BMD at multiple sites and risk of fracture of multiple types: long-term results from the Study of Osteoporotic Fractures

Feasibility of three-dimensional MRI of proximal femur microarchitecture at 3 tesla using 26 receive elements without and with parallel imaging

PURPOSE

High-resolution imaging of deeper anatomy such as the hip is challenging due to low signal-to-noise ratio (SNR), necessitating long scan times. Multi-element coils can increase SNR and reduce scan time through parallel imaging (PI). We assessed the feasibility of using a 26-element receive coil setup to perform 3 Tesla (T) MRI of proximal femur microarchitecture without and with PI.

MATERIALS AND METHODS

This study had institutional review board approval. We scanned 13 subjects on a 3T scanner using 26 receive-elements and a three-dimensional fast low-angle shot (FLASH) sequence without and with PI (acceleration factors [AF] 2, 3, 4). We assessed SNR, depiction of individual trabeculae, PI performance (1/g-factor), and image quality with PI (1 = nonvisualization to 5 = excellent).

RESULTS

SNR maps demonstrate higher SNR for the 26-element setup compared with a 12-element setup for hip MRI. Without PI, individual proximal femur trabeculae were well-depicted, including microarchitectural deterioration in osteoporotic subjects. With PI, 1/g values for the 26-element/12-element receive-setup were 0.71/0.45, 0.56/0.25, and 0.44/0.08 at AF2, AF3, and AF4, respectively. Image quality was: AF1, excellent (4.8 ± 0.4); AF2, good (4.2 ± 1.0); AF3, average (3.3 ± 1.0); AF4, nonvisualization (1.4 ± 0.9).

CONCLUSION

A 26-element receive-setup permits 3T MRI of proximal femur microarchitecture with good image quality up to PI AF2.

The effect of fall prevention exercise programmes on fall induced injuries in community dwelling older adults: systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To determine whether, and to what extent, fall prevention exercise interventions for older community dwelling people are effective in preventing different types of fall related injuries.

DATA SOURCES

Electronic databases (PubMed, the Cochrane Library, Embase, and CINAHL) and reference lists of included studies and relevant reviews from inception to July 2013.

STUDY SELECTION

Randomised controlled trials of fall prevention exercise interventions, targeting older (>60 years) community dwelling people and providing quantitative data on injurious falls, serious falls, or fall related fractures.

DATA SYNTHESIS

Based on a systematic review of the case definitions used in the selected studies, we grouped the definitions of injurious falls into more homogeneous categories to allow comparisons of results across studies and the pooling of data. For each study we extracted or calculated the rate ratio of injurious falls. Depending on the available data, a given study could contribute data relevant to one or more categories of injurious falls. A pooled rate ratio was estimated for each category of injurious falls based on random effects models.

RESULTS

17 trials involving 4305 participants were eligible for meta-analysis. Four categories of falls were identified: all injurious falls, falls resulting in medical care, severe injurious falls, and falls resulting in fractures. Exercise had a significant effect in all categories, with pooled estimates of the rate ratios of 0.63 (95% confidence interval 0.51 to 0.77, 10 trials) for all injurious falls, 0.70 (0.54 to 0.92, 8 trials) for falls resulting in medical care, 0.57 (0.36 to 0.90, 7 trials) for severe injurious falls, and 0.39 (0.22 to 0.66, 6 trials) for falls resulting in fractures, but significant heterogeneity was observed between studies of all injurious falls (I(2)=50%, P=0.04).

CONCLUSIONS

Exercise programmes designed to prevent falls in older adults also seem to prevent injuries caused by falls, including the most severe ones. Such programmes also reduce the rate of falls leading to medical care.

Evaluating bone quality in patients with chronic kidney disease

Bone of normal quality and quantity can successfully endure physiologically imposed mechanical loads. Chronic kidney disease-mineral and bone disorder (CKD-MBD) adversely affects bone quality through alterations in bone turnover and mineralization, whereas bone quantity is affected through changes in bone volume. Changes in bone quality can be associated with altered bone material, structure, or microdamage, which can result in an elevated rate of fracture in patients with CKD-MBD. Fractures cannot always be explained by reduced bone quantity and, therefore, bone quality should be assessed with a variety of techniques from the macro-organ level to the nanoscale level. In this Review, we demonstrate the importance of evaluating bone from multiple perspectives and hierarchical levels to understand CKD-MBD-related abnormalities in bone quality. Understanding the relationships between variations in material, structure, microdamage, and mechanical properties of bone in patients with CKD-MBD should aid in the development of new modalities to prevent, or treat, these abnormalities.

Development of an Inertia-Driven Model of Sideways Fall for Detailed Study of Femur Fracture Mechanics

A new method for laboratory testing of human proximal femora in conditions simulating a sideways fall was developed. Additionally, in order to analyze the strain state in future cadaveric tests, digital image correlation (DIC) was validated as a tool for strain field measurement on the bone of the femoral neck. A fall simulator which included models for the body mass, combined lateral femur and pelvis mass, pelvis stiffness, and trochanteric soft tissue was designed. The characteristics of each element were derived and developed based on human data from the literature. The simulator was verified by loading a state-of-the-art surrogate femur and comparing the resulting force-time trace to published, human volunteer experiments. To validate the DIC, 20 human proximal femora were prepared with a strain rosette and speckle paint pattern, and loaded to 50% of their predicted failure load at a low compression rate. Strain rosettes were taken as the gold standard, and minimum principal strains from the DIC and the rosettes were compared using descriptive statistics. The initial slope of the force-time curve obtained in the fall simulator matched published human volunteer data, with local peaks superimposed in the model due to internal vibrations of the spring used to model the pelvis stiffness. Global force magnitude and temporal characteristics were within 2% of published volunteer experiments. The DIC minimum principal strains were found to be accurate to 127±239μɛ. These tools will allow more biofidelic laboratory simulation of falls to the side, and more detailed analysis of proximal femur failure mechanisms using human cadaver specimens.

The value of laboratory tests in diagnosing secondary osteoporosis at a fracture and osteoporosis outpatient clinic

BACKGROUND

As more and more patients meeting the criteria for osteoporosis are referred to a fracture and osteoporosis outpatient clinic (FO clinic), the laboratory costs to screen for secondary osteoporosis also increases. This study was conducted to determine the value of screening on underlying diseases at an FO clinic by obtaining a standard set of laboratory tests.

METHODS

We included all 541 patients ≥50 years with a fracture referred to our FO clinic, during the period January 2005 to January 2007. The bone mineral density (BMD) was measured by dual energy x-ray absorptiometry and expressed as a T score. A standard set of laboratory tests was obtained to screen on underlying diseases.

RESULTS

Laboratory results were as often abnormal in patients with a normal BMD compared to patients with a low BMD. Underlying diseases were infrequently diagnosed. However, the prevalence of secondary osteoporosis in men was quite high, up to 18.2%. The costs to diagnose 1 patient with an underlying disease did vary between €92 and €972 depending on the group of patients described.

CONCLUSION

Screening all patients, referred to an FO clinic, for underlying diseases by obtaining a standard set of laboratory tests is probably not useful since laboratory tests are as often abnormal in patients with a normal BMD compared to patients with a low BMD. Moreover, the prevalence of secondary osteoporosis is low, while laboratory costs are substantial.

Treatment implications for men when switching from male to female bone mineral density reference data: the Manitoba Bone Density Program

Since 2001, the International Society for Clinical Densitometry Official Position has been to use a young female normative database in women and a young male normative in men for T-scores. Several prospective studies have shown that men and women with identical hip bone mineral density (BMD) have the same fracture rates, and so there has been reconsideration of whether female reference data should be adopted for men. We studied 4691 men age 50 yr and older with baseline dual-energy X-ray absorptiometry assessments to explore how a change in BMD reference data from male to female would affect the number of men meeting National Osteoporosis Foundation (NOF) intervention criteria. We found that use of male vs female BMD reference data for T-score calculation did affect individual eligibility criteria for treatment under the NOF guidelines, but that overall differences in treatment rates were small when eligibility for treatment considered any of the NOF intervention criteria. Specifically, the majority of men who no longer qualified for treatment based upon T-scores calculated from female as opposed to male reference data would still qualify for treatment based upon other NOF intervention criteria. In addition, men only eligible for treatment under NOF criteria when using male reference data were at low fracture risk. We conclude that choice of male or female reference data for T-score calculation in men has little effect on overall treatment eligibility rates under NOF guidelines.

