Bone densitometry is not a good predictor of hip fracture

High-resolution local trabecular strain within trabecular structure under cyclic loading

Trabecular bone structure is a complex microstructure consisting of rods and plates, which poses challenges for its mechanical characterization. Digital image correlation (DIC) offers the possibility to characterize the strain response on the surface of trabecular bone. This study employed DIC equipped with a telecentric lens to investigate the strain state of individual trabeculae within their trabecular structure by assessing the longitudinal strain of the trabeculae at both the middle and near the edges of the trabeculae. Due to the high-resolution of the used DIC system, local surface strain of trabeculae was analyzed too. Lastly, the correlation between longitudinal trabecular strain and the orientation and slenderness of the trabeculae was investigated. The results showed that the strain magnification close to the edge of the trabeculae was higher and reached up to 8-folds the strain along the middle of the trabeculae. On the contrary, no strain magnification was found for most of the trabeculae between the longitudinal trabecular strain along the middle of the trabeculae and the globally applied strain. High-resolution full-field strain maps were obtained on the surface of trabeculae showing heterogeneous strain distribution with increasing load. No significant correlation was found between longitudinal trabecular strain and its orientation or slenderness. These findings and the applied methodology can be used to broaden our understanding of the deformation mechanisms of trabeculae within the trabecular network.

Asia-pacific consensus on osteoporotic fracture prevention in postmenopausal women with low bone mass or osteoporosis but no fragility fractures

Postmenopausal women are at significant risk for osteoporotic fractures due to their rapid bone loss. Half of all postmenopausal women will get an osteoporosis-related fracture over their lifetime, with 25% developing a spine deformity and 15% developing a hip fracture. By 2050, more than half of all osteoporotic fractures will occur in Asia, with postmenopausal women being the most susceptible. Early management can halt or even reverse the progression of osteoporosis. Consequently, on October 31, 2020, the Taiwanese Osteoporosis Association hosted the Asia-Pacific (AP) Postmenopausal Osteoporotic Fracture Prevention (POFP) consensus meeting, which was supported by the Asian Federation of Osteoporosis Societies (AFOS) and the Asia Pacific Osteoporosis Foundation (APOF). International and domestic experts developed ten applicable statements for the prevention of osteoporotic fractures in postmenopausal women with low bone mass or osteoporosis but no fragility fractures in the AP region. The experts advocated, for example, that postmenopausal women with a high fracture risk be reimbursed for pharmaceutical therapy to prevent osteoporotic fractures. More clinical experience and data are required to modify intervention tactics.

Bone Organic-Inorganic Phase Ratio Is a Fundamental Determinant of Bone Material Quality

Background

Bone mineral density is widely used by clinicians for screening osteoporosis and assessing bone strength. However, its effectiveness has been reported unsatisfactory. In this study, it is demonstrated that bone organic-inorganic phase ratio is a fundamental determinant of bone material quality measured by stiffness, strength, and toughness.

Methods and Results

Two-hundred standard bone specimens were fabricated from bovine legs, with a specialized manufacturing method that was designed to reduce the effect of bone anisotropy. Bone mechanical properties of the specimens, including Young's modulus, yield stress, peak stress, and energy-to-failure, were measured by mechanical testing. Organic and inorganic mass contents of the specimens were then determined by bone ashing. Bone density and organic-inorganic phase ratio in the specimens were calculated. Statistical methods were applied to study relationships between the measured mechanical properties and the organic-inorganic phase ratios. Statistical characteristics of organic-inorganic phase ratios in the specimens with top material quality were investigated. Bone organic-inorganic phase ratio had strong Spearman correlation with bone material properties. Bone specimens that had the highest material quality had a very narrow scope of organic-inorganic phase ratio, which could be considered as the “optimal” ratio among the tested specimens.

Conclusion

Bone organic-inorganic phase ratio is a fundamental determinant of bone material quality. There may exist an “optimal” ratio for the bone to achieve top material quality. Deviation from the “optimal” ratio is probably the fundamental cause of various bone diseases. This study suggests that bone organic-inorganic phase ratio should be considered in clinical assessment of fracture risk.

