How well do the FRAX (Australia) and Garvan calculators predict incident fractures? Data from the Geelong Osteoporosis Study

This study reports that both FRAX and Garvan calculators underestimated fractures in Australian men and women, particularly in those with osteopenia or osteoporosis. Major osteoporotic fractures were poorly predicted, while both calculators performed acceptably well for hip fractures.

INTRODUCTION

This study assessed the ability of the FRAX (Australia) and Garvan calculators to predict fractures in Australian women and men.

METHODS

Women (n = 809) and men (n = 821) aged 50-90 years, enrolled in the Geelong Osteoporosis Study, were included. Fracture risk was estimated using FRAX and Garvan calculators with and without femoral neck bone mineral density (BMD) (FRAX_BMD, FRAX_noBMD, Garvan_BMD, Garvan_noBMD). Incident major osteoporotic (MOF), fragility, and hip fractures over the following 10 years were verified radiologically. Differences between observed and predicted numbers of fractures were assessed using a chi-squared test. Diagnostics indexes were calculated.

RESULTS

In women, 115 MOF, 184 fragility, and 42 hip fractures occurred. For men, there were 73, 109, and 17 fractures, respectively. FRAX underestimated MOFs, regardless of sex or inclusion of BMD. FRAX accurately predicted hip fractures, except in women with BMD (20 predicted, p = 0.004). Garvan underestimated fragility fractures except in men using BMD (88 predicted, p = 0.109). Garvan accurately predicted hip fractures except for women without BMD (12 predicted, p < 0.001). Fractures were underestimated primarily in the osteopenia and osteoporosis groups; MOFs in the normal BMD group were only underestimated by FRAX_BMD and fragility fractures by Garvan_noBMD, both in men. AUROCs were not different between scores with and without BMD, except for fragility fractures predicted by Garvan in women (0.696, 95% CI 0.652-0.739 and 0.668, 0.623-0.712, respectively, p = 0.008) and men, which almost reached significance (0.683, 0.631-0.734, and 0.667, 0.615-0.719, respectively, p = 0.051). Analyses of sensitivity and specificity showed overall that MOFs and fragility fractures were poorly predicted by both FRAX and Garvan, while hip fractures were acceptably predicted.

CONCLUSIONS

Overall, the FRAX and Garvan calculators underestimated MOF and fragility fractures, particularly in individuals with osteopenia or osteoporosis. Hip fractures were predicted better by both calculators. AUROC analyses suggest that Garvan_BMD performed better than Garvan_noBMD for prediction of fragility fractures.

Increased bone mineral density in Aboriginal and Torres Strait Islander Australians: impact of body composition differences

Bone mineral density (BMD) has been reported to be both higher and lower in Indigenous women from different populations. Body composition data have been reported for Indigenous Australians, but there are few published BMD data in this population. We assessed BMD in 161 Indigenous Australians, identified as Aboriginal (n=70), Torres Strait Islander (n=68) or both (n=23). BMD measurements were made on Norland-XR46 (n=107) and Hologic (n=90) dual-energy X-ray absorptiometry (DXA) machines. Norland BMD and body composition measurements in these individuals, and also in 36 Caucasian Australians, were converted to equivalent Hologic BMD (BMD(H)) and body composition measurements for comparison. Femoral neck (FN) and lumbar spine Z-scores were high in Indigenous participants (mean FN Z-score: Indigenous men +0.98, p<0.0001 vs. mean zero; Indigenous women +0.82, p<0.0001 vs. mean zero). FN BMD(H) was higher in Aboriginal and/or Torres Strait Islander than Caucasian participants, after adjusting for age, gender, diabetes and height and remained higher in men after addition of lean mass to the model. We conclude that FN BMD is higher in Aboriginal and/or Torres Strait Islander Australians than Caucasian Australian reference ranges and these differences still remained significant in men after adjustment for lean mass. It remains to be seen whether these BMD differences translate to differences in fracture rates.

Prognosis of fracture: evaluation of predictive accuracy of the FRAX algorithm and Garvan nomogram

We evaluated the prognostic accuracy of fracture risk assessment tool (FRAX) and Garvan algorithms in an independent Australian cohort. The results suggest comparable performance in women but relatively poor fracture risk discrimination in men by FRAX. These data emphasize the importance of external validation before widespread clinical implementation of prognostic tools in different cohorts.

INTRODUCTION

Absolute risk assessment is now recognized as a preferred approach to guide treatment decision. The present study sought to evaluate accuracy of the FRAX and Garvan algorithms for predicting absolute risk of osteoporotic fracture (hip, spine, humerus, or wrist), defined as major in FRAX, in a clinical setting in Australia.

METHODS

A retrospective validation study was conducted in 144 women (69 fractures and 75 controls) and 56 men (31 fractures and 25 controls) aged between 60 and 90 years. Relevant clinical data prior to fracture event were ascertained. Based on these variables, predicted 10-year probabilities of major fracture were calculated from the Garvan and FRAX algorithms, using US (FRAX-US) and UK databases (FRAX-UK). Area under the receiver operating characteristic curves (AUC) was computed for each model.

RESULTS

In women, the average 10-year probability of major fracture was consistently higher in the fracture than in the nonfracture group: Garvan (0.33 vs. 0.15), FRAX-US (0.30 vs. 0.19), and FRAX-UK (0.17 vs. 0.10). In men, although the Garvan model yielded higher average probability of major fracture in the fracture group (0.32 vs. 0.14), the FRAX algorithm did not: FRAX-US (0.17 vs. 0.19) and FRAX-UK (0.09 vs. 0.12). In women, AUC for the Garvan, FRAX-US, and FRAX-UK algorithms were 0.84, 0.77, and 0.78, respectively, vs. 0.76, 0.54, and 0.57, respectively, in men.

CONCLUSION

In this analysis, although both approaches were reasonably accurate in women, FRAX discriminated fracture risk poorly in men. These data support the concept that all algorithms need external validation before clinical implementation.

Reference ranges for bone densitometers adopted Australia-wide: Geelong osteoporosis study

Bone densitometry reports a measure of fracture risk in comparison with young adults (T-scores) and age-matched peers (Z-scores). To date, each manufacturer has provided its own reference range resulting in lack of uniformity. The Australia and New Zealand Bone and Mineral Society and Osteoporosis Australia have recognized the need to standardize the reference range and have recommended that data generated by the Geelong Osteoporosis Study (GOS) be used Australia-wide. The GOS recruited a random, population-based sample of adult women and measured bone mineral density (BMD) at the proximal femur and spine using a Lunar DPX-L. These data were used to establish reference ranges for Lunar machines and, using conversion equations, for Norland and Hologic machines. The new standardized Australian reference ranges for BMD will enable consistent diagnosis of osteoporosis and categorization of fracture risk across different types of densitometers.