Previous exposure to simulated microgravity does not exacerbate bone loss during subsequent exposure in the proximal tibia of adult rats

Extended periods of inactivity cause severe bone loss and concomitant deterioration of the musculoskeletal system. Considerable research has been aimed at better understanding the mechanisms and consequences of bone loss due to unloading and the associated effects on strength and fracture risk. One factor that has not been studied extensively but is of great interest, particularly for human spaceflight, is how multiple or repeated exposures to unloading and reloading affect the skeleton. Space agencies worldwide anticipate increased usage of repeat-flier crewmembers, and major thrust of research has focused on better understanding of microgravity effects on loss of bone density at weightbearing skeletal sites; however there is limited data available on repeat microgravity exposure. The adult hindlimb unloaded (HU) rat model was used to determine how an initial unloading cycle will affect a subsequent exposure to disuse and recovery thereafter. Animals underwent 28 days of HU starting at 6 months of age followed by 56 days of recovery, and then another 28 days of HU with 56 days of recovery. In vivo longitudinal pQCT was used to quantify bone morphological changes, and ex vivo μCT was used to quantify trabecular microarchitecture and cortical shell geometry at the proximal tibia metaphysis (PTM). The mechanical properties of trabecular bone were examined by the reduced platen compression mechanical test. The hypothesis that the initial HU exposure will mitigate decrements in bone mass and density for the second HU exposure was supported as pre- to post-HU declines in total BMC, total vBMD, and cortical area by in vivo pQCT at the proximal tibia metaphysis were milder for the second HU (and not significant) compared to an age-matched single HU (3% vs. 6%, 2% vs. 6%, and 2% vs. 6%, respectively). In contrast, the hypothesis was not supported at the microarchitectural level as losses in BV/TV and Tb.Th. were similar during 2nd HU exposure and age-matched single HU. Recovery with respect to post-HU values and compared to aging controls for total BMC, vBMD and cortical area were slower in older animals exposed to single or double HU cycles compared to recovery of younger animals exposed to a single HU bout. Despite milder recovery at the older age, there was no difference between unloaded animals and controls at the end of second recovery period. Therefore, the data did not support the hypothesis that two cycles of HU exposure with recovery would have a net negative effect. Mechanical properties of trabecular bone were affected more severely than densitometric measures (35% loss in trabecular bone ultimate stress vs. 9% loss in trabecular vBMD), which can be attributed most prominently to reductions in trabecular bone density and tissue mineral density. Together, our data demonstrate that initial exposure to mechanical unloading does not exacerbate bone loss during a subsequent unloading period and two cycles of unloading followed by recovery do not have a cumulative net negative effect on total bone mineral content and density as measured by pQCT at the proximal tibia metaphysis.

Inflammatory bowel disease and the risk of osteoporosis and fracture

Inflammatory bowel disease (IBD) is commonly believed to increase the risk of bone mineral loss, leading to osteoporosis and an increased risk of disabling fractures. In this narrative review, we will presenting a summary of the published medical literature in regards to the relationship between IBD and the development of osteoporosis, bone mineral loss, and fractures. We will explore the epidemiology of metabolic bone disease in IBD, focusing on the prevalence and both the general and IBD-specific risk factors for the development of osteoporosis and of fracture in persons with IBD. We will also examine the role of the inflammatory process in IBD promoting excessive bone mineral loss, as well as the role that low body mass, corticosteroid use, diet, and nutrient malabsorption play in contributing to bone disease. Last, we will discuss our recommendation for: screening for osteoporosis in IBD patients, the use of preventative strategies, and therapeutic interventions for treating osteoporosis in persons with IBD.

Diagnosis of osteoporosis by extraction of trabecular features from hip radiographs using support vector machine: an investigation panorama with DXA

BACKGROUND

Lifespan and its quality can be improved by early diagnosis of osteoporosis. Analysis of trabecular boundness on digital hip radiographs could be useful for identifying subjects with low bone mineral density (BMD) or osteoporosis. The main aim of our study was to evaluate the ability of a kernel-based support vector machine (SVM) with respect to diagnosis and add to knowledge about the trabecular features of digital hip radiographs for identifying subjects with low BMD.

METHOD

In this paper we present an SVM kernel classifier-based computer-aided diagnosis (CAD) system for osteoporotic risk detection using digital hip radiographs. Initially, the original radiograph was intensified, then trabecular features such as boundness, orientation, solidity of spur and delta were evaluated and radial bias function (RBF) based discrimination was manifested. The next step was the evaluation of the diagnostic capability of the proposed method in order to spot subjects with low BMD at the femoral neck in 50 (50.7 ± 14.3 years) South Indian women with no previous history of osteoporotic fracture. Out of 50 subjects, 28 were used to train the classifier and the other 22 were used for testing.

RESULTS

The proposed system has achieved the highest classification accuracy documented so far by means of a fivefold cross-validation analysis with mean accuracy of 90% (95% confidence interval (CI): 82 to 98%); sensitivity and positive predictive value (PPV) were 90% (95% CI: 82 to 98%) and 89% (95% CI: 81 to 97%), respectively. Pearson's correlation was observed at the level of p<0.001, between extracted image trabecular features with age and BMDs measured by dual energy x-ray absorptiometry (DXA). Extracted image features also demonstrated significant differences between high and low BMD groups at the level of p<0.001.

CONCLUSION

Our findings suggest that the proposed CAD system with SVM would be useful for spotting women vulnerable to osteoporotic risk.

Variation in type I collagen fibril nanomorphology: the significance and origin

Although the axial D-periodic spacing is a well-recognized nanomorphological feature of type I collagen fibrils, the existence of a distribution of values has been largely overlooked since its discovery seven decades ago. Studies based on single fibril measurements occasionally noted variation in D-spacing values, but accredited it with no biological significance. Recent quantitative characterizations supported that a 10-nm collagen D-spacing distribution is intrinsic to collagen fibrils in various tissues as well as in vitro self-assembly of reconstituted collagen. In addition, the distribution is altered in Osteogenesis Imperfecta and long-term estrogen deprivation. Bone collagen is organized into lamellar sheets of bundles at the micro-scale, and D-spacings within a bundle of a lamella are mostly identical, whereas variations among different bundles contribute to the full-scale distribution. This seems to be a very general phenomenon for the protein as the same type of D-spacing/bundle organization is observed for dermal and tendon collagen. More research investigation of collagen nanomorphology in connection to bone biology is required to fully understand these new observations. Here we review the data demonstrating the existence of a D-spacing distribution, the impact of disease on the distribution and possible explanations for the origin of D-spacing variations based on various collagen fibrillogenesis models.

Predictors of fracture from falls reported in hospital and residential care facilities: a cross-sectional study

OBJECTIVES

Fall-related fractures are associated with substantial human and economic costs. An improved understanding of the predictors of fall-related fractures in healthcare settings would be useful in developing future interventions. The objective of this study was to identify such predictors by exploring associations between fall-related factors and fracture outcomes through logistic regression analysis of routinely collected fall incident data.

DESIGN

Retrospective cross-sectional study.

SETTING

197 public healthcare facilities in Queensland, Australia.

PARTICIPANTS

We included data from incident reports completed after falls among admitted adult hospital patients (n=24 218 falls, 229 fractures) and aged-care residents (n=8980 falls, 74 fractures) between January 2007 and November 2009.

PRIMARY AND SECONDARY OUTCOMES

The outcomes of interest were fall-related predictors of fracture.

RESULTS

Hospital patients who reported to have been screened for their risk of falling at admission were less likely to fracture after a fall (OR: 0.60, 95% CI 0.41 to 0.89) than those who had not been screened. Further, falls from standing (OR: 2.08, 95% CI 1.22 to 3.55) and falls while walking (OR: 1.86, 95% CI 1.32 to 2.62) were associated with higher fracture odds than falls during other activities. In line with these results, falls while reaching in standing (OR: 3.51, 95% CI 1.44 to 8.56) and falls while walking (OR: 2.11, 95% CI 1.24 to 3.58) were also predictive of fracture in the adjusted residential care model.

CONCLUSIONS

Our findings indicate that screening of hospital patients for their risk of falling may contribute towards the prevention of fall-related injury. Falls from upright postures appear to be more likely to result in fractures than other falls in healthcare settings. Further prospective research is warranted.

Public health impact of osteoporosis

OBJECTIVE

To describe the public health impact of osteoporosis including the magnitude of the problem and important consequences of osteoporotic fractures.

METHODS

Literature review of key references selected by author.

RESULTS

Current demographic trends leading to an increased number of individuals surviving past age 65 will result in an increased number of osteoporotic fractures. Important consequences of osteoporotic fractures include an increased mortality that for hip fractures extends to 10 years after the fracture. Increased mortality risk also extends to major and minor fractures, especially, in those over 75 years. Hip and vertebral fractures have important functional consequences and reductions in quality of life. The economic impact of osteoporotic fractures is large and growing. Significant health care resources are required for all fractures.

CONCLUSIONS

To alleviate the public and private burden of osteoporosis related fractures, assessment of risk and reduction of individual risk is critical.

