The relationship of trabecular and cortical bone mineral density to spinal fractures

Quantitative computed tomography has higher sensitivity detecting critical bone mineral density compared to dual-energy X-ray absorptiometry in postmenopausal women and elderly men with osteoporotic fractures: a real-life study

INTRODUCTION

Dual-energy X-ray absorptiometry (DXA) is considered the gold standard for the diagnosis of osteoporosis and assessment of fracture risk despite proven limitations. Quantitative computed tomography (QCT) is regarded as a sensitive method for diagnosis and follow-up. Pathologic fractures are classified as the main clinical manifestation of osteoporosis. The objective of the study was to compare DXA and QCT to determine their sensitivity and discriminatory power.

MATERIALS AND METHODS

Patients aged 50 years and older were included who had DXA of the lumbar spine and femur and additional QCT of the lumbar spine within 365 days. Fractures and bone mineral density (BMD) were retrospectively examined. BMD measurements were analyzed for the detection of osteoporotic fractures. Sensitivity and receiver operating characteristic curve were used for calculations. As an indication for a second radiological examination was given, the results were compared with control groups receiving exclusively DXA or QCT for diagnosis or follow-up.

RESULTS

Overall, BMD measurements of 404 subjects were analyzed. DXA detected 15 (13.2%) patients having pathologic fractures (n = 114) with normal bone density, 66 (57.9%) with osteopenia, and 33 (28.9%) with osteoporosis. QCT categorized no patients having pathologic fractures with healthy bone density, 14 (12.3%) with osteopenia, and 100 (87.7%) with osteoporosis. T-score DXA, trabecular BMD QCT, and cortical BMD QCT correlated weakly. Trabecular BMD QCT and cortical BMD QCT classified osteoporosis with decreased bone mineral density (AUC 0.680; 95% CI 0.618-0.743 and AUC 0.617; 95% CI 0.553-0.682, respectively). T-score DXA could not predict prevalent pathologic fractures. In control groups, each consisting of 50 patients, DXA and QCT were significant classifiers to predict prevalent pathologic fractures.

CONCLUSION

Our results support that volumetric measurements by QCT in preselected subjects represent a more sensitive method for the diagnosis of osteoporosis and prediction of fractures compared to DXA.

Osteoporosis diagnostics in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic connective tissue disease. The development of comorbidities often occurs in the course of RA. One of them is osteoporosis, which has serious social and economic effects and may contribute to the increase in the degree of disability and premature death of the patient. Due to the young age in which RA disease occurs, densitometry (DXA) of the lumbar spine is the basic examination in osteoporosis diagnostics. In the course of RA, much more frequently than in healthy persons of the same age, osteoporotic fractures of vertebral bodies occur, which hinder a correct assessment in the DXA test. Rheumatoid arthritis patients often undergo computed tomography (CT) examination of the abdominal cavity for other medical indications than suspected spinal injury. Then, CT examination may also serve for the assessment of bone density, especially in patients with osteoporotic fractures.

Analysis of bone mineral density distribution at trabecular bones in thoracic and lumbar vertebrae using X-ray CT images

The number of participants in thoracic or abdominal examinations using multi-detector-row CT (MDCT) has been increasing recently. If the degree of progress of osteoporosis can be estimated using these images, it may be useful as it will allow predictions of vertebral fractures without an additional radiation exposure. The aims of this study were to investigate segmental variations in bone mineral density (BMD) distributions of thoracic and lumbar vertebral bodies and to show specific differences according to age and gender. A large database including 1,031 Japanese subjects for whom MDCT was used to examine various organs and tissues was utilized in this study for trabecular BMD at thoracic and lumbar vertebrae. In relationship to vertebral level, L3 had the lowest trabecular BMD. BMD tended to gradually increase from L3 to T1 in all age categories. Also, there was a moderate correlation between vertebrae whose distance from each other was great whereas there was a high correlation between adjacent vertebrae. It may be appropriate to use an arbitrary vertebra as a first approximation for assessing vertebrae that are in the area of predilection for the fracture; however, to better understand their behavior, it may be necessary to measure BMD directly in this region. This study showed trabecular BMD distribution at healthy thoracic and lumbar vertebrae in Japanese subjects and specific differences in age and gender. Improved knowledge about vertebral BMD may help with the diagnosis of primary osteoporosis using MDCT.

