The role of dual energy X-ray absorptiometry of lumbar spine and proximal femur in the diagnosis and follow-up of osteoporosis

Prudent and traditional dietary patterns are positively and negatively associated with bone mineral density in Iranian adults, respectively

To assess the association of dietary patterns and bone mineral density (BMD), 340 healthy Iranian adults (mean age 41.5 ± 7.7 y; 79.1% female) participated in this cross-sectional study. Lumbar spine and femoral neck BMDs were measured using dual-energy X-ray absorptiometry. Dietary intakes were evaluated by a valid and reliable 168-item food frequency questionnaire, and three major dietary patterns were identified using principal component factor analysis. Mean values for lumbar spine and femoral neck BMDs in participants were 0.96 ± 0.13 and 0.92 ± 0.12 g/cm², respectively. After controlling for age, body mass index, physical activity, energy intake, sunlight exposure, gender, education, employment status, supplement intake, and smoking in the analysis of covariance models, multivariable adjusted means of femoral neck BMD of participants in the highest tertile of the prudent pattern score (rich in green leafy vegetables, other vegetables, tomatoes, yellow vegetables, fruits and fruit juices, olives, nuts, fish, low-fat dairy products, and Doogh) were significantly higher than those in the lowest tertile (mean difference and 95% CI: 0.043 [0.003; 0.083] g/cm², P = 0.032). In contrast, multivariable adjusted means of lumbar spine BMD of participants in the highest tertile of the traditional pattern score (high in Abgoosht, vegetable oils, salt, legumes, pickles, cruciferous vegetables, refined grains, potatoes, and organ meats) were significantly lower than those in the lowest tertile (mean difference and 95% CI: -0.057 [-0.098; -0.015] g/cm², P = 0.003). The Western pattern was not associated with BMD. In conclusion, the prudent and traditional dietary patterns are positively and negatively associated with BMD in Iranian adults, respectively.

Preoperative dual-energy X-ray absorptiometry and FRAX in patients with lumbar spinal stenosis

Background

Osteoporosis implies an increased risk of complications after orthopedic surgery. For the mostly elderly group of patients undergoing lumbar spinal stenosis surgery (LSS), it is important to include skeletal health evaluation in the preoperative planning. The aim of this study was to assess spine and femoral neck (FN) bone mineral density (BMD) in LSS patients and to evaluate whether the World Health Organization (WHO) fracture risk assessment tool (FRAX) can identify patients with reduced BMD levels in the spine.

Methods

The study involved 65 LSS patients and 53 patients with hip osteoarthritis (HOA) for comparison. BMD was measured with dual-energy X-ray absorptiometry (DXA) in the lumbar spine in three projections: anterior-posterior (AP), lateral and lateral-mid (the mid-portion of the vertebrae), and FN. The LSS patients filled out the FRAX questionnaire.

Results

In the LSS group, 43% of the women and 8% of the men were classified as being osteoporotic/osteopenic by AP spine measurement. The corresponding proportions using the lateral spine T-score ≤ − 2.5 were 87% and 57%, respectively, and 82% and 53%, respectively, for the FN. The FN BMD T-score was significantly lower in the LSS group compared with the HOA group. The FRAX questionnaire identified 40% of the LSS patients with a moderate/high risk of sustaining an osteoporotic fracture within 10 years, with or without simultaneous FN BMD, while 71% of these patients were classified as being osteoporotic with DXA lateral spine measurement.

Conclusion

It is common with osteoporosis/osteopenia in patients undergoing spine surgery, and the identification may influence the surgical treatment why the evaluation of BMD is important preoperatively. FRAX evaluation could not replace DXA measurement of the spine regarding the identification of osteoporosis patients in the preoperative planning phase.