The effect of room temperature on dual-energy X-ray absorptiometry

There has been little published data on the effects of temperature on the performance of dual-energy X-ray absorptiometry (DXA) machines. We examined the effect of changes in ambient room temperature on the performance of three DXA scanners (DPXL, Expert-XL and Prodigy). The study involved repeat measurements of bone mineral density (BMD) using three different spine phantoms scanned at different ambient room temperatures, both before and after calibration procedures. The calibration or quality assurance (QA) scan calibrates the scanner, adjusting for the ambient room temperature at the time of calibration. There was a moderate correlation between change in temperature and change in BMD measured prior to recalibration for the Expert-XL ( r=0.58) during normal clinical scanning conditions. There was no observed change in phantom BMD with change in temperature measured using the DXPL or Prodigy. After temperature change, without repeat calibration measurements, there was a strong correlation between temperature change and change in BMD measured using the Expert-XL ( r=0.96, p<0.001). From the regression equation, a change of 2.5 degrees C could alter the calculated BMD result measured by the Expert-XL by 1.5%, which would significantly affect the precision of the DXA system. There was no significant correlation between temperature and BMD in the DXPL or Prodigy. The observed differences between the densitometers and the effect of temperature change are most likely due to the differing types of detector systems used. Operators must be made aware that solid state detectors of the sort used in the Expert-XL (charge-coupled devices, CCDs) are significantly affected by changes in ambient room temperature.

Coincidence detection FDG PET in the management of oncological patients: attenuation correction versus non-attenuation correction

The aim of this study was to determine if attenuation correction (AC) in a dual-head, coincidence, positron emission tomography imaging system (Co-PET) improved image quality, lesion detection, patient staging and management of various malignant neoplasms, compared to non-attenuation corrected (NAC) images. Thirty patients with known or suspected malignant neoplasms underwent fluorodeoxyglucose (FDG) Co-PET, which was correlated with histopathology, computed tomography (CT) and other conventional imaging modalities and clinical follow-up. The number and location of FDG avid lesions detected on the AC images and NAC Co-PET images were blindly assessed by two independent observers. Semi-quantitative grading of image clarity and lesion-to-background quality was performed. This revealed markedly improved image clarity and lesion-to-background quality in the AC versus NAC Co-PET images. AC Co-PET was statistically superior to NAC Co-PET in relation to lesion detection (P<0.01) and tumour staging (P<0.01). NAC Co-PET demonstrated 51 of the 65 lesions (78%) detected by AC Co-PET. AC Co-PET altered tumour staging in five additional patients (16%) compared to NAC Co-PET. Management was altered in two of these five patients.

Potential roles for quantitative ultrasound in the management of osteoporosis

OBJECTIVE

To assess the validity of four models for the role of quantitative ultrasound (QUS) in the management of osteoporosis.

DESIGN

Cross-sectional survey and review of literature.

SETTINGS

Nuclear medicine departments of three teaching hospitals in Sydney.

SUBJECTS

1000 women aged 22 to 88 years (mean, 59 years) referred for assessment of osteoporotic fracture risk.

MAIN OUTCOME MEASURES

BMD categories as defined by dual-energy x-ray absorptiometry (DEXA) of the lumbar spine and proximal femur, and QUS category as defined by calcaneal ultrasound stiffness; prevalence of DEXA-defined osteoporosis in the different QUS categories.

RESULTS

In women with QUS Achilles stiffness < or = 70 the prevalence of axial osteoporosis was 51%, whereas in the group with stiffness > 70 the prevalence of axial osteoporosis was 8%. In women 65 years and over the corresponding values were 59% and 17%.

CONCLUSIONS

Of the four possible models for QUS, the use of QUS for the estimation of BMD, or in a "standalone" model, can not be recommended at the current time. The model of QUS as a "prescreening" modality may be acceptable assuming adequate education of clinicians and patients of its limitations, particularly the risk of false negatives. The model of QUS as one factor in a composite risk factor assessment of patients is promising but more data are required.

Temperature dependency of quantitative ultrasound

Quantitative ultrasound (QUS) parameters are temperature dependent. We examined the effect of temperature on QUS using Lunar Achilles+ and Hologic Sahara units. In vivo studies were performed in a cadaveric foot and in 5 volunteers. QUS scans were performed in the cadaveric foot, using both machines, at temperatures ranging from 15 to 40 degrees C. To assess the effect of change in water bath temperature in the Achilles+, independently of foot temperature, 5 volunteers were studied at water temperatures ranging from 10 to 42 degrees C. In the cadaveric foot there were strong negative correlations between temperature and speed of sound (SOS) but a moderately positive correlation between temperature and broadband ultrasound attenuation (BUA). Stiffness and the Quantitative Ultrasound Index (QUI) in the cadaveric foot showed strong negative correlations with temperature, reflecting their high dependence on SOS. In the 5 volunteers, in whom foot temperature was assumed to be constant, there was a small change in Stiffness in the Achilles+, with variation in water temperature. In conclusion, while there are opposite effects of temperature on SOS and BUA in vivo, there is still a significant effect of temperature variation on Stiffness and the QUI. This may have clinical significance in particular subjects. The precision of QUS may be affected by temperature variation of the environment or of the patient's limb. Instruments utilizing a water bath may be able partly to compensate for changes in environmental temperature, but standardization of water bath temperature is crucial to maximize precision.

Quantitative heel ultrasound as a predictor for osteoporosis

OBJECTIVE

To determine the diagnostic value of quantitative ultrasound (QUS) to predict bone mineral density (BMD) categories as defined by dual-energy x-ray absorptiometry.

DESIGN

Cross-sectional survey.

SETTING

Rheumatology department of a tertiary care hospital (Royal North Shore Hospital, Sydney, NSW), 1997-1998.

SUBJECTS

326 healthy women aged 45-80 years who had volunteered for a twin study. Our study included both members of non-identical twin pairs but only one randomly selected member of identical twin pairs.