Recent progress in bone imaging for osteoporosis research

Advances in bone imaging techniques have provided tools for analyzing bone structure at the macro-, micro- and nano-level. Quantitative assessment of macrostructure can be achieved using dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT), particularly volumetric quantitative CT (vQCT). In vivo quantitative techniques for assessing the microstructure of trabecular bone non-invasively and non-destructively include high-resolution CT (HR-CT) and high-resolution magnetic resonance (HR-MR). Compared with MR imaging, CT-based techniques have the advantage of directly visualizing the bone in the axial skeleton, with high spatial resolution, but the disadvantage of delivering a considerable radiation dose. Micro-CT (μCT), which provides a higher resolution of the microstructure and is principally applicable in vitro, has undergone technological advances such that it is now able to elucidate the physiological skeletal change mechanisms associated with aging and determine the effects of therapeutic intervention on the bone microstructure. In particular, synchrotron μCT (SR-CT) provides a more detailed view of trabecular structure at the nano-level. For the assessment of hip geometry, DXA-based hip structure analysis (HSA) and CT-based HSA have been developed. DXA-based HSA is a convenient tool for analyzing biomechanical properties and for assuming cross-sectional hip geometry based on two-dimensional (2D) data, whereas CT-based HSA provides these parameters three-dimensionally in robust relationship with biomechanical properties, at the cost of greater radiation exposure and the lengthy time required for the analytical procedure. Further progress in bone imaging technology is promising to bring new aspects of bone structure in relation to bone strength to light, and to establish a means for analyzing bone structural properties in the everyday clinical setting.

Influence of menopause on mandibular bone quantity and quality in Japanese women receiving dental implants

SUMMARY

The purpose of this study was to evaluate the effect of menopause on bone mineral density and bone width of the mandible. Results indicate that menopause affects the bone quality and quantity of the partially edentulous molar region of the mandible, which should be considered in dental implant treatment for postmenopausal women.

INTRODUCTION

The recovery of oral function with dental implant is clinically effective and highly predictable. Bone quantity and quality at the implant installation site affect its prognosis; however, the effects of menopause on jaw bone have not been well documented. The purpose of this study was to evaluate the effect of menopause on bone mineral density (BMD) and bone width of the mandible.

METHODS

The subjects were 72 female patients with a partially edentulous molar region of the mandible: 30 premenopausal and 42 postmenopausal women aged 30 to 70 years. Trabecular BMD was measured with quantitative computed tomography. Trabecular region width (TW) and cortical width (CW) were measured with CT. The BMD, TW, and CW of the two groups were compared.

RESULTS

The trabecular BMD of postmenopausal women was lower than that of the premenopausal women. The TW of postmenopausal women was greater than that of premenopausal women, whereas the CW of postmenopausal women was significantly smaller than that of premenopausal women. In all these women, BMD correlated negatively with TW and positively with CW. In the premenopausal women, BMD negatively correlated with TW, but it did not correlate with CW. In the postmenopausal women, there was no correlation between BMD and bone width.

CONCLUSION

These results indicate that menopause affects the bone quality and quantity of the partially edentulous molar region of the mandible, which should be considered in dental implant treatment for postmenopausal women.