Interpretation of hip fracture patterns using areal bone mineral density in the proximal femur

INTRODUCTION

Bone mineral density scans are currently interpreted based on an average score of the entire proximal femur. Improvements in technology now allow us to measure bone density in specific regions of the proximal femur. The study attempts to explain the pathophysiology of neck of femur (NOF) and intertrochanteric/basi-cervical (IT) fractures by correlating areal BMD (aBMD) scores with fracture patterns, and explore possible predictors for these fracture patterns.

MATERIALS AND METHODS

This is a single institution retrospective study on all patients who underwent hip surgeries from June 2010 to August 2012. A total of 106 patients (44 IT/basi-cervical, 62 NOF fractures) were studied. The data retrieved include patient characteristics and aBMD scores measured at different regions of the contralateral hip within 1 month of the injury. Demographic and clinical characteristic differences between IT and NOF fractures were analyzed using Fisher's Exact test and two-sample t test. Relationship between aBMD scores and fracture patterns was assessed using multivariable regression modeling.

RESULTS

After adjusted multivariable analysis, T-Troc and T-inter scores were significantly lower in intertrochanteric/basi-cervical fractures compared to neck of femur fractures (P = 0.022 and P = 0.026, respectively). Both intertrochanteric/basi-cervical fractures (mean T.Tot -1.99) and neck of femur fractures (mean T.Tot -1.64) were not found to be associated with a mean T.tot less than -2.5. However, the mean aBMD scores were consistently less than -2.5 for both intertrochanteric/basi-cervical fractures and neck of femur fractures. Gender and calcium intake at the time of injury were associated with specific hip fracture patterns (P = 0.002 and P = 0.011, respectively).

CONCLUSIONS

Hip fracture patterns following low energy trauma may be influenced by the pattern of reduced bone density in different areas of the hip. Intertrochanteric/basi-cervical fractures were associated with significantly lower T-Troc and T-Inter scores compared to neck of femur fractures, suggesting that the fracture traversed through the areas with the lowest bone density in the proximal femur. In the absence of reduced T.Troc and T.Inter, neck of femur fractures occurred more commonly. T-Total scores may underestimate the severity of osteoporosis/osteopenia and measuring T-score at the neck of femur may better reflect the severity of osteoporosis and likelihood of a fragility fracture.

Propolis accelerates the consolidation phase in distraction osteogenesis

We evaluated the effect of propolis on new bone formation after distraction osteogenesis (DO). This study examined 3 groups: control group, P100, and P200. Rabbits underwent DO of the left mandible after an osteotomy between the first molar and the mental foramen. Bone mineral content and bone mineral density were evaluated using dual-energy x-ray absorption 1 and 4 weeks after the procedure. The volume of connective tissue and new bone and the number of capillaries were measured using stereologic analysis after the subjects were killed. Dual-energy x-ray absorption showed that the bone mineral content and bone mineral density were higher in the groups treated with propolis by week 4, and these parameters were higher in the P200 group. Stereologic analysis showed no significant differences in connective tissue volume and number of capillaries among the groups. New bone volume was lowest in the P200 group. We concluded that propolis accelerates bone formation and may shorten the consolidation phase with DO.

Motor speed and lower extremity strength as predictors of fall-related bone fractures in elderly individuals

BACKGROUND AND AIMS

The purpose of this prospective population-based study was to examine the combined effects of motor speed and knee extension strength on risk of fall-related bone fractures in elderly individuals over a 10-year period.

METHODS

Participants were 307 men and women aged 75 or 80 years at baseline, who visited the research laboratory at the University of Jyväskylä, Finland. Multi-choice motor speed tests and maximal isometric knee extension strength tests were carried out at baseline. Information on fractures was collected from hospital and health center records. The presence of impairment was defined as a score in the lowest tertile of sex- and age-stratified distribution of results in each test.

RESULTS

During the 10-year period, 93 participants had at least one fracture. In Cox proportional hazards models for motor speed and knee extension strength, the risk of fracture was almost double in the lowest vs the highest tertile of each test score. For those in the poorest speed and strength tertiles compared with the best speed and strength tertiles, the relative risk of fracture adjusted for age, sex and bone mineral density was 4.69 (95% confidence interval 1.72-12.81).