MAIN OUTCOME MEASURES

BMD categories as defined by dual-energy x-ray absorptiometry of lumbar spine and left hip, and QUS of calcaneus; sensitivity, specificity and likelihood ratios (LRs) of QUS parameters to diagnose osteoporosis as defined by BMD.

RESULTS

The sensitivity of QUS to diagnose BMD osteoporosis varied between 9% and 47%, depending on the QUS parameter. The specificity of QUS was high (88%-100%). If all QUS parameters were normal, osteoporosis was unlikely (LR, 0-0.2). One QUS parameter, broadband ultrasound attenuation (BUA), was highly predictive of osteoporosis by BMD when in the osteoporotic range (LR, infinity), but had low sensitivity (9%). QUS results in the osteoporotic range for other parameters and all QUS results in the osteopenic range were less predictive (LR, 1.0-5.2) of osteoporotic BMD.

CONCLUSION

These results suggest that, for most of those tested for osteoporosis by QUS in the community, uncertainty remains about expected BMD.

The potential effect on hip fracture incidence of mass screening for osteoporosis

With ageing of the Australian population, treatment of osteoporosis-related hip fractures will impose an increasing burden on the healthcare system. Based on current age-adjusted hip fracture incidence and population projections for New South Wales, we estimated a 90% increase in hip fractures by the year 2021. Contributing significantly to this increase will be the number of men reaching the high risk age group for osteoporotic hip fractures. A suggested solution--screening and appropriate therapy for individuals at high risk of osteoporosis--may have only a modest impact. Our calculations show that, even with optimistic screening and therapy compliance rates, hip fractures could still increase by over 50%. Other approaches need to be further explored.

Quantitative diagnostic methods in osteoporosis: a review

During the last two decades there have been major advances in the understanding of pathophysiology and in the diagnosis of osteoporosis. There are now, in addition to standard radiographs, a number of different diagnostic modalities available to doctors for the quantitative assessment of bone mass. These methodologies are having an increasingly important role, not only in the clinical diagnosis, but also in the monitoring of patients with osteoporosis. As the population ages there will be an increasing demand for these services, and radiologists need to be aware of the strength and limitations of the different modalities available.

Femoral neck axis length, height loss and risk of hip fracture in males and females

Hip axis length (HAL) has been proposed as an independent predictor of hip fracture risk in Caucasian females. Femoral neck axis length (FNAL) is a similar measure of femoral geometry but does not include acetabular structures. The aim of this study was to examine the association between hip geometry, using FNAL, and hip fractures in elderly males and females in relation to other anthropometric data. The study group comprised 123 females (23 hip fracture patients and 100 age-matched controls) and 137 males (13 hip fracture patients, 65 age-matched controls and 59 current-height-matched controls). All subjects had femoral neck bone mineral density measured by dual-energy X-ray absorptiometry. From these scans, FNAL was measured as the linear distance from the base of the greater trochanter to the apex of the femoral head. FNAL was correlated significantly with current height (r = 0.47 and r = 0.56 for females and males respectively; p < 0.0001) and peak height (r = 0.45 and r = 0.57 for females and males respectively; p < 0.0001) in both sexes. In females, FNAL in the fracture patients (91.5 +/- 5.4 mm, mean +/- SD) was not significantly different from FNAL in controls (89.7 +/- 5.4 mm; p = 0.2). Fracture patients had the same current height as controls and a trend towards a greater peak height (163 +/- 6 cm vs 160 +/- cm; p = 0.09). After adjusting FNAL for current or peak height there was no difference in FNAL between fracture patients and controls. In males, FNAL in the fracture patients (103.9 +/- 3.9 mm) was not significantly different from that of age-matched controls (103.4 +/- 6.3 mm; p = 0.79). Fracture patients had a significantly lower current height (168 +/- 6 cm) than the age-matched controls (174 +/- 6 cm; p = 0.0008) but had the same peak height. When adjusted for peak height there were no significant differences between height of hip fracture patients (102.0 +/- 4.9 cm), age-matched controls (102.1 +/- 5.1 cm) and current-height-matched controls (102.6 +/- 5.3 cm). Fracture patients had a significantly greater height loss (peak height minus current height) than either control group. In logistic regression analyses peak height in females and height loss in males but not FNAL were independent predictors of hip fracture. The greater height, FNAL and presumably HAL in males versus females is not associated with increased hip fracture risk. However, in this study of elderly males and females, peak height (females) and height loss (males) were independent risk factors for hip fracture. Moreover, FNAL appears to have limited utility in the prediction of hip fracture risk and any role of HAL in the prediction of hip fracture does not relate to its major component of femoral neck length.

A comparison of longitudinal measurements in the spine and proximal femur using lunar and hologic instruments

Absolute values of bone mineral density (BMD), using dual-energy X-ray absorptiometry (DXA), differ between instruments from different manufacturers. Despite these differences, the rates of change calculated from serial measurements on different densitometers have been assumed to be comparable. We compared the change in BMD in 34 subjects in the lumbar spine and at the standard sites in the proximal femur, from measurements performed using a Lunar DPX-L and a Hologic QDR-1000. Measurements were obtained on the same day, and repeated on the same day, on both machines after a mean interval of 4.8 years (range 4.1-6.3 years). There were strong positive correlations between the percentage change in BMD calculated using the two machines in the lumbar spine, trochanteric region, and total proximal femur: r = 0.82, 0.84, and 0.73, respectively (p < 0.0001 at all sites). In the femoral neck and in Ward's triangle, the correlations were not as high: r = 0.55 (p = 0.003) and 0.43 (p = 0.028), respectively. At all sites, despite the significant correlations, the agreement between the two densitometers was not high and there may be significant errors in individual subjects if one uses measurements from one densitometer to predict the change in BMD using the scanner of the other manufacturer. There is less of a problem comparing group data in the lumbar spine and trochanteric region, although errors are still likely to occur in comparing group data of bone loss, calculated using different densitometers, in the other proximal femur sites. In conclusion, the study suggests that caution is necessary in combining bone loss data derived using densitometers from different manufacturers, particularly in the proximal femur. This has important implications for multicenter studies.

