Clinical practice. Osteopenia

Preventive machine learning models incorporating health checkup data and hair mineral analysis for low bone mass identification

Machine learning (ML) models have been increasingly employed to predict osteoporosis. However, the incorporation of hair minerals into ML models remains unexplored. This study aimed to develop ML models for predicting low bone mass (LBM) using health checkup data and hair mineral analysis. A total of 1206 postmenopausal women and 820 men aged 50 years or older at a health promotion center were included in this study. LBM was defined as a T-score below - 1 at the lumbar, femur neck, or total hip area. The proportion of individuals with LBM was 59.4% (n = 1205). The features used in the models comprised 50 health checkup items and 22 hair minerals. The ML algorithms employed were Extreme Gradient Boosting (XGB), Random Forest (RF), Gradient Boosting (GB), and Adaptive Boosting (AdaBoost). The subjects were divided into training and test datasets with an 80:20 ratio. The area under the receiver operating characteristic curve (AUROC), accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and an F1 score were evaluated to measure the performances of the models. Through 50 repetitions, the mean (standard deviation) AUROC for LBM was 0.744 (± 0.021) for XGB, the highest among the models, followed by 0.737 (± 0.023) for AdaBoost, and 0.733 (± 0.023) for GB, and 0.732 (± 0.021) for RF. The XGB model had an accuracy of 68.7%, sensitivity of 80.7%, specificity of 51.1%, PPV of 70.9%, NPV of 64.3%, and an F1 score of 0.754. However, these performance metrics did not demonstrate notable differences among the models. The XGB model identified sulfur, sodium, mercury, copper, magnesium, arsenic, and phosphate as crucial hair mineral features. The study findings emphasize the significance of employing ML algorithms for predicting LBM. Integrating health checkup data and hair mineral analysis into these models may provide valuable insights into identifying individuals at risk of LBM.

Balancing Performance and Interpretability in Medical Image Analysis: Case study of Osteopenia

Multiple studies within the medical field have highlighted the remarkable effectiveness of using convolutional neural networks for predicting medical conditions, sometimes even surpassing that of medical professionals. Despite their great performance, convolutional neural networks operate as black boxes, potentially arriving at correct conclusions for incorrect reasons or areas of focus. Our work explores the possibility of mitigating this phenomenon by identifying and occluding confounding variables within images. Specifically, we focused on the prediction of osteopenia, a serious medical condition, using the publicly available GRAZPEDWRI-DX dataset. After detection of the confounding variables in the dataset, we generated masks that occlude regions of images associated with those variables. By doing so, models were forced to focus on different parts of the images for classification. Model evaluation using F1-score, precision, and recall showed that models trained on non-occluded images typically outperformed models trained on occluded images. However, a test where radiologists had to choose a model based on the focused regions extracted by the GRAD-CAM method showcased different outcomes. The radiologists' preference shifted towards models trained on the occluded images. These results suggest that while occluding confounding variables may degrade model performance, it enhances interpretability, providing more reliable insights into the reasoning behind predictions. The code to repeat our experiment is available on the following link: https://github.com/mikulicmateo/osteopenia .

Developing and comparing deep learning and machine learning algorithms for osteoporosis risk prediction

Introduction

Osteoporosis, characterized by low bone mineral density (BMD), is an increasingly serious public health issue. So far, several traditional regression models and machine learning (ML) algorithms have been proposed for predicting osteoporosis risk. However, these models have shown relatively low accuracy in clinical implementation. Recently proposed deep learning (DL) approaches, such as deep neural network (DNN), which can discover knowledge from complex hidden interactions, offer a new opportunity to improve predictive performance. In this study, we aimed to assess whether DNN can achieve a better performance in osteoporosis risk prediction.

Methods

By utilizing hip BMD and extensive demographic and routine clinical data of 8,134 subjects with age more than 40 from the Louisiana Osteoporosis Study (LOS), we developed and constructed a novel DNN framework for predicting osteoporosis risk and compared its performance in osteoporosis risk prediction with four conventional ML models, namely random forest (RF), artificial neural network (ANN), k-nearest neighbor (KNN), and support vector machine (SVM), as well as a traditional regression model termed osteoporosis self-assessment tool (OST). Model performance was assessed by area under 'receiver operating curve' (AUC) and accuracy.