Plain vitamin D or active vitamin D in the treatment of osteoporosis: where do we stand today?

Osteoporosis is a major cause of morbidity and mortality worldwide and its prevention in order to avert fractures was considered of great importance in maintaining well-being and independence among the elderly. Strategies for osteoporosis prevention are well delineated, but research shows that the treatment options offered today could still be improved. The role of plain vitamin D (cholecalciferol) in bone health and the prevention of osteoporosis are well documented; however, as a treatment for osteoporosis, either with or without calcium, it has been shown to be ineffective. This is due in part to the strong negative feedback mechanisms in place in vitamin D-replete patients. However, other factors linked directly to ageing such as oestrogen depletion, reduced kidney or liver function may also be involved in reducing the body's capability to activate plain vitamin efficiently. This is why active vitamin D analogues such as alfacalcidol, 1-α-(OH)D3, are of clinical interest. Alfacalcidol requires only one hydroxylation reaction to become active 1,25-(OH)2-vitamin D3, and the 25-hydroxylase catalyzing this reaction is found in the liver and also interestingly in osteoblasts suggesting a local effect. Registered for use in postmenopausal osteoporosis, in most countries worldwide, alfacalcidol has also shown efficacy in glucocorticoid-induced and male osteoporosis. The present review provides compelling evidence for the efficacy of this compound in the treatment of osteoporosis and prevention of fractures both in monotherapy and when combined with other osteoporotic drugs where additive effects are clear. The safety profile of alfacalcidol is shown to be highly acceptable and it is considered less likely to induce hypercalcaemia than another more widely used analogue, calcitriol. Therefore, it remains unclear as to why alfacalcidol is not more widely used in clinical practice.

Non-steroidal anti-inflammatory drugs and the risk of a second hip fracture: a propensity-score matching study

Background

Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently prescribed for elderly patients, particularly after a hip fracture. However, we are not clear about the effect of NSAIDs on the risk of a second hip fracture because of confounding factors.

Methods

This was a Taiwan National Health Insurance Research Database-based study using propensity-score matching (PSM) to control for confounding. Enrollees were selected from patients with a hip fracture during 1996–2004 and followed longitudinally until December 2009. After PSM for comorbidities and bisphosphonate therapy, 94 patients with a second hip fracture were assigned to the Cases group and 461 without it to the Controls group. The target drugs are NSAIDs; paracetamol and dexamethasone are used for comparison.

Results

The correlation between the mean daily-dose (MDD) ratios of NSAIDs and the probability values of the current statistical tests were highly negative (Pearson’s r = −0.920, P = 0.003), which indicated that the higher the MDD ratios, the greater the risks of a second hip fracture. A Kaplan-Meier survival analysis showed a time-dependent trend of increasing risk of a second hip fracture in patients taking NSAIDs (P < 0.001). Moreover, patients ≥60 years old had a higher risk of a second hip fracture than did those <60 and taking the NSAIDs diclofenac (P = 0.016) and celecoxib (P = 0.003) and the corticosteroid dexamethasone (P = 0.018), but not those taking analgesic paracetamol (P = 0.074).

Conclusions

We conclude that taking NSAIDs after a fragility hip fracture dose- and time-dependently significantly increases the risk of a second hip fracture, especially in elderly patients. To lower the risk of a second hip fracture, any underlying causes for excessively using NSAIDs should be treated and thus fewer NSAIDs prescribed after a first hip fracture.

Medication use before and after hip fracture: a population-based cohort and case-control study

BACKGROUND

Osteoporosis, together with age, is the main risk factor for hip fracture, the incidence of which has also been associated with an increased risk of falling or co-morbidities and related pharmacological treatments.

OBJECTIVES

The aim of this study was to investigate changes in concomitant pharmacological treatments prescribed before and after hip fracture in elderly patients compared with treatments prescribed to a matched cohort of subjects without hospitalisation for fractures.

METHODS

Data relating to the study population were extracted from a large population-based administrative database of the Italian National Health Authorities. A retrospective analysis was conducted involving female patients (6,431) aged ≥65 years and hospitalised for a hip fracture. The control group comprised age-matched subjects (38,586) not hospitalised for fracture. Changes in drug prescriptions 1 year before and 1 year after hip fracture and differences versus controls were compared.