CONCLUSIONS

Increased risk of fracture was observed for those with either slow motor speed or poor lower extremity strength; however, a combination of these impairments increased the fracture risk significantly when compared with those with no impairments. A co-impairment approach may prove useful in gaining better understanding of the risk of fall-related bone fractures and the development of effective interventions.

Patient variables impact lumbar spine dual energy X-ray absorptiometry precision

INTRODUCTION

Changes in bone mineral density are used to monitor osteoporosis therapy. To determine whether a change in bone mass is clinically significant, the precision of bone mineral density measurements must be known.

METHODS

We therefore measured the impact of vertebral body exclusion on dual energy X-ray absorptiometry (DXA) precision. At one university and one Veterans Affairs DXA center, three radiology technologists each scanned 30 participants twice, with repositioning between scans, to estimate DXA precision. Three International Society for Clinical Densitometry-certified physicians reviewed all lumbar spinal scans to note the presence of focal structural defects. We calculated precision for subsets of vertebrae, and for virtual samples of patients with and without physician-identified vertebral focal structural defects. We graphed the reciprocal of least significant change versus bone area to determine the dependence of precision on interpreted scan area.

RESULTS

Within each sample, greater interpretable bone area improved precision. The contribution of interpreted bone area to precision differed among the samples, ranging from 57 to 94%. Greater population bone mineral density heterogeneity and presence of focal structural defects each decreased precision.

CONCLUSION

All bone densitometry centers must determine precision using a sample representative of their served populations. Failure to do so may lead to incorrect determination of least significant change. Population heterogeneity, vertebral body exclusion and presence of focal structural defects each decreases precision.

The insulin-like growth factor-I gene and osteoporosis: a critical appraisal

Osteoporosis, a disorder of skeletal fragility, is common in the elderly, and its prevalence is increasing as more individuals with low bone mineral density (BMD), the strongest predictor of fracture risk, are detected. Previous basic and clinical studies imply there is a significant role for insulin-like growth factor-I (IGF-I) in determining BMD. Recently, polymorphisms upstream of the P1 promoter region of the human IGF-I gene have been found to be associated with serum levels of IGF-I, BMD and fracture risk in various ethnic groups. Multiple quantitative trait loci (QTLs) have been identified that underlie serum IGF-I in a mouse intercross between two inbred strains. The most promising QTL on mouse chromosome 6 has provided clues for unraveling the molecular mechanisms that regulate osteoblast differentiation. Genomic engineering resulting in IGF-I deficient mice, and mice with targeted over-expression of IGF-I reinforce the essential role of IGF-I in bone development at both the embryonic and postnatal stages. Thus, it is apparent that significant new insights into the role of the IGF-I gene in bone remodeling occur through several distinct mechanisms: (1) the skeletal IGF regulatory system; (2) the systemic growth hormone/IGF-I axis; (3) parathyroid hormone signaling; (4) sex steroids; and (5) the OPG/RANKL/RANK cytokine system. Molecular dissection of the IGF regulatory system and its signaling pathway in bone may reveal novel therapeutic targets for the treatment of osteoporosis.

Gene variants for osteoporosis and their pleiotropic effects in aging

The prevalence of osteoporosis is raising worldwide as improving conditions of living and treatment of other common diseases continuously increases life expectancy. Thus, osteoporosis affects most women above 80 years of age and, at the age of 50, the lifetime risk of suffering an osteoporosis-related fracture approaches 50% in women and 20% in men. Numerous genetic, hormonal, nutritional and life-style factors contribute to the acquisition and maintenance of bone mass. Among them, genetic variations explain as much as 70% of the variance for bone mineral density (BMD) in the population. Dozens of quantitative trait loci (QTLs) for BMD have been identified by genome screening and linkage approaches in humans and mice, and more than 100 candidate gene polymorphisms tested for association with BMD and/or fracture. Sequence variants in the vitamin D receptor (VDR), collagen 1 alpha 1 chain (Col1A1), estrogen receptor alpha (ESR1), interleukin-6 (IL-6) and LDL receptor-related protein 5 (LRP5) genes were all found to be significantly associated with differences in BMD and/or fracture risk in multiple replication studies. Moreover, some genes, such as VDR and IL-6, were shown to interact with non-genetic factors, i.e. calcium intake and estrogens, to modulate BMD. Since these gene variants have also been associated with other complex disorders, including cancer and coronary heart disease, they may represent common genetic susceptibility factors exerting pleiotropic effects during the aging process.

