Comparisons of noninvasive bone mineral measurements in assessing age-related loss, fracture discrimination, and diagnostic classification

Mendelian Randomization Study of Lipid Metabolites Reveals Causal Associations with Heel Bone Mineral Density

BACKGROUND

Osteoporosis, which is a bone disease, is characterized by low bone mineral density and an increased risk of fractures. The heel bone mineral density is often used as a representative measure of overall bone mineral density. Lipid metabolism, which includes processes such as fatty acid metabolism, glycerol metabolism, inositol metabolism, bile acid metabolism, carnitine metabolism, ketone body metabolism, sterol and steroid metabolism, etc., may have an impact on changes in bone mineral density. While some studies have reported correlations between lipid metabolism and heel bone mineral density, the overall causal relationship between metabolites and heel bone mineral density remains unclear.

OBJECTIVE

to investigate the causal relationship between lipid metabolites and heel bone mineral density using two-sample Mendelian randomization analysis.

METHODS

Summary-level data from large-scale genome-wide association studies were extracted to identify genetic variants linked to lipid metabolite levels. These genetic variants were subsequently employed as instrumental variables in Mendelian randomization analysis to estimate the causal effects of each lipid metabolite on heel bone mineral density. Furthermore, metabolites that could potentially be influenced by causal relationships with bone mineral density were extracted from the KEGG and WikiPathways databases. The causal associations between these downstream metabolites and heel bone mineral density were then examined. Lastly, a sensitivity analysis was conducted to evaluate the robustness of the results and address potential sources of bias.

RESULTS

A total of 130 lipid metabolites were analyzed, and it was found that acetylcarnitine, propionylcarnitine, hexadecanedioate, tetradecanedioate, myo-inositol, 1-arachidonoylglycerophosphorine, 1-linoleoylglycerophoethanolamine, and epiandrosterone sulfate had a causal relationship with heel bone mineral density (p < 0.05). Furthermore, our findings also indicate an absence of causal association between the downstream metabolites associated with the aforementioned metabolites identified in the KEGG and WikiPathways databases and heel bone mineral density.

CONCLUSION

This work supports the hypothesis that lipid metabolites have an impact on bone health through demonstrating a causal relationship between specific lipid metabolites and heel bone mineral density. This study has significant implications for the development of new strategies to osteoporosis prevention and treatment.

The impact of disease time, cervical alignment and range of motion on cervical vertebral Hounsfield unit value in surgery patients with cervical spondylosis

STUDY DESIGN

This study was a retrospective review.

OBJECTIVE

Bone mineral density (BMD) at the surgical site is associated with complications of surgical internal fixation, and it is very important to study the cervical BMD of patients with cervical spondylosis who need surgery and the related factors that affect cervical BMD. It is still unclear about the age-related influence of disease time, cervical alignment and range of motion (ROM) on cervical vertebral Hounsfield unit (HU) value.

METHODS

This retrospective study was conducted on patients who underwent cervical surgery at one institution between January 2014 and December 2021. Age, sex, body mass index (BMI), disease type, comorbidities, neck pain, disease time, C2-7 Cobb angle (CA), cervical ROM and the C2-C7 vertebral HU value were recorded. The association between cervical HU value and each parameter of interest was assessed using the Pearson correlation coefficient. Multivariable linear regression analysis was performed to examine the relative influence of the multiple factors on cervical vertebral HU value.

RESULTS

Among patients younger than 50 years old, the HU value of the cervical vertebral in females was higher than that of males, but after the age of 50 years, the value of females was lower than that of males and decreased significantly after 60 years old. In addition, cervical HU value was significantly correlated with the disease time, flexion CA and ROM. Our age-related subgroup of multivariate linear regression analyses shows that disease time and flexion CA negatively affected the C6-7 HU value in more than 60-year-old males and in more than 50-year-old females.

CONCLUSIONS

Disease time and flexion CA were negatively affecting the C6-7 HU values in more than 60-year-old males and in more than 50-year-old females. More attention should be paid to bone quality in cervical spondylosis patients with longer disease time and larger convex of flexion CA.

[Individual aspects in eldery patients with fragility fractures]

BACKGROUND

Due to our ageing population, the number of elderly patients who are treated in the emergency department due to low-energy trauma (e.g., tripping) continues to rise. These minor accidents often result in fragility fractures classically located in the proximal humerus, distal radius, spine, pelvis, and near the hip joint. Pre-existing conditions, polypharmacy, and general frailty increase the risk of fragility fractures in this patient population.

METHODS

Geriatric trauma fractures and especially insufficiency fractures of the posterior pelvic ring are often difficult to diagnose by plain X‑ray. Therefore, in geriatric trauma patients, cross-sectional imaging, e.g., computed tomography (CT), dual-energy CT (DECT), or magnetic resonance imaging (MRI), should be considered early for reliable evaluation of a suspected fracture. This also allows for the identification of older fractures. Particularly in cognitively impaired elderly patients, difficult examination conditions or an unclear fall event, cross-sectional imaging is often indicated. However, this may also involve risks, e.g., use of contrast medium in patients with impaired renal function, so that each case must be considered individually. Furthermore, the diagnosis and treatment of osteoporosis, which is an underlying disease that leads to fragility fractures, is of particular importance. In the diagnostic workup, measurement of bone density using dual energy X‑ray absorptiometry (DXA) is the standard method according to guidelines. In specific situations, high-resolution peripheral quantitative CT (HR-pQCT) may also be used.

CONCLUSION

Due to the special challenges of correctly detecting fragility fractures and being able to quickly initiate adequate therapy, good cooperation between radiologists and trauma surgeons is necessary.

Correlation of Transferrin Saturation and Serum Ferritin with Bone Mass Density in Adult Transfusion Dependent Beta-Thalassemia Patients

BACKGROUND

The use of regular blood transfusions and iron chelation therapy to treat thalassemia has improved survival and increased the incidence of osteoporosis. Moreover, iron toxicity is one of the contributing factors that reduce bone mass density in adult transfusion-dependent beta-thalassemia patients. Therefore, this study aims to determine the proportion of low bone mass density in adult thalassemia patients and transferrin saturation, as well as serum ferritin, which correlates to the skeletal condition.

METHODS

This is a cross-sectional study conducted in Thalassemia and Hematology Medical Oncology Clinics of Cipto Mangunkusumo Hospital in March 2016. The anthropometric data and hemoglobin levels were obtained before transfusion. Subsequently, the average ferritin levels, bone mineral density, and radiographic results were obtained.

RESULTS

The percentage of adult thalassemia major and intermedia patients with low bone mass density was 68%. Also, there was a weak inverse correlation between bone mass density and transferrin saturation (r = -0.329, p = 0.01), while no correlation was shown between bone mass density and ferritin (r = -0.088, p = 0.504). The transferrin saturation cutoff point value used to distinguish the incidence of low and normal bone density in patients with transfusion-dependent beta-thalassemia was 89.5%. In addition, there was weak correlation between Singh index and bone mass density (r = 0.273, p = 0.038).

CONCLUSION

Among the transfusion-dependent beta-thalassemia patients, 68% had low bone mass density, which inversely correlated to transferrin saturation. Furthermore, the cutoff value of transferrin saturation to differentiate the incidence of low and normal bone density in thalassemia major compared to thalassemia intermedia was 89.5%. Singh Index correlates weakly with bone mass density and might be used to detect low bone mass density in remote healthcare facilities.