Clinical factors associated with trabecular bone score

Dual-energy X-ray absorptiometry (DXA) measurement of bone mineral density (BMD) is the reference standard for diagnosing osteoporosis but does not directly reflect deterioration in bone microarchitecture. The trabecular bone score (TBS), a novel grey-level texture measurement that can be extracted from DXA images, predicts osteoporotic fractures independent of BMD. Our aim was to identify clinical factors that are associated with baseline lumbar spine TBS. In total, 29,407 women ≥50 yr at the time of baseline hip and spine DXA were identified from a database containing all clinical results for the Province of Manitoba, Canada. Lumbar spine TBS was derived for each spine DXA examination blinded to clinical parameters and outcomes. Multiple linear regression and logistic regression (lowest vs highest tertile) was used to define the sensitivity of TBS to other risk factors associated with osteoporosis. Only a small component of the TBS measurement (7-11%) could be explained from BMD measurements. In multiple linear regression and logistic regression models, reduced lumbar spine TBS was associated with recent glucocorticoid use, prior major fracture, rheumatoid arthritis, chronic obstructive pulmonary disease, high alcohol intake, and higher body mass index. In contrast, recent osteoporosis therapy was associated with a significantly lower likelihood for reduced TBS. Similar findings were seen after adjustment for lumbar spine or femoral neck BMD. In conclusion, lumbar spine TBS is strongly associated with many of the risk factors that are predictive of osteoporotic fractures. Further work is needed to determine whether lumbar spine TBS can replace some of the clinical risk factors currently used in fracture risk assessment.

Intervertebral T-score differences in younger and older women

The T-score discordance among skeletal sites is an important aspect of dual-energy X-ray absorptiometry (DXA) measurements. In the spine, large T-score differences between vertebrae are frequently seen in elderly patients owing to degenerative disease. However, it is unclear how often such differences occur in younger adults with healthy spines. The T-scores for individual lumbar vertebrae were compared for 2391 female singletons (18-79 yr) recruited to the Twins UK Adult Twin Register. Women were divided into 6 age bands and 5 bands by body weight, respectively, and the T-score differences between the pairs of vertebrae were examined using correlation coefficients and the standard error of the estimate (SEE) from linear regression analysis. Correlations between the T-scores for adjacent lumbar vertebrae were r = 0.92 decreasing to r = 0.79 between L1 and L4. When plotted as a function of age, r-values were constant for the 5 younger age bands, but decreased in the oldest group. In contrast, the T-score SEE values increased progressively with age from 0.4 to 0.5 for the younger groups to 0.7 for the oldest. Similar trends were seen when women were divided according to body weight. Both increasing age and higher body weight were statistically significantly associated with a higher T-score SEE. The incidence of large T-score differences between vertebrae varies with age and body weight, but is common even among younger women. Clinically significant T-score differences can occur in the absence of osteoarthritis, and visual assessment of spine DXA scans for evidence of degenerative disease is advised before vertebrae are omitted from scan analyses.

C-reactive protein, bone strength, and nine-year fracture risk: data from the Study of Women's Health Across the Nation (SWAN)

Higher levels of C-reactive protein (CRP), an inflammatory marker, are associated with increased fracture risk, although previous studies on CRP and bone mineral density (BMD) have yielded conflicting results. We aimed to test the hypotheses that composite indices of femoral neck strength relative to load, which are inversely associated with fracture risk, would also be inversely associated with CRP, and would explain part of the association between CRP and fracture risk. We analyzed data from a multisite, multiethnic prospective cohort of 1872 community-dwelling women, premenopausal or early perimenopausal at baseline. Femoral neck composite strength indices in three failure modes were calculated using dual-energy X-ray absorptiometry (DXA)-derived femoral neck width (FNW), femoral neck axis length (FNAL), femoral neck BMD and body size at baseline, as BMD*FNW/weight for compression strength, BMD*(FNW)(2) /(FNAL*weight) for bending strength, and BMD*FNW*FNAL/(height*weight) for impact strength. Incident nondigital, noncraniofacial fractures were ascertained annually over a median follow-up of 9 years. In analyses adjusted for age, race/ethnicity, diabetes, menopause transition stage, body mass index, smoking, alcohol use, physical activity, medications, prior fracture, and study site, CRP was associated inversely with each composite strength index (0.035-0.041 SD decrement per doubling of CRP, all p < 0.001), but not associated with femoral neck or lumbar spine BMD. During the follow-up, 194 women (10.4%) had fractures. In Cox proportional hazards analyses, fracture hazard increased linearly with loge (CRP), only for CRP levels ≥ 3 mg/L. Addition of femoral neck or lumbar spine BMD to the model did not attenuate the CRP-fracture association. However, addition of any of the composite strength indices attenuated the CRP-fracture association and made it statistically nonsignificant. We conclude that fracture risk increases with increasing CRP, only above the threshold of 3 mg/L. Unlike BMD, composite strength indices are inversely related to CRP levels, and partially explain the increased fracture risk associated with inflammation.

Is there a specific fracture 'cascade'?

Different kinds of epidemiologic data provide varying views of the relationships among the main osteoporotic fractures. Descriptive incidence data indicate that distal forearm fractures typically occur earlier than vertebral fractures that, in turn, precede hip fractures late in life. In addition, relative risk estimates document the fact that one osteoporotic fracture increases the risk of subsequent ones. These two observations support the notion of a 'fracture cascade' and justify the recent emphasis on secondary prevention, that is, more aggressive treatment of patients presenting with a fracture in order to prevent recurrences. However, the absolute risk of a subsequent fracture given an initial one is modest, and the degree to which the second fracture can be attributed to the first one is unclear. Moreover, the osteoporotic fractures encountered in the majority of patients are the first one experienced, and even these initial fractures lead to substantial morbidity and cost. These latter points reemphasize the importance of primary prevention, that is, the management of bone loss and other risk factors to prevent the first fracture. Continued efforts are needed to refine risk assessment algorithms so that candidates for such fracture prophylaxis can be identified more accurately and efficiently.

Clinical imaging of bone microarchitecture with HR-pQCT

Osteoporosis, a disease characterized by loss of bone mass and structural deterioration, is currently diagnosed by dual-energy x-ray absorptiometry (DXA). However, DXA does not provide information about bone microstructure, which is a key determinant of bone strength. Recent advances in imaging permit the assessment of bone microstructure in vivo using high-resolution peripheral quantitative computed tomography (HR-pQCT). From these data, novel image processing techniques can be applied to characterize bone quality and strength. To date, most HR-pQCT studies are cross-sectional comparing subjects with and without fracture. These studies have shown that HR-pQCT is capable of discriminating fracture status independent of DXA. Recent longitudinal studies present new challenges in terms of analyzing the same region of interest and multisite calibrations. Careful application of analysis techniques and educated clinical interpretation of HR-pQCT results have improved our understanding of various bone-related diseases and will no doubt continue to do so in the future.

Femur neck bone mineral density and fracture risk by age, sex, and race or Hispanic origin in older US adults from NHANES III

Differences in the relationship between femur neck bone mineral density (FNBMD) and fracture risk were examined by age, sex, and race/ethnicity in the third National Health and Nutrition Examination Survey (NHANES III) cohort. FNBMD had similar, significant predictive utility for fracture in the different subgroups, but it did not completely account for subgroup differences in risk.

PURPOSE

Few previous studies of FNBMD and fracture risk examined the relationship by age, sex, and race within the same cohort. The present study examined the relationship between FNBMD and risk of incident major osteoporotic fracture (hip, spine, radius, and humerus) in older US adults from NHANES III (1988-1994).

METHODS

Incident fractures were identified using linked mortality and Medicare records obtained through 2007 for 2,743 men and women ages 65 years and older. FNBMD was measured by dual-energy X-ray absorptiometry. Cox proportional hazards models were used to estimate the hazards ratio (HR) of fracture for FNBMD and femur neck T score and risk of major osteoporotic fracture.

RESULTS

The sample included 380 incident major osteoporotic fractures. Fracture risk approximately doubled for each SD decrease in FNBMD. HR's for FNBMD were similar within age, sex, or race/Hispanic origin subgroups, and also for T scores calculated with either white female or sex- and race/ethnic-specific reference data. Adding FNBMD to Cox models slightly attenuated HR for age, sex, or race/Hispanic origin, but all three variables remained significant predictors of fracture risk.

CONCLUSIONS

FNBMD had similar, significant predictive utility within age, sex, and race/Hispanic origin subgroups. However, FNBMD did not appear to completely account for fracture risk differences in these subgroups. Similarity of HR's for T scores calculated with two different reference databases support use of a uniform reference database to calculate these scores.