RESULTS

Prior to the fracture, patients were taking more anti-Parkinson medications, antidepressants, medications for chronic obstructive pulmonary disease (COPD), bisphosphonates and calcium-vitamin D supplements, although the intake of the routinely monitored drug classes was significantly infrequent. Polypharmacy was less frequent in fractured women before fracture than in controls (22 vs. 25 %, respectively; P < 0.001), but it was more frequent (30 %, P < 0.001) post-fracture. The incidence of fracture was associated with a significant increase in the use of a number of drug classes: insulin, NSAIDs or analgesics, gastroprotectants, loop diuretics, β-blockers, antidepressants, antiparkinson drugs, antiepileptics and drugs for COPD.

CONCLUSION

Our study confirms a strong association between the use of some drugs (antidepressants, antiparkinson drugs, drugs for COPD) and the risk of hip fracture, but drug use is globally less common than in controls. Hip fracture is associated with a significant increase in drug use, suggesting a global deterioration of health conditions.

Modeling of femoral neck cortical bone for the numerical simulation of ultrasound propagation

Quantitative ultrasound assessment of the cortical compartment of the femur neck (FN) is investigated with the goal of achieving enhanced fracture risk prediction. Measurements at the FN are influenced by bone size, shape and material properties. The work described here was aimed at determining which FN material properties have a significant impact on ultrasound propagation around 0.5 MHz and assessing the relevancy of different models. A methodology for the modeling of ultrasound propagation in the FN, with a focus on the modeling of bone elastic properties based on scanning acoustic microscopy data, is introduced. It is found that the first-arriving ultrasound signal measured in through-transmission at the FN is not influenced by trabecular bone properties or by the heterogeneities of the cortical bone mineralized matrix. In contrast, the signal is sensitive to variations in cortical porosity, which can, to a certain extent, be accounted for by effective properties calculated with the Mori-Tanaka method.

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.

Accurate in vitro identification of fracture onset in bones: failure mechanism of the proximal human femur

Bone fractures have extensively been investigated, especially for the proximal femur. While failure load can easily be recorded, and the fracture surface is readily accessible, identification of the point of fracture initiation is difficult. Accurate location of fracture initiation is extremely important to understand the multi-scale determinants of bone fracture. In this study, a recently developed technique based on electro-conductive lines was applied to the proximal femoral metaphysis to elucidate the fracture mechanism. Eight cadaveric femurs were prepared with 15-20 electro-conductive lines (crack-grid) covering the proximal region. The crack-grid was connected to a dedicated data-logger that monitored electrical continuity of each line at 700 kHz. High-speed videos (12,000 frames/s, 0.1-0.2 mm pixel size) of the destructive tests were acquired. Most crack-grid-lines failed in a time-span of 0.08-0.50 ms, which was comparable to that identified in the high-speed videos, and consistent with previous video recordings. However, on all specimens 1-3 crack-grid-lines failed significantly earlier (2-200 ms) than the majority of the crack-grid-lines. The first crack-grid-line to fail was always the closest one to the point of fracture initiation identified in the high-speed videos (superior-lateral neck region). Then the crack propagated simultaneously, at comparable velocity on the anterior and posterior sides of the neck. Such a failure pattern has never been observed before, as spatial resolution of the high-speed videos prevented from observing the initial opening of a crack. This mechanism (fracture onset, time-lag, followed by catastrophic failure) can be explained with a transfer of load to the internal trabecular structure caused by the initial fracture of the thin cortical shell. This study proves the suitability of the crack-grid method to investigate bone fractures associated to tensile stress. The crack-grid method enables significantly faster sampling than high-speed cameras. The present findings elucidate some aspects of the failure mechanism of the proximal human femoral metaphysis.

The initiative on hip fractures of the Veneto Region

OBJECTIVE

to assess the prevalence of the most relevant environmental and individual risk factors in subjects with a recent hip fracture was the aim of this observational study promoted by the Health Authorities of the Regione Veneto (Italy).