Magnification error of femoral geometry using fan beam densitometers

Hip axis length (HAL) has been reported as an independent risk factor for hip fracture. DEXA machines using fan beam techniques have become increasingly available. Errors in calculated hip axis length may be expected because of different degrees of magnification by the fan beam. The magnitude of this error on measurement of hip geometry was studied, using an anthropomorphic femur phantom with both fan beam (Lunar Expert and Hologic QDR-2000) and pencil beam (Lunar DPXL) densitometers. The clinical relevance of these findings was also examined using patient measurements of buttock soft tissue thickness. Femoral neck axis length (FNAL), which correlates well with HAL, was used as a measurement of hip geometry. There was a linear increase or decrease of FNAL with increasing distance of the phantom above the scanning table, when measured with the Lunar Expert or Hologic QDR-2000, respectively. There was no significant difference in FNAL at different heights using the pencil beam densitometer. The maximal difference in buttock soft tissue thickness in 30 women studied was 8.7 cm. From the equations, derived from the phantom studies, this difference would result in an 8.2% (1.4 SD) increase, or an 11.4% (1.9 SD) decrease in FNAL in the largest woman as compared with the smallest woman when measured using the Lunar Expert or Hologic QDR-2000, respectively. We conclude that there may be unpredictable degrees of magnification of FNAL in vivo, caused by differences in buttock thickness, when measured using a fan beam densitometers. Until these problems are resolved. FNAL, or related parameters of femoral geometry, should be measured using pencil beam instruments.

Influence of handedness on calcaneal ultrasound: implications for assessment of osteoporosis and study design

Calcaneal ultrasound has been increasingly studied for its potential in the assessment of osteoporotic fracture risk. The accuracy of such an assessment is, in part, dependent on the reproducibility of the measurement. This study examines the impact of handedness on ultrasound measurements [broadband ultrasound attenuation (BUA) and velocity of sound (VOS)] in the calcaneus. Two hundred and sixty-four subjects (57 men and 297 women) aged 51.1 +/- 13.6 years (mean +/- SD) were studied. For each subject, calcaneal ultrasound measurements were performed on both heels with a McCue CUBA ultrasound densitometer. Right-handed dominance (94.7%) was determined by structured interview. In men, BUA measurements were significantly higher on the dominant side: mean difference 4.1 +/- 1.5 dB/MHz (mean +/- SD; p = 0.009), equivalent to 4.2 +/- 1.5% and more than 4 times the average rate of annual change in BUA. The difference between sides was greater in young (< 50 years) than old men (> 50 years). Among the women, the difference was not statistically significant (0.7 +/- 0.9 dB/MHz; p = 0.4); however, it was significant in younger women (20-30 years) (99 +/- 4 vs 90 +/- 4 dB/MHz, p = 0.01). By contrast VOS did not differ between sides in either men or women irrespective of age. Within-subject standard deviation of BUA was 9.8 dB/MHz for men and 8.6 dB/ MHz for women and the component due to right and left difference was 8.4 dB/MHz for men and 6.9 dB/MHz for women. This variability of BUA between right and left heels could increase the false-positive rate by up to 28% for a cut-off of 2 SD below the mean. These data indicate that variation between left and right heel measurements of BUA is higher than that of random error measurements, particularly in men and younger, presumably more physically active subjects. Although VOS measurements were not side dependent, in the smaller number of studies examining VOS and fracture risk, VOS appears to have a weaker predictive power than BUA. Clinical and epidemiological studies involving calcaneal BUA measurements should standardize the side measured to either the dominant or non-dominant heel, to reduce within-subject variation and increase their power.

Correcting the magnification error of fan beam densitometers

Dual-energy X-ray absorptiometry (DXA), using a narrow pencil-shaped X-ray beam coupled to a single detector, has been used extensively. More recently, DXA using a fan- shaped X-ray beam coupled to an array of detectors has been introduced. This new generation of scanners causes an inherent magnification of scanned structures as the distance from the X-ray source decreases. This magnification, which occurs in the medial-lateral direction but not in the craniocaudal direction, does not affect bone mineral density (BMD). There are, however, significant changes of bone mineral content (BMC), bone area, and parameters of hip geometry, with varying distance of the bone scanned from the X-ray source. Variability of soft tissue thickness in vivo, by altering the distance of the skeleton from the scanning table and X-ray source, may cause clinically significant errors of BMC, bone area, and proximal femur geometry when measured using fan-beam densitometers. We analyzed the geometry of Lunar and Hologic fan beam scanners to derive equations expressing the true width of scanned structures in terms of the apparent width and machine dimensions. We also showed mathematic ally that performing an additional scan, at a different distance from the X-ray source than the first scan, provides simultaneous equations that can be solved to derive the real width of a scanned bone. This hypothesis was tested on the Lunar Expert using aluminium phantoms scanned at different table heights. There was an excellent correlation, r = 0.99 (p < 0.001), between the predicted phantom width and the measured phantom width. In conclusion, this study shows that the magnification error of fan beam DXA can be corrected using a dual scanning technique. This has important implications in the clinical usefulness of BMC and geometrical measurements obtained from these scanners.

Screening for osteoporosis: what is the role of heel ultrasound?

Could focused population screening detect osteoporosis earlier and improve the management of this major health care problem? Quantitative ultrasound of the calcaneus is currently being proposed as a suitable screening technique. Correlations between quantitative ultrasound of the calcaneus and dual energy x-ray absorptiometry of bone mineral density of the spine and proximal femur are not high enough to reliably predict bone mineral density at the lumbar spine or proximal femur from the ultrasound results. Some ongoing longitudinal studies suggest that quantitative ultrasound may none the less detect individuals at increased risk of fracture, but its use for mass screening for osteoporosis would be premature.