Determination of Cutoff Values for the Screening of Osteosarcopenia in Obese Postmenopausal Women

Osteosarcopenic obesity (OSO) describes the concurrent presence of obesity, low bone mass, and low muscle mass in an individual. Currently, no established criteria exist to diagnose OSO. We hypothesized that obese individuals require different cut-points from standard cut-points to define low bone mass and low muscle mass due to their higher weight load. In this study, we determined cutoff values for the screening of osteosarcopenia (OS) in obese postmenopausal Malaysian women based on the measurements of quantitative ultrasound (QUS), bioelectrical impedance analysis (BIA), and functional performance test. Then, we compared the cutoff values derived by 3 different statistical modeling methods, (1) receiver operating characteristic (ROC) curve, (2) lowest quintile of the study population, and (3) 2 standard deviations (SD) below the mean value of a young reference group, and discussed the most suitable method to screen for the presence of OS in obese population. One hundred and forty-one (n = 141) postmenopausal Malaysian women participated in the study. Bone density was assessed using calcaneal quantitative ultrasound. Body composition was assessed using bioelectrical impedance analyzer. Handgrip strength was assessed using a handgrip dynamometer, and physical performance was assessed using a modified Short Physical Performance Battery test. ROC curve was determined to be the most suitable statistical modeling method to derive the cutoffs for the presence of OS in obese population. From the ROC curve method, the final model to estimate the probability of OS in obese postmenopausal women is comprised of five variables: handgrip strength (HGS, with area under the curve (AUC) = 0.698 and threshold ≤ 16.5 kg), skeletal muscle mass index (SMMI, AUC = 0.966 and threshold ≤ 8.2 kg/m²), fat-free mass index (FFMI, AUC = 0.946 and threshold ≤ 15.2 kg/m²), broadband ultrasonic attenuation (BUA, AUC = 0.987 and threshold ≤ 52.85 dB/MHz), and speed of sound (SOS, AUC = 0.991 and threshold ≤ 1492.15 m/s). Portable equipment may be used to screen for OS in obese women. Early identification of OS can help lower the risk of advanced functional impairment that can lead to physical disability in obese postmenopausal women.

Fragility fracture discriminative ability of radius quantitative ultrasound: a systematic review and meta-analysis

The fragility fracture discriminative ability of radius quantitative ultrasound (QUS) was evaluated in a systematic review of 13 studies, including 16,681 individuals and 1296 fractures. The radial speed of sound (SOS) per standard deviation (SD) decrease contributed to an increased risk of total and hip fracture by 32% and 66% in women. Osteoporotic fracture, as a devastating consequence of osteoporosis, brings severe socio-economic burden. The availability of dual-energy X-ray absorptiometry (DXA), as the gold standard of diagnosis, was quite limited in remote areas. Radius QUS measured by SOS shows potential in fracture discriminative ability where DXA equipment is not available. This study aimed to provide a comprehensive evaluation of the association between radius QUS and fracture risk. A detailed article search was carried out on PubMed, EMBASE, Cochrane Libraries, CNKI, Wan-Fang database, VIP, and SinoMed for studies published between January 1980 and February 2020. We determined the estimated relative risk (RR) for fracture per each radial SOS SD decrease. A meta-analysis of studies was performed under the random-effects model. A total of 16,681 individuals were included in this review. Among the participants, 5892 were male and 10,789 were female. A total of 1296 cases of fragility fracture were included. With each SD decrease in radial SOS, the risk of overall fragility fracture and hip fracture was increased by 21% and 55%, respectively. Particularly, the risk was increased by 32% and 66% for women. The association was even stronger for postmenopausal women. Radius QUS showed great potential as an effective tool for fracture risk evaluation, especially for women.

Total vs. Bioavailable: Determining a Better 25(OH)D Index in Association with Bone Density and Muscle Mass in Postmenopausal Women

The concurrent presence of low bone density (osteopenia/osteoporosis) and low muscle mass (sarcopenia) in older adults has led to the recognition of “osteosarcopenia” (OS) as a singular entity. Vitamin D may play important role in the manifestation of OS, in terms of intake, absorption, and bioavailability. Evidence suggests that bioavailable 25(OH)D may be a better indicator of Vitamin D compared to total 25(OH)D due to its weak bind to albumin, increasing its ‘availability’. The aim of this study was to assess total and bioavailable 25(OH)D levels in postmenopausal women and to determine their associations to bone density and muscle mass. We assessed body composition, bone density, and 25(OH)D indices of multiethnic, postmenopausal Malaysian women. A significant and negative correlation was found between body fat % and each index of 25(OH)D. Both bioavailable and total 25(OH)D were positively correlated with serum calcium and negatively correlated with iPTH(intact parathyroid hormone). VDBP(Vitamin D binding protein) level was significantly correlated with bioavailable 25(OH)D level, but not with the total 25(OH)D level. Stepwise regression analysis revealed that bioavailable, but not total, 25(OH)D was significantly correlated to bone density and muscle mass, (where stronger correlation was found with bone density), suggesting its superiority. Nevertheless, the low effect size warrants further studies.

Quantitative Computed Tomography (QCT) of the Distal Forearm in Men Using a Spiral Whole-Body CT Scanner - Description of a Method and Reliability Assessment of the QCT Pro Software

The Mr F study investigates the pathogenesis of low trauma distal forearm fractures in men and includes volumetric bone mineral density (vBMD) measurements at the ultradistal forearm as there are no current data. A standard 64 slice CT scanner was used to determine if it was possible to adapt the existing Mindways quantitative computed tomography Pro software for measuring vBMD values at the hip and spine sites. For calculation of intra- and interobserver reliability 40 forearm scans out of the 300 available were chosen randomly. The images were analyzed using the Slice Pick module and Bone Investigational Toolkit. The 4% length of the radius was chosen by measuring the length of the radius from the scaphoid fossa distally to the radial head. The acquired image then underwent extraction, isolation, rotation, and selection of region of interest in order to generate a report on vBMD. A cross-sectional image was created to allow the generation of data on the cortical and trabecular components separately. Repeat analyses were undertaken by 3 independent observers who were blinded as to whether the image was from a participant with or without fracture. The images were presented in random order at each time point. The following parameters were recorded: cortical cross sectional area, total vBMD, trabecular vBMD, and cortical vBMD (CvBMD). Data were analyzed by calculating intraclass correlation coefficients for intra- and interobserver reliability. The lowest values occurred at the CvBMD with intraobserver reliability of 0.92 (95% confidence interval [CI] of 0.86-0.96) and interobserver reliability of 0.92 (95% CI 0.89-0.96). All other parameters had reliability values between 0.97 and 0.99 with tighter 95% CI than for CvBMD. The method of adapting the Mindways Pro software using a standard CT to produce vBMD and structural data at the ultradistal radius is reliable.

Prevalence of and Risk Factors for Low Bone Mineral Density Assessed by Quantitative Computed Tomography in People Living With HIV and Uninfected Controls

BACKGROUND

Low bone mineral density (BMD) has been described in people living with HIV (PLWH). We examined the prevalence of low BMD measured by quantitative computed tomography (QCT), a method that allows 3-dimensional volumetric density measures at the thoracic spine, in well-treated PLWH and uninfected controls and assessed risk factors for reduced BMD.

METHODS

Cross-sectional study including 718 PLWH from the Copenhagen Co-Morbidity in HIV infection (COCOMO) study and 718 uninfected controls matched on age and sex from the Copenhagen General Population Study (CGPS). Trabecular BMD was determined by QCT.

RESULTS

Median BMD was 144.2 mg/cm in PLWH vs. 146.6 mg/cm in controls (P = 0.580). HIV status was not associated with BMD in univariable or multivariable linear analyses. However, a higher prevalence of very low BMD (T-score ≤ -2.5) was found in PLWH (17.2% vs. 11.0% in controls, P = 0.003). In unadjusted analysis, HIV was associated with very low BMD (odds ratio 1.68 [95% confidence interval: 1.24-2.27], P = 0.001), but this association was not significant after adjusting for age, sex, smoking, alcohol, body mass index, physical activity, and ethnicity. Previous AIDS-defining disease was associated with lower BMD, but no other associations with HIV-specific variables were identified.

CONCLUSION

Using QCT, we found a higher prevalence of very low BMD in PLWH than in controls. However, HIV status was not independently associated with BMD indicating that traditional risk factors contribute to the difference in prevalence of very low BMD. Focus on improvement of lifestyle factors, especially in PLWH with previous AIDS-defining disease, may prevent very low BMD in PLWH.