METHODS

patients aged > 60 years of both genders with a recent hip fracture not associated with malignancies, were administered questionnaires on dietary habits, sun exposure, disability score. A complete family, pharmacological and pathology history was collected together with previous falls, details of the fracture index, anthropometric data. In a subgroup of patients blood was taken for the measurements of serum 25 hydroxy-vitamin D (25OHD).

RESULTS

the study includes 704 patients (573 women and 131 men). Mean age was 81±8 years (range 60-102). Severe pre-fracture disability was a common feature (58%) associated with multiple co-morbidities (84%), more frequently cardiovascular and neurological diseases, and specific medications. In a large proportion (86%) of the patients environmental or individual risk factors for falling were found. Vitamin D insufficiency was quite common, particularly in the regional Health Districts were strategies for preventing vitamin D deficiency were not implemented. Only a small proportion (17%) of the study population had been evaluate and treated for osteoporosis.

CONCLUSIONS

in senile patients with a recent hip fracture pre-existing disability, multiple co-morbidities, high risk of falling and inadequate intake of calcium and vitamin D was quite common. Community and case-finding interventions are highly warranted.

Ibandronate does not reduce the anabolic effects of PTH in ovariectomized rat tibiae: a microarchitectural and mechanical study

Osteoporosis remains a challenging problem. Understanding the regulation on osteoclast and osteoblast by drugs has been of great interest. Both anabolic and anti-resorptive drugs yield positive results in the treatment of osteoporosis. However, whether the concurrent administration of parathyroid hormone (1-34) and ibandronate may offer an advantage over monotherapy is still unknown. This study, therefore, attempts to compare the efficacy of two therapeutical approaches and to investigate the beneficial effects in concurrent therapy in a rat model using three-point bending, pQCT and μCT analysis. A total of 60 female Sprague-Dawley rats of age 10 to 12 weeks were divided into 5 groups (SHAM, OVX+VEH, OVX+PTH, OVX+IBAN, OVX+PTH+IBAN) and subjected to ovariectomy or sham surgery accordingly. Low-dose parathyroid hormone (PTH) and/or ibandronate or its vehicle were administered subcutaneously to the respective groups starting from 4th week post-surgery at weekly intervals. Three rats from each group were euthanized every 2 weeks and their tibiae were harvested. The tibiae were subjected to metaphyseal three-point bending, pQCT and μCT analysis. Serum biomarkers for both bone formation (P1NP) and resorption (CTX) were studied. A total of 11 indices showed a significant difference between SHAM and OVX+VEH groups, suggesting the successful establishment of osteoporosis in the rat model. Compared to the previous studies which showed impedance from bisphosphonates in combination therapy with PTH, our study revealed that ibandronate does not block the anabolic effects of PTH in ovariectomized rat tibiae. Maximum load, strength-strain indices and serum bone formation markers of OVX+PTH+IBAN group are significantly higher than both monotherapy groups. With the proper ratio of anabolic and anti-resorptive drugs, the effect could be more pronounced.

Evaluation of the Singh index and femur geometry in osteoporotic women

We aimed to compare the Singh index with bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), body mass index (BMI) and femur geometry in the right proximal femur of osteoporotic women, using different statistical tests. Radiographs of each patient were assessed to determine the Singh index by five observers. The observers consisted of a consultant radiologist, physical therapist and anatomists who studied the series of radiographs. They were asked to apply the Singh index by comparing the trabecular bone pattern in the proximal right femur with the reference scale published by Singh et al. [1]. This has a six point scale from grade VI to grade I. We evaluated 47 osteoporotic women in this study. The subjects’ mean age, weigth, and height were 63,21 ± 10,106, 66,72 ± 12.523, 154,94 ± 7,026 respectively. We found a significant relationship between the Singh index and BMD. The Singh index correlated significantly with hip axis length, femoral neck diamater and trochanteric width. And, BMD correlated significantly with femoral head and neck diameter, femoral neck cortex width, medial calcar femoral cortex width and femoral shaft cortex width. The evaluation of the Singh index grades in its self, there was a significant relation among them.