Results

By using 16 discriminative variables, we observed that the DNN approach achieved the best predictive performance (AUC = 0.848) in classifying osteoporosis (hip BMD T-score ≤ -1.0) and non-osteoporosis risk (hip BMD T-score > -1.0) subjects, compared to the other approaches. Feature importance analysis showed that the top 10 most important variables identified by the DNN model were weight, age, gender, grip strength, height, beer drinking, diastolic pressure, alcohol drinking, smoke years, and economic level. Furthermore, we performed subsampling analysis to assess the effects of varying number of sample size and variables on the predictive performance of these tested models. Notably, we observed that the DNN model performed equally well (AUC = 0.846) even by utilizing only the top 10 most important variables for osteoporosis risk prediction. Meanwhile, the DNN model can still achieve a high predictive performance (AUC = 0.826) when sample size was reduced to 50% of the original dataset.

Conclusion

In conclusion, we developed a novel DNN model which was considered to be an effective algorithm for early diagnosis and intervention of osteoporosis in the aging population.

Development and internal validation of a clinical prediction model for osteopenia in Chinese middle-aged and elderly men: a prospective cohort study

BACKGROUND

Early identification of patients at risk of osteopenia is an essential step in reducing the population at risk for fractures. We aimed to develop and validate a prediction model for osteopenia in Chinese middle-aged and elderly men that provides individualized risk estimates.

METHODS

In this prospective cohort study, 1109 patients who attend regular physical examinations in the Second Medical Centre of Chinese PLA General Hospital were enrolled from 2015.03 to 2015.09. The baseline risk factors included dietary habits, exercise habits, medical histories and medication records. Osteopenia during follow-up were collected from Electronic Health Records (EHRs) and telephone interviews. Internal validation was conducted using bootstrapping to correct the optimism. The independent sample T-test analysis, Mann_Whitney U test, Chi-Square Test and multivariable Cox regression analysis were utilized to identify predictive factors for osteopenia in Chinese middle-aged and elderly men. A nomogram based on the seven variables was built for clinical use. Concordance index (C-index), receiver operating characteristic curve (ROC), decision curve analysis (DCA) and calibration curve were used to evaluate the efficiency of the nomogram.

RESULTS

The risk factors included in the prediction model were bone mineral density at left femoral neck (LNBMD), hemoglobin (Hb), serum albumin (ALB), postprandial blood glucose (PBG), fatty liver disease (FLD), smoking and tea consumption. The C-index for the risk nomogram was 0.773 in the prediction model, which presented good refinement. The AUC of the risk nomogram at different time points ranged from 0.785 to 0.817, exhibiting good predictive ability and performance. In addition, the DCA showed that the nomogram had a good clinical application value. The nomogram calibration curve indicated that the prediction model was consistent.

CONCLUSIONS

Our study provides a novel nomogram and a web calculator that can effectively predict the 7-year incidence risk of osteopenia in Chinese middle-aged and elderly men. It is convenient for clinicians to prevent fragility fractures in the male population.

Vitamin D status and its associations with bone mineral density, bone turnover markers, and parathyroid hormone in Chinese postmenopausal women with osteopenia and osteoporosis

Background

Vitamin D is a key factor in bone metabolism, yet vitamin D insufficiency and deficiency are prevalent among postmenopausal women, with potential repercussions on bone mineral density (BMD), bone turnover markers (BTMs), and parathyroid hormone (PTH). Nonetheless, the findings from existing studies exhibit inconsistency, and a notable gap exists in the availability of large-scale investigations.

Methods

In this real-world study, 8,532 postmenopausal women over 50 years old with a diagnosis of osteopenia (50.9%) and osteoporosis (49.1%) at the first visit were enrolled in this study. Serum 25(OH)D level, PTH, osteocalcin (OC) and Beta-CrossLaps of type 1 collagen containing cross-linked C-telopeptide (β-CTX), were measured. BMD at all sites, including the lumbar spine, femoral neck, and total hip were obtained by dual-energy X-ray absorptiometry (DXA). The associations of serum 25(OH)D level with BMDs and BTMs were investigated using spearman correlation analysis and analysis of general linear model adjusted by age and body mass index.

Results

The serum 25(OH)D level was 22.17 ± 9.75 ng/mL among all patients included in this study. For the osteopenia group, the serum 25(OH)D level was 22.40 ± 9.41 ng/mL, while for the osteoporosis group, it measured 21.93 ± 10.08 ng/mL. In the osteopenia group, the prevalence of vitamin D deficiency, insufficiency and sufficiency was 45.8, 34.6, and 19.6%, respectively, which was close to that of the osteoporosis group (47.4, 34.3, and 18.3%) (p = 0.202). Spearman correlation analysis unveiled negative associations between serum 25(OH)D concentrations and both BTMs and PTH within both the osteopenia and osteoporosis group. In the osteoporosis group, there were positive correlations between 25(OH)D levels and femoral neck BMD (r = 0.040, p = 0.010) and total hip BMD (r = 0.053, p = 0.001). Furthermore, we found that for the osteopenia group, greater vitamin D levels were associated with greater femoral neck BMD (p = 0.020) and total hip BMD (p = 0.008) and lower β-CTX (p < 0.001), OC (p < 0.001), and PTH (p < 0.001). The same trends were seen in osteoporosis patients (p < 0.05), and with greater lumbar spine BMD with higher levels of 25(OH)D (p = 0.009).