Bone density of first and second segments of normal and dysmorphic sacra

Background

Iliosacral screw fixation is safe and effective but can be complicated by loss of fixation, particularly in patients with osteopenic bone. Sacral morphology dictates where iliosacral screws may be placed when stabilizing pelvic ring injuries. In dysmorphic sacra, the safe osseous corridor of the upper sacral segment (S1) is smaller and lacks a transsacral corridor, increasing the need for fixation in the second sacral segment (S2). Previous evidence suggests that S2 is less dense than S1. The aim of this cross-sectional study is to further evaluate bone mineral density (BMD) of the S1 and S2 iliosacral osseous pathways through morphology stratification into normal and dysmorphic sacra.

Materials and methods

Pelvic computed tomography scans of 50 consecutive trauma patients, aged 18 to 50 years, from a level 1 trauma center were analyzed prospectively. Five radiographic features (upper sacral segment not recessed in the pelvis, mammillary bodies, acute alar slope, residual S1 disk, and misshapen sacral foramen) were used to identify dysmorphic characteristics, and sacra with four or five features were classified as dysmorphic. Hounsfield unit values were used to estimate the regional BMD of S1 and S2. Student’s t-test was utilized to compare the mean values at each segment, with statistical significance being set at p < 0.05. No change in clinical management occurred as a result of inclusion in this study.

Results

A statistical difference in BMD was appreciated between S1 and S2 in both normal and dysmorphic sacra (p < 0.0001), with 28.4% lower density in S2 than S1. Further, S1 in dysmorphic sacra tended to be 4% less dense than S1 in normal sacra (p = 0.047). No difference in density was appreciated at S2 based on morphology.

Conclusions

Our results would indicate that, based on BMD alone, fixation should be maximized in S1 prior to fixation in S2. In cases where S2 fixation is required, we recommend that transsacral fixation should be strongly considered if possible to bypass the S2 body and achieve fixation in the cortical bone of the ilium and sacrum.

Level of evidence

Level III.

Quantitative computed tomography discriminates between postmenopausal women with low spine bone mineral density with vertebral fractures and those with low spine bone mineral density only: the SHATTER study

Lumbar spine volumetric bone mineral density (BMD) measured using quantitative computed tomography (QCT) can discriminate between postmenopausal women with low areal BMD with and without vertebral fractures. QCT provides a 3D measure of BMD, excludes the vertebral posterior elements and accounts for bone size. This knowledge could contribute to effective treatment targeting of patients with low BMD.

INTRODUCTION

We evaluated the ability of lumbar spine bone mineral apparent density (BMAD), trabecular bone score (TBS) and volumetric bone mineral density (vBMD) to discriminate between postmenopausal women with low areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry (DXA) with and without vertebral fractures. The discriminatory ability of lumbar spine aBMD was compared with that of BMAD, TBS and vBMD.

METHODS

We studied three groups of postmenopausal women, i.e. group 1, aBMD T-score < - 1.0 and ≥ 1 vertebral fracture (n = 39); group 2, aBMD T-score < - 1.0 and no vertebral fracture, age- and aBMD-matched to group 1 (n = 34); group 3, aBMD score > - 1 and no vertebral fracture, age-matched to group 1 (n = 37). Lumbar spine aBMD was measured by DXA. BMAD was calculated using the DXA scan results. TBS was derived following DXA scan image reanalysis. Lumbar spine vBMD was assessed by quantitative computed tomography and Mindways Pro software. Differences in variables between groups 1, 2 and 3 were examined using general linear univariate modelling approaches. Area under the receiver operating characteristic (ROC) curve was calculated for BMAD, TBS and vBMD to determine the ability of lumbar spine measurement variables to discriminate between group 1 and group 2. A comparison of ROCs was performed.

RESULTS

Lumbar spine BMAD and TBS measurement variables were similar for groups 1 and 2. However, vBMD was significantly lower in group 1 and could discriminate between those women with low aBMD with (group 1) and without vertebral fractures (group 2).

CONCLUSIONS

We conclude that lumbar spine vBMD may discriminate well between postmenopausal women with low aBMD with and without vertebral fractures as it provides a 3D measure of bone mineral density, excludes the posterior elements of the vertebrae and takes into account bone size. A unique feature of the SHATTER study is that groups 1 and 2 were matched for aBMD, thus our study findings are independent of aBMD. Furthermore, we observed that neither BMAD nor TBS could distinguish between women with low aBMD with and without vertebral fractures. The knowledge gained from the SHATTER study will influence clinical and therapeutic decision-making, thereby optimising the care of patients with and without vertebral and other fragility fractures.

X-ray-based quantitative osteoporosis imaging at the spine

Osteoporosis is a metabolic bone disease with a high prevalence that affects the population worldwide, particularly the elderly. It is often due to fractures associated with bone fragility that the diagnosis of osteoporosis becomes clinically evident. However, early diagnosis would be necessary to initiate therapy and to prevent occurrence of further fractures, thus reducing morbidity and mortality. X-ray-based imaging plays a key role for fracture risk assessment and monitoring of osteoporosis. Whereas over decades dual-energy X-ray absorptiometry (DXA) has been the main method used and still reflects the reference standard, another modality reemerges with quantitative computed tomography (QCT) because of its three-dimensional advantages and the opportunistic exploitation of routine CT scans. Against this background, this article intends to review and evaluate recent advances in the field of X-ray-based quantitative imaging of osteoporosis at the spine. First, standard DXA with the recent addition of trabecular bone score (TBS) is presented. Secondly, standard QCT, dual-energy BMD quantification, and opportunistic BMD screening in non-dedicated CT exams are discussed. Lastly, finite element analysis and microstructural parameter analysis are reviewed.

Differences in bone density on chest CT according to smoking status in males without chronic obstructive lung disease

The goals of this study were to determine whether bone density measured using CT (CTBD) can show significant differences in bone loss according to smoking status and pack-years, and to examine the correlation between CTBD and bone mineral density when measured by dual-energy X-ray absorptiometry (DEXA-BMD) in males without chronic obstructive pulmonary disease (COPD). In this cross-sectional study, 1,011 males without airflow obstruction ≥50 years old were included. CTBD and DEXA-BMD were compared among groups with different smoking statuses. The correlation between CTBD and DEXA-BMD and the association of CTBD with pack-years were also investigated. CTBD of all vertebral bodies (VBs) and DEXA-BMD of all VBs without L1 showed significant differences among never, former, and current smokers. CTBD was significantly lowest in ≥30-pack-year smokers and was significantly lower in ≥30-pack-year smokers than in <15-pack-year smokers (all P < 0.05). There were significant correlations between DEXA-BMD and CTBD at all VB levels (correlation coefficient [r], 0.448~0.640; all P < 0.01). A lower CTBD had a significant association with a 15 ≤ x < 30-pack-year smoking history and ≥30-pack-year smoking history, while there was no association with never-smokers. In conclusion, CTBD demonstrated significant differences in bone quality according to smoking status and pack-years in males without COPD.

Discrimination of osteoporosis-related vertebral fractures by DXA-derived 3D measurements: a retrospective case-control study

A retrospective case-control study assessing the association of DXA-derived 3D measurements with osteoporosis-related vertebral fractures was performed. Trabecular volumetric bone mineral density was the measurement that best discriminates between fracture and control groups.

INTRODUCTION

The aim of the present study was to evaluate the association of DXA-derived 3D measurements at the lumbar spine with osteoporosis-related vertebral fractures.

METHODS

We retrospectively analyzed a database of 74 postmenopausal women: 37 subjects with incident vertebral fractures and 37 age-matched controls without any type of fracture. DXA scans at the lumbar spine were acquired at baseline (i.e., before the fracture event for subjects in the fracture group), and areal bone mineral density (aBMD) was measured. DXA-derived 3D measurements, such as volumetric BMD (vBMD), were assessed using a DXA-based 3D modeling software (3D-SHAPER). vBMD was computed at the trabecular, cortical, and integral bone. Cortical thickness and cortical surface BMD were also measured. Differences in DXA-derived measurements between fracture and control groups were evaluated using unpaired t test. Odds ratio (OR) and area under the receiver operating curve (AUC) were also computed. Subgroup analyses according to fractured vertebra were performed.