BMD T-score discriminates trochanteric fractures from unfractured controls, whereas geometry discriminates cervical fracture cases from unfractured controls of similar BMD

The ability of bone mineral density (BMD) to discriminate cervical and trochanteric hip fractures was studied. Since the majority of fractures occur among people who are not diagnosed as having osteoporosis, we also examined this population to elucidate whether geometrical risk factors can yield additional information on hip fracture risk beside BMD. The study showed that the T-score criterion was able to discriminate fracture patients from controls in the cases of trochanteric fractures, whereas geometrical measures may discriminate cervical fracture cases in patients with T-score >-2.5.

INTRODUCTION

Low bone mineral density (BMD) is a well-established risk factor for hip fracture. However, majority of fractures occur among people not diagnosed as having osteoporosis. We studied the ability of BMD to discriminate cervical and trochanteric hip fractures. Furthermore, we examined whether geometrical measures can yield additional information on the assessment of hip fracture risk in the fracture cases in subjects with T-score >-2.5.

METHODS

Study group consisted of postmenopausal females with non-pathologic cervical (n = 39) or trochanteric (n = 18) hip fracture (mean age 74.2 years) and 40 age-matched controls. BMD was measured at femoral neck, and femoral neck axis length, femoral neck and shaft cortex thicknesses (FNC and FSC), and femoral neck-shaft angle (NSA) were measured from radiographs.

RESULTS

BMD T-score threshold of -2.5 was able to discriminate trochanteric fractures from controls (p < 0.001). Seventeen out of 18 trochanteric fractures occurred in individuals with T-score <or=-2.5. However, the T-score criterion was not able to discriminate cervical fractures. Twenty of these fractures (51.3%) occurred in individuals with BMD in osteoporotic range and 19 (48.7%) in individuals with T-score >-2.5. Within these non-osteoporotic cervical fracture patients (N = 19) and non-osteoporotic controls (N = 35), 83.3% were classified correctly based on a model including NSA and FNC (p < 0.001), area under the receiver operating characteristics curve being 0.85 for the model, while it was only 0.56 for BMD alone.

CONCLUSIONS

The study suggests that the risk of trochanteric fractures could be discriminated based on a BMD T-score <-2.5 criterion, whereas cervical fracture cases would remain under-diagnosed if solely using this criterion. Instead, geometrical risk factors are able to discriminate cervical fracture cases even among individuals with T-score >-2.5. For cervical and trochanteric fractures combined, BMD and geometric measures independently contributed to hip fracture discrimination. Our data support changing from T-score <-2.5 to a more comprehensive assessment of hip fracture etiology, in which fracture type is also taken into account. The findings need to be confirmed with a larger sample, preferably in a prospective study.

Marketing disease: is osteoporosis an example of 'disease mongering'?

Osteoporosis is often described as a disease, yet the symptoms are imperceptible and reliable diagnostic criteria have not been formulated. It is probably better described as a potential risk factor in patients with underlying illness. However, the marketing of osteoporosis has created the impression that all women (and many men) are at risk of suffering fragile bones, hip fracture and death. Large sums of money have been spent on raising awareness, diagnosing and treating osteoporosis, yet its link to hip fracture is not strong and the drug therapies used may be of little benefit or cause actual harm. This article draws parallels in the development of such pseudo-illness with the medicalization of the menopause and the pathologizing of a number of phenomena, including blood pressure, unhappiness, cholesterol levels, sexual and social function. Similarly, in these cases, the manufacture of 'lifestyle' drugs has been costly without significant improvement in mortality or morbidity. Indeed, as was the case with hormone replacement therapy, which resulted in the unnecessary deaths of thousands of women, there may be significant risks attached to treating non-existent diseases. The influence of the medical profession and large drug manufacturers is evaluated and their vested interest in the manufacture of illness is explained. Finally, the crucial role of nursing in challenging these shibboleths is discussed.

