practice. It includes a function for measuring calcaneal height, which makes it possible to calculate volumetric bone mineral apparent density (BMAD). The aims of the present study were to evaluate the method when used in children, to create pediatric reference values in healthy Swedish 2-, 4-, and 7-yr-old children for BMD, bone mineral content (BMC), and BMAD, and to study whether these parameters were related to auxological data. The method was well tolerated by all children. Intraindividual coefficients of variation for BMC and BMD decreased with increasing age. The mean BMD was 0.17+/-0.003 g/cm2 in 2-yr-old children, 0.22+/-0.003 g/cm2 in 4-yr-old children, and 0.30+/-0.005 g/cm2 in 7-yr-old children. This study provides normative data as percentile values for BMD, BMC, and BMAD in young children measured with DXL Calscan. BMD was significantly correlated with age (p<0.001), height (p=0.001), weight (p<0.001), and body mass index standard deviation score (p<0.001). Seven-year-old girls showed significantly higher BMD than boys.

Prevalence of osteoporosis using bone mineral measurements at the calcaneus by dual X-ray and laser (DXL).

Using manufacturers reference data the prevalence of osteoporosis using a T-score threshold of -2.5 for heel measurements by DXL technology was compared to dual-energy X-ray absorptiometry (DXA) measurements at the femoral neck, spine and forearm. The prevalence of osteoporosis for women aged 50 years or older was 28% for DXL measurements of the heel bone and 30, 22 and 32% for DXA measurements of the lumbar spine, femoral neck and forearm respectively. Bone mineral density (BMD) was also measured by DXL in the heel bone and by DXA in spine and femoral neck in 251 women (mean age 62 +/- 14.5 years) when attending an osteoporosis clinic. The sensitivity and specificity for osteoporosis and osteopenia for the DXL measurements were calculated assuming a low T-score at the spine or femoral neck as the criterion for a correct diagnosis. The sensitivity was found to be 80% for osteoporosis and 82% for osteopenia and the specificity was 82% for osteoporosis and 89% for osteopenia. We conclude that DXL measurement at the heel bone, using a T-score threshold of -2.5 for classification of osteoporosis, is in concordance with the World Health Organization (WHO) definition of osteoporosis.

[Technical improvements in bone densitometry]. / Teknikutveckling inom bendensitometri.

The SBU-report no 127 "Mätning av bentäthet" [Measuring bone density] was published in 1995 and its conclusions are still valid. However, since then new treatment modalities have placed increasing demands on the diagnostic capability and performance of the apparatus used for bone densitometry. The most well-established and widely used technique for bone mineral determination is dual energy X-ray absorptiometry. Several international studies have shown that quantitative ultrasound should not be used for diagnosis or monitoring of osteoporosis. The reproducibility of one's method is important for monitoring, and the method's accuracy is important for diagnosis. Due to the limitations of the techniques and the slow turnover of the skeleton, repeated measurements are not meaningful until at least two years have passed. In order to maintain high quality in measurement results it is important to have trained personnel and to have a regular quality assurance program for the apparatus.

Determination of bone mineral density in the third lumbar vertebral body using photon absorptiometry techniques.

Dual-photon absorptiometry and triple-energy X-ray absorptiometry were used to investigate the total bone mineral content and density as well as the trabecular bone mineral density in the third lumbar vertebral body. Both anteroposterior (AP) and lateral (LAT) measurements were performed. By combining the two projections it was found that the mean trabecular bone mineral density for all 202 subjects included in the study was 52% (SD +/- 20%) of the total bone mineral density in the third lumbar vertebral body. The mean trabecular bone mineral density as a fraction of the total vertebral body bone mineral density decreased as a function of age. The relative annual change in this fraction differed between males and females. It was also found that neither trabecular nor total bone mineral density differed significantly between male and female subjects aged 25-35 years, and bone mineral density (BMD), expressed in g/cm3, showed no correlation to subject height, body weight or body mass index (BMI). Male and female individuals showed different rates of change of trabecular bone mineral density with age.

The feasibility of triple-energy absorptiometry for the determination of bone mineral, Ca and P in vivo.

The theoretical feasibility of triple-energy absorptiometry in general and the experimental conditions when using triple-energy absorptiometry for the determination of bone mineral, elemental calcium and phosphorus content in vivo have been investigated. A theoretical analysis of the decomposition of the mass attenuation coefficients is presented and discussed. The main obstacle to the effective use of triple-energy absorptiometry in vivo is the large number of pulses which must be detected to reduce the statistical fluctuations.

Measurement of bone mineral using multiple-energy x-ray absorptiometry.

Our laboratory has previously reported a method of determining the amount of bone mineral using triple-energy absorptiometry with a continuous x-ray spectrum. In the present study, the experimental properties of the technique were examined. The accuracy, the influence of fat content and body thickness and the in vitro and in vivo precision were analysed. The results found in this investigation showed that despite the complexity of the technique, the amount of bone mineral can be accurately determined. The in vivo precision was determined to be 3.4%, expressed as the coefficient of variation (CV), for different skeletal parts. The in vitro precision was found to be 2.1% (CV). Neither the fat content nor the body thickness had any effect on the measured bone mineral values. Excellent linearity and a close correlation were found between the true and the measured bone mineral values.

In vitro study of the accuracy of bone mineral measuring devices in Norway and Sweden.

PURPOSE: The aim of the study was to investigate the performance of +different types of equipment for bone mineral assessment in Sweden and Norway with standardised phantoms. MATERIAL AND METHODS: Measurements of the bone mineral content of 2 semianthropomorphic phantoms, one simulating the human torso and one the lower arm, at 21 hospitals in Norway and Sweden, were undertaken. The phantoms had inserts of hydroxyapatite in different concentrations and were measured together with additions of stearic acid simulating fat. The phantoms were repeatedly measured on 14 dual X-ray absorptiometry, 5 single X-ray absorptiometry, and 3 single photon absorptiometry devices and 1 quantitative CT device. RESULTS: The measurements showed a large spread in the measured hydroxyapatite concentrations among different devices. The inaccuracy was slightly lower than 10% without fat present when the results were expressed as bone mineral areal mass (BMA, g/cm2). With fat included the inaccuracy was at worst 50%. CONCLUSION: The large inaccuracy found in this study gives rise to a large overlap between healthy and osteoporotic cases and make the diagnosis of osteoporosis difficult in the individual patient.