Inflammatory bowel disease and the risk of fracture after controlling for FRAX

Subjects with inflammatory bowel disease (IBD) are at increased risk for hip and other major osteoporotic fractures. However, previous analyses have not fully accounted for differences in bone mineral density (BMD) and other clinical factors that affect the risk of fracture. The World Health Organization Fracture Risk Assessment tool (FRAX) can be used to predict the 10-year fracture risk from BMD and clinical risk factors. A population-based database containing clinical information on all IBD subjects in the province of Manitoba, Canada, was linked with the Manitoba Bone Mineral Density Database, which contains results of all dual X-ray absorptiometry (DXA) scans in the province. FRAX probabilities were calculated for all subjects aged 50 years or more undergoing baseline DXA testing. Subjects were followed for occurrence of major osteoporotic fractures (MOF; hip, clinical spine, wrist, humerus). Cox proportional hazards models were used to determine whether IBD was independently predictive of MOF or hip fracture. After controlling for FRAX fracture probability computed with BMD, IBD was not associated with a significantly increased risk for MOF (hazard ratio [HR] = 1.12, 95% confidence interval [CI], 0.83-1.55) but was associated with an increased risk for hip fracture (HR = 2.14; 95% CI, 1.26-3.65). The addition of femoral neck T-score to FRAX probability without knowledge of BMD had a negligible effect on the estimated HRs for IBD, suggesting that IBD mediates any effect on fracture risk independently of femoral neck BMD. After controlling for FRAX probability, subjects with IBD are not at an increased risk for overall MOF, but may be at increased risk of hip fracture.

The (a)-Symptomatic Vertebral Fracture: A Frequently Discovered Entity With Clinical Relevance in Fracture Patients Screened on Osteoporosis

OBJECTIVE

Description of the prevalence of vertebral fractures in a fracture and osteoporosis outpatient clinic (FO-Clinic) and evaluation of the value of spinal radiographs by screening on osteoporosis.

DESIGN

Retrospective data collection, description, and analysis.

METHODS

All patients admitted to the FO-Clinic during the period of December 2005 until October 2006 were enrolled in this study. At the FO-Clinic spinal radiographs were obtained and bone mineral density (BMD) was measured by Dual energy X-ray-Absorptiometry (DXA).

RESULTS

During the study period, a total of 176 patients were screened at our FO-Clinic. In 41.5% of these patients, a vertebral fracture was diagnosed. There appeared to be an indication for anti-osteoporotic medication in 95 of the 176 patients. Of these 95 patients, 77% could be identified by spinal radiographs. Moreover, only 36% of all patients with a vertebral fracture did suffer from osteoporosis.

CONCLUSION

The prevalence of vertebral fractures in patients screened at an FO-Clinic is high and spinal radiographs can identify up to 77% of patients in which anti-osteoporotic medication should be considered. However, fracture risk is not only dependent on bone quality but also on bone density. Therefore, the preferred method of screening on osteoporosis is DXA with vertebral fracture assessment and, if necessary, spinal radiographs. If DXA is not available, spinal radiographs might be used as a first step in osteoporosis screening.

Premenopausal women with a distal radial fracture have deteriorated trabecular bone density and morphology compared with controls without a fracture

BACKGROUND

Measurement of bone mineral density by dual x-ray absorptiometry combined with clinical risk factors is currently the gold standard in diagnosing osteoporosis. Advanced imaging has shown that older patients with fragility fractures have poor bone microarchitecture, often independent of low bone mineral density. We hypothesized that premenopausal women with a fracture of the distal end of the radius have similar bone mineral density but altered bone microarchitecture compared with control subjects without a fracture.

METHODS

Forty premenopausal women with a recent distal radial fracture were prospectively recruited and matched with eighty control subjects without a fracture. Primary outcome variables included trabecular and cortical microarchitecture at the distal end of the radius and tibia by high-resolution peripheral quantitative computed tomography. Bone mineral density at the wrist, hip, and lumbar spine was also measured by dual x-ray absorptiometry.

RESULTS

The fracture and control groups did not differ with regard to age, race, or body mass index. Bone mineral density was similar at the femoral neck, lumbar spine, and distal one-third of the radius, but tended to be lower in the fracture group at the hip and ultradistal part of the radius (p = 0.06). Trabecular microarchitecture was deteriorated in the fracture group compared with the control group at both the distal end of the radius and distal end of the tibia. At the distal end of the radius, the fracture group had lower total density and lower trabecular density, number, and thickness compared with the control group (-6% to -14%; p < 0.05 for all). At the distal end of the tibia, total density, trabecular density, trabecular thickness, and cortical thickness were lower in the fracture group than in the control group (-7% to -14%; p < 0.01). Conditional logistic regression showed that trabecular density, thickness, separation, and distribution of trabecular separation remained significantly associated with fracture after adjustment for age and ultradistal radial bone mineral density (adjusted odds ratios [OR]: 2.01 to 2.98; p < 0.05). At the tibia, total density, trabecular density, thickness, cortical area, and cortical thickness remained significantly associated with fracture after adjustment for age and femoral neck bone mineral density (adjusted OR:1.62 to 2.40; p < 0.05).

CONCLUSIONS

Despite similar bone mineral density values by dual x-ray absorptiometry, premenopausal women with a distal radial fracture have significantly poorer bone microarchitecture at the distal end of the radius and tibia compared with control subjects without a fracture. Early identification of women with poor bone health offers opportunities for interventions aimed at preventing further deterioration and reducing fracture risk.

Measuring apparent trabecular density and bone structure using peripheral quantitative computed tomography at the tibia: precision in participants with and without spinal cord injury

The objective of the study was to investigate the precision of standard outcomes obtained using peripheral quantitative computed tomography as well as apparent trabecular structure measures in adults with and without spinal cord injury (SCI). Twelve individuals with SCI, mean (standard deviation [SD]) 20 (13)yrs postinjury and mean (SD) age 44 (9)yrs, and 21 individuals without SCI (mean [SD] age: 27 [5]yrs) participated. Repeat scans of tibia epiphysis (4%) and shaft (66%) were performed using a Stratec XCT-2000 (Stratec Medizintechnik, Pforzheim, Germany). Bone mineral density and geometry variables (e.g., cortical thickness, bone area, polar moment of inertia) were derived with manufacturer's software. The following apparent trabecular structure variables were determined using custom software: average trabecular thickness (TrTh) (mm), trabecular spacing (TrSp) (mm), and trabecular number (TrN) (1/mm); average hole size (HA) and maximum hole size (HM) (mm(2)); connectivity index (CI); cortical thickness (CTh) (mm); bone volume to total volume (BVTV) ratio. Root mean square standard deviation and root mean square coefficient of variation (RMSCV; root mean square coefficient of variation percent [RMSCV%]) were calculated. The RMSCV% for all standard bone mineral density and geometry variables was ≤2% except for total area (4% site), where precision was 3.8%. RMSCV% for bone structure variables were as follows: CTh 5.1, TrTh 1.7, TrN 1.9, TrSp 2.6, HA 9.5, HM 20.1, CI 5.1, and BVTV 1.4. Precision for bone density and geometry was excellent across a range of bone mineral densities. RMSCVs for some apparent trabecular structure variables were comparable to that of standard variables. The RMSCV for others may necessitate larger studies to detect between-group differences.

Factors affecting kyphotic angle reduction in osteoporotic vertebral compression fractures with kyphoplasty

This article describes the independent factors that affect kyphotic angle reduction in the treatment of osteoporotic vertebral compression fractures with kyphoplasty. Between January 2008 and September 2011, one hundred twenty-six patients with a single-level osteoporotic compression fracture who underwent kyphoplasty were evaluated for a minimum of 1 year postoperatively. Nine independent variables related to patient characteristics (age, sex, bone mineral density [BMD], and body mass index), fracture characteristics (fracture level, fracture age, and preoperative kyphotic angle), and surgical variables (total injected cement volume and cement leakage) were assessed. Kyphotic angle reduction was the dependent variable. Univariate and multivariate linear regression analyses were used to determine the factors associated with kyphotic angle reduction.Significant improvements occurred in mean anterior vertebral height variation, middle vertebral height variation, kyphotic angle, and visual analog scale and Oswestry Disability Index scores immediate postoperatively and at final follow-up compared with the preoperative values. Univariate analyses indicated correlations between kyphotic angle reduction with BMD, fracture age, preoperative kyphotic angle, and cement volume. The final multiple linear regression model resulted in a formula that accounted for 23.3% of the variability in kyphotic angle reduction: preoperative kyphotic angle (b=0.260; P=.002), BMD (b=-0.249; P=.004), and fracture age (b=-0.226; P=.009). Kyphoplasty is a safe and effective treatment for osteoporotic compression fractures.

The health burden and costs of incident fractures attributable to osteoporosis from 2010 to 2050 in Germany--a demographic simulation model

To predict the burden of incident osteoporosis attributable fractures (OAF) in Germany, an economic simulation model was built. The burden of OAF will sharply increase until 2050. Future demand for hospital and long-term care can be expected to substantially rise and should be considered in future healthcare planning.