Bone mass, bone strength, and their relationship in developing CD-1 mice

Optimizing nutrition during development may provide effective prevention strategies to protect against osteoporosis during later life. Because the mouse model is commonly used to test nutritional interventions on bone health, the overall objective of this study was to determine how bone develops during the first 4 months of life by assessing bone mass (bone mineral content (BMC) and bone mineral density (BMD)) and biomechanical strength properties such as peak load in male and female CD-1 mice. Bone outcomes were assessed at 1 month intervals from 1 to 4 months of age. Femur and spine BMC and BMD at 3 months were similar to 4 months, indicating that the accumulation of bone mass occurs primarily during the first 3 months of life. In contrast, the timing of changes in peak load, a measure of bone strength, varied by skeletal site. Regression analyses demonstrated that femur BMC is a significant predictor of femur peak load at the femur midpoint and neck. The study findings suggest that nutritional interventions aimed at optimizing peak bone mass to prevent osteoporosis may be most effective during pubertal growth.

Diet, nutrition and the prevention of osteoporosis

Objective:

To review the evidence on diet and nutrition relating to osteoporosis and provide recommendations for preventing osteoporosis, in particular, osteopototic fracture.

Approach:

Firstly, to review the definition, diagnosis and epidemiology of osteoporosis, to discuss the difficulties in using bone mineral density to define osteoporosis risk in a world-wide context and to propose that fragility fracture should be considered as the disease endpoint. Secondly, to provide an overview of the scientific data, the strengths and weaknesses of the evidence and the conceptual difficulties in interpreting studies linking diet, nutrition and osteoporosis. The following were considered: calcium, vitamin D, phosphorus, magnesium, protein and fluorine. Other potential dietary influences on bone health were also discussed, including vitamins, trace elements, electrolytes, acid–base balance, phyto-oestrogens, vegetarianism and lactose intolerance.

Conclusions:

There is insufficient knowledge linking bone mineral status, growth rates or bone turnover in children and adolescents to long-term benefits in old age for these indices to be used as markers of osteoporotic disease risk. For adults, the evidence of a link between intakes of any dietary component and fracture risk is not sufficiently secure to make firm recommendations, with the exception of calcium and vitamin D. For other aspects of the diet, accumulating evidence suggests that current healthy-eating advice to decrease sodium intake, to increase potassium intake, and to consume more fresh fruits and vegetables is unlikely to be detrimental to bone health and may be beneficial.

Validation of the Cummings’ risk score; how well does it identify women with high risk of hip fracture: The Tromsø Study

OBJECTIVE

We examined a two-step case-finding strategy where the Cummings' risk score (NEJM 1995) was applied in a population-based setting together with bone mineral density (BMD) measurements in order to validate its ability to identify women with high risk of hip fracture.

METHODS

All Tromsø women aged between 65 and 74 were invited to the Tromsø Osteoporosis Study (TROST) together with a 5% random sample of women aged 75-84 years (n = 1410). All had forearm BMD measurements in 1994/95 and were followed for 5 years with respect to first hip fracture. A risk score was constructed matching the Cummings score as closely as possible.

RESULTS

In all 759, 578 and 73 women had 0-2, 3-4 and 5+ risk factors, respectively. Women with 5+ risk factors had a 5-year hip fracture risk of 11% (95% confidence interval (CI) 3.7-18.2%). BMD screening applied to these women identified 74% of them as osteoporotic and 19% as osteopenic with, respectively, 5-year hip fracture risk of 13% and 7.1%.

CONCLUSION

In a population different from the one the score was generated in, this simple risk score identifies a group of women with high risk of hip fractures. With no additional BMD measurements, those high-risk women could benefit from early intervention measures.

Health professionals, their medical interventions and uncertainty: A study focusing on women at midlife

Health professionals face a tension between focusing on the individual and attending to health issues for the population as a whole. This tension is intrinsic to medicine and gives rise to medical uncertainty, which here is explored through accounts of three medical interventions focused on women at midlife: breast screening, hormone replacement therapy and bone densitometry. The accounts come from interviews with UK health professionals using these medical interventions in their daily work. Drawing on the analysis of Fox [(2002). Health and Healing: The public/private divide (pp. 236-253). London: Routledge] we distinguish three aspects of medical uncertainty and explore each one of them in relation to one of the interventions. First is uncertainty about the balance between the individual and distributive ethic of medicine, explored in relation to breast screening. Second is the dilemma faced by health professionals when using medical evidence generated through studies of populations and applying this to individuals. We explore this dilemma for hormone replacement therapy. Thirdly there is uncertainty because of the lack of a conceptual framework for understanding how new micro knowledge, such as human genetic information, can be combined with knowledge of other biological and social dimensions of health. The accounts from the bone denistometry clinic indicate the beginnings of an understanding of the need for such a framework, which would acknowledge complexity, recognising that factors from many different levels of analysis, from heredity through to social factors, interact with each other and influence the individual and their health. However, our analysis suggests biomedicine continues to be dominated by an individualised, context free, concept of health and health risk with individuals alone responsible for their own health and for the health of the population. This may continue to dominate how we perceive responsibilities for health until we establish a conceptual framework that recognises the complex interaction of many factors at macro and micro level affecting health.