Lifestyle factors and bone density in the elderly: implications for osteoporosis prevention

Epidemiologic evidence suggests that lifestyle factors, such as exercise, calcium intake, and tobacco consumption, have effects on bone density. However, the influence of these factors in the elderly has not been well documented. To examine the effects of lifestyle factors in the elderly, we measured bone density (BMD) at the lumbar spine and proximal femur in 709 elderly men and 1080 women participating in the Dubbo Osteoporosis Epidemiology study (DOES), a community-based, longitudinal, epidemiologic study of osteoporosis in men and women over the age of 60. BMD was significantly higher in men than in women (20% at all sites). There was an age-related decline in BMD at the femoral neck in both sexes and at the lumbar spine in women. Between the ages of 60 and 80, the decrease in BMD at the femoral neck among women was 18.9%, which is almost twice the decrease in BMD among men (10.1%). Tobacco consumption was associated with a reduction in BMD at both sites in both sexes (5-8%), and this effect was independent of calcium intake or body weight. Exsmokers had BMD intermediate between that of current smokers and never smokers, suggesting the influence of tobacco was partially reversible. Quadriceps strength predicted bone density at the proximal femur in elderly men but not in women. Analyzing BMD (adjusted for age and weight) in tertiles of muscle strength and calcium intake revealed an interaction between calcium intake and muscle strength on bone density; BMD at the femoral neck among those with higher quadriceps strength and calcium intake was approximately 5% higher (P < 0.05) than in those with low quadriceps strength and calcium intake in both men and women.(ABSTRACT TRUNCATED AT 250 WORDS)

Peak bone mass and osteoporosis prevention

The incidence of osteoporotic fractures increases with advancing age. Despite advances in therapy, reversal of bone loss in established osteoporosis remains problematic and deformities and disability due to fractures often persist. Therefore the logical approach to osteoporosis treatment is preventive. Risk of fracture is determined largely by bone density, which is the end result of peak value achieved at skeletal maturity and subsequent age- and menopause-related bone loss. Thus the determinants of peak bone density and bone loss require full characterization. Environmental and lifestyle factors are important determinants of bone density, particularly physical activity and diet. For example, muscle strength and physical fitness predict bone density, so that regular moderate exercise may help maintain bone mass but probably does not reverse loss. Long-term calcium intake appears to be important for achievement and maintenance of peak bone density, especially in males. Smoking and excessive alcohol intake are deleterious to bone mass. Cultural norms in diet, lifestyle and physical activity obviously have an impact on bone density. Genetic factors have a strong role in determining the wide range in 'normal' peak bone mass. Moreover we have found strong genetic determinants of rates of change of bone mass in the lumbar spine and similar trends for sites in the femoral neck. We have shown previously that genetic factors influence bone turnover indices, particularly osteocalcin. Investigating these relationships with restriction fragment length polymorphisms, we have identified variants of the vitamin D receptor gene which predict osteocalcin levels and presumably bone turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of spinal and femoral bone density by dual X-ray absorptiometry: comparison of lunar and hologic instruments

Clinical application of techniques for assessing bone mineral density (BMD) requires accurate and precise measurements that can be related to clearly defined normal ranges. In this study we investigated the clinical interpretation of BMD values in a group of individuals measured on the same day with two different dual-energy x-ray densitometers (Lunar DPX and Hologic QDR 1000). The BMD results were analyzed as absolute values in g/cm2 and with respect to young and age-specific normals as defined by each manufacturer. Absolute BMD values measured by the two instruments were highly correlated (lumbar spine r = 0.98, femoral neck r = 0.95; p less than 0.0001). In the lumbar spine, the two instruments assigned almost identical values when expressed as a percentage of age-matched values and as a percentage of young normals, despite a small but systematic difference between the values assigned for the latter index. In the femoral neck, however, there were significant differences in assignments between instruments, expressed both as a percentage of young normal (mean difference 6.2%) and with respect to age-matched values (mean difference 3.3%). In particular, in premenopausal subjects femoral neck values with the Hologic instrument were assigned significantly lower values. This study shows effective comparability between these two instruments for absolute and relative values for the lumbar spine, as well as for absolute values at the femoral neck, but important differences for normality assignments at the femoral neck. These latter differences may produce bias in the "diagnosis" of femoral neck osteoporosis and may have important implications for clinical decision making.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic factors in bone turnover

Genetic factors are major determinants of adult bone density, however, it is unknown how these effects may be mediated. Since bone mineral density is the net result of bone formation and bone resorption we studied biochemical indices of bone formation (serum osteocalcin) and resorption [fasting urinary calcium:creatinine (Ca/Crt) and hydroxyproline:creatinine (OH/Crt)] in adult female twins; 39 monozygotic (MZ) and 31 dizygotic (DZ) twin pairs (age, mean +/- SEM, MZ: 51.1 +/- 1.5 yrs; DZ: 46.5 +/- 1.5 yrs, P = NS). Of these subjects, 18 MZ twin pairs and 10 DZ twin pairs were postmenopausal. The MZ twin pair correlations (rMZ) for each index of bone turnover exceeded that between DZ pairs (rDZ), but this difference was only significant for osteocalcin (rMZ = 0.81, rDZ = 0.21, P less than 0.001). Similarly, in the postmenopausal group examined alone, the rMZ (r = 0.84) for serum osteocalcin was significantly greater than rDZ (r = -0.003, P less than 0.03). These osteocalcin data imply that 80% of the variance in serum osteocalcin could be explained by genetic factors. Although genetic effects on fasting urinary hydroxyproline:creatine and calcium:creatinine were not demonstrable, these indices may be less precise and specific. The data indicate that circulating osteocalcin, and therefore bone formation, is strongly genetically determined. These studies suggest at least one of the mechanisms of the genetic effect on bone mass relates to the regulation of bone turnover.

Dietary calcium, sex hormones, and bone mineral density in men

OBJECTIVE

To evaluate the factors that determine bone mineral density at axial and appendicular sites in normal men.

DESIGN

Measurement of bone mineral density of the radius by single photon absorptiometry and of the lumbar spine and hip by dual photon absorptiometry to assess their relation with various determinants of bone mineral density. Dietary calcium was assessed from a questionnaire validated against a four day dietary record.

SETTING

Local community, Sydney, Australia.

PATIENTS

48 Men (aged 21-79, median 44) recruited from the local community including 35 male cotwins of twin pairs of differing sex recruited from the Australian National Health and Medical Research Council twin registry for epidemiological studies on determinants of bone mineral density.

MAIN OUTCOME MEASURES

Bone mineral density of the axial and appendicular skeleton and its relation to age, anthropometric features, dietary calcium intake, and serum sex hormone concentrations.

RESULTS

Dietary calcium intake (g/day) was a significant predictor of bone mineral density of axial bones, explaining 24% and 42% of the variance at the lumbar spine and femoral neck respectively. This effect was independent of weight. In contrast with the axial skeleton, bone mineral density at each forearm site was predicted by weight and an index of free testosterone but not by dietary calcium intake.

CONCLUSIONS

Dietary calcium intake has a role in the determination or maintenance, or both, of the axial but not the appendicular skeleton in adult men.