Conclusion

This study showed high prevalence of vitamin D deficiency and insufficiency in Chinese postmenopausal women with osteopenia and osteoporosis and the relationships between vitamin D and BMD, BTMs and PTH. The results contribute to a more comprehensive understanding of how vitamin D may impact bone health.

Application of machine learning algorithms to predict osteoporosis in postmenopausal women with type 2 diabetes mellitus

PURPOSE

The screening and diagnosis of osteoporosis in patients with type 2 diabetes mellitus (T2DM) based on bone mineral density remains challenging because of the limited availability and accessibility of dual-energy X-ray absorptiometry. We aimed to develop and validate models to predict the risk of osteoporosis in postmenopausal women with T2DM based on machine learning (ML) algorithms.

METHODS

This retrospective study included 303 postmenopausal women with T2DM. To develop prediction models for osteoporosis, we applied nine ML algorithms combined with demographic, clinical, and laboratory data. The least absolute shrinkage and selection operator were used to perform feature selection. We used the bootstrap resampling technique for model training and validation. To test the performance of the models, we calculated indices including the area under the receiver operating characteristic curve (AUROC), accuracy, sensitivity, specificity, positive predictive value, negative predictive value, F1 score, calibration curve, and decision curve analysis. Furthermore, we conducted fivefold cross-validation for parameter optimization and model validation. Feature importance was assessed using the SHapley additive explanation (SHAP).

RESULTS

We identified 10 independent predictors as the most valuable features. An AUROC of 0.616-1.000 was observed for nine ML algorithms. The extreme gradient boosting (XGBoost) model exhibited the best performance, outperforming conventional risk assessment tools and registering 0.993 in the training set, 0.798 in the validation set, and 0.786 in the test set for fivefold cross-validation. Using SHAP, we found that the explanatory variables contributed to the model and their relationship with osteoporosis occurrence. Furthermore, we developed a user-friendly tool for calculating the risk of osteoporosis.

CONCLUSIONS

With the integration of demographic and clinical risk factors, ML algorithms can accurately predict osteoporosis. The XGBoost model showed ideal performance. With the incorporation of these models in the clinic, patients may benefit from early osteoporosis diagnosis and treatment.

Nanotechnology enabled radioprotectants to reduce space radiation-induced reactive oxidative species

Interest in space exploration has seen substantial growth following recent launch and operation of modern space technologies. In particular, the possibility of travel beyond low earth orbit is seeing sustained support. However, future deep space travel requires addressing health concerns for crews under continuous, longer-term exposure to adverse environmental conditions. Among these challenges, radiation-induced health issues are a major concern. Their potential to induce chronic illness is further potentiated by the microgravity environment. While investigations into the physiological effects of space radiation are still under investigation, studies on model ionizing radiation conditions, in earth and micro-gravity conditions, can provide needed insight into relevant processes. Substantial formation of high, sustained reactive oxygen species (ROS) evolution during radiation exposure is a clear threat to physiological health of space travelers, producing indirect damage to various cell structures and requiring therapeutic address. Radioprotection toward the skeletal system components is essential to astronaut health, due to the high radio-absorption cross-section of bone mineral and local hematopoiesis. Nanotechnology can potentially function as radioprotectant and radiomitigating agents toward ROS and direct radiation damage. Nanoparticle compositions such as gold, silver, platinum, carbon-based materials, silica, transition metal dichalcogenides, and ceria have all shown potential as viable radioprotectants to mitigate space radiation effects with nanoceria further showing the ability to protect genetic material from oxidative damage in several studies. As research into space radiation-induced health problems develops, this review intends to provide insights into the nanomaterial design to ameliorate pathological effects from ionizing radiation exposure. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Nanotechnology Approaches to Biology > Cells at the Nanoscale Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Adjusting phosphate feeding regimen according to daily rhythm increases eggshell quality via enhancing medullary bone remodeling in laying hens

BACKGROUND

Body phosphorus metabolism exhibits a circadian rhythm over the 24-h daily cycle. The egg laying behavior makes laying hens a very special model for investigating phosphorus circadian rhythms. There is lack of information about the impact of adjusting phosphate feeding regimen according to daily rhythm on the phosphorus homeostasis and bone remodeling of laying hens.