INTRODUCTION

The aim of this study was to develop an innovative simulation model to predict the burden of incident OAF occurring in the German population, aged >50, in the time period of 2010 to 2050.

METHODS

A Markov state transition model based on five fracture states was developed to estimate costs and loss of quality adjusted life years (QALYs). Demographic change was modelled using individual generation life tables. Direct (inpatient, outpatient, long-term care) and indirect fracture costs attributable to osteoporosis were estimated by comparing Markov cohorts with and without osteoporosis.

RESULTS

The number of OAF will rise from 115,248 in 2010 to 273,794 in 2050, cumulating to approximately 8.1 million fractures (78 % women, 22 % men) during the period between 2010 and 2050. Total undiscounted incident OAF costs will increase from around 1.0 billion Euros in 2010 to 6.1 billion Euros in 2050. Discounted (3 %) cumulated costs from 2010 to 2050 will amount to 88.5 billion Euros (168.5 undiscounted), with 76 % being direct and 24 % indirect costs. The discounted (undiscounted) cumulated loss of QALYs will amount to 2.5 (4.9) million.

CONCLUSIONS

We found that incident OAF costs will sharply increase until the year 2050. As a consequence, a growing demand for long-term care as well as hospital care can be expected and should be considered in future healthcare planning. To support decision makers in managing the future burden of OAF, our model allows to economically evaluate population- and risk group-based interventions for fracture prevention in Germany.

Phytonutrients for bone health during ageing

Osteoporosis is a skeletal disease characterized by a decrease in bone mass and bone quality that predispose an individual to an increased risk of fragility fractures. Evidence demonstrating a positive link between certain dietary patterns (e.g. Mediterranean diet or high consumption of fruits and vegetables) and bone health highlights an opportunity to investigate their potential to protect against the deterioration of bone tissue during ageing. While the list of these phytonutrients is extensive, this review summarizes evidence on some which are commonly consumed and have gained increasing attention over recent years, including lycopene and various polyphenols (e.g. polyphenols from tea, grape seed, citrus fruit, olive and dried plum). Evidence to define a clear link between these phytonutrients and bone health is currently insufficient to generate precise dietary recommendations, owing to mixed findings or a scarcity in clinical data. Moreover, their consumption typically occurs within the context of a diet consisting of a mix of phytonutrients and other nutrients rather than in isolation. Future clinical trials that can apply a robust set of outcome measurements, including the determinants of bone strength, such as bone quantity (i.e. bone mineral density) and bone quality (i.e. bone turnover and bone microarchitecture), will help to provide a more comprehensive outlook on how bone responds to these various phytonutrients. Moreover, future trials that combine these phytonutrients with established bone nutrients (i.e. calcium and vitamin D) are needed to determine whether combined strategies can produce more robust effects on skeletal health.

A comparison of bone density and bone morphology between patients presenting with hip fractures, spinal fractures or a combination of the two

Background

Currently it is uncertain how to define osteoporosis and who to treat after a hip fracture. There is little to support the universal treatment of all such patients but how to select those most in need of treatment is not clear. In this study we have compared cortical and trabecular bone status between patients with spinal fractures and those with hip fracture with or without spinal fracture with the aim to begin to identify, by a simple clinical method (spine x-ray), a group of hip fracture patients likely to be more responsive to treatment with current antiresorptive agents.

Methods

Comparison of convenience samples of three groups of 50 patients, one with spinal fractures, one with a hip fracture, and one with both. Measurements consist of bone mineral density at the lumbar spine, at the four standard hip sites, number, distribution and severity of spinal fractures by the method of Genant, cortical bone thickness at the infero-medial femoral neck site, femoral neck and axis length and femoral neck width.

Results

Patients with spinal fractures alone have the most deficient bones at both trabecular and cortical sites: those with hip fracture and no spinal fractures the best at trabecular bone and most cortical bone sites: and those with both hip and spinal fractures intermediate in most measurements. Hip axis length and neck width did not differ between groups.

Conclusion

The presence of the spinal fracture indicates poor trabecular bone status in hip fracture patients. Hip fracture patients without spinal fractures have a bone mass similar to the reference range for their age and gender. Poor trabecular bone in hip fracture patients may point to a category of patient more likely to benefit from therapy and may be indicated by the presence of spinal fractures.

Impaired bone mineralization accompanied by low vitamin D and secondary hyperparathyroidism in patients with femoral neck fracture

SUMMARY

Although it is well established that a decrease in bone mass increases the risk of osteoporotic fractures, the proportion of fractures attributable to areal bone mineral density (BMD) is rather low. Here, we have identified bone mineralization defects together with low serum 25-hydroxyvitamin D (25-(OH) D) levels as additional factors associated with femoral neck fractures.

INTRODUCTION

Osteoporotic fractures of the femoral neck are associated with increased morbidity and mortality. Although it is well established that a decrease in bone mass increases the risk of osteoporotic fractures, the proportion of fractures attributable to areal BMD is rather low. To identify possible additional factors influencing femur neck fragility, we analyzed patients with femoral neck fracture.

METHODS

We performed a detailed clinical and histomorphometrical evaluation on 103 patients with femoral neck fracture including dual-energy X-ray absorptiometry, laboratory parameters, and histomorphometric and bone mineral density distribution (BMDD) analyses of undecalcified processed biopsies of the femoral head and set them in direct comparison to skeletal healthy control individuals.

RESULTS

Patients with femoral neck fracture displayed significantly lower serum 25-(OH) D levels and increased serum parathyroid hormone (PTH) compared to controls. Histomorphometric analysis revealed not only a decreased bone volume and trabecular thickness in the biopsies of the patients, but also a significant increase of osteoid indices. BMDD analysis showed increased heterogeneity of mineralization in patients with femoral neck fracture. Moreover, patients with femoral neck fracture and serum 25-(OH) D levels below 12 μg/l displayed significantly thinner trabecular bone.

CONCLUSION

Taken together, our data suggest that impaired bone mineralization accompanied by low serum 25-(OH) D levels is of major importance in the etiology of femoral neck fractures. Therefore, balancing serum 25-(OH) D levels and thereby normalizing PTH serum levels may counteract pronounced mineralization defects and might decrease the incidence of femoral neck fractures.

Discrimination of fractures by low-frequency axial transmission ultrasound in postmenopausal females

SUMMARY

In this cross-sectional study, 95 postmenopausal women, with and without fracture history, were measured by low-frequency axial transmission ultrasound. The measured ultrasound velocity discriminated the fractured subjects from the nonfractured ones equally or better than peripheral quantitative computed tomography (pQCT) and dual energy x-ray absorptiometry (DXA). These results suggest that low-frequency ultrasound is suitable for bone fragility assessment.

INTRODUCTION

Quantitative low-frequency axial transmission ultrasound is a promising modality for assessing mineral density and geometrical properties of long bones such as radius and tibia. The aim of the current study was to evaluate the ability of low-frequency axial transmission ultrasound to discriminate fractures retrospectively in postmenopausal women.

METHODS

A cross-sectional study involved 95 female subjects aged 45-88 years, whose fracture information was gathered retrospectively. The fracture group was defined as subjects with one or more low-/moderate-energy fractures. The radius and tibial shaft were measured with a custom-made ultrasonometer to assess the velocity of the low-frequency first-arriving signal (V (LF)). Site-matched pQCT was used to measure volumetric cortical and subcortical bone mineral density (sBMD), and cortical thickness (CTh). Areal BMD (aBMD) was measured using DXA for the whole body (WB), lumbar spine, and hip.

RESULTS

The majority (19/32; 59 %) of the fractures were in the upper limb. V (LF) in the radius, but not in the tibia, discriminated fractures with an age- and BMI-adjusted odds ratio (OR) of 2.06 (95 % CI 1.21-3.50, p < 0.01). In the radius, CTh and cortical BMD (CBMD) significantly discriminated fractures, as did the total, cortical, and sBMD in the tibia (adjusted OR 1.35-2.15, p < 0.05). Sensitivity and specificity were similar among all the measurements (area under the receiver operating characteristic curve 0.74-0.81, p < 0.001).

CONCLUSIONS

Low-frequency axial transmission ultrasound in the radius was able to discriminate fractured subjects from the nonfractured ones. This suggests that low-frequency axial transmission ultrasound has the potential to assess bone fragility in postmenopausal women.