Somatomedin-C, physical fitness, and bone density

Somatomedin-C (Sm-C) or insulin-like growth factor-I, GH and physical fitness decline with age. Physical fitness and muscle strength are important determinants of bone density, and the age-related decline in bone density may be related in part to a decline in fitness and muscle strength. Also, Sm-C has been shown to stimulate osteoblasts in vitro and may effect skeletal muscle mass. We postulated that the age-related decline in GH and Sm-C levels may be related to an age-related decline in physical fitness and/or muscle strength, and the effect of physical fitness and muscle strength on bone may be mediated by Sm-C. We, therefore, examined the relationship between circulating GH and Sm-C levels and physical fitness, as determined by predicted maximal oxygen uptake (VO2max) in 134 normal women, 34 of whom were postmenopausal. In a subgroup of 62 women overall muscle strength was estimated as the sum of the Z-sores for biceps, quadriceps, and grip strength. Overall muscle strength correlated with GH levels (r = 0.28; P less than 0.02), but not with Sm-C levels. There was a significant positive relationship between plasma Sm-C levels and VO2max in all women (r = 0.47; P less than 0.001) and in the postmenopausal group alone (r = 0.05; P less than 0.01). Although there was a significant negative relationship between Sm-C and age (r = -0.36; P = 0.001), VO2max was a better independent predictor than age (r = 0.47; P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Age and menopause-related changes in indices of bone turnover

Age-related bone loss has been attributed to a decline in bone formation due to decreased osteoblast function. However, studies examining the relationship between age or menopausal status and indices of bone formation such as serum osteocalcin have yielded conflicting results. To examine these relationships we studied indices of bone formation and resorption and bone mineral density in 247 normal women, including 96 postmenopausal women ranging in age from 20-75 yr. A cubic polynomial regression best fit the relationship between age and serum osteocalcin (r = 0.32; n = 228; P = 0.0001) and urinary hydroxyproline/creatinine excretion (r = 0.40; n = 228; P = 0.0001), with both indices declining before the menopause, rising at the menopause, and subsequently falling through the seventh and eighth decades. While a significant decline in osteocalcin levels was observed in the postmenopausal group older than 60 yr, levels in subjects older than 60 yr remained higher (+31%) than those in late premenopausal subjects. Urinary calcium to creatinine excretion rose in the premenopausal years, increased markedly after the menopause, and remained at this level subsequently. Urinary hydroxyproline/creatinine, but not serum osteocalcin or urinary calcium/creatinine excretion, was a significant predictor of bone mineral density at the lumbar spine and the femoral neck independent of age. These data are consistent with the hypothesis that age-related bone loss after the menopause occurs in the presence of initially increased but subsequently decreasing bone turnover with maintenance of a relative excess of bone resorption.

Effects of low dose corticosteroids on bone mass in rheumatoid arthritis: a longitudinal study

Low dose corticosteroids are effective in suppressing synovitis in rheumatoid arthritis (RA), but there remains concern about their side effects, particularly osteoporosis. To examine the effects of low dose corticosteroids on bone loss in RA bone mineral density (BMD) was measured in the lumbar spine and hip for up to two years in 15 patients treated with these agents (mean dose prednis(ol)one 6.6 mg/day). 15 patients not receiving them, and 15 age matched controls. The initial BMD at both skeletal sites was significantly reduced in both patient groups compared with controls. The mean change in bone density was 0.2, 0.1, and -0.1% a year in the spine and -2.0, -1.9, and -1.0% a year in the hip respectively for the three groups. These rates of bone loss were not significantly different between groups at either site. These findings suggest that low dose corticosteroid treatment in RA is not associated with an increased risk of osteoporosis.

A simple method for assessing calcium intake in Caucasian women

Calcium intake has been implicated in the etiology of age-related osteoporosis. There is evidence to suggest that many postmenopausal women consume inadequate calcium to maintain calcium balance. One of the most accurate methods of calculating dietary intake is the weighed food record; however, that method is time consuming and unsuitable for large numbers of individuals. To determine the adequacy of calcium intake in the large numbers of postmenopausal women at risk of osteoporosis, simpler methods of assessing calcium intake are required. We therefore developed a food frequency questionnaire and tested it against a 4-day weighed food record in 54 Caucasian women, between 29 and 72 years of age. Twenty-six of the women (Group 1) completed a 4-day record and questionnaire within 1 week. Another 28 women (Group 2) completed the questionnaire 1 to 12 months after completing the 4-day food diary. A good correlation (r = .79, p less than .001) was found between the two methods of calculating calcium intake for the 54 women. Independent analysis of Group 1 and Group 2 showed correlation coefficients of 0.81 and 0.78, respectively. The correlation for postmenopausal women (r = .84) was similar to that of premenopausal women (r = .79). The data show that a short, simple questionnaire can be used to rank individuals according to adequacy of calcium intake as a prerequisite to nutrition intervention.

Effects of tobacco use on axial and appendicular bone mineral density

Tobacco use has been identified as being a risk factor for the development of osteoporosis. While some data have suggested an effect on peripheral bone mass there are little previous data examining the role of tobacco use in axial skeletal bone loss. We examined tobacco use in relation to lumbar spine and proximal femur bone mineral density and forearm bone mineral content in 203 women. Data from identical twin pairs, comprising a subgroup of the larger group as well as a small number of male twin pairs, was also analyzed. The data show a difference in lumbar and proximal femur BMD of 0.03 and 0.06 g/cm2 respectively between smoking and nonsmoking identical twins. There was however no difference in the cross-sectional studies and no significant deleterious effect detected of tobacco use on forearm bone mineral content. The effect of smoking on lumbar and proximal femur bone mineral density, in identical twins discordant for tobacco use, was equivalent on average to 3 to 4 years of normal postmenopausal bone loss.

Bone mineral density in Australia compared with the United States

Bone density measurements are currently being performed throughout the world in the diagnosis and management of osteoporosis as well as in research into this major health problem. However, it is not clear to what extent bone mineral density (BMD) values determined by dual-photon absorptiometry at one center can be applied to another. This is particularly relevant for the quantitative comparison of results from studies carried out in different laboratories. Furthermore, many centers now acquiring densitometers may not have the resources to determine their own normal range, relying instead on a "normal" range provided by the manufacturer. The question of the comparability of BMD data obtained in different centers was examined by comparing the normal range for the lumbar spine and proximal femur in 203 normal white Australian women and 892 normal white U.S. women, obtained using the same model densitometer. The two populations were compared according to decade. From superimposition of the Australian individual values on the North American normal ranges, only minor differences between the two populations were seen at any of the sites measured at any decade. None of these minor differences were statistically significant. This study shows a close similarity between BMD values in both the proximal femur and lumbar spine in normal white women in Australia and North America, provided the same model densitometer is used. Thus data obtained from different centers in populations with similar ethnic composition may be compared directly. These findings provide for the first time a sound basis for the quantitative comparison of the at times conflicting studies carried out in widely differing settings around the world.