Lebanese guidelines for osteoporosis assessment and treatment: who to test? What measures to use? When to treat?

With the demographic explosion of the population worldwide, the human, social, and economic costs of osteoporosis will continue to rise. It is estimated that the magnitude of the problem might be even larger in developing countries, including those in the Middle East. Although several organizations and countries have developed or adapted guidelines to their local needs, as of today there are no guidelines for osteoporosis assessment in the Middle East. In April 2002, a panel of osteoporosis experts met and discussed practice guidelines for osteoporosis assessment and treatment in Lebanon. The process, which involved an overview of international guidelines as well as local data on osteoporosis, resulted in a draft for Lebanese guidelines that addressed three main questions: "Who to test?" "What measures to use?" and "When to treat?". Representatives from five major Lebanese societies (Endocrinology, Rheumatology, Orthopedics, Obstetrics and Gynecology, and Radiology) subsequently reviewed, discussed, and officially endorsed the guidelines after revisions. The Lebanese guidelines were also endorsed by the Eastern Mediterranean branch of the World Health Organization.

Effect of loading rate on endplate and vertebral body strength in human lumbar vertebrae

Previous studies have implied that increases in loading rate resulted in changes in vertebral mechanical properties and these changes were causative factors in the different fracture types seen with high-speed events. Thus many researchers have explored the vertebral body response under various loading rate conditions. No other study has investigated the role of the endplate in high-speed vertebral injuries. The current study determined changes in the endplate and vertebral body strength with increases in displacement rate. The endplate and vertebral body failure loads in individual lumbar vertebrae were documented for two displacement rates: 10 and 2500 mm/s. Using cross-sectional areas from the endplate and vertebral body, failure stresses for both components were calculated and compared. Both the endplate and vertebral body failure loads increased significantly with increased loading rate (p<0.005). Although the vertebral body failure stress increased significantly with loading rate as well (p<0.01), the endplate stresses did not (p>0.35). In addition, the endplate and vertebral strengths were not significantly different under high-speed loading (p>0.60), which inhibits possible predictions as to which bony component would fail initially during a high-speed injury event. It is possible that load distribution may contribute more to the fracture patterns seen at high speeds over vertebral component strength.

Correlates of low bone density in females with anorexia nervosa

The objectives were to delineate those factors which correlate with low bone density in patients with anorexia nervosa and in turn to predict those at greatest risk for osteopenia.

DESIGN

Bone density was evaluated by dual energy x-ray absorptiometry in 28 postmenarchal females with anorexia nervosa who had never received hormonal therapy. Bone density results were correlated with specific historical and physical factors utilizing descriptive statistics, scatter plots, and the Spearman correlation coefficient.