Forearm bone mineral density in an unselected population of 2,779 men and women--the HUNT Study, Norway

The fracture incidence in Norway is among the highest in Europe, presumably due to osteoporosis. As part of a multipurpose health study in the county of Nord-Trondelag, Norway (the HUNT study), a 5% randomly selected sample (n=4,646) of the population >19 years of age was invited to undergo single X-ray absorptiometry (SXA) of the forearm. A total of 1,274 men (50.5 years) and 1,505 women (49.9 years) participated (60%). The aim of the study was to describe the variation in bone mineral density (BMD) and the prevalence of forearm BMD 2.5 standard deviations (SD) below the mean value for young adults in an unselected population sample. In women the BMD remained stable until the age of 50 years, whereupon a strong decline in BMD was observed. In men, a BMD increase was observed until about the age of 40 years; the decline after the age of 65 was, however, similar to that in women. Based on age and gender-specific reference values, the age-adjusted prevalence of T-scores <-2.5 SD in women and men aged 50-69 years was 16.0% and 5.6%, respectively. In the age group of 70 years or older the prevalence was 65.8% and 30.6% for women and men, respectively. The accelerated BMD reduction in women aged 50-65 explains the higher prevalence of T-score <-2.5 SD in elderly women than in men. Further studies on bone loss and falls are required to explain the high fracture incidence in Norway.

Genome scan for QTLs underlying bone size variation at 10 refined skeletal sites: genetic heterogeneity and the significance of phenotype refinement

To identify quantitative trait loci (QTLs) underlying variation in bone size, we conducted a whole-genome linkage scan in 53 pedigrees with 630 subjects using 380 microsatellite markers. Lumbar area 1, 2, 3, and 4 at the spine, femoral neck, trochanter, intertrochanter areas at the hip, ultradistal, mid-distal, and one-third distal areas at the wrist were measured by dual-energy X-ray absorptiometry (DXA), and adjusted for age, height, weight, and sex. Two-point and multipoint linkage analyses were performed for skeletal bone size at each site and their composite measurements using the SOLAR package. Two chromosomal regions (1q22 and 10q21) were identified with significant evidence of linkage (LOD > 4.32) to one-third distal area, and three were identified with suggestive evidence of linkage (LOD > 2.93) to bone size in one skeletal site. Our results indicated that the low power of QTLs mapping for composite phenotypic measurements may result from genetic heterogeneity of complex traits.

The effect of DXA scanning on clinical decision making by general practitioners: a randomized, prospective trial of direct access versus referral to a hospital consultant

The objective of the study was to assess the impact of direct access DXA scanning (DADS) upon GPs' management decisions in patients considered to be at risk of osteoporosis. It was designed as a randomized, prospective, parallel group trial, set within the primary care environment and a university teaching hospital. The participants were 330 patients aged 31 to 89 years from 18 general practices in Edinburgh. Patients were randomized to either DADS or to the current system of specialist referral (controls). The primary outcome measure was frequency of change of management after DXA scanning. Secondary outcome measures were: change in health status, adherence to therapy, clinical events and resource use at one-year follow-up. The primary outcome was that 60% each of DADS patients (98/165) and controls (99/165) had changes in management following DXA scanning. In 30% of patients (12/41) in whom GPs had proposed changing management even in the absence of a scan, different therapy was chosen after the scan (no difference between DADS and control groups). There was an improvement in health utility (p =0.014 for both groups combined), differing slightly between the two groups even after age correction (p =0.014). 68% of the DADS group and 70% of controls were adherent to therapy after one year. In terms of clinical events, at one year there was one major adverse event (control group patient), 5 new fractures in the DADS group and 3 in controls - there were no hip fractures in this study. With regard to resource use, there were 24 referrals to hospital specialist after DXA scanning among the DADS group, vs 12 among controls (p < 0.05). The total number of visits to health professionals was 525 in DADS and 585 in controls (p=ns); mean waiting time from randomization to receipt of report/clinic letter was 4 weeks for DADS vs 13 weeks for controls( p < 0.0001). In conclusion, DXA scanning resulted in management change in at least 60% of cases. Direct access does not result in a clinical outcome significantly different from a consultant led service, and is more economically efficient than the current model of hospital referral.