METHODS AND RESULTS

Two experiments were conducted. In Exp. 1, Hy-Line Brown laying hens (n = 45) were sampled according the oviposition cycle (at 0, 6, 12, and 18 h post-oviposition, and at the next oviposition, respectively; n = 9 at each time point). Diurnal rhythms of body calcium/phosphorus ingestions and excretions, serum calcium/phosphorus levels, oviduct uterus calcium transporter expressions, and medullary bone (MB) remodeling were illustrated. In Exp. 2, two diets with different phosphorus levels (0.32% and 0.14% non-phytate phosphorus (NPP), respectively) were alternately presented to the laying hens. Briefly, four phosphorus feeding regimens in total (each included 6 replicates of 5 hens): (1) fed 0.32% NPP at both 09:00 and 17:00; (2) fed 0.32% NPP at 09:00 and 0.14% NPP at 17:00; (3) fed 0.14% NPP at 09:00 and 0.32% NPP at 17:00; (4) fed 0.14% NPP at both 09:00 and 17:00. As a result, the regimen fed 0.14% NPP at 09:00 and 0.32% NPP at 17:00, which was designed to strengthen intrinsic phosphate circadian rhythms according to the findings in Exp. 1, enhanced (P < 0.05) MB remodeling (indicated by histological images, serum markers and bone mineralization gene expressions), elevated (P < 0.05) oviduct uterus calcium transportation (indicated by transient receptor potential vanilloid 6 protein expression), and subsequently increased (P < 0.05) eggshell thickness, eggshell strength, egg specific gravity and eggshell index in laying hens.

CONCLUSIONS

These results underscore the importance of manipulating the sequence of daily phosphorus ingestion, instead of simply controlling dietary phosphate concentrations, in modifying the bone remodeling process. Body phosphorus rhythms will need to be maintained during the daily eggshell calcification cycle.

The role of bone mineral density in adult spinal deformity patients undergoing corrective surgery: a matched analysis

STUDY DESIGN

Retrospective cohort.

BACKGROUND

Over 44 million adults are estimated to have either osteoporosis or osteopenia. Adult spinal deformity (ASD) is estimated to affect between 32 and 68% of the elderly population.

OBJECTIVE

Retrospective investigation comparing rates of postoperative complications following thoracolumbar scoliosis surgery in patients with normal bone mineral density (BMD) to those with osteopenia or osteoporosis in addition to analyzing the effects of pretreatment with anti-osteoporotic medications in patients with low BMD.

METHODS

Using administrative database of Humana beneficiaries, ICD-9 and ICD-10 diagnosis codes were used to identify ASD patients undergoing multilevel thoracolumbar fusions between 2007 and 2017.

RESULTS

The propensity matched population analyzed in this study contained 1044 patients equally represented by those with a history of osteopenia, osteoporosis, or normal BMD. Osteopenia and osteoporosis were associated with increased odds of revision surgery (OR 2.01 95% CI 1.36-2.96 and OR 1.57, 95% CI 1.05-2.35), respectively. Similarly, there was an almost twofold increased odds of proximal and distal junctional kyphosis in patients with osteopenia and osteoporosis (OR 1.95, 95% CI 1.40-2.74 and OR 1.88, 95% CI 1.34-2.64), respectively. A total of 258 (37.1%) patients with osteoporosis were pretreated with anti-osteoporotic medications and there was no statistically significant decrease in odds of proximal or distal junctional kyphosis or revision surgery in these patients.

CONCLUSION

Patients with ASD undergoing multilevel thoracolumbar fusion surgery have significantly higher rates of postoperative pseudarthrosis, proximal and distal junctional kyphosis, and revision surgery rates compared to patients with normal BMD.

Change in Bone Mineral Density in Stroke Patients with Osteoporosis or Osteopenia

We aimed to investigate the correlation between changes in bone mineral density (BMD) of the lumbar spine (LS) and femoral neck (FN) and osteoporosis-related factors in stroke patients with osteoporosis or osteopenia, and we suggest the need for active rehabilitation treatment. This study included 63 osteoporosis and 34 osteopenia patients who underwent a BMD test following primary stroke onset. The osteoporosis group was followed up with a BMD test after 12 months of bisphosphonate treatment, and the osteopenia group was followed up without medication. The correlation between BMD changes and functional factors was analyzed, biochemical markers were measured, and hematology tests were performed. In the osteoporosis group, a significant increase was observed in LS BMD (p < 0.05), and in the osteopenia group, there was a significant decrease in FN BMD (p < 0.05). The group with a functional ambulatory category of 1 or more showed a significant improvement in BMD (p < 0.05). Comparative analysis was performed on various indicators, but no significant correlation was found between any variable. In stroke patients with osteoporosis or osteopenia, early appropriate drug treatment is important to prevent bone loss and reduce the risk of fractures, and comprehensive rehabilitation treatment, such as appropriate education and training to prevent falls, is essential.