RESULTS

Mean age was 18.6 years, mean age at menarche was 12.9 yrs, mean length of illness was 19.8 months and mean duration of amenorrhea was 13.4 months. Mean % ideal body weight was 84% at the time of bone density, 75% at minimum weight and 100% at maximum weight. Mean lumbar spine bone density was -1.69 standard deviations from the norm; mean lateral spine bone density was -1.45 standard deviations from the norm; mean femoral neck of the hip bone density was -1.18 standard deviations from the norm. There was a strong negative correlation between duration of amenorrhea and bone density at the lumbar spine (r = -0.50, p < .01) and a mild correlation at the lateral spine (r = -0.49, p < 0.05) and femoral neck (r = -0.41, p < 0.05). There was also a strong negative correlation between length of illness and bone density at the lumbar spine (r = -0.53, p < 0.01) and lateral spine (r = -0.77, p < 0.0001), and a mild correlation with the femoral neck (r = -0.48, p < 0.05). Scatter plots of lumbar bone density versus duration of amenorrhea, and versus length of illness clearly showed not only that longer duration of amenorrhea and longer length illness correlated to bone loss, but also strikingly that within a short time of being ill and amenorrheic, significant bone loss was seen. Age, and age at menarche correlated mildly with osteopenia at the lateral spine; age correlated mildly with osteopenia at the femoral neck as well. There was a trend for minimum BMI to correlate with osteopenia at the lateral spine. There were no correlations of bone density with % IBW at bone density, minimum % IBW, maximum % IBW, change in % IBW, BMI at the time of the bone density, maximum BMI or change in BMI.

CONCLUSIONS

Low bone density, especially in the lumbar spine, correlated with both a longer duration of amenorrhea and longer length of illness, but not with other factors, in our patients with anorexia nervosa. As many of these patients, even those with a short duration of illness and amenorrhea, were osteopenic, it is advisable to continue to perform bone density studies in all patients with anorexia nervosa, on both a clinical and research basis.

Markers of bone turnover in postmenopausal women receiving hormone replacement therapy

We investigated the effects of hormone replacement therapy (n = 27) on biochemical markers of bone turnover in a cross-sectional study of 127 postmenopausal women (according to WHO guidelines 18 patients had normal bone mineral density and 109 suffered from bone loss). Urinary excretion of free deoxypyridinoline and C- or N-telopeptide fragments of type I collagen served as bone resorption markers, serum osteocalcin as a bone formation marker. In women with no hormone replacement therapy, only C- and N-telopeptides correlated significantly with the lumbal T-score as an index for bone mineral density. Patients with bone loss receiving hormone replacement therapy exhibited significantly lower C-telopeptide, N-telopeptide and osteocalcin levels than those with no therapy (mean -45%, -43% and -26%, respectively), while deoxypyridinoline showed no significant differences. Among the markers investigated, C- and N-telopeptides seemed to be more reliable to detect therapeutic effects on bone metabolism. We present a preliminary model to evaluate bone turnover and resorption/formation rate.

Effect of distraction rate on biomechanical, mineralization, and histologic properties of an ovine mandible model

Craniofacial microsomia is a common congenital malformation. Ilizarov's method of distraction osteogenesis applied to the mandible has yielded promising results both experimentally and clinically. Because the technique is used predominantly in a pediatric population, length of treatment and compliance may be problematic. To date, the limits of distraction rate in the craniofacial skeleton have not been defined. This study was designed to investigate the effects of distraction rate, in a large animal model, on the mineralization, biomechanical, and histologic properties of lengthened mandibles. Clinically faster distraction rates would decrease the overall treatment time. Twenty-four animals were divided into four groups, with varying rates of distraction (1, 2, 3, and 4 mm/day). A uniaxial distractor at the angle of the mandible was used. The mandibles were lengthened to 24 mm and fixed for a period of 5 weeks, when the animals were killed. The specimens were analyzed with respect to mineralization using dual energy x-ray absorptiometry, biomechanical strength, through a modified three-point bending test, and histologic properties with hematoxylin and eosin stains. Biomechanical, mineralization, and histologic analyses of the samples indicated that group 1 (1 mm/day) samples were significantly superior (p<0.05) to those of group 4 (4 mm/day). Although bone formation was achieved in all groups, group 1 (1 mm/day) demonstrated the strongest biomechanical and histologic properties. Bone mineral density obtained using dual energy x-ray absorptiometry may be clinically useful as a reliable, noninvasive, and relatively cheap predictor for removal time of the fixator.