The acute response of indium-111 labelled platelets to arteriotomy closure

A standard 40 mm arteriotomy was created in canine iliac and carotid arteries and then closed by either direct suture without a patch, with a vein patch or with a polytetrafluoroethylene patch (PTFE). The uptake of 111-Indium oxine labelled platelets at 2 hours after operation was compared between the groups. Arteriotomies closed with a PTFE patch demonstrated significantly greater platelet aggregation than those closed with a vein patch. Primary closure without a patch was associated with the least platelet uptake of all (PTFE versus vein patch, P less than 0.01; PTFE versus no patch, P less than 0.01; vein patch versus no patch, P less than 0.05). Light and electron microscopy confirmed the radioisotopic findings.

Serum insulin and bone density in normal subjects

A relationship between circulating insulin and bone mass has been postulated. To test this hypothesis we measured fasting serum insulin and quantitated bone density in the forearm, spine and femoral neck by single and dual photon absorptiometry of 70 normal women. There was no statistically significant relationship between insulin and bone density at any site by correlation or regression analysis. Although the relationship between a single measurement of a hormone (at one point in time) and bone density (the result of lifelong factors) should be interpreted with caution, our findings do not support the hypothesis that there is an association between serum insulin and bone mass.

Sex hormone status and osteoporosis in postmenopausal women with rheumatoid arthritis

Sex hormones have important effects on bone, especially in postmenopausal women. These hormones may be of particular significance in patients with rheumatoid arthritis (RA), who have a high frequency of osteoporosis. To examine this, we measured estrogen and androgen concentrations and bone mineral density (BMD) in 49 postmenopausal women with RA and 49 normal postmenopausal women. Compared with the controls, postmenopausal RA patients had significantly reduced levels of estrone (median 18 pmoles/liter versus 49; P less than 0.001), dehydroepiandosterone sulfate (DHEAS) (median 0.3 mumoles/liter versus 2.0; P less than 0.001), testosterone (median 0.6 nmoles/liter versus 0.95; P less than 0.001), and femoral BMD (mean 0.72 gm/cm2 versus 0.80; P less than 0.002). Prednisolone therapy in 22 patients (mean dosage 8 mg/day) was associated with reductions in estrone and testosterone levels; however, DHEAS and femoral BMD were also decreased in RA patients who were not receiving corticosteroids. Reduced DHEAS levels in postmenopausal women with RA may increase their risk of osteoporosis.

Nutritional intake of pre- and postmenopausal Australian women with special reference to calcium

Dietary factors, in particular calcium intake, have been implicated as risk factors in the aetiology of osteoporosis. In Australia there are few published data on the calcium intake of either premenopausal or postmenopausal women. The dietary intakes of calcium and 14 other nutrients were measured in 82 premenopausal and in 65 postmenopausal Caucasian women aged between 23 and 75 years. We found that 75 per cent of the postmenopausal and 61 per cent of the premenopausal women failed to meet the Australian recommended dietary allowance (RDA) for calcium of 1000 mg and 800 mg/d respectively. Moreover, 29 per cent of the postmenopausal women consumed less than 500 mg/d of calcium. Other nutrients including zinc, magnesium and iron were also deficient for many subjects. These data are relevant to the evaluation of dietary factors in the aetiology of osteoporosis.

Dietary intake and bone mineral density

Osteoporosis, a major health problem in all Western countries, is a condition in which many dietary factors have been implicated. To determine the influence of diet on bone mass in the proximal femur, the intake of 14 nutrients was measured in 159 Caucasian women, aged 23-75 years and bone mineral density (BMD) quantitated in the hip by dual photon absorptiometry. BMD was also measured in the spine and bone mineral content (BMC) in the forearm by single photon absorptiometry. No significant correlation was found between current calcium intake and bone mass at any site. Iron was a positive predictor of BMD in the femoral neck and alcohol intake a positive predictor of BMD in the trochanteric region of the proximal femur in premenopausal women by multiple regression analysis. Iron, zinc and magnesium intake were positively correlated with forearm BMC in premenopausal women. Iron and magnesium were significant predictors of forearm BMC in premenopausal and postmenopausal women respectively by multiple regression analysis. These results suggest that bone mass is influenced by dietary factors other than calcium.

Genetic determinants of bone mass in adults. A twin study

The relative importance of genetic factors in determining bone mass in different parts of the skeleton is poorly understood. Lumbar spine and proximal femur bone mineral density and forearm bone mineral content were measured by photon absorptiometry in 38 monozygotic and 27 dizygotic twin pairs. Bone mineral density was significantly more highly correlated in monozygotic than in dizygotic twins for the spine and proximal femur and in the forearm of premenopausal twin pairs, which is consistent with significant genetic contributions to bone mass at all these sites. The lesser genetic contribution to proximal femur and distal forearm bone mass compared with the spine suggests that environmental factors are of greater importance in the aetiology of osteopenia of the hip and wrist. This is the first demonstration of a genetic contribution to bone mass of the spine and proximal femur in adults and confirms similar findings of the forearm. Furthermore, bivariate analysis suggested that a single gene or set of genes determines bone mass at all sites.

Recovery from steroid-induced osteoporosis

The reversibility of steroid-induced osteoporosis, a major complication of Cushing syndrome and long-term use of exogenous corticosteroids, is not well documented. We measured the bone mineral density of lumbar vertebras and the femoral neck by dual-photon absorptiometry and determined the biochemical variables of bone turnover in two patients successfully treated for Cushing syndrome who were followed for the next 24 months. Our data are the first to show marked increases in bone density (up to 20%) during the recovery period. The accompanying biochemical changes, particularly the marked increase in serum osteocalcin levels, confirm that enhanced bone formation occurred during the recovery phase. These findings suggest that steroid-induced osteoporosis can be reversed at least in young persons.