Nonhuman anthropoid primate femoral neck trabecular architecture and its relationship to locomotor mode

Functional analyses of human and nonhuman anthropoid primate femoral neck structure have largely ignored the trabecular bone. We tested hypotheses regarding differences in the relative distribution and structural anisotropy of trabecular bone in the femoral neck of quadrupedal and climbing/suspensory anthropoids. We used high-resolution X-ray computed tomography to analyze quantitatively the femoral neck trabecular structure of Ateles geoffroyi, Symphalangus syndactylus, Alouatta seniculus, Colobus guereza, Macaca fascicularis, and Papio cynocephalus (n = 46). We analyzed a size-scaled superior and inferior volume of interest (VOI) in the femoral neck. The ratio of the superior to inferior VOI bone volume fraction indicated that the distribution of trabecular bone was inferiorly skewed in most (but not all) quadrupeds and evenly distributed the climbing/suspensory species, but interspecific comparisons indicated that all taxa overlapped in these measurements. Degree of anisotropy values were generally higher in the inferior VOI of all species and the results for the two climbing/suspensory taxa, A. geoffroyi (1.71 +/- 0.30) and S. syndactylus (1.55 +/- 0.04), were similar to the results for the quadrupedal anthropoids, C. guereza (male = 1.64 +/- 0.13; female = 1.68 +/- 0.07) and P. cynocephalus (1.47 +/- 0.13). These results suggest strong trabecular architecture similarity across body sizes, anthropoid phylogenetic backgrounds, and locomotor mode. This structural similarity might be explained by greater similarity in anthropoid hip joint loading mechanics than previously considered. It is likely that our current models of anthropoid hip joint mechanics are overly simplistic.

Peripheral quantitative computed tomography (pQCT) is useful for monitoring bone mineral density of the patients who receive hormone replacement therapy

OBJECTIVE

A forearm fracture (Colles' fracture) is often the first sign of osteoporosis and should alert the patient and physician to the possibility of underlying skeletal fragility. Therefore, the establishment of a more accurate and reliable method for the measurement of bone mineral density (BMD) at the distal radius would be beneficial for the patients who suffer from osteoporosis. The objective of the present study was to evaluate the usefulness of peripheral quantitative computed tomography (pQCT) to assess the change of BMD at the distal radius in early postmenopausal women who receive hormone replacement therapy (HRT).

METHODS

Twenty healthy early postmenopausal women who were diagnosed as osteoporosis or osteopenia were randomized to either HRT or placebo treatment. We analyzed BMD of the distal radius by pQCT, lumbar spine by dual-energy X-ray absorptiometry (DXA) and the biochemical markers of bone turn over (osteocalcin, deoxypyridinoline) every 6 months.

RESULTS

The placebo group showed a significant decrease from the baseline in the trabecular BMD of the radius at 12 months (7.4+/-2.5%) (p<0.05), whereas the HRT group showed a slight increase (0.7+/-2.2%). The changes in the trabecular BMD of the radius between the HRT and placebo groups were statistically different at 12 months (p<0.05). On the other hand, in the cortical BMD of the radius, no significant differences were seen between the changes of bone densities in the HRT and control groups after 1 year of treatment. pQCT could detect a significant loss of BMD of the radius in early postmenopausal women after 1 year and HRT prevented its loss.

CONCLUSION

Our preliminary clinical trial showed that pQCT might be useful for the early detection of bone loss in early postmenopausal women and for the monitoring BMD of the patients who receive HRT.

Population-based study of age and sex differences in bone volumetric density, size, geometry, and structure at different skeletal sites

In a population-based, cross-sectional study, we assessed age- and sex-specific changes in bone structure by QCT. Over life, the cross-sectional area of the vertebrae and proximal femur increased by approximately 15% in both sexes, whereas vBMD at these sites decreased by 39-55% and 34-46%, respectively, with greater decreases in women than in men.

INTRODUCTION

The changes in bone structure and density with aging that lead to fragility fractures are still unclear.

MATERIALS AND METHODS

In an age- and sex-stratified population sample of 373 women and 323 men (age, 20-97 years), we assessed bone geometry and volumetric BMD (vBMD) by QCT at the lumbar spine, femoral neck, distal radius, and distal tibia.