Mechanical properties of subchondral cancellous bone of the radial head

OBJECTIVE

To quantify the mechanical properties of subchondral bone of the radial head, with special interest in the regional variations in bone stiffness and strength.

DESIGN

Transverse subchondral cancellous bone slices obtained from the proximal radial head were subjected to indentation tests.

SETTING

Biomechanics laboratory with a servohydraulic materials testing machine.

SPECIMENS

Thirteen previously frozen, cadaver proximal radii of mean age 69 +/- 9 years.

MAIN OUTCOME MEASUREMENTS

The mean indentation modulus and local yield strength were calculated for the anteromedial (AM), anterolateral (AL), posteromedial (PM), and posterolateral (PL) quadrants of the radial head.

RESULTS AND CONCLUSIONS

There were no differences in mean indentation modulus across all 4 quadrants (AL, 55.56 +/- 16.20 MPa; AM, 53.48 +/- 20.67 MPa; PM, 49.20 +/- 18.31 MPa; PL, 49.96 +/- 14.97 MPa) (P > 0.05). The AM quadrant had higher local yield strength than the PL and PM quadrants, as did the AL compared with the PL quadrant (AL, 24.89 +/- 8.52 Mpa; AM, 28.39 +/- 10.52 Mpa; PM, 23.01 +/- 6.99; PL, 20.62 +/- 4.83 MPa) (P < 0.05). This suggests that the high frequency of radial head fractures in the AL quadrant is likely not due to the local strength of cancellous bone. Rather, the location of fracture may be influenced by the composite strength or the mechanisms of loading at the radiocapitellar and proximal radioulnar joints. The modulus results suggest that similar screw purchase can be achieved in all areas of the radial head during internal fixation of fractures. These results may also influence implant design and fixation. This study was limited to an older population and may not be representative of a younger population.

Association of polymorphisms of the estrogen receptor alpha gene with bone mineral density and fracture risk in women: a meta-analysis

The contribution of genetic polymorphisms to bone mineral density (BMD) and fracture risk in women is a controversial topic. We evaluated the effect of the XbaI and PvuII polymorphisms of the estrogen receptor a to BMD and fracture risk in a meta-analysis, including published data and additional information from investigators. Five thousand eight hundred thirty-four women from 30 study groups were analyzed with fixed and random effects models. The PvuII polymorphism was not associated with BMD at any skeletal site examined and 95% CIs exclude effects over 0.015 g/cm2 for both the femoral neck and the lumbar spine. Conversely, XX homozygotes (women carrying two copies of the gene variant without an XbaI restriction site) consistently had higher BMD than other subjects. The magnitude of the effect was similar in the femoral neck and lumbar spine (0.014 g/cm2 [95% CI, 0.003-0.025] and 0.015 g/cm2 [95% CI, 0.000-0.030], respectively; no between-study heterogeneity for either). Total body BMD was also significantly higher in XX homozygotes (by 0.039 g/cm2 and 0.029 g/cm2 compared with Xx and xx, respectively). Available data on fractures suggested a protective effect for XX (odds ratio [OR], 0.66 [95% CI, 0.47-0.93] among 1591 women), but not PP (OR, 0.93 [95% CI, 0.72-1.18] among 2,229 women). In summary, we have found that XX homozygotes may have higher BMD and also a decreased risk of fractures when compared with carriers of the x allele, whereas the PvuII polymorphism is not associated with either BMD or fracture risk.