RESULTS

aBMD of fracture group was 9.3% lower compared with control group (p < 0.01); a higher difference was found for trabecular vBMD in the vertebral body (- 16.1%, p < 0.001). Trabecular vBMD was the measurement that best discriminates between fracture and control groups, with an AUC of 0.733, against 0.682 for aBMD. Overall, similar findings were observed within the subgroup analyses. The L1 vertebral fractures subgroup had the highest AUC at trabecular vBMD (0.827), against aBMD (0.758).

CONCLUSION

This study showed the ability of cortical and trabecular measurements from DXA-derived 3D models to discriminate between fracture and control groups. Large cohorts need to be analyzed to determine if these measurements could improve fracture risk prediction in clinical practice.

Improved prediction of incident vertebral fractures using opportunistic QCT compared to DXA

Objectives

To compare opportunistic quantitative CT (QCT) with dual energy X-ray absorptiometry (DXA) in their ability to predict incident vertebral fractures.

Methods

We included 84 patients aged 50 years and older, who had routine CT including the lumbar spine and DXA within a 12-month period (baseline) as well as follow-up imaging after at least 12 months or who sustained an incident vertebral fracture documented earlier. Patients with bone disorders aside from osteoporosis were excluded. Fracture status and trabecular bone mineral density (BMD) were retrospectively evaluated in baseline CT and fracture status was reassessed at follow-up. BMD_QCT was assessed by opportunistic QCT with asynchronous calibration of multiple MDCT scanners.

Results

Sixteen patients had incident vertebral fractures showing lower mean BMD_QCT than patients without fracture (p = 0.001). For the risk of incident vertebral fractures, the hazard ratio increased per SD in BMD_QCT (4.07; 95% CI, 1.98–8.38), as well as after adjusting for age, sex, and prevalent fractures (2.54; 95% CI, 1.09–5.90). For DXA, a statistically significant increase in relative hazard per SD decrease in T-score was only observed after age and sex adjustment (1.57; 95% CI, 1.04–2.38). The predictability of incident vertebral fractures was good by BMD_QCT (AUC = 0.76; 95% CI, 0.64–0.89) and non-significant by T-scores. Asynchronously calibrated CT scanners showed good long-term stability (linear drift ranging from − 0.55 to − 2.29 HU per year).

Conclusions

Opportunistic screening of mainly neurosurgical and oncologic patients in CT performed for indications other than densitometry allows for better risk assessment of imminent vertebral fractures than dedicated DXA.

Key Points

• Opportunistic QCT predicts osteoporotic vertebral fractures better than DXA reference standard in mainly neurosurgical and oncologic patients.

• More than every second patient (56%) with an incident vertebral fracture was misdiagnosed not having osteoporosis according to DXA.

• Standard ACR QCT-cutoff values for osteoporosis (< 80 mg/cm³) and osteopenia (≤ 120 mg/cm³) can also be applied scanner independently in calibrated opportunistic QCT.

The Changes of CTX, DPD, Osteocalcin, and Bone Mineral Density During the Postmenopausal Period

Objective

To investigate appropriate treatment time and useful bone turnover markers (BTMs) for monitoring bone turnover during the postmenopausal period, we analyzed changes of two bone resorption markers; serum carboxyterminal telopeptide of collagen I (s-CTX), urine deoxypyridinoline (u-DPD), one bone formation marker; serum osteocalcin (s-OC), and bone mineral density (BMD) in Korean postmenopausal women.

Methods

Seventy-eight menopausal women were divided into three groups according to postmenopausal period: group I (0–5 years), group II (6–10 years), group III (≥10 years). All groups were subdivided into an osteoporosis group (T-score≤-2.5) and a non-osteoporosis group (T-score>-2.5). BTMs such as s-CTX, u-DPD, s-OC, and BMD (g/cm²) were measured by dual-energy X-ray absorptiometry (DXA) in all patients. Analysis of variables among groups based on the postmenopausal period was performed using ANOVA.

Results

There was significant negative correlation between BMD and postmenopausal period. The levels of all BTMs including s-CTX, u-DPD, and s-OC were highest in group II and the increased levels of all BTMs subsequently declined in group III. The levels of BTMs were higher in the osteoporosis groups than in the non-osteoporosis groups in all subjects. It was statistically significant that the level of s-CTX in group I was higher in the osteoporosis group than in the non-osteoporosis group.

Conclusion

This study showed that bone resorption and bone formation were the highest 5–10 years after menopause, and s-CTX is more useful than u-DPD among the bone resorption markers. It’s important to measure serially both BMD and BTM within 10 years after menopause for accurate diagnosis and management for postmenopausal osteoporosis.

Nonunion of Transpsoas Lateral Lumbar Interbody Fusion Using an Allograft: Clinical Assessment and Risk Factors

Introduction

This retrospective study was performed to evaluate the clinical influence of - and to identify the risk factors for nonunion of transpsoas lateral lumbar interbody fusion (LLIF) with use of allograft.

Methods

Sixty-three patients who underwent transpsoas LLIF (69.8 ± 8.9 years, 21 males and 42 females, 125 segments) were followed for a minimum 2 years postoperatively. For all LLIF segments, polyetheretherketone (PEEK) cages packed with allogenic bone were applied with supplemental bilateral pedicle screws (PSs). Bone bridge formation was evaluated by computed tomography (CT) 2 years postoperative, and a segment without any bridge formation was determined to be a nonunion. Sixty-one participants (96.8%) were classified into two groups for clinical evacuation: Group N that contained one or more nonunion segments and Group F that contained no nonunion segment. Visual analogue scales (VAS) scores and the effective rates of the five domains of the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) were compared between Groups N and F. The risk factors for nonunion were determined by univariate and multivariate analyses.

Results

Twenty segments (16%) were diagnosed as nonunion. There were no significant differences in all VAS scores, and the ratio of effective cases in all domains of JOABPEQ between Group N (n = 14) and F (n = 47). Multivariate analysis identified percutaneous PS (PPS) usage (odds ratio [OR]: 3.14, 95% confidence interval: 1.13-8.68, p = 0.028) as a positive risk factor for nonunion.

Conclusions

We should be aware of the higher nonunion rate in the LLIF segments supplemented with PPS, though nonunion does not affect significantly clinical outcomes at 2 years postoperative.

Dual-energy X-ray absorptiometry underestimates in vivo lumbar spine bone mineral density in overweight rats

Dual-energy X-ray absorptiometry (DXA) is currently the most widely used technique for measuring areal bone mineral density (BMD). However, several studies have shown inaccuracy, with either overestimation or underestimation of DXA BMD measurements in the case of overweight or obese individuals. We have designed an overweight rat model based on junk food to compare the effect of obesity on in vivo and ex vivo BMD and bone mineral content measurements. Thirty-eight 6-month old male rats were given a chow diet (n = 13) or a high fat and sucrose diet (n = 25), with the calorie amount being kept the same in the two groups, for 19 weeks. L1 BMD, L1 bone mineral content, amount of abdominal fat, and amount of abdominal lean were obtained from in vivo DXA scan. Ex vivo L1 BMD was also measured. A difference between in vivo and ex vivo DXA BMD measurements (P < 0.0001) is evidenced with an underestimation of in vivo BMD by (8.47 ± 10.54)%. This difference was found for the chow and high fat, high sucrose diets (P = 0.008), and a significant interaction between in vivo measurements, ex vivo measurements, and diet was observed (P = 0.030). Also, the data show a positive significant correlation of ex vivo BMD with body weight, perirenal fat, abdominal fat, and abdominal lean. Multiple linear regression analysis shows that body weight, abdominal fat, and abdominal lean were independently related to ex vivo BMD. DXA underestimated lumbar in vivo BMD in overweight rats, and this measurement error is related to body weight and abdominal fat. Therefore, caution must be used when one is interpreting BMD among overweight and obese individuals.