RESULTS

In young adulthood, men had 35-42% larger bone areas than women (p < 0.001), consistent with their larger body size. Bone area increased equally over life in both sexes by approximately 15% (p < 0.001) at central sites and by approximately 16% and slightly more in men at peripheral sites. Decreases in trabecular vBMD began before midlife and continued throughout life (p < 0.001), whereas cortical vBMD decreases began in midlife. Average decreases in trabecular vBMD were greater in women (-55%) than in men (-46%, p < 0.001) at central sites, but were similar (-24% and -26%, respectively) at peripheral sites. With aging, cortical area decreased slightly, and the cortex was displaced outwardly by periosteal and endocortical bone remodeling. Cortical vBMD decreased over life more in women ( approximately 25%) than in men (approximately 18%, p < 0.001), consistent with menopausal-induced increases in bone turnover and bone porosity.

CONCLUSIONS

Age-related changes in bone are complex. Some are beneficial to bone strength, such as periosteal apposition with outward cortical displacement. Others are deleterious, such as increased subendocortical resorption, increased cortical porosity, and, especially, large decreases in trabecular vBMD that may be the most important cause of increased skeletal fragility in the elderly. Our findings further suggest that the greater age-related decreases in trabecular and cortical vBMD and perhaps also their smaller bone size may explain, in large part, why fragility fractures are more common in elderly women than in elderly men.

Ultrasound velocity in the tibia in Japanese patients with hip fracture

The speed of sound in the tibia (tibial SOS) was measured in elderly women to determine whether the tibial SOS declined with age, similarly to bone mineral density (BMD), as determined by dual-energy X-ray absorptiometry (DXA), and whether the tibial SOS in elderly hip fracture patients was lower than that in a control group. The subjects in this study included 38 female patients with hip fracture aged 65 years or more and 38 age-matched women living in a nursing home as the control group. There was a significant decline in the tibial SOS with age in women in the control group, but not in those with hip fracture. In all subjects aged under 80 years, the tibial SOS in women with hip fracture was significantly lower than that in women in the control group. In all subjects who were 80 years or older, the tibial SOS was not significantly different between women with hip fracture and the control group; thus, the tibial SOS in both groups was low, and they were considered to have progressive osteoporosis. The tibial ultrasound velocity can be expected to be useful as an indicator of the risk of limb fracture in the elderly.

Trabecular architecture in women and men of similar bone mass with and without vertebral fracture: I. Two-dimensional histology

While osteoporosis is characterized by a low bone mass there is a well-recognized overlap in bone mineral density (BMD) measurements between groups of subjects with and without vertebral fracture. To investigate whether differences in trabecular architecture may contribute to the presence or absence of fractures independent of the bone mass, fracture and nonfracture groups matched for age, gender, and BMD were assembled. Transiliac biopsies and corresponding lumbar spine BMD measurements from 31 women and 16 men with vertebral fracture were compared with those from 22 women and 11 men without fracture. Lumbar BMD (L1-4) was measured using a Hologic 2000 densitometer. The lumbar BMD was similar in women with and without fracture (0.63 g/cm(3) +/- 0.10 SD and 0.71 g/cm(3) +/- 0.17 SD, n.s.) and in men with and without fracture (0.72 g/cm(3) +/- 0.12 SD and 0.76 g/cm(3) +/- 0.17 SD, n.s.). Undecalcified iliac crest biopsy sections, 8 microm thick, were analyzed for remodeling variables and trabecular architecture using OsteoMeasure and TAS image analysis systems. No significant difference was found in either gender between fracture and nonfracture groups in percent bone volume (mean 10% in all groups), or in the wide range of remodeling and architectural variables measured, including the trabecular width, number, and separation, mean trabecular plate density and fractal dimension, as well as several indirect indices of connectivity including the node:terminus ratio, marrow star volume, and trabecular pattern factor. On the basis of this evidence it was concluded that there is no difference in the trabecular architecture between patients with crush fracture and controls when account is taken of bone mass. This suggests that microanatomical disruption is a predictable intrinsic feature of bone loss. However, there remains the possibility that the two-dimensional character of the structural deterioration measured indirectly is not sufficiently sensitive for the complex cancellous system. This is considered further in part II.

