The increasing use of peripheral bone densitometry

DXA in the assessment of subchondral bone mineral density in knee osteoarthritis--A semi-standardized protocol after systematic review

INTRODUCTION

Subchondral bone mineral density (sBMD) contributes to the initiation and progression of knee osteoarthritis (OA). Reliable methods to assess sBMD status may predict the response of specific OA phenotypes to targeted therapies. While dual-energy X-ray absorptiometry (DXA) of the knee can determine sBMD, no consensus exists regarding its methodology.

OBJECTIVE

Construct a semi-standardized protocol for knee DXA to measure sBMD in patients with OA of the knee by evaluating the varying methodologies present in existing literature.

METHODS

We performed a systematic review of original papers published in PubMed and Web of Science from their inception to July 2014 using the following search terms: subchondral bone, osteoarthritis, and bone mineral density.

RESULTS

DXA of the knee can be performed with similar reproducibility values to those proposed by the International Society for Clinical Densitometry for the hip and spine. We identified acquisition view, hip rotation, knee positioning and stabilization, ROI location and definition, and the type of analysis software as important sources of variation. A proposed knee DXA protocol was constructed taking into consideration the results of the review.

CONCLUSIONS

DXA of the knee can be reliably performed in patients with knee OA. Nevertheless, we found substantial methodological variation across previous studies. Methodological standardization may provide a foundation from which to establish DXA of the knee as a valid tool for identification of SB changes and as an outcome measure in clinical trials of disease modifying osteoarthritic drugs.

Is calcaneal quantitative ultrasound useful as a prescreen stratification tool for osteoporosis?

Calcaneal quantitative ultrasound (QUS) is attractive as a prescreening tool for osteoporosis, alternative to dual-energy X-ray absorptiometry. We investigated the literature of the usability of calcaneal QUS. We found large heterogeneity between studies and uncertainty about cutoff, device, and measured variable. Despite osteoporosis-related fractures being a major health issue, osteoporosis remains underdiagnosed. Dual-energy X-ray absorptiometry (DXA) of the hip or spine is currently the preferred method for diagnosis of osteoporosis, but the method is limited by low accessibility. QUS is a method for assessing bone alternative to DXA. The aim of this systematic review was to explore the usability of QUS as a prescreen stratification tool for assessment of osteoporosis. Studies that evaluated calcaneal QUS with DXA of the hip or spine as the gold standard was included. We extracted data from included studies to calculate number of DXAs saved and misclassification rates at cutoffs equal to high sensitivity and/or specificity. The number of DXAs saved and percentage of persons misclassified were measures of usability. We included 31 studies. Studies were heterogeneous regarding study characteristics. Analyses showed a wide spectrum of percentage of DXAs saved (2.7-68.8%) and misclassification rates (0-12.4%) depending on prescreen strategy and study characteristics, device, measured variable, and cutoff. Calcaneal QUS is potentially useful as a prescreen tool for assessment of osteoporosis. However, there is no consensus of device, variable, and cutoff. Overall, there is no sufficient evidence to recommend a specific cutoff for calcaneal QUS that provides a certainty level high enough to rule in or out osteoporosis. Calcaneal QUS in a prescreen or stratification algorithm must be based on device-specific cutoffs that are validated in the populations for which they are intended to be used.

Bone fragility and imaging techniques

Bone fragility is a silent condition that increases bone fracture risk, enhanced by low bone mass and microarchitecture deterioration of bone tissue that lead to osteoporosis. Fragility fractures are the major clinical manifestation of osteoporosis.A large body of epidemiological data indicates that the current standard for predicting fragility fracture risk is an areal BMD (aBMD) measurement by DXA. Although mineral density measurements assess the quantity of bone, the quality of the tissue is an important predictor of fragility. Thus, bone strength is explained not only by BMD but also by macrostructural and microstructural characteristics of bone tissue. Imaging diagnostics, through the use of X-rays, DXA, Ultrasonography, CT and MR, provides methods for diagnosis and characterization of fractures, and semi- and quantitative methods for assessment of bone consistency and strength, that become precious for bone fragility clinical management if they are integrated by clinical risk factors. The last employment of sophisticated non-invasively imaging techniques in clinical research as high-resolution CT (hrCT), microCT (μ-CT), high-resolution MR (hrMR) and, microRM (μRM), combined with finite element analysis methods, open to new challenges in a better bone strength assessment to enhance the comprehension of biomechanical parameters and the prediction of fragility fractures.