Thoracic Quantitative Computed Tomography (QCT) Can Sensitively Monitor Bone Mineral Metabolism: Comparison of Thoracic QCT vs Lumbar QCT and Dual-energy X-ray Absorptiometry in Detection of Age-relative Change in Bone Mineral Density

RATIONALE AND OBJECTIVE

Sensitive detection of bone mineral density (BMD) change is a key issue to monitor and evaluate the individual bone health status, as well as bone metabolism and bone mineral status. The ability to use thoracic quantitative computed tomography (QCT) to detect the annual change of BMD remains unclear. We aimed to investigate the sensitivity in detecting age-related bone mineral loss using the thoracic QCT from the electrocardiographically gated heart scans in comparison to whole-body dual-energy X-ray absorptiometry (DXA) and standard lumbar QCT.

MATERIALS AND METHODS

A total of 121 asymptomatic patients' imaging data, including DXA whole body scan, cardiac CT scan, and abdomen scans were analyzed. The BMD of the thoracolumbar spine, upper, and lower extremities were measured using QCT and DXA, respectively. The age-related annual rate of bone density loss was computed and compared to the thoracic and lumbar QCT, as well DXA measures.

RESULTS

The age-related annual rate of bone loss with QCT was -0.70 mg/mL³ (-0.75%/y) in women, -0.83 mg/mL³ (-0.86%/y) in men in the thoracic and the lumbar trabecular QCT, respectively. Compared to the QCT, DXA demonstrates a lower annual rate of bone loss in the area of BMD measurement (P < .05 in all, excluding legs of women) in -0.45, -0.42, -0.67, and -0.46 in women, in -0.32, -0.02, -0.12, and -0.08 in men for thoracic, lumbar, leg, and arm, respectively.

CONCLUSION

We conclude that the thoracic and the lumbar QCT provide a similar and more sensitive method for detecting bone mineral loss when compared to DXA.

Cervical spine bone density in young healthy adults as a function of sex, vertebral level and anatomic location

PURPOSE

Bone mineral density (BMD) measured using quantitative computed tomography (QCT) has been shown to correlate with bone mechanical properties. Knowledge of BMD within specific anatomic regions of the spine is valuable to surgeons who must secure instrumentation to the vertebrae, to medical device developers who design screws and disc replacements, and to researchers who assign mechanical properties to computational models. The objective of this study was to comprehensively characterize BMD in the cervical spine of young healthy adults.

METHODS

QCT was used to determine BMD in the cervical spines of 31 healthy adults (age 20-35). Subject-specific 3D models of each vertebra were created from CT scans, and anatomic regions of interest were identified in each bone (C1: 3 regions; C2: 9 regions, C3-C7: 13 regions). Statistical tests were performed to identify differences in BMD according to vertebral level, anatomic regions within vertebrae, and sex.

RESULTS

BMD varied significantly among vertebral levels and among anatomic regions within each vertebra. Females had higher BMD than males (p = .041) primarily due to higher BMD in the posterior regions of each vertebra.

CONCLUSIONS

These data can serve as a baseline to identify BMD changes in older and symptomatic patients. This data set is also the first report of volumetric bone density within different anatomic regions of the atlas and axis of the cervical spine. The finding of higher BMD in females is in agreement with the previous QCT results but contradicts DEXA results that are known to be dependent upon bone size.

A Comparison of Peripheral Imaging Technologies for Bone and Muscle Quantification: a Mixed Methods Clinical Review

PURPOSE OF REVIEW

Bone and muscle peripheral imaging technologies are reviewed for their association with fractures and frailty. A narrative systematized review was conducted for bone and muscle parameters from each imaging technique. In addition, meta-analyses were performed across all bone quality parameters.

RECENT FINDINGS

The current body of evidence for bone quality's association with fractures is strong for (high-resolution) peripheral quantitative computed tomography (pQCT), with trabecular separation (Tb.Sp) and integral volumetric bone mineral density (vBMD) reporting consistently large associations with various fracture types across studies. Muscle has recently been linked to fractures and frailty, but the quality of evidence remains weaker from studies of small sample sizes. It is increasingly apparent that musculoskeletal tissues have a complex relationship with interrelated clinical endpoints such as fractures and frailty. Future studies must concurrently address these relationships in order to decipher the relative importance of one causal pathway from another.

Multicenter analysis of CIREN occupant lumbar bone mineral density and correlation with age and fracture incidence

OBJECTIVE

This study aimed to quantify lumbar volumetric bone mineral density (vBMD) for 873 seriously injured Crash Injury Research and Engineering Network (CIREN) motor vehicle crash occupants (372 male, 501 female) from 8 centers using phantomless computed tomography scans and to associate vBMD with age, fracture incidence, and osteopenia/osteoporosis diagnoses. The novelty of this work is that it associates vBMD with region of injury by applying an established method for vBMD measurement using phantomless computed tomography (CT).

METHODS

A validated phantomless CT calibration method that uses patient-specific fat and muscle measurements to calibrate vBMD measured from the L1-L5 trabeculae was applied on 873 occupants from various CIREN centers. CT-measured lumbar vBMD < 145 mg/cc is indicative of osteopenia using a published threshold. CIREN occupant lumbar vBMD in milligrams per cubic centimeter was regressed against age, osteopenia/osteoporosis comorbidities, height, weight, body mass index (BMI), and the incidence of fracture in vertebral (cervical, thoracic, lumbar) and rib/sternum regions.

RESULTS

Among the 873 occupants analyzed, 11% (92 occupants) were diagnosed as osteopenic in CIREN. Of these 92 occupants, 42% (39 occupants) had normal vBMD measures (≥145 mg/cc), suggesting possible misclassification in CIREN. Of the 134 occupants classified as osteopenic in vBMD analysis, 60% were not classified as osteopenic in CIREN, suggesting undiagnosed osteopenia, and 40% were correctly classified in CIREN. Age was negatively correlated with vBMD (P <.0001) and occupants with <145 mg/cc vBMD sustained a median number of 2 rib/sternum fractures compared to a median value of 0 rib/sternum fractures for the ≥145 mg/cc vBMD group (P <.0001). Vertebral fracture analysis revealed that the thoracolumbar region was the most common region of injury in the spine. Though the incidence of fracture was not significantly different in the thoracic (10% versus 6%, P =.122) and lumbar (16% versus 13%, P =.227) regions between the 2 bone quality groups, the proportion of thoracolumbar fractures was significantly higher in occupants with <145 mg/cc vBMD versus occupants with ≥145 mg/cc vBMD (24% versus 17%, P =.043).

CONCLUSIONS

Low lumbar vertebral bone quality is associated with an increased number of rib/sternum fractures and a greater incidence of thoracolumbar vertebral body fractures within the CIREN population analyzed.

Simultaneous estimation of cortical bone thickness and acoustic wave velocity using a multivariable optimization approach: Bone phantom and in-vitro study

The paper presents a method that allows the thickness of a compact bone layer and longitudinal wave velocity in the bone to be determined simultaneously with the use of reflected waves, with particular emphasis on the case of layers when the propagation time through the layer is shorter than the time duration of the interrogating pulse. The proposed method estimates simultaneously the thickness of the cortical bone layer and acoustic wave velocity by fitting the temporal spectrum of the simulated reflected wave to the spectrum of the reflected wave measured experimentally. For the purpose of echo-simulations the model of "soft tissue - compact bone layer - cancellous bone" was developed. Next, the cost function was defined as the least square error between the measured and simulated temporal spectra. Minimization of the cost function allowed us to determine the values of the parameters of the cortical bone layer which best fitted the measurements. To solve the optimization problem a simulated annealing algorithm was used. The method was tested using acoustic data obtained at the frequency of 0.6 MHz and 1 MHz respectively for a custom designed bone mimicking phantom and a calf femur. For the cortical shell of the calf femur whose thickness varies from 2.1 mm to 2.4 mm and velocity of 2910 m/s, the relative errors of the thickness estimation ranged from 0.4% to 5.5%. The corresponding error of the acoustic wave velocity estimation in the layer was 3.1%. In the case of artificial bone the thickness of the cortical layer was equal to 1.05 and 1.2 mm and acoustic wave velocity was 2900 m/s. These parameters were determined with the errors ranging from 1.9% to 10.8% and from 3.9% to 4.5% respectively.