Effect of Paget's disease of bone on areal lumbar spine bone mineral density measured by DXA, and density of cortical and trabecular bone measured by quantitative CT

Although bone density may be increased in bone that is affected by Paget's disease, density changes in cortical and trabecular bone and the effect on bone that is apparently unaffected by Paget's disease are relatively unexplored. We have investigated 81 vertebrae (28 affected, 53 unaffected) in 27 patients with Paget's disease, by dual X-ray absorptiometry (DXA) and by quantitative CT (QCT) bone density measurements of trabecular and cortical bone. DXA bone density was high (mean z-score = 1.62, p < 0.001) in vertebrae affected by Paget's disease, but not significantly different from normal in unaffected vertebrae (mean z-score = 0.07, ns). Mean QCT z-score in Paget's vertebrae was 2.07 (p = 0.009) for cortical bone and 1.37 (p = 0.008) for trabecular bone. DXA correlated with QCT cortical values in affected and unaffected bone (r = 0.8 and 0.56, respectively), and with QCT trabecular values (r = 0.72 and 0.48, respectively). There was no significant difference in the slopes for the correlations in affected or unaffected bone. Cortical QCT values are underestimated in Paget's disease compared with physical measurements of density, owing to the computer algorithm used. High DXA values may alert to the possibility of Paget's disease, especially if the value deviates from the expected normal sequence in lumbar vertebrae. Osteoporotic vertebrae may be overlooked if the average value of bone mineral density is taken in the lumbar spine without reviewing each vertebra.

Differential effects of menopause and metabolic disease on trabecular and cortical bone assessed by peripheral quantitative computed tomography (pQCT)

The usefulness of peripheral quantitative computed tomography (pQCT) was investigated in the diagnosis of metabolic bone diseases, including osteoporosis, and especially in the different diagnostic values in trabecular and cortical components. The subjects were 460 Japanese women aged 20-86 years, including 318 healthy volunteers, 58 osteoporotics with fracture and 84 patients with diseases including amenorrhoea, steroid-induced osteoporosis, renal osteodystrophy (ROD) and primary hyperparathyroidism. Bone mineral density (BMD) was measured for more than 4 years in 74 of the healthy volunteers. BMD was measured by spinal QCT, dual X-ray absorptiometry (DXA) of the spine, radius, and heel, and pQCT of the radius and tibia. High resolution images were obtained for geometry of the radius. Radial pQCT showed a higher correlation with radial DXA than with spinal QCT, and spinal QCT showed a higher correlation with spinal DXA than with radial pQCT. The annual bone loss rates at predominantly trabecular bone sites were accelerated in both the axial and appendicular skeleton. In the fracture study, radial pQCT showed a higher odds ratio (OR = 4.4) than radial DXA, and cortical area ratio seemed to be a good predictor of fracture risk (OR = 5.2). Amenorrhoea and steroid-induced osteoporosis predominantly affected trabecular bone, ROD predominantly affected cortical bone and hyperparathyroidism affected both components, especially the cortical component. pQCT is useful for assessing both trabecular and cortical bone, to provide information on individual bone changes in metabolic bone disease and to estimate the risk of fracture.

Accuracy limits for the determination of cortical width and density: the influence of object size and CT imaging parameters

In this study we analysed the accuracy of computed tomography (CT) measurements in assessing cortical bone. We determined the dependency of thickness and density measurements on the true width and density of the cortex and on the spatial resolution in the CT images using two optimized segmentation methods. As a secondary goal, we assessed the ability of CT to reflect small changes in cortical thickness. Two different bone-mimicking phantoms with varying cortical thickness were scanned with single-slice CT on a Somatom Plus 4 scanner. Images were reconstructed with both a standard and a high-resolution convolution kernel. Two special operator-independent segmentation methods were used to automatically detect the edges of the cortical shell. We measured cortical thickness and density and compared the phantom measurements with theoretical computations by simulating a cross-sectional shape of the cortical shell. Based on the simulations, we calculated CT's power to detect small changes in cortical thickness. Simulations and phantom measurements were in very good agreement. Cortical thickness could be measured with an error of less than 10% if the true thickness was larger than 0.9 (0.7) mm for the standard (high-resolution) kernel which is close to the full width at half maximum (FWHM) of the point spread functions for these kernels and our scanner. Density measurements yielded errors of less than 10% for true cortical thickness values above two to three times the FWHM corresponding to 2.5 (2) mm in our case. The simulations showed that a 10% change in cortical width would not be detected with satisfying probability in bones with a cortical shell thinner than 1.2 mm. An accurate determination of the cortical thickness is limited to bones with a thickness higher than the FWHM of the scanner's point spread function. Therefore, the use of a high-resolution reconstruction kernel is crucial. Cortical bone mineral density can only be measured accurately in bones two to three times thicker than this number. In thinner bones, the measured density becomes dependent on the thickness. Changes in cortical thickness can only be assessed if the change is rather large or if the measured bone has sufficient thickness. Therefore, assessing density or thickness of the vertebral shell by CT should be treated with caution.