Thyroid hormone-induced demineralisation of the vertebral skeleton of the eel, Anguilla anguilla

The role of thyroid hormones (TH) in bone remodelling is controversial. Indeed, in humans, while they are necessary for normal growth and development, their overproduction can induce important mineral bone loss and osteoporosis. Intense bone resorption is a natural phenomenon also observed in some teleosts, during reproductive migration and fasting. Our work aimed at investigating the effects of chronic treatments with TH (thyroxin, T4 or triiodothyronine, T3) on bone resorption in a migratory fish, the European eel (Anguilla anguilla), a representative species of an ancient group of teleosts (Elopomorphs). The incineration method showed that TH induced a significant mineral loss in eel vertebral skeleton. Histology and histophysical (qualitative and quantitative microradiographs) methods were then applied to vertebral sections to determine which types of resorption were induced by TH. Quantitative image analysis of microradiographs showed that TH significantly increased the porosity of the vertebrae, demonstrating the induction of a severe bone loss. Histology revealed the appearance of large osteoclastic lacunae, indicating a stimulation of osteoclastic resorption. Quantitative image analysis of ultrathin microradiographs showed a significant increase of the size of osteocytic lacunae, indicating a stimulation of periosteocytic osteolysis. Finally, quantitative microradiographs indicated a significant fall of mineralisation degree. TH treatments did not stimulate the production of the calcium-bonded lipo-phospho-protein vitellogenin, indicating that TH-induced bone demineralisation was not mediated by any indirect effect on vitellogenesis. Our study demonstrates that TH may participate in the mobilisation of bone mineral stores in the eel, by inducing different types of vertebral bone resorption, such as osteoclastic resorption and periosteocytic osteolysis. These data suggest that the stimulatory action of TH on bone resorption may be an ancient regulatory mechanism in vertebrates.

Low bone mineral density measurements in care home residents--a treatable cause of fractures

PURPOSE

to assess predictors of fracture risk and treatment for osteoporosis among elderly care home residents.

SUBJECTS AND METHODS

DESIGN

cross-sectional survey;

SETTING

residents of care homes in Newcastle upon Tyne, UK;

PARTICIPANTS

representative sample from residential care (87), nursing homes (105) and specialist homes for elderly people with dementia [elderly mentally infirm (EMI)]: residential (124) and nursing (76);

MAIN OUTCOME MEASURES

dual-energy X-ray absorptiometry bone mineral density (BMD) at calcaneum; functional assessments, including cognition, using Mini-Mental State Examination (MMSE), Clifton Assessment Procedure for the Elderly-Behaviour Rating Score (CAPE-BRS) and Functional Assessment Staging Test (FAST) scores; current drug prescription.

RESULTS

MMSE, CAPE, FAST (all ANOVA P < 0.001) and weight (ANOVA P < 0.02) were lower in EMI homes. Drugs with sedative effects (chi-square, P < 0.0001) were more likely and calcium and vitamin D (CaD) supplementation (chi-square, P < 0.02) less likely in EMI care. For residential care, the odds ratio (OR) for sedative drugs in EMI was 2.13 (95% CI 1.11-4.06) with no significant difference between nursing homes. For CaD supplementation, the OR for EMI nursing homes was 0.19 (95% CI 0.05-0.72) and for EMI residential homes 0.38 (NS to 95% CI 0.12-1.27). BMD was low: mean T-score was -2.29 (95% CI -2-48 to -2.09) and Z-score -0.96 (95% CI -1.16 to -0.76) with a prevalence of osteoporosis (T-score < -1.6) of 69.2%. MMSE and FAST scores did not predict BMD. In EMI residential care, a decrease of CAPE score by 5 points was associated with a decrease in T-score by 0.6 (95% CI 0.15-1.1).