Epidemiology of Vertebral Fractures

Vertebral fractures are one of the most common fractures associated with skeletal fragility and can cause as much morbidity as hip fractures. However, the epidemiology of vertebral fractures differs from that of osteoporotic fractures at other skeletal sites in important ways, largely because only one quarter to one-third of vertebral fractures are recognized clinically at the time of their occurrence and otherwise require lateral spine imaging to be recognized. This article first reviews the prevalence and incidence of clinical and radiographic vertebral fractures in populations across the globe and secular trends in the incidence of vertebral fracture over time. Next, associations of vertebral fractures with measures of bone mineral density and bone microarchitecture are reviewed followed by associations of vertebral fracture with various textural measures of trabecular bone, including trabecular bone score. Finally, the article reviews clinical risk factors for vertebral fracture and the association of vertebral fractures with morbidity, mortality, and other subsequent adverse health outcomes.

A Trimodality Comparison of Volumetric Bone Imaging Technologies. Part III: SD, SEE, LSC Association With Fragility Fractures

Part II of this 3-part series demonstrated 1-yr precision, standard error of the estimate, and 1-yr least significant change for volumetric bone outcomes determined using peripheral (p) quantitative computed tomography (QCT) and peripheral magnetic resonance imaging (pMRI) modalities in vivo. However, no clinically relevant outcomes have been linked to these measures of change. This study examined 97 women with mean age of 75 ± 9 yr and body mass index of 26.84 ± 4.77 kg/m(2), demonstrating a lack of association between fragility fractures and standard deviation, least significant change and standard error of the estimate-based unit differences in volumetric bone outcomes derived from both pMRI and pQCT. Only cortical volumetric bone mineral density and cortical thickness derived from high-resolution pQCT images were associated with an increased odds for fractures. The same measures obtained by pQCT erred toward significance. Despite the smaller 1-yr and short-term precision error for measures at the tibia vs the radius, the associations with fractures observed at the radius were larger than at the tibia for high-resolution pQCT. Unit differences in cortical thickness and cortical volumetric bone mineral density able to yield a 50% increase in odds for fractures were quantified here and suggested as a reference for future power computations.

Endpoint comparison for bone mineral density measurements in North Central Cancer Treatment Group cancer clinical trials N02C1 and N03CC (Alliance)

Bone mineral density (BMD) measurement can vary depending upon anatomical site, machine, and normative values used. This analysis compared different BMD endpoints in two clinical trials. Trial results differed across endpoints. Future clinical trials should consider inclusion of multiple endpoints in sensitivity analysis to ensure sound overall study conclusions.

INTRODUCTION

Methodological issues hamper efficacy assessment of osteoporosis prevention agents in cancer survivors. Osteoporosis diagnosis can vary depending upon which bone mineral density (BMD) anatomical site and machine is used and which set of normative values are applied. This analysis compared different endpoints for osteoporosis treatment efficacy assessment in two clinical studies.

METHODS

Data from North Central Cancer Treatment Group phase III clinical trials N02C1 and N03CC (Alliance) were employed involving 774 patients each comparing two treatments for osteoporosis prevention. Endpoints for three anatomical sites included raw BMD score (RawBMD); raw machine-based, sample-standardized, and reference population-standardized T scores (RawT, TSamp, TRef); and standard normal percentile corresponding to the reference population-standardized T score (TPerc). For each, treatment arm comparison was carried out using three statistical tests using change and percentage change from baseline (CB, %CB) at 1 year.

RESULTS

Baseline correlations among endpoints ranged from 0.79 to 1.00. RawBMD and TPerc produced more statistically significant results (14 and 19 each out of 36 tests) compared to RawT (11/36), TSamp (8/36), and TRef (7/36). Spine produced the most statistically significant results (26/60) relative to femoral neck (20/60) and total hip (13/60). Lastly, CB resulted in 44 statistically significant results out of 90 tests, whereas %CB resulted in only 15 significant results.

CONCLUSIONS

Treatment comparisons and interpretations were different across endpoints and anatomical sites. Transforming via sample statistics provided similar results as transforming via reference or machine-based norms. However, RawBMD and TPerc may be more sensitive to change as clinical trial endpoints.

Bone densitometry

Dual-energy x-ray absorptiometry (DXA) is the method of choice to measure bone mineral density in elderly patients and others at risk for osteoporosis. Early detection is important because fractures represent an enormous health burden. In this article, the authors discuss the application and interpretation of DXA scans as well as limitations and conditions that can affect results.

Investigation of bone quality of the first and second sacral segments amongst trauma patients: concerns about iliosacral screw fixation

Background

Iliosacral screw fixation has become a common method for surgical stabilization of acute disruptions of the pelvic ring. Placement of iliosacral screws into the first sacral (S1) body is the preferred method of fixation, but size limitations and sacral dysmorphism may preclude S1 fixation. In these clinical situations, fixation into the second sacral (S2) body has been recommended. The objective of this study was to evaluate the bone quality of the S1 compared to S2 in the described “safe zone” of iliosacral screw fixation in trauma patients.

Materials and methods

The pelvic computed tomography scans of 25 consecutive trauma patients, ages 18–49, at a level 1 trauma center were prospectively analyzed. Hounsfield units, a standardized computed tomography attenuation coefficient, was utilized to measure regional cancellous bone mineral density of the S1 and S2. No change in the clinical protocol or treatment occurred as a consequence of inclusion in this study.

Results

A statically significant difference in bone quality was found when comparing the first and second sacral segment (p = 0.0001). Age, gender, or smoking status did not independently affect bone quality.

Conclusion

In relatively young, otherwise healthy trauma patients there is a statistically significant difference in the bone density of the first sacral segment compared to the second sacral segment. This study highlights the need for future biomechanical studies to investigate whether this difference is clinically relevant. Due to the relative osteopenia in the second sacral segment, which may impact the quality of fixation, we feel this technique should be used with caution.

Level of evidence

III

Imaging Findings and Evaluation of Metabolic Bone Disease

Bone is a dynamic organ of the endoskeleton, playing an important role in structural integrity, mineral reservoirs, blood production, coagulation, and immunity. Metabolic bone disease encompasses a broad spectrum of inherited and acquired disorders that disrupt the normal homeostasis of bone formation and resorption. For patients affected by these processes, radiologic imaging plays a central role in diagnosis, monitoring treatment, and risk stratification. Radiologists should be familiar with the diseases, intimately aware of the imaging findings, and possessive of multimodality expertise to wisely guide the best practice of medicine. The purpose of this paper is to review the imaging features and characteristics of the most common types of metabolic bone disease with highlights of clinically relevant information so that readers can better generate appropriate differential diagnoses and recommendations. For this review, a thorough literature search for the most up-to-date information was performed on several key types of metabolic bone disease: osteoporosis, osteomalacia, rickets, scurvy, renal osteodystrophy, hyperparathyroidism, Paget’s disease, osteogenesis imperfecta, acromegaly, and osteopetrosis. Although they all affect the bone, these diseases have both shared characteristic features that can be discerned through imaging.