Use of peripheral quantitative computed tomography for densitometry of the femoral neck and spine in cynomolgus monkeys (Macaca fascicularis)

Quantitative computed tomography (QCT) allows for the separate densitometric examination of cortical and cancellous bone in vivo. With the new peripheral QCT (pQCT) instrument (the Norland/Stratec XCT-3000A), we evaluated the clinically relevant axial sites of spine and femoral neck in nonhuman primates in vivo. The reproducibility was good (coefficient of variation [CV] <3% at both sites for cortical, trabecular, and total bone mineral density [BMD]; CV 3%-7% for bone mineral content [BMC] and cross-sectional bone area). One hundred sixty intact female cynomolgus monkeys (M. fascicularis) were scanned at the femoral neck. There was less variability among monkeys in cortical BMD (mean 802 mg/mL, CV 6%) as opposed to trabecular BMD (mean 334 mg/mL, CV 28%) or transition zone BMD (mean 457 mg/mL, CV 12%). Scans were performed on lumbar vertebrae (L-4, L-5, and L-6) from five monkeys in vivo and ex vivo. Removal of soft tissue increased measured BMD. Decreasing voxel size from 0.4 mm to 0.2 mm increased measured BMD by diminishing the partial volume effect. Factor analysis demonstrated the expected relationships between pQCT parameters and physical measurement of bone mass and volume ex vivo. Preliminary results in eight ovariectomized and eight reproductively intact monkeys revealed a lower transition zone BMD at the femoral neck, and lower total BMD of the vertebral body in estrogen-deficient animals.

Vertebral bone density evaluated by dual-energy X-ray absorptiometry and quantitative computed tomography in vitro

Vertebral bone density is evaluated mainly by dual-energy X-ray absorptiometry (DXA) or quantitative computed tomography (QCT). Densitometry is used as an estimator of bone strength and forms the basis for choice of treatment. DXA expresses bone density in grams per square centimeter (area density) and QCT expresses bone density in milligrams per cubic centimeter (volumetric density). The aim of this study was to identify the differences between the two techniques, DXA and QCT, when applied to a group of female and male subjects over a wide age range. The data consisted of 221 lumbar vertebral bodies (L3 and L4) excised at autopsy. There were 90 females with a mean age of 65.6 (range 18-94) years and 131 males with a mean age of 62.0 (range 21-94) years. The vertebrae were scanned en bloc in demineralized water in Plexiglas containers with both DXA and QCT. DXA was performed using posteroanterior (PA) and lateral projection. QCT was performed in the center of each vertebra with 1 cm slice thickness. Both methods showed decreasing bone density with age. Lateral DXA showed a decrease in bone density with age from approximately 0.8 g/cm2 to approximately 0.4 g/cm2. QCT showed a decrease in bone density with age from approximately 180 mg/cm3 to approximately 30 mg/cm3. Lateral DXA bone mineral densities (BMD) were correlated with QCT densities in both females (r2 = 0.68, p < 0.00001) and males (r2 = 0.53, p < 0.00001), but females had constantly lower DXA BMDs than males at a given QCT density. QCT and width-adjusted midlateral DXA (g/cm3) were significantly correlated, with r2 = 0.64 (p < 0.00001) for females and r2 = 0.61 (p < 0.00001) for males. In conclusion, age- and gender-related differences in human vertebral bone density were shown to be dependent on the scanning method used. DXA bone mineral content (BMC) and BMD showed that females had lower values than males at all ages. When the "volumetric" DXA measurements and QCT were used, the females had the highest densities in the younger decades and males had the highest densities in the oldest decades. Finally, the area density (BMD) measured by DXA was lower in females than in males with identical QCT volumetric bone densities.