CONCLUSIONS

of the tools used to assess function, only CAPE predicted low BMD in EMI residential care. Rates of CaD supplementation are particularly low in EMI care, where risk factors for fracture were the greatest. We conclude that fracture risk is neglected in these homes, and targeted education and treatment are warranted.

¿Qué opinan los internistas españoles de la osteoporosis?

OBJECTIVE

To conduct an opinion survey on osteoporosis in Spanish internists.

METHOD

Survey sent by mail and by personal visit to members of the Spanish Internists Society. Collection of data on opinion on the disease, diagnostic and therapeutic attitude and means available (general laboratory analyses, conventional radiology, biochemical markers of bone remodeling, densitometry and ultrasounds) and preference when choosing a certain treatment.

RESULTS

A total of 538 internists answered. More than 90% of those surveyed consider that osteoporosis is a disease that should be treated by internists. A total of 93% consider that osteoporosis is a prevalent disease. More than 80% have access to densitometry.

CONCLUSIONS

The majority of Spanish internists consider that osteoporosis is a disease that should be treated by internists and that it is a disease that enters into their action scope. In general, they have the means necessary for its study and treatment. Bisphosphonates constitute the drug of choice and calcium and vitamin D supplements are indicated in almost all the cases.

Contralateral differences in quantitative ultrasound of the heel: the importance of side in clinical practice

Quantitative ultrasound (QUS) of the heel is becoming increasingly popular for the assessment of skeletal status, although there appears to be a general lack of agreement regarding which side to measure. The purpose of the present study was to evaluate possible side differences (right versus left) in heel QUS within the general population, including children (10-15 years old, n=406), adults (26-33 years old, n=339), and elderly subjects (60-75 years old, n=455) of both genders (818 females and 382 males), and to examine the impact of these differences on prevalence estimates of osteoporosis and individual fracture risk assessment. All participants had both their heels measured twice with the Sahara device, which measures broadband ultrasound attenuation (BUA) and speed of sound (SOS) through the os calcis; a composite parameter, that is, quantitative ultrasound index (QUI) and an estimate of heel BMD (eBMD) were also derived. Significant side differences were detected for BUA and SOS (P<0.05), but not for QUI or eBMD. Contralateral differences were rather small in absolute terms, but were in the order of 12.6% for BUA, 0.72% for SOS, 7.9% for QUI, and 9.9% for eBMD, when expressed as percentage of the mean values for the two heels. Bilateral differences appeared to vary across age and gender. Significant correlations between QUS indices of the right and left heel were observed (r=0.75-0.85; P<0.001), which seemed to be stronger among the elderly and among male individuals. Prevalence rates of osteopenia and osteoporosis were not significantly different when estimated from eBMD T-scores for the one or the other foot (chi(2)=1.781, df=2, P=0.410). However, cross-classification analysis revealed that only 84% of the subjects classified into each risk category by the two calcanei were actually the same persons. In conclusion, results from the present study strongly suggest that QUS measurements of opposite heels may not be equivalent with respect to the evaluation of bone status and classification of individual fracture risk assessment, although the degree of discrepancy appears to be related to the primary outcome of interest.

Postmenopausal osteoporosis and alendronate

Osteoporosis is a systemic metabolic disorder associated with a decreased bone mass and resistance. Bisphosphonates suppress bone resorption and bone turnover by a mechanism that depends on their structure. They are characterized by low gastrointestinal absorption. In postmenopausal women, alendronate (ALN) reduces bone resorption markers and increases bone mineral density (BMD) in the lumbar spine, femoral neck, and total body. Individuals receiving ALN have been studied for up to 10 years with an apparent linear increase in BMD over that time period estimated at 13.7% at the lumbar spine. Treatment with ALN reduced the risk of both vertebral and non-vertebral fractures, including hip fractures, in postmenopausal women with osteoporosis. Direct comparisons of the results obtained with different antiresortive agents is difficult, because the designs of the respective studies, populations and other factors. However, the meta-analysis of available publications seems to indicate that ALN reduces the relative risk of vertebral fractures in a greater proportion than any other agent. Furthermore, ALN prevents the reduction in BMD after hormone replacement therapy discontinuation.