Femoral volumetric bone density, geometry, and strength in relation to 25-hydroxy vitamin D in older men

Low serum 25-hydroxy vitamin D (25(OH)D) concentrations are associated with increased hip fracture risk and decreased femoral areal bone mineral density (BMD) among elderly men. Structural dimensions of the proximal femur and volumetric BMD in cortical and trabecular compartments are also associated with hip fracture risk. However, associations of volumetric BMD or structural dimensions with serum 25(OH)D concentrations among older men remain unclear. In a random sample of 1608 men aged ≥65 years from the Osteoporotic Fractures in Men Study (MrOS), baseline serum 25(OH)D concentrations were measured by liquid chromatography/mass spectrometry assays. Femoral neck geometry and volumetric BMD derived from quantitative computed tomography included integral, cortical, and trabecular volumetric BMD; cross-sectional area; integral and cortical volume; and cortical volume as a percent of integral volume. We studied 888 men with vitamin D, parathyroid hormone (PTH), femoral neck geometry, and BMD measures. Whole-bone femoral strength and load-strength ratio from finite element (FE) analysis were also available for 356 men from this sample. Multivariable linear regression was used to estimate least square means of each femoral measure within quartiles of 25(OH)D adjusted for age, race, body mass index, height, latitude, and season of blood draw. Tests of linear trend in the means were performed across increasing quartile of serum 25(OH)D levels. Mean cortical volume (p trend = 0.006) and cortical volume as a percent of integral volume (p trend < 0.001) increased across increasing quartile of 25(OH)D level. However, overall femoral neck size (area and integral volume) did not vary by 25(OH)D level. Femoral neck volumetric BMD measures increased in a graded manner with higher 25(OH)D levels (p trend < 0.001). Femoral strength, but not load-strength ratio, increased with increasing 25(OH)D. Adjustment for PTH did not materially change these associations. We conclude that in older men, higher levels of endogenous 25(OH)D may increase whole-bone strength by increasing femoral volumetric BMD and cortical volume.

Fat and Bone: An Odd Couple

In this review, we will first discuss the concept of bone strength and introduce how fat at different locations, including the bone marrow, directly or indirectly regulates bone turnover. We will then review the current literature supporting the mechanistic relationship between marrow fat and bone and our understanding of the relationship between body fat, body weight, and bone with emphasis on its hormonal regulation. Finally, we will briefly discuss the importance and challenges of accurately measuring the fat compartments using non-invasive methods. This review highlights the complex relationship between fat and bone and how these new concepts will impact our diagnostic and therapeutic approaches in the very near future.

Bone quality: the determinants of bone strength and fragility

Bone fragility is a major health concern, as the increased risk of bone fractures has devastating outcomes in terms of mortality, decreased autonomy, and healthcare costs. Efforts made to address this problem have considerably increased our knowledge about the mechanisms that regulate bone formation and resorption. In particular, we now have a much better understanding of the cellular events that are triggered when bones are mechanically stimulated and how these events can lead to improvements in bone mass. Despite these findings at the molecular level, most exercise intervention studies reveal either no effects or only minor benefits of exercise programs in improving bone mineral density (BMD) in osteoporotic patients. Nevertheless, and despite that BMD is the gold standard for diagnosing osteoporosis, this measure is only able to provide insights regarding the quantity of bone tissue. In this article, we review the complex structure of bone tissue and highlight the concept that its mechanical strength stems from the interaction of several different features. We revisited the available data showing that bone mineralization degree, hydroxyapatite crystal size and heterogeneity, collagen properties, osteocyte density, trabecular and cortical microarchitecture, as well as whole bone geometry, are determinants of bone strength and that each one of these properties may independently contribute to the increased or decreased risk of fracture, even without meaningful changes in aBMD. Based on these findings, we emphasize that while osteoporosis (almost) always causes bone fragility, bone fragility is not always caused just by osteoporosis, as other important variables also play a major role in this etiology. Furthermore, the results of several studies showing compelling data that physical exercise has the potential to improve bone quality and to decrease fracture risk by influencing each one of these determinants are also reviewed. These findings have meaningful clinical repercussions as they emphasize the fact that, even without leading to improvements in BMD, exercise interventions in patients with osteoporosis may be beneficial by improving other determinants of bone strength.

Association between calcaneus quantitative ultrasound (QUS) parameters and thyroid status in middle-aged and elderly Chinese men with euthyroidism: a population-based cross-sectional study

Although it is generally accepted that thyroid hormones affect bone metabolism, there is little data on the association of thyroid antibodies with bone status. We aimed to investigate the association between thyroid hormones or antibodies and quantitative ultrasound (QUS) parameters. This was a cross-sectional, population-based study conducted in Nanjing, China. A total of 1,001 Chinese men over 40 years were enrolled. We measured free triiodothyronine, free thyroxin (fT4), thyroid-stimulating hormone, anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin, 25-hydroxyvitamin D, and QUS parameters. After adjusting for potential confounders, QUS values decreased from the lowest to highest tertiles of fT4 in euthyroid men [quantitative ultrasound index (QUI) p = 0.002, broadband ultrasound attenuation (BUA) p = 0.000, speed of sound (SOS) p = 0.009, respectively]. Men with high anti-TPO levels (≥200 IU/ml) were found to have lower QUI (p = 0.030), BUA (p = 0.034), and SOS (p = 0.041) values than controls (<200 IU/ml). The prevalence of vitamin D deficiency was significantly higher in individuals with high anti-TPO than those in lower levels (87.5 vs. 59.5 %, p = 0.001). Our results suggest that high fT4 or anti-TPO values are associated with lower QUS parameters. Prospective studies are needed to confirm the precise relationship between thyroid status and osteoporosis.

Quantitative ultrasound measurements of the calcaneus and hand phalanges in elderly Spanish men: relationship with peripheral bone mineral density of the hand phalanges

OBJECTIVES

The aims of this pilot study were to describe quantitative ultrasound (US) measurements and peripheral bone mineral density (BMD) of the hand phalanges on dual-energy x-ray absorptiometry and to examine the correlations between them in elderly Spanish men.

METHODS

We studied 199 healthy men (mean age ± SD, 73.31 ± 5.10 years). The participants were not taking any medications, and they reported no diseases, including diseases that are associated with abnormalities in mineral metabolism. Phalangeal and calcaneal quantitative US measurements and phalangeal BMD measurements were performed in all participants.

RESULTS

A bivariate correlation analysis showed no association between quantitative US assessments at the phalanges or the calcaneus (P = .409). After adjustment for potential confounders, the correlation between phalangeal BMD and phalangeal quantitative US measurements was r = 0.417 (P < .0001), and the correlation for calcaneal quantitative US was r = 0.26 (P = .001). Further adjustment by percentage of body fat increased quantitative US correlations with phalangeal BMD: r = 0.450 (P < .0001) at the phalanges; r = 0.291 (P = .001) at the calcaneus.

CONCLUSIONS

There is a small correlation between quantitative US measurements at the calcaneus and phalangeal BMD that increases to a moderate level with quantitative US measurements at the phalanges in elderly Spanish men.

Definition of osteoporosis by bone density criteria in men: effect of using female instead of male young reference data depends on skeletal site and densitometer manufacturer

Whether to use young male or young female reference data to calculate bone mineral density (BMD) T-scores in men remains controversial. The third National Health and Nutrition Examination and Survey (NHANES III) data show that the mean and standard deviation of femoral neck and total hip BMD is greater in young men than young women, and therefore differences in T-scores at these sites using NHANES III female vs male norms becomes less as BMD decreases. In contrast, manufacturer-specific reference databases generally assume similar standard deviations of BMD in men and women. Using NHANES III reference data for the femoral neck and total hip, respectively we found that men with T-scores of -2.5 when young male norms are used have T-scores of -2.4 and -2.3 when young female norms are used. Using manufacturer-specific reference data, we found that men with T-scores of -2.5 when young male norms are used at the femoral neck, total hip, lumbar spine, or one-third of the forearm would have T-scores ranging from -2.4 to -0.4 when young female norms are used, depending on skeletal site and densitometer manufacturer. The change of proportions of men diagnosed with osteoporosis when young female norms are used instead of young male reference data differs substantially according to skeletal site and densitometer manufacturer.

Microstructural, densitometric and metabolic variations in bones from rats with normal or altered skeletal states

Background

High resolution μCT, and combined μPET/CT have emerged as non-invasive techniques to enhance or even replace dual energy X-ray absorptiometry (DXA) as the current preferred approach for fragility fracture risk assessment. The aim of this study was to assess the ability of µPET/CT imaging to differentiate changes in rat bone tissue density and microstructure induced by metabolic bone diseases more accurately than current available methods.