Genetic aspects of osteoporosis

At a given age, bone mass represents the difference between the maximal amount of bone mineral mass gained during growth (peak bone mass) and post-menopausal and/or senile bone loss. Twins and parents-offspring models have shown a strong inheritance of peak bone mass and it is now known that familial resemblance in various bone mass constituents is detectable well before the pubertal growth spurt. Recent developments in the molecular epidemiology of osteoporosis have focused on the association between areal bone mineral density and common polymorphisms in several candidate genes. Among them, vitamin D receptor (VDR), estrogen receptor and collagen-1 -alpha-1 (COL1A1) genes have been the most extensively investigated. Although controversial results have been reported and osteoporosis cannot be predicted by any single polymorphic gene marker, recent advances in this field have emphasized the complexity of bone mineral mass determination, because of gene-gene and gene-environment interactions.

Moments and forces during pedicle screw insertion. In vitro and in vivo measurements

STUDY DESIGN

Moments and forces during pedicle screw insertion were measured in vivo and in vitro and were correlated to several parameters of the screw-bone interface.

OBJECTIVES

To compare the in vitro and in vivo screw insertion loads and to relate these measurements to bone mineral density, pedicle size, and other screw parameters (material, diameter).

SUMMARY OF BACKGROUND DATA

The in vitro screw insertion torque has been correlated to the screw pullout forces and the number of cycles to ultimate interface failure. However, there are no comparable in vivo data.

METHODS

One hundred three pedicle screws were included in the study, 43 in vivo and 60 in vitro. Duel-energy x-ray absorptiometry boen mineral density data were available for 20 in vivo and 32 in vitro specimens. A custom-made sterilizable six-axis load cell was integrated into a torque wrench, enabling the recording of the applied moments and forces during screw insertion. Statistical analysis was performed to detect differences and correlations.

RESULTS

The mean in vivo insertion torque (1.29 Nm) was significantly greater than the in vitro value (0.67 Nm). The linear correlation between insertion torque and bone mineral density was significant for the in vitro data but not for the in vivo data. No correlation was observed between insertion torque and pedicle diameter. Two patterns of torque were observed during the insertion process.

CONCLUSIONS

There is a significant difference between the insertion loads measured in vivo and those measured in vitro. Additional research is needed to verify whether this method provides an indication of screw fixation quality.

Heritable and nutritional influences on bone mineral mass

Osteoporosis is the net result of the maximal amount of bone mineral mass achieved by the end of pubertal growth (peak bone mass) minus post-menopausal and elderly bone losses. Peak bone mineral mass is determined from early childhood by both heritable and environmental factors. Recent developments in the molecular epidemiology of osteoporosis have shown the interest, but also the limitations, of specific molecular markers, such as the vitamin D receptor gene polymorphisms Bsm 1 and Fok 1, to explain bone mineral density differences across the population. Importantly, however, interactions between VDR gene polymorphisms and environmental factors, particularly dietary calcium, have provided new insights into the complex determination of bone mineral mass.

The epidemiology and pathogenesis of osteoporosis

Osteoporosis is an increasing health care concern as populations age throughout the developed and developing world. The social and economic costs of osteoporosis are due to its clinical outcome of fracture which increases exponentially with age. This review will highlight some of the key epidemiological aspects of osteoporosis incorporating areas of more recent interest. These include the definition; the magnitude of the problem encompassing differing incidence and prevalence patterns of both low bone mass and fracture in different cultural groups; the social consequences of fracture, including economic costs, morbidity and mortality; the evaluation of fracture risk, including the role of bone density, bone quality and the risk of falling; as well as an overview of some of the factors involved in determining low bone mass. Bone mineral density (BMD) is the most easily measured and accurate predictor of fracture risk. For any individual, BMD is the combination of their peak bone density and subsequent bone loss, both of which are influenced by genetic, hormonal and environmental factors. An understanding of key issues relating to this important disease may lead to earlier detection of the individual at high risk for fracture and rational approach to prevention and management.