Quantitative ultrasound calcaneus measurements: normative data for the Greek population

Quantitative ultrasound (QUS) is a peripheral bone densitometry technique that is rapidly gaining in popularity, and is widely used worldwide for the assessment of skeletal status. This, however, generally occurs in the absence of adequate clinical guidelines. As accurate interpretation of the results and correct classification in individual fracture risk assessment are of great value, the present study was carried out to establish a reference database for calcaneal QUS measurements across age group and gender in Greece. A total of 1205 subjects (821 females and 384 males) from three age groups (409 children, 341 adults and 455 elderly) were recruited. QUS measurements were performed at the heel with the Sahara device, which measures broadband ultrasound attenuation (BUA) and speed of sound (SOS), and then combines these variables into a single parameter, the quantitative ultrasound index (QUI). Overall, gender-related differences were more pronounced among the elderly, while age-related differences were more pronounced among females. Elderly men had higher QUS parameters than women of peer age, but no major gender differences were observed in children and adults. In males, only BUA showed a variation with age, being higher in adult and elderly men compared to boys. On the other hand, all QUS parameters varied significantly with age in females, the general trends being mildly positive from childhood to adulthood, when peak levels were observed, and negative thereafter. The results for the Greek population were in the range reported previously for other populations, but some discrepancies were evident, probably resulting from ethno-specific characteristics and different QUS instrumentation. Importantly, using the manufacturer's or the local database as the reference population for computing T-scores led to significantly different classification of subjects into conventional categories of risk. These data could be useful as a guide for comparing the results of individual studies, as well as for the assessment of Greek men and women at risk of fracture.

Body composition changes with age have gender-specific impacts on bone mineral density

Body weight, smoking, alcohol, physical activity, and diet have been proven to affect bone mineral density (BMD) directly or indirectly. Of these, body weight is perhaps best known to affect BMD. However, there is some debate as to whether lean body mass (LBM) or fat mass (FM), the two components of body weight, most determines BMD. Recently, newer peripheral densitometry devices have been developed, which have the advantages of low cost and portability, and this has made field epidemiologic study of osteoporosis possible. As the number of studies that have focused on the contribution made by body composition to BMD is limited, we investigated the relative contribution of LBM and FM to BMD in healthy Korean subjects. 402 age- and weight-matched subjects over 45 years old were selected from a population-based cohort. The mean ages of men and women were 64.1 +/- 8.7 (mean +/- SD) and 64.2 +/- 12.7 years, and mean weights were 63.0 +/- 8.2 and 63.1 +/- 8.2 kg, respectively. BMD was measured by peripheral dual-energy X-ray absorptiometry (DEXA) and body composition by bioelectrical impedance. Sociodemographic characteristics and physical activities were investigated using a standard questionnaire delivered by face-to-face interview. BMDs were 0.48 +/- 0.01 and 0.37 +/- 0.11 g/cm2 in men and women, respectively. In men, age, weight, body mass index (BMI), LBM, FM, physical activity, smoking, alcohol, and education were significantly correlated with BMD. In women, age, weight, BMI, LBM, FM, education, years since menopause, number of deliveries, and number of children breast-fed were significantly correlated with BMD. By multiple regression, LBM, education, smoking, and alcohol in men, and age, LBM, FM, smoking, and number of delivery in women were independent determinants of BMD. LBM was an important contributor for BMD in men, but both LBM and FM were equally important contributors in female to BMD. This stems from the fact that body composition changes with age differ in men and women. Thus, the augmentation of muscle mass in men and the maintenance of an optimal weight in women act to prevent osteoporosis.