Towards patient-specific material modeling of trabecular bone post-yield behavior

Bone diseases such as osteoporosis are one of the main causes of bone fracture and often result in hospitalization and long recovery periods. Researchers are aiming to develop new tools that consider the multiple determinants acting at the different scales of bone, and which can be used to clinically estimate patient-specific fracture risk and also assess the efficacy of new therapies. The main step towards this goal is a deep understanding of the bone organ, and is achieved by modeling the complexity of the structure and the high variability of the mechanical outcome. This review uses a hierarchical approach to evaluate bone mechanics at the macroscale, microscale, and nanoscale levels and the interactions between scales. The first section analyzes the experimental evidence of bone mechanics in the elastic and inelastic regions, microdamage generation, and post-yield toughening mechanisms from the organ level to the ultrastructural level. On the basis of these observations, the second section provides an overview of the constitutive models available to describe bone mechanics and predict patient-specific outcomes. Overall, the role of the hierarchical structure of bone and the interplay between each level is highlighted, and their effect is evaluated in terms of modeling biological variability and patient specificity.

Quantitative ultrasound of cortical bone in the femoral neck predicts femur strength: results of a pilot study

A significant risk of femoral neck (FN) fracture exists for men and women with an areal bone mineral density (aBMD) higher than the osteoporotic range, as measured with dual-energy X-ray absorptiometry (DXA). Separately measuring the cortical and trabecular FN compartments and combining the results would likely be a critical aspect of enhancing the diagnostic capabilities of a new technique. Because the cortical shell determines a large part of FN strength a novel quantitative ultrasound (QUS) technique that probes the FN cortical compartment was implemented. The sensitivity of the method to variations of FN cortical properties and FN strength was tested. Nine femurs (women, mean age 83 years) were subjected to QUS to measure the through transmission time-of-flight (TOF) at the FN and mechanical tests to assess strength. Quantitative computed tomography (QCT) scans were performed to enable analysis of the dependence of TOF on bone parameters. DXA was also performed for reference. An ultrasound wave propagating circumferentially in the cortical shell was measured in all specimens. Its TOF was not influenced by the properties of the trabecular compartment. Averaged TOF for nine FN measurement positions/orientations was significantly correlated to strength (R2  = 0.79) and FN cortical QCT variables: total BMD (R(2)  = 0.54); regional BMD in the inferoanterior (R2  = 0.90) and superoanterior (R2  = 0.57) quadrants; and moment of inertia (R2  = 0.71). The results of this study demonstrate that QUS can perform a targeted measurement of the FN cortical compartment. Because the method involves mechanical guided waves, the QUS variable is related to the geometric and material properties of the cortical shell (cortical thickness, tissue elasticity, and porosity). This work opens the way to a multimodal QUS assessment of the proximal femur, combining our approach targeting the cortical shell with the existing modality sensitive to the trabecular compartment. In vivo feasibility of our approach has to be confirmed with experimental data in patients.

TBS (trabecular bone score) and diabetes-related fracture risk

CONTEXT

Type 2 diabetes is associated with increased fracture risk but paradoxically greater bone mineral density (BMD). Trabecular bone score (TBS) is derived from the texture of the spine dual x-ray absorptiometry (DXA) image and is related to bone microarchitecture and fracture risk, providing information independent of BMD.

OBJECTIVE

This study evaluated the ability of lumbar spine TBS to account for increased fracture risk in diabetes.

DESIGN AND SETTING

We performed a retrospective cohort study using BMD results from a large clinical registry for the province of Manitoba, Canada.

PATIENTS

We included 29,407 women 50 years old and older with baseline DXA examinations, among whom 2356 had diagnosed diabetes.

MAIN OUTCOME MEASURES

Lumbar spine TBS was derived for each spine DXA examination blinded to clinical parameters and outcomes. Health service records were assessed for incident nontraumatic major osteoporotic fractures (mean follow-up 4.7 years).

RESULTS

Diabetes was associated with higher BMD at all sites but lower lumbar spine TBS in unadjusted and adjusted models (all P < .001). The adjusted odds ratio (aOR) for a measurement in the lowest vs the highest tertile was less than 1 for BMD (all P < .001) but was increased for lumbar spine TBS [aOR 2.61, 95% confidence interval (CI) 2.30-2.97]. Major osteoporotic fractures were identified in 175 women (7.4%) with and 1493 (5.5%) without diabetes (P < .001). Lumbar spine TBS was a BMD-independent predictor of fracture and predicted fractures in those with diabetes (adjusted hazard ratio 1.27, 95% CI 1.10-1.46) and without diabetes (hazard ratio 1.31, 95% CI 1.24-1.38). The effect of diabetes on fracture was reduced when lumbar spine TBS was added to a prediction model but was paradoxically increased from adding BMD measurements.

CONCLUSIONS

Lumbar spine TBS predicts osteoporotic fractures in those with diabetes, and captures a larger portion of the diabetes-associated fracture risk than BMD.

Discordant recovery of bone mass and mechanical properties during prolonged recovery from disuse

Profound bone loss at weight bearing sites is a primary effect of long-duration spaceflight. Moreover, a significant increase in estimated fracture risk remains even 1 year after returning to Earth; hence, it is important to define how quickly bone integrity can recover following prolonged disuse. This study characterized the loss and recovery dynamics of bone following a period of rodent hindlimb unloading in three anatomic sites. We hypothesized that the rat femoral neck would exhibit a discordant recovery dynamic most similar to that observed in astronauts' proximal femur; that is, bone mineral content (absolute mass) at this site would recover faster and more completely than would bone density and cortical area, and they will all recover before bone strength does. We characterized loss and long-term recovery of densitometric properties at the femoral neck, proximal tibia metaphysis, and tibia diaphysis, and also mechanical properties at the femoral neck and tibia diaphysis for which mechanical testing is amenable. We assessed the relationship between calculated strength indices and measured mechanical properties. Adult male Sprague-Dawley rats (6 months) were assigned to baseline, age-matched control (AC), and hindlimb unloaded (HU) groups. The HU group was unloaded for 28 days and then returned to normal cage activity for 84 days of weight bearing recovery (3 times the duration of HU). Fifteen animals were euthanized from each of the HU and AC groups on days 28, 56, 84, and 112 of the study. At baseline and then every 28 days in vivo longitudinal pQCT scans were taken at proximal tibia metaphysis (PTM) and tibia diaphysis (TD); ex vivo pQCT scans were taken later at the femoral neck (FN). TD and FN were tested to failure to measure mechanical properties. The hypothesis that the femoral neck in rats will exhibit a discordant recovery dynamic most similar to that observed in astronauts' proximal femurs was not supported by our data. At the femoral neck, densitometric and geometric variables (total BMC, total vBMD, cancellous vBMD, and cortical area) recovered to age-matched control levels after a recovery period twice the duration of unloading. Contrary to our hypothesis, changes in densitometric variables at the PTM provided a better model for changes in the human femoral neck with prolonged weightlessness. Following 28 days of HU, PTM total BMC recovered to age-matched control levels after roughly two times the duration of unloading; however, total vBMD did not recover even after three recovery periods. Cortical thinning occurred at the PTM following HU likely due to inhibition of periosteal growth; cortical shell thickness did not recover even after three recovery periods. Calculated strength indices suggested a loss in strength at the tibial diaphysis, which was not confirmed with direct testing of mechanical properties. HU had no effect on maximum fracture force at mid-tibia diaphysis; however, femoral neck experienced a significant loss of maximum force due to unloading that fully recovered after 28 days. Estimated strength indices for the femoral neck suggested a recovery period of 56 days in contrast to the 28-day recovery that was observed with mechanical testing. However, the inaccuracy of strength indices vs. directly measured mechanical properties highlights the continued importance of ground based animal models and mechanical testing. Our results demonstrate that the PTM in the rat better matches loss and recovery dynamics observed in astronauts' proximal femur than does the rat FN, at least in terms of densitometric variables. More complete utility of the rat PTM as a model in this case, however, depends upon meaningful characterization of changes in mechanical properties as well.

Cost-effectiveness of bone densitometry among Caucasian women and men without a prior fracture according to age and body weight

We used a microsimulation model to estimate the threshold body weights at which screening bone densitometry is cost-effective. Among women aged 55-65 years and men aged 55-75 years without a prior fracture, body weight can be used to identify those for whom bone densitometry is cost-effective.

INTRODUCTION

Bone densitometry may be more cost-effective for those with lower body weight since the prevalence of osteoporosis is higher for those with low body weight. Our purpose was to estimate weight thresholds below which bone densitometry is cost-effective for women and men without a prior clinical fracture at ages 55, 60, 65, 75, and 80 years.

METHODS

We used a microsimulation model to estimate the costs and health benefits of bone densitometry and 5 years of fracture prevention therapy for those without prior fracture but with femoral neck osteoporosis (T-score ≤ -2.5) and a 10-year hip fracture risk of ≥3%. Threshold pre-test probabilities of low BMD warranting drug therapy at which bone densitometry is cost-effective were calculated. Corresponding body weight thresholds were estimated using data from the Study of Osteoporotic Fractures (SOF), the Osteoporotic Fractures in Men (MrOS) study, and the National Health and Nutrition Examination Survey (NHANES) for 2005-2006.