Bone density determination

Bone mineral density determination is an integral part of the diagnosis, therapeutic planning, and monitoring of a patient with osteoporosis. Although the utility of measuring bone density seems intuitive, decisions must be made regarding whom to test, when to test, which technique to use, and which body site to evaluate. Once a determination has been made, consideration has to be given to what to do with the results. Each patient must be individually considered, incorporating genetic, nutritional, lifestyle, pharmacologic, and endocrine risk factors. Other diseases that may be associated with a reduced bone mass must be excluded.

Calcaneal bone mineral density predicts fracture occurrence: a five-year follow-up study in elderly people

A 5-year follow-up study investigated calcaneal bone mineral density (BMD) and changes in BMD in relation to fracture occurrence. The subjects comprised two cohorts born in 1914 and 1910 living in the city of Jyväskylä in central Finland. One hundred and three men (82%) and 188 women (73%), aged 75, and 57 men (74%) and 136 women (65%), aged 80, of the eligible population participated in the baseline bone measurements. The follow-up bone measurements were obtained for 59 men (68%) and 119 women (66%), aged 80 years, and for 21 men (53%) and 61 women (48%), aged 85 years. During the follow-up period, 8 men and 36 women from the younger and 11 men and 24 women from the older cohort sustained at least one fracture. When the baseline levels of BMD were related to fracture occurrence, the results clearly showed that with increased BMD values the probability of fracture decreased. Where men and women had similar BMD values, they also had a similar fracture probability. Except for one woman in the older cohort, none of those who had initial BMD values more than 1 standard deviation above the mean for their age developed a fracture during the follow-up period. The mean annual decrease in BMD was greater in the women (2.5-2.7%) than in the men (0.8-1.0%). The BMD change tended to associate with fracture occurrence only in the 75-year-old women (p = 0.075). The results suggest that calcaneus BMD can be used as a predictor of fracture occurrence in 75- to 80-year-old men and women. However, associating fractures with the change in BMD was difficult due to the limited number of survivors and initial differences in BMD values.

Discrimination of spinal fracture with various bone mineral measurements

For several different bone mineral measurements and various skeletal sites, we compared capability to discriminate between women in various age decades with and without spinal fracture, and attempted to identify the most effective cutoff level in discrimination of spinal fracture. The subjects were 88 women aged 50-59 years (including 32 with fracture), 95 women aged 60-69 years (including 54 with fracture), and 34 women aged 70-79 years (including 18 with fracture). Spinal trabecular and cortical bone mineral density (BMD) were measured using quantitative computed tomography (CT), and spinal, radial (ultra-distal, 10% distal and 33% distal), and calcaneal BMD were measured by dual X-ray absorptiometry. These BMD values were obtained in each subject on the same day. Three statistical techniques-Student's t-test, the logistic regression analysis, and the receiver operating characteristics (ROC) analysis- were applied and accuracy was calculated using the various cutoff values. The capability to discriminate between women with and those without fracture using these BMD values was different among the three age groups. In women aged 50-59 and 60-69 years, all measurements showed good capabilities for discriminating women with fracture. In women aged 70-79 years, these measurements showed lower capability than in those aged 50-59 and 60-69 years, but among them, the calcaneal and ultradistal radial BMD showed relatively good capability. The 10% and 33% distal radial BMD values were not useful in the detection of the high risk women with fracture. The cutoff BMD values for discrimination of women with fracture varied according to the sites and methods of measurement. For each specific age group, the most suitable measurement methods and the appropriate skeletal sites should be considered, and the effective cutoff values to discriminate those with fracture may differ according to the measurement methods, the skeletal sites examined, and age.