The use of digital X-ray radiogrammetry and peripheral dual energy X-ray absorptiometry in patients attending fracture clinic after distal forearm fracture

Despite the fact that 50% of postmenopausal women with Colles' fracture have evidence of osteoporosis, the vast majority of women with forearm fractures are neither investigated nor treated for osteoporosis. Digital X-ray radiogrammetry (DXR) provides an attractive option in patients with distal forearm fracture, as it requires no additional X-rays over and above those performed as part of clinical management. We have compared DXR analysis of nonstandardised plain films taken routinely in accident and emergency with peripheral dual energy X-ray absorptiometry (pDXA) in a group presenting with distal forearm fracture. Women presenting with a fracture of the distal forearm underwent pDXA measurements of the calcaneus. Plain X-rays performed at the time of presentation were taken to allow adequate fracture treatment. No additional radiographer training or standardisation of films was performed. The DXR technique relies upon visualisation of the metacarpal shafts and this was not visualised on 123 of 201 (61%) films. The AP plain film was thus assessed using DXR for BMD in the remaining 78 patients with a mean age of 70.6 years (SE = 1.3). Mean BMD for DXR was 0.46 g/cm2 (SE = 0.01) and for pDXA was 0.40 g/cm2 (SE = 0.01). The correlation between BMD measured using the two techniques was 0.55 (P < 0.001). Although DXR measurements could not be performed in all patients, this proportion could easily be increased by routinely including the metacarpal shaft region in X-rays obtained after suspected distal forearm fracture. The correlation between the pDXA and DXR results is comparable with those reported between DXA measurements at the forearm, spine and hip. Our study suggests that DXR may provide a feasible method for the assessment of future fracture risk. The potential advantage of DXR over calcaneal pDXA measurements is that standard forearm X-ray obtained as part of fracture management could be used.

Evaluation of calcaneus bone densitometry against hip and spine for diagnosis of osteoporosis

Dual X-ray absorptiometry (DXA) is now widely available as a method for assessing bone density. However, the place of peripheral bone densitometry in clinical practice for diagnosis of osteoporosis is not yet clear. To examine the potential use in our district general hospital setting, we compared calcaneus measurements with conventional DXA of the hip and spine in 100 patients referred for assessment following identification of risk factors for osteoporosis. Measurements were made on both heels and the results were found to be similar but not completely interchangeable. Use of receiver operating characteristic curves confirmed that a threshold T-score of -1.6 could be used to identify many of the high risk subjects. However, there was only moderate agreement between fracture risk classifications derived from heel T-scores, and diagnostic classification (osteoporosis/osteopenia/normal) derived from axial DXA. The specificity of heel measurements was high, but sensitivity was poorer. Heel measurements could therefore be valuable in some circumstances for finding patients for whom treatment of osteoporosis would be appropriate, such as in a population with a low prevalence of osteoporosis. They may also be of value in a population with a high prevalence of disease, particularly if there were no alternative means of bone densitometry. However, with an intermediate prevalence, the relatively high risk of false negative values would mean that false reassurance could be given to many of those classed as "low risk". This could be a major drawback in clinical practice if heel densitometry were used as the initial investigation and axial measurements were also available, since they would give conflicting results for a substantial proportion of these patients.

A comparison of calcaneal dual-energy X-ray absorptiometry and calcaneal ultrasound for predicting the diagnosis of osteoporosis from hip and spine bone densitometry

Peripheral densitometry is increasingly being used in the management of osteoporosis, but the optimal diagnostic thresholds have not been defined. The aim of this study was to determine the optimal T-score for peripheral dual-energy X-ray absorptiometry (pDXA) of the heel using a GE Lunar PIXI and quantitative ultrasound (QUS) of the heel using a GE Lunar Achilles Plus when compared with dual-energy X-ray absorptiometry (DXA) of central sites (spine, femoral neck, or total hip). Ninety-nine women (mean age 69 +/- 8, range 33-86 yr) referred from the metabolic bone clinic were studied. The optimal T-score for pDXA from ROC analysis was -1.7 and for QUS was -2.5. The pDXA T-score that defined the same prevalence of osteoporosis at any central site was also -1.7 and for QUS was -2.4. These results are similar to the manufacturer's recommendations. There is no significant difference in performance between the PIXI and QUS.