RESULTS

Assuming a willingness to pay of $75,000 per quality adjusted life year (QALY) and drug cost of $500/year, body weight thresholds below which bone densitometry is cost-effective for those without a prior fracture were 74, 90, and 100 kg, respectively, for women aged 55, 65, and 80 years; and were 67, 101, and 108 kg, respectively, for men aged 55, 75, and 80 years.

CONCLUSIONS

For women aged 55-65 years and men aged 55-75 years without a prior fracture, body weight can be used to select those for whom bone densitometry is cost-effective.

A health economic analysis of osteoporotic fractures: who carries the burden?

This is a cost-of-illness study of osteoporotic fractures in Denmark estimating the incremental societal cost associated with osteoporotic fractures, with both direct cost and productivity cost. This study includes cost regarding hospitals, general practices, the patients, the municipalities and regions. The total cost of osteoporotic fractures in Denmark was estimated at EUR 1.563 billion.

PURPOSE

The aim of this study is to estimate the societal burden imposed by osteoporotic fractures in Denmark. In contrast to prior studies, this study will present a comprehensive model for the cost of osteoporotic fractures regarding hospitals, general practices, the municipalities, the regions and the patients.

METHODS

This cost-of-illness study applied an incidence-based bottom-up approach from a societal perspective, including both direct costs and productivity costs. The study focused on incremental cost associated with osteoporotic fractures using a Markov model. Danish citizens ≥50 years with an osteoporotic fracture between 2001 and 2010 were studied.

RESULTS

The total cost of osteoporotic fractures in Denmark was estimated to EUR 1.563 billion in 2011, at EUR 628 million and EUR 936 million for men and women, respectively. The most expensive fracture for both genders was first hip fracture. The municipalities carried the majority of the costs, with 55-57 % of incremental lifetime cost.

CONCLUSIONS

This study showed that the incremental societal burden of osteoporotic fractures is an important health problem. Medical costs of the osteoporotic fractures were substantial cost for the health care sector, but were by far exceeded by the cost for the municipality in terms of social services and rehabilitation.

Bone fragility beyond strength and mineral density: Raman spectroscopy predicts femoral fracture toughness in a murine model of rheumatoid arthritis

Clinical prediction of bone fracture risk primarily relies on measures of bone mineral density (BMD). BMD is strongly correlated with bone strength, but strength is independent of fracture toughness, which refers to the bone's resistance to crack initiation and propagation. In that sense, fracture toughness is more relevant to assessing fragility-related fracture risk, independent of trauma. We hypothesized that bone biochemistry, determined by Raman spectroscopy, predicts bone fracture toughness better than BMD. This hypothesis was tested in tumor necrosis factor-transgenic mice (TNF-tg), which develop inflammatory-erosive arthritis and osteoporosis. The left femurs of TNF-tg and wild type (WT) littermates were measured with Raman spectroscopy and micro-computed tomography. Fracture toughness was assessed by cutting a sharp notch into the anterior surface of the femoral mid-diaphysis and propagating the crack under 3 point bending. Femoral fracture toughness of TNF-tg mice was significantly reduced compared to WT controls (p=0.04). A Raman spectrum-based prediction model of fracture toughness was generated by partial least squares regression (PLSR). Raman spectrum PLSR analysis produced strong predictions of fracture toughness, while BMD was not significantly correlated and produced very weak predictions. Raman spectral components associated with mineralization quality and bone collagen were strongly leveraged in predicting fracture toughness, reiterating the limitations of mineralization density alone.

Phalangeal bone mineral density predicts incident fractures: a prospective cohort study on men and women--results from the Danish Health Examination Survey 2007–2008 (DANHES 2007–2008)

This prospective study investigates the use of phalangeal bone mineral density (BMD) in predicting fractures in a cohort (15,542) who underwent a BMD scan. In both women and men, a decrease in BMD was associated with an increased risk of fracture when adjusted for age and prevalent fractures.

PURPOSE

The aim of this study was to evaluate the ability of a compact and portable scanner using radiographic absorptiometry (RA) to predict major osteoporotic fractures.

METHODS

This prospective study included a cohort of 15,542 men and women aged 18–95 years, who underwent a BMD scan in Danish Health Examination Survey 2007–2008. BMD at the middle phalanges of the second, third and fourth digits of the non-dominant hand was measured using RA (Alara MetriScan®). These data were merged with information on incident fractures retrieved from the Danish National Patient Registry comprising the International Classification of Diseases (ICD-10). Follow-up was 27–45 months. Major osteoporotic fractures (vertebral fractures, humerus fractures, forearm fractures and hip fractures) were used in the analyses. Fracture events were calculated as "persons with fracture" and evaluated using survival analysis.

RESULTS

A total of 307 (1.98 %) of the participants had experienced a new fracture during follow-up. BMD was significantly lower in subjects with fracture (0.32 vs. 0.34 g/cm(2); p < 0.001 adjusted for age, gender, prevalent fractures, height, weight and smoking). In both women and men, a 1 SD decrease in BMD (T score units) was associated with an increased risk of fracture when adjusted for age and prevalent fractures (women: HR = 1.39, CI 1.24–1.54, p < 0.001; men: HR = 1.47, CI 1.20–1.79, p < 0.001).

CONCLUSION

Phalangeal BMD as measured using RA predicts the incidence of major osteoporotic fractures.

Clinical review: Ethnic differences in bone mass--clinical implications

CONTEXT

Differences in bone mineral density (BMD) as assessed with dual-energy x-ray absorptiometry are observed between geographic and ethnic groups, with important implications in clinical practice.

EVIDENCE ACQUISITION

PubMed was employed to identify relevant studies. A review of the literature was conducted, and data were summarized and integrated.

EVIDENCE SYNTHESIS

The available data highlight the complex ethnic variations in BMD, which only partially account for observed variations in fracture rates. Factors contributing to ethnic differences include genetics, skeletal size, body size and composition, lifestyle, and social determinants. Despite BMD differences, the gradient of risk for fracture from BMD and other clinical risk factors appears to be similar across ethnic groups. Furthermore, BMD variation is greater within an ethnic population than between ethnic populations. New imaging technologies have identified ethnic differences in bone geometry, volumetric density, microarchitecture, and estimated bone strength that may contribute to a better understanding of ethnic differences in fracture risk.

CONCLUSIONS

Factors associated with ethnicity affect BMD and fracture risk through direct and indirect mechanisms.

Burden of non-hip, non-vertebral fractures on quality of life in postmenopausal women: the Global Longitudinal study of Osteoporosis in Women (GLOW)

Among 50,461 postmenopausal women, 1,822 fractures occurred (57% minor non-hip, non-vertebral [NHNV], 26% major NHNV, 10% spine, 7% hip) over 1 year. Spine fractures had the greatest detrimental effect on EQ-5D, followed by major NHNV and hip fractures. Decreases in physical function and health status were greatest for spine or hip fractures.

INTRODUCTION

There is growing evidence that NHNV fractures result in substantial morbidity and healthcare costs. The aim of this prospective study was to assess the effect of these NHNV fractures on quality of life.

METHODS

We analyzed the 1-year incidences of hip, spine, major NHNV (pelvis/leg, shoulder/arm) and minor NHNV (wrist/hand, ankle/foot, rib/clavicle) fractures among women from the Global Longitudinal study of Osteoporosis in Women (GLOW). Health-related quality of life (HRQL) was analyzed using the EuroQol EQ-5D tool and the SF-36 health survey.

RESULTS

Among 50,461 women analyzed, there were 1,822 fractures (57% minor NHNV, 26% major NHNV, 10% spine, 7% hip) over 1 year. Spine fractures had the greatest detrimental effect on EQ-5D summary scores, followed by major NHNV and hip fractures. The number of women with mobility problems increased most for those with major NHNV and spine fractures (both +8%); spine fractures were associated with the largest increases in problems with self care (+11%), activities (+14%), and pain/discomfort (+12%). Decreases in physical function and health status were greatest for those with spine or hip fractures. Multivariable modeling found that EQ-5D reduction was greatest for spine fractures, followed by hip and major/minor NHNV. Statistically significant reductions in SF-36 physical function were found for spine fractures, and were borderline significant for major NHNV fractures.

CONCLUSION

This prospective study shows that NHNV fractures have a detrimental effect on HRQL. Efforts to optimize the care of osteoporosis patients should include the prevention of NHNV fractures.

Osteoporosis healthcare disparities in postmenopausal women

BACKGROUND

Previous studies in referral populations have shown that fewer African American women complete dual-energy x-ray absorptiometry (DXA) screening and are prescribed medications for osteoporosis. This study examines if these disparities exist in primary care practices.