Methods

Thirty three rats were divided into three groups of control, ovariectomy and vitamin-D deficiency. At the conclusion of the study, animals were subjected to glucose (¹⁸FDG) and sodium fluoride (Na¹⁸F) PET/CT scanning. Then, specimens were subjected to µCT imaging and tensile mechanical testing.

Results

Compared to control, those allocated to ovariectomy and vitamin D deficiency groups showed 4% and 22% (significant) increase in ¹⁸FDG uptake values, respectively. DXA-based bone mineral density was higher in the vitamin D deficiency group when compared to the other groups (cortical bone), yet μCT-based apparent and mineral density results were not different between groups. DXA-based bone mineral density was lower in the ovariectomy group when compared to the other groups (cancellous bone); yet μCT-based mineral density results were not different between groups, and the μCT-based apparent density results were lower in the ovariectomy group compared to the other groups.

Conclusion

PET and micro-CT provide an accurate three-dimensional measurement of the changes in bone tissue mineral density, as well as microstructure for cortical and cancellous bone and metabolic activity. As osteomalacia is characterized by impaired bone mineralization, the use of densitometric analyses may lead to misinterpretation of the condition as osteoporosis. In contrast, µCT alone and in combination with the PET component certainly provides an accurate three-dimensional measurement of the changes in both bone tissue mineral density, as well as microstructure for cortical and cancellous bone and metabolic activity.

A cross-sectional randomised study of fracture risk in people with HIV infection in the probono 1 study

Objective

To determine comparative fracture risk in HIV patients compared with uninfected controls.

Design

A randomised cross-sectional study assessing bone mineral density (BMD), fracture history and risk factors in the 2 groups.

Setting

Hospital Outpatients.

Subbbjects

222 HIV infected patients and an equal number of age-matched controls. Assessments: Fracture risk factors were assessed and biochemical, endocrine and bone markers measured. BMD was assessed at hip and spine. 10-year fracture probability (FRAX) and remaining lifetime fracture probability (RFLP) were calculated.

Main Outcome Measures

BMD, and history of fractures.

Results

Reported fractures occurred more frequently in HIV than controls, (45 vs. 16; 20.3 vs. 7%; OR=3.27; p=0.0001), and unsurprisingly in this age range, non-fragility fractures in men substantially contributed to this increase. Osteoporosis was more prevalent in patients with HIV (17.6% vs. 3.6%, p<0.0001). BMD was most reduced, and predicted fracture rates most increased, at the spine. Low BMD was associated with antiretroviral therapy (ART), low body mass index and PTH. 10-year FRAX risk was <5% for all groups. RLFP was greater in patients with HIV (OR=1.22; p=0.003) and increased with ART (2.4 vs. 1.50; OR= 1.50; p=0.03).

Conclusions

The increased fracture rate in HIV patients in our relatively youthful population is partly driven by fractures, including non-fragility fractures, in men. Nonetheless, these findings may herald a rise in osteoporotic fractures in HIV patients. An appropriate screening and management response is required to assess these risks and identify associated lifestyle factors that are also associated with other conditions such as cardiovascular disease and diabetes.

Advanced CT based in vivo methods for the assessment of bone density, structure, and strength

Based on spiral 3D tomography a large variety of applications have been developed during the last decade to asses bone mineral density, bone macro and micro structure, and bone strength. Quantitative computed tomography (QCT) using clinical whole body scanners provides separate assessment of trabecular, cortical, and subcortical bone mineral density (BMD) and content (BMC) principally in the spine and hip, although the distal forearm can also be assessed. Further bone macrostructure, for example bone geometry or cortical thickness can be quantified. Special high resolution peripheral CT (hr-pQCT) devices have been introduced to measure bone microstructure for example the trabecular architecture or cortical porosity at the distal forearm or tibia. 3D CT is also the basis for finite element analysis (FEA) to determine bone strength. QCT, hr-pQCT, and FEM are increasingly used in research as well as in clinical trials to complement areal BMD measurements obtained by the standard densitometric technique of dual x-ray absorptiometry (DXA). This review explains technical developments and demonstrates how QCT based techniques advanced our understanding of bone biology.

Treatment and Management of Postmenopausal Osteoporosis within an Ambulatory Care Network

Background:

Postmenopausal osteoporosis (PMO) is associated with substantial morbidity and mortality. Despite established guidelines for the care of PMO, the treatment and management of this disease remain suboptimal.

Objective:

To examine the treatment and management of PMO in a community-based ambulatory care setting.

Methods:

Women with a new diagnosis of PMO (International Classification of Diseases, 9th Revision, code 733.01) were identified through the electronic health records (EHR) of a community-based ambulatory care network in northern California between January 1, 2007, and December 31, 2008. Patients were included if they were 65 years of age or older and had EHR activity 26 months or more after diagnosis. They were excluded if they had a diagnosis of osteoporosis (ICD-9:733.xx) prior to the study period. A retrospective review of the EHR and medical charts was performed to identify patients who were prescribed FDA-approved pharmacotherapy, who received bone mineral density (BMD) testing via dual-energy X-ray absorptiometry (DXA), and who experienced a fracture.

Results:

One hundred thirty-one PMO patients were identified who met study eligibility criteria. Fifty-nine patients (45%) were prescribed FDA-approved pharmacotherapy at diagnosis. Ninety patients (69%) were prescribed pharmacotherapy at any point during follow-up. Sixty-four patients (49%) had a baseline DXA scan and 95 patients (73%) had 1 or more DXA scans during follow-up. Seventeen of 90 patients (19%) who received pharmacotherapy had 2 DXA scans within 2 years of follow-up. Nineteen fractures were reported among 16 patients during the study period.

Conclusions:

The proportion of patients with PMO who received pharmacologic treatment at diagnosis and had a baseline DXA scan was relatively low; however, the majority of these patients received treatment and had 1 or more DXA scans at some point during the 26-month follow-up period. Future studies should be conducted to assess the role of early BMD testing and pharmacologic intervention in optimizing outcomes among women with PMO.

Early diagnosis of vertebral fractures

Vertebral fractures are a common clinical entity, caused by trauma or related to osteoporosis (benign). Their recognition is especially important in the post-menopausal female population but also important is their differentiation from pathological (malignant) fractures (1). A vertebral fracture is evidenced by vertebral body deformity or reduction in vertebral body height beyond a certain threshold value in the absence of bone discontinuity. For prognosis and treatment it is extremely important to recognize the cause of the fracture. In contrast to fractures that occur in other locations, vertebral fractures often go unrecognized in the acute phase as the pain may be transient and radiographic and evaluation of the spine may be difficult (2). Objective measurement of the vertebral deformity provides invaluable information to the interpreting physician and helps grade fracture severity. The recognition and diagnosis of vertebral fractures can be performed using additional diagnostic tools.

Correlation between bone mineral density measured by peripheral and central dual energy X-ray absorptiometry in healthy Indian children and adolescents aged 10-18 years

There are few large-scale studies on the utility of peripheral dual energy X-ray absorptiometry (pDXA) in children. As central dual energy X-ray absorptiometry (cDXA) equipment is not commonly available in the developing world, we assessed the correlation of bone mineral density (BMD) with cDXA and pDXA in children to determine the optimal Z-score thresholds of pDXA for predicting two predefined Z-score cutoffs (≤-1, ≤-2) of cDXA in 844 subjects (441 boys, 403 girls) aged 10-18 years. The BMD of antero-posterior lumbar spine (L1-L4), proximal femur and forearm was measured by cDXA, while the peripheral BMD of forearm and calcaneus was estimated using pDXA. The correlation was statistically significant at all sites (p<0.01). The coefficients ranged from 0.56 to 0.79 in boys and 0.17 to 0.32 in girls. A significant positive correlation was observed between BMD by pDXA and cDXA in Indian children, with a strong gender difference in both the extent of correlation and the ability of peripheral BMD to predict central BMD.