Determinants of axial bone loss in rheumatoid arthritis

To assess mechanisms that cause generalized osteoporosis in rheumatoid arthritis (RA), we measured bone mineral density (BMD) by dual photon absorptiometry in the lumbar spine and femoral neck of 111 patients with RA. BMD was significantly reduced at both sites in these patients. Physical activity correlated significantly with BMD in patients with RA, and was found, by multiple regression analysis, to be a significant predictor of femoral bone density in female patients. Multiparity exerted a protective effect on lumbar bone density. Prednisolone (mean dosage 8 mg/day) was not associated with significantly increased bone loss in women, whereas higher dosages in men (mean 10.3 mg/day) were associated with increased lumbar bone loss. Reduced physical activity leading to a form of disuse osteoporosis appears to be an important factor in axial bone loss in RA.

Computer modeling and analysis of cross-sectional bone density studies with respect to age and the menopause

Controversy exists about rates of bone mineral loss from the lumbar spine at the menopause. Cross-sectional studies of lumbar bone mineral against age have been interpreted as evidence for or against a menopause-related change in lumbar bone loss, depending on their goodness of fit to either linear or nonlinear equations. To investigate the ability of cross-sectional studies to detect accelerated lumbar bone loss at the menopause, we constructed models of different patterns of loss and evaluated the findings in cross-sectional analyses of computer-simulated populations of normal women. A sample size of greater than 300 was needed to distinguish between linear and nonlinear patterns of bone loss with a power of 90% when the data was analyzed throughout life. Examining for differences between the slopes of the regressions of pre- and postmenopausal women was more useful for detecting nonlinear bone loss under some circumstances. A difference between slopes was apparent in studies containing 100 subjects if lumbar bone density (BMD) was assumed to be unchanged prior to the menopause, but a larger study size was needed (greater than 1000) if BMD was assumed to fall before the menopause. We also measured lumbar BMD by dual photon absorptiometry in 141 normal females. When the data was analyzed against age throughout life, a nonlinear pattern of bone loss was found, and comparison of pre- and postmenopausal subjects showed a significant difference in the slopes of the linear regressions. Our patient data support the concept of a relatively stable lumbar BMD prior to the menopause with a rapid but transient decline postmenopausally.(ABSTRACT TRUNCATED AT 250 WORDS)

Dual-photon bone densitometry in normal Australian women: a cross-sectional study

Osteoporosis is a major health problem in Australia, as it is in most Western societies. Bone mineral density in the spine and femoral neck are accurate indicators of osteopenia and thus useful indicators of the risk of a fracture. Dual-photon absorptiometry is a non-invasive technique that allows the accurate quantitation of bone mineral density in the lumbar vertebrae and proximal femur with a low radiation exposure. The increasing availability of this technique dictates the requirement for "normal" ranges and quality control. We report here lumbar vertebral and proximal femur bone mineral density as measured by dual-photon absorptiometry in 179 normal Australian women. Forearm bone mineral content in these subjects, as measured by single-photon absorptiometry, is also presented. There was a relative stability of lumbar bone mineral density and forearm bone mineral content before the menopause, after which there was an age-related decline. On the other hand, bone mineral density at all three sites in the proximal femur showed an age-related decline throughout adult life. Intraoperator variability in calculated bone mineral density did not exceed 2.3%. The requirement for correct positioning of the patient is illustrated. The data allow statistical analysis and the development of normal ranges. They provide an Australian base against which individual patient values can now be compared.

Osteoporosis in rheumatoid arthritis: safety of low dose corticosteroids

Fear of inducing generalised osteoporosis is one reason why corticosteroids are withheld in patients with rheumatoid arthritis (RA). No studies, however, have directly measured bone density in such patients at clinically relevant sites. To assess this risk we measured bone mineral density in the lumbar spine and femoral neck by dual photon absorptiometry in 84 patients with RA, 44 of whom had been treated with low dose prednis(ol)one (mean dose +/- SE 8.0 +/- 0.5 mg/day; mean duration of treatment 89.6 +/- 12.0 months). There were significant reductions in bone mineral density in patients treated with corticosteroids (lumbar 9.6%, p less than 0.001; femoral 12.2%, p less than 0.001) and in those who had not received corticosteroids (lumbar 6.9%, p less than 0.01; femoral 8.9%, p less than 0.001), but the differences between the two groups were not significant. We conclude on the basis of these studies that low dose oral corticosteroids do not increase the risk of generalised osteoporosis in patients with rheumatoid arthritis.

Physical fitness is a major determinant of femoral neck and lumbar spine bone mineral density

The relationship between physical fitness and bone mass in the femoral neck, lumbar spine, and forearm was studied in 84 normal women. Femoral neck and lumbar spine bone mineral density and forearm bone mineral content were estimated by absorptiometry. Fitness was quantitated from predicted maximal oxygen uptake. Femoral neck and lumbar bone mineral density were significantly correlated with fitness as well as age and weight. In the 46 postmenopausal subjects, fitness was the only significant predictor of femoral neck bone mineral density, and both weight and fitness predicted the lumbar bone mineral density. These data represent the first demonstration of a correlation between physical fitness, and, by implication, habitual physical activity, and bone mass in the femoral neck; they also support the previous reported correlation between lumbar bone mass and physical activity. The data suggest that increased physical fitness may increase bone mass at the sites of clinically important fractures in osteoporosis.

Limitations of forearm bone densitometry as an index of vertebral or femoral neck osteopenia

Osteoporosis of the spine and femoral neck is a major problem in aging populations, but detection prior to a fracture remains a challenge. Forearm bone mineral content has been advocated as a useful screening test in this situation. We have examined the correlation between distal forearm bone mineral content, by single photon absorptiometry, and lumbar vertebral and femoral neck bone mineral density, by dual photon absorptiometry. Eighty women aged 20 to 76 years were studied and significant correlations (p less than .001) were found between the measurements on the forearm and at the two axial sites (r = 0.66 and 0.69, respectively). However, forearm bone mineral content was an unreliable predictor of axial bone mineral density. For prediction of lumbar spine osteopenia with a sensitivity of 88%, the false positive rate was 91%. Conversely, to achieve a specificity of 82%, the false negative rate was 65%. Similarly, for prediction of femoral neck osteopenia at a sensitivity of 92%, the false positive rate was 87%, and at a specificity of 90%, the false negative rate was 33%. These data demonstrate that forearm bone densitometry cannot be used as a screening procedure for osteopenia of the lumbar spine or femoral neck.