METHODS

Of 4748 eligible women ≥60 years of age in primary care practices, we randomly selected 500 African American and 500 Caucasian women. We compared the DXA screening referral rate and results, follow-up rate, and medication prescribing for low bone mineral density (BMD) between African American and Caucasian women and analyzed provider demographics. We used logistic regression analysis to control confounding variables, such as age and BMI.

RESULTS

Among the initial 1000 women, only 29.8% African American Women were referred to DXA compared to 38.4% Caucasian women (p<0.05), and 20.8% African American vs. 27.0% Caucasian (p<0.05) women completed the test. Among women with a diagnosis of osteoporosis, African Americans were less likely to receive medication (79.6% vs. 89.2%, p<0.05), without a difference in follow-up visit pattern between races. Female providers were more likely to refer women for DXA (27.7%) than male providers (21.7%) (p=0.035), and this gender difference in referral was more pronounced for African American patients.

CONCLUSIONS

Not enough eligible women are being screened and treated for osteoporosis in primary care. Even fewer African American women receive DXA screenings and are treated for osteoporosis. Controlling for age and BMI attenuated but did not eliminate the difference. Female providers were more likely than male providers to refer women for DXA.

Bone resorption and fracture across the menopausal transition: the Study of Women's Health Across the Nation

OBJECTIVE

Bone turnover markers (BTMs) predict fracture in older women, whereas data on younger women are lacking. To test the hypothesis that BTMs measured before and after menopause predict fracture risk, we performed a cohort study of 2,305 women.

METHODS

Women attended up to nine clinic visits for an average of 7.6 ± 1.6 years; all were aged 42 to 52 years and were premenopausal or early perimenopausal at baseline. Incident fractures were self-reported. Serum osteocalcin and urinary cross-linked N-telopeptide of type I collagen (NTX) were measured at baseline. NTX was measured at each annual follow-up. Interval-censored survival models or generalized estimating equations were used to test whether baseline BTMs and changes in NTX, respectively, were associated with fracture risk. Hazard ratios (HRs) or odds ratios were calculated with 95% CIs.

RESULTS

Women who experienced fractures (n = 184) had about a 10% higher baseline median NTX (34.4 vs 31.5 nanomoles of bone collagen equivalents per liter per nanomole of creatinine per liter; P = 0.001), but there was no difference in osteocalcin. A 1-SD decrease in lumbar spine bone mineral density (BMD) measured premenopausally was associated with a higher fracture risk during menopause (HR, 1.50; 95% CI, 1.28-1.68). Women with a baseline NTX greater than the median had a 45% higher risk of fracture, multivariable-adjusted (HR, 1.46; 95% CI, 1.05-2.26). The HR of fracture among women with both the lowest spine BMD (quartile 1) and the highest NTX (quartile 4) at baseline was 2.87 (95% CI, 1.61-6.01), compared with women with lower NTX and higher BMD. Women whose NTX increased more than the median had a higher risk of fracture (odds ratio, 1.51; 95% CI, 1.08-2.10). Women who had baseline NTX greater than the median experienced greater loss of spine and hip BMD.

CONCLUSIONS

A higher urinary NTX excretion measured before menopause and across menopause is associated with a higher risk of fracture. Our results are consistent with the pathophysiology of transmenopausal changes in bone strength.

Fracture risk assessment without race/ethnicity information

CONTEXT

Dual-energy x-ray absorptiometry-derived bone mineral density (BMD) does not explain interracial differences in fracture risk; thus, BMD-based fracture risk assessment requires patient race/ethnicity information and ethnicity-specific BMD reference databases.

OBJECTIVE

The objective of the study was to investigate whether composite femoral neck strength indices, which integrate dual-energy x-ray absorptiometry-derived femoral neck size, femoral neck BMD, and body size, will allow fracture risk assessment without requiring race/ethnicity information.

DESIGN

This was a prospective cohort study.

SETTING AND PARTICIPANTS

A total of 1940 community-dwelling women aged 42-53 yr from four race/ethnicity groups (968 Caucasian, 512 African-American, 239 Japanese, and 221 Chinese) were followed up for 9 yr.

OUTCOME MEASUREMENTS

Self-reported, nondigital, noncraniofacial fractures were measured.

RESULTS

Two hundred and two women (10.4%) sustained fractures and 82 (4.3%) had minimum-trauma fractures. Each sd increment in any of the strength indices was associated with a 34-41% reduction in fracture hazard over 9 yr (each P<0.001). Race/ethnicity predicted fracture hazard independent of BMD (P=0.02) but did not predict fracture hazard independent of any of the composite indices (P=0.11-0.22). Addition of race/ethnicity did not improve risk discrimination ability of the strength indices, but did significantly improve the discrimination ability of BMD. The discrimination ability of BMD with race/ethnicity was not statistically different from that of any of the strength indices without race/ethnicity.

CONCLUSIONS

Composite strength indices of the femoral neck can predict fracture risk without race/ethnicity information as accurately as bone mineral density does in combination with race/ethnicity information and therefore would allow risk prediction in people of mixed race/ethnicity and in groups without a BMD reference database.

Age-dependence of power spectral density and fractal dimension of bone mineralized matrix in atomic force microscope topography images: potential correlates of bone tissue age and bone fragility in female femoral neck trabeculae

There is an increasing interest in bone nano-structure, the ultimate goal being to reveal the basis of age-related bone fragility. In this study, power spectral density (PSD) data and fractal dimensions of the mineralized bone matrix were extracted from atomic force microscope topography images of the femoral neck trabeculae. The aim was to evaluate age-dependent differences in the mineralized matrix of human bone and to consider whether these advanced nano-descriptors might be linked to decreased bone remodeling observed by some authors and age-related decline in bone mechanical competence. The investigated bone specimens belonged to a group of young adult women (n = 5, age: 20-40 years) and a group of elderly women (n = 5, age: 70-95 years) without bone diseases. PSD graphs showed the roughness density distribution in relation to spatial frequency. In all cases, there was a fairly linear decrease in magnitude of the power spectra with increasing spatial frequencies. The PSD slope was steeper in elderly individuals (-2.374 vs. -2.066), suggesting the dominance of larger surface morphological features. Fractal dimension of the mineralized bone matrix showed a significant negative trend with advanced age, declining from 2.467 in young individuals to 2.313 in the elderly (r = 0.65, P = 0.04). Higher fractal dimension in young women reflects domination of smaller mineral grains, which is compatible with the more freshly remodeled structure. In contrast, the surface patterns in elderly individuals were indicative of older tissue age. Lower roughness and reduced structural complexity (decreased fractal dimension) of the interfibrillar bone matrix in the elderly suggest a decline in bone toughness, which explains why aged bone is more brittle and prone to fractures.

Fracture risk assessment: state of the art, methodologically unsound, or poorly reported?

Osteoporotic fractures, including hip fractures, are a global health concern associated with significant morbidity and mortality as well as a major economic burden. Identifying individuals who are at an increased risk of osteoporotic fracture is an important challenge to be resolved. Recently, multivariable prediction tools have been developed to assist clinicians in the management of their patients by calculating their 10-year risk of fracture (FRAX, QFracture, Garvan) using a combination of known risk factors. These prediction models have revolutionized the way clinicians assess the risk of fracture. Studies evaluating the performance of prediction models in this and other areas of medicine have, however, been characterized by poor design, methodological conduct, and reporting. We examine recently developed fracture prediction models and critically discuss issues in their design, validation, and transparency.

Can Hip Fracture Prediction in Women be Estimated beyond Bone Mineral Density Measurement Alone?

The etiology of hip fractures is multifactorial and includes bone and fall-related factors. Low bone mineral density (BMD) and BMD-related and BMD-independent geometric components of bone strength, evaluated by hip strength analysis (HSA) and finite element analysis analyses on dual-energy X-ray absorptiometry (DXA) images, and ultrasound parameters are related to the presence and incidence of hip fracture. In addition, clinical risk factors contribute to the risk of hip fractures, independent of BMD. They are included in the fracture risk assessment tool (FRAX) case finding algorithm to estimate in the individual patient the 10-year risk of hip fracture, with and without BMD. Fall risks are not included in FRAX, but are included in other case finding tools, such as the Garvan algorithm, to predict the 5- and 10-year hip fracture risk. Hormones, cytokines, growth factors, markers of bone resorption and genetic background have been related to hip fracture risk. Vitamin D deficiency is endemic worldwide and low serum levels of 25-hydroxyvitamin D [25(OH)D] predict hip fracture risk. In the context of hip fracture prevention calculation of absolute fracture risk using clinical risks, BMD, bone geometry and fall-related risks is feasible, but needs further refinement by integrating bone and fall-related risk factors into a single case finding algorithm for clinical use.