Body composition and bone mineral density of Chinese women with vertebral fracture

This study was designed to compare the body composition and bone mineral density measurements (BMD) in Chinese women with vertebral fracture and normal controls. A total of 400 community dwelling Chinese women aged 70-79 years old were studied. Vertebral height ratios were calculated from lateral thoracic and lumbar spine X-rays and subjects were classified into definite cases (n = 122), doubtful cases (n = 138) and normal controls (n = 140). Bone mineral density and body composition measurements were made by dual X-ray densitometry. The height, fat mass, lean mass, and BMD at all sites were significantly lower in patients with definite fracture than normal controls. Nevertheless, BMD at the hip was more predictive of vertebral fracture than BMD at the spine, the odds ratio in the lowest quartile of hip BMD being 3.8 (95% C.I. = 1.3 to 10.9). Finally, the extent of spinal deformity was poorly predicted by a combination of the anthropometric and BMD measurements, as only 12% of the total variance in TD1 was accounted for.

Usefulness of panoramic radiography in the diagnosis of postmenopausal osteoporosis in women. Width and morphology of inferior cortex of the mandible

OBJECTIVES

To evaluate the usefulness of width and morphology of the inferior cortex of the mandible on panoramic radiographs in the diagnosis of postmenopausal osteoporosis.

METHODS

The width and morphology of the mandibular inferior cortex on panoramic radiographs were compared with trabecular bone mineral density (TBMD) of the 3rd lumbar vertebrae (L3) measured by dual energy quantitative computed tomography in 29 premenopausal and 95 postmenopausal women.

RESULTS

There was a significant negative correlation between the width (Kendall's tau = -0.36, p < 0.001) and morphology (Kendall's tau = -0.49, p < 0.001) of the mandibular inferior cortex and the L3 TBMD. Regression analysis showed that significant linear relationships were observed between the L3 TBMD and age (p < 0.001), cortical width (p < 0.05), morphology (p < 0.05), controlling body mass index, number of teeth present and menopausal status (R2 = 0.42).

CONCLUSION

Our results suggest that panoramic radiography could be reliable in screening for osteoporosis.

Relationship between the mandibular and lumbar vertebral bone mineral density at different postmenopausal stages

OBJECTIVE

To analyse the relationship between mandibular and general skeletal mineral status at two different postmenopausal stages.

METHODS

Using dual energy quantitative computed tomography, the mandibular and 3rd lumbar (L3) vertebral bone mineral density (BMD) were evaluated in 21 women within five years after the menopause (recent postmenopause) and 23 women more than five years after (long-term postmenopause).

RESULTS

There were significant correlations between the mandibular cortical and L3 vertebral BMD (p < 0.01) in the recent postmenopausal women and between the mandibular BMD and the trabecular BMD of L3 vertebrae (p < 0.05) in the long-term postmenopausal women.

CONCLUSION

These results suggest that the general mineral status more markedly affects the mandibular cortex in the recent postmenopausal stage and both cortical and trabecular bone in the long-term postmenopausal stage.

The European Spine Phantom--a tool for standardization and quality control in spinal bone mineral measurements by DXA and QCT

The lack of standardization in bone mineral measurements of the lumbar spine and other skeletal sites is generally recognized as an important and unresolved issue. We report and discuss efforts at standardization and cross-calibration of DXA and QCT equipment. We have designed and tested a geometrically defined, semi-anthropomorphic phantom, the European Spine Phantom (ESP). It contains a spine insert consisting of three vertebrae of increasing bone mineral densities and thicknesses of cortical structures; the respective parameters are given in tabular form for the final phantom design. Results for cross-calibration with the ESP compare well with patient results. Measurements on the first 30 phantoms confirmed that the ESP can be manufactured with a variation of about 1%. We conclude that the ESP is suitable for daily quality assurance, cross-calibration of instruments and universal standardization. The ESP was used to establish standardized BMD (sBMD) units for DXA equipment going into effect in late 1995. Its acceptance by manufacturers as a calibration standard for DXA and QCT measurements appears imminent.