The relative importance of vertebral bone density and disc degeneration in spinal flexibility and interbody implant performance. An in vitro study

STUDY DESIGN

An in vitro biomechanical investigation in the human lumbar spine focuses on the functional significance of vertebral bone density and intervertebral disc degenerations.

OBJECTIVE

To determine that interrelationship between vertebral bone density and intervertebral disc degeneration, their effect on normal spine motion, and their significance in the biotechnical performance of interbody fixation techniques.

SUMMARY OF BACKGROUND DATA

A relationship between vertebral bone density and intervertebral disc degeneration has been suggested, but a definitive relationship has not been established. The effect of vertebral bone density and intervertebral disc degeneration on interbody stabilization remains unknown despite the rapidly increasing use of this surgical method for patients with chronic low back pain.

METHODS

The vertebral bone density and intervertebral disc degeneration of 72 functional spinal units were determined using dual energy x-ray absorptiometry scans and macroscopic grading, respectively. A three-dimensional flexibility test was performed on 24 functional spinal units in the intact and stabilised conditions. The compressive behavior of the bone-implant interface was evaluated in 48 functional spinal units.

RESULTS

The vertebral bone density in moderately degenerated disc was significantly lower than at all other levels of intervertebral disc degeneration. Increasing intervertebral disc degeneration resulted in more axial rotation and less lateral bending. In flexion-extension and lateral bending, better vertebral bone resulted in significantly better stabilization. This trend was observed also in axial compression in which higher failure loads were observed with greater bone densities.

CONCLUSION

The authors conclude a significant relationship exists between bone density and disc degeneration, bone density is a highly important factor in the performance of interbody stabilization, and disc degeneration, is of moderate importance in signal motion.

DXA scanning

The steady improvement in densitometric technique is reviewed in this paper culminating in the newest generation of DXA scanners. The suitability of the lumbar spine, femur and hand as sites for the densitometric measurement of bone loss in rheumatoid disease is assessed. The recent improvement in hand scanning technique using DXA has led to improved clinical utility in the detection of juxta-articular bone loss. The enhanced resolution offered by the newest, solid state detector DXA scanners, and their ability to detect bone loss where no systemic features are evident, makes it possible that DXA scanning of the hand will be a useful modality for the monitoring of early rheumatoid disease.

Classification of osteoporosis in the elderly is dependent on site-specific analysis

Vertebral osteoporosis accounts for over 500,000 spinal fractures annually, the majority of which occur in older women. Despite these statistics, data regarding the rate of spinal bone loss in this population are conflicting. Moreover, the site of skeletal evaluation may significantly alter classification of osteoporosis in this age group. To examine trabecular-rich spinal bone loss with a measurement less affected by age-related artifacts than the AP spine, we measured lateral lumbar spine bone density (BMD) using dual-energy X-ray absorptiometry in 120 healthy, ambulatory, community-dwelling women 65 years of age and older (mean 70 +/- 5 years, range 65-88). We also examined cortical-rich sites in the forearm and total body along with AP spine and femoral BMD to assess the impact of site specificity using the World Health Organization (WHO) classification of osteoporosis. Significant losses in BMD were observed at the lateral spine (-1.1%/year, P < 0.01), forearm (-0. 77%/year, P </= 0.01), total hip (-0.75%/year, P </= 0.01), femoral neck (-0.70%/year, P </= 0.05), and trochanter (-0.78%/year, P </= 0. 01), but not the AP spine. Using the WHO criteria, lateral spine BMD determinations classified 66% of women with osteoporosis in contrast to 29% using the AP projection. Osteoporosis was diagnosed in 55% of women using measurements of the femoral neck, 43% using the total radius, and 19% using the total body. We conclude that elderly women lose bone at trabecular- and cortical-rich sites (lateral spine and total radius, respectively) in addition to sustaining significant age-related bone loss at mixed cortical/trabecular sites such as the hip. Classification of osteoporosis in this age group more than doubles using lateral versus AP spinal projections, supporting the necessity of developing more uniform agreement on site-specific analyses.