Cumulative Incidence and Factors Associated with Subsequent Vertebral Compression Fractures: A Nationwide Population-based Study

OBJECTIVE

Patients who experience vertebral compression fractures are vulnerable to subsequent vertebral compression fractures (SVCFs). The purpose of this nationwide population-based study was to determine the age-specific cumulative incidence and factors associated with SVCFs in South Korea.

METHODS

Diagnostic codes, medical costs, and comorbid diseases in patients who had a vertebral compression fracture in 2011 and 2012 were collected from the National Health Insurance Service database of South Korea from 2007 to 2018. Demographic data, mortality rate, medical cost, and frequency of vertebroplasty or kyphoplasty were compared between patients with an initial fracture (IF) and those with a subsequent fracture (SF).

RESULTS

The cumulative incidence of SVCFs over 4 years was 24.4% and increased rapidly within a few months after the IF. In 2011, SVCFs occurred in 17,004 patients, and the incidence rate per 100,000 people was 113.6 (84.9 in men vs. 138.5 in women). The odds ratio (OR) of SVCFs in units of 10 years was the highest in women in their 60s, at 2.89. However, in men in their 70s, the OR was the highest, at 2.51. The rates of vertebroplasty or kyphoplasty, medical expenses, and mortality rate were significantly higher in the SF group than in the IF group (p < 0.01).

CONCLUSION

The age-specific cumulative incidence of SVCFs per 100,000 people was 113.6. SVCFs were more frequent among women, the elderly, and patients who underwent vertebroplasty or kyphoplasty. Women in their 60s or above and men in their 70s or above were at highest risk.

Association between osteoporosis or osteopenia and taking antiplatelet agents in general US population of NHANES

BACKGROUND

Osteoporosis (OP) and osteopenia are common bone disorders in old age, and lots of patients suffering from OP or osteopenia need to take antiplatelet agents to treat basic diseases. However, clinical data on the link between osteopenia or OP and antiplatelet agents are limited.

METHODS

Data in this study were collected and screened from the NHANES from 2013 to 2014 and 2017 to 2018. The variables were extracted from interviews and compared between OP or osteopenia participants and normal. The relationship between OP or osteopenia and taking antiplatelet drugs was analyzed by weighted multivariate logistic regression.

RESULTS

After excluding individuals who were not eligible and had invalid data, we finally identified 894 participants for inclusion in the study. We found a negative association between OP or osteopenia and taking antiplatelet agents (OR = 0.53; 95% CI, 0.33-0.84; p < 0.05). These results did not change on multiple imputations (OR = 0.32, 95% CI, 0.19-0.56; p <0.01). In the subgroup analyses, the associations were more significant in women (OR = 0.18, 95% CI, 0.05-0.62; p <0.05).

CONCLUSION

This study demonstrated that the association between OP or osteopenia and taking antiplatelet agents was significant. Therefore, it is necessary to confirm the result by extending further research.

Undercarboxylated Osteocalcin and Its Associations With Bone Mineral Density, Bone Turnover Markers, and Prevalence of Osteopenia and Osteoporosis in Chinese Population: A Cross-Sectional Study

OBJECTIVE

Undercarboxylated osteocalcin (ucOC) is one form of osteocalcin lacking full carboxylation, which plays an important role in bone homeostasis, glucose homeostasis, and energy metabolism. Our aim is to obtain the profile of serum ucOC level according to gender and age and explore its associations with bone mineral density (BMD), bone turnover markers (BTMs), and prevalence of osteopenia and osteoporosis in the Chinese population.

METHODS

This is a cross-sectional study with 900 subjects, composed of 431 men and 469 women. Clinical information was collected, and BMD values of the lumbar spine (L1-4), left femoral neck, and total hip were scanned. Biochemical markers including hepatic and renal function, serum calcium, serum phosphorus, procollagen type 1 N-propeptide (P1NP) β-CrossLaps of type I collagen-containing cross-linked C-telopeptide (β-CTX) intact parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), and ucOC were measured.

RESULTS

We found that the median ucOC level was higher in men than women [men, 2.6 ng/ml; women, 1.6 ng/ml; p < 0.001]. The profile according to age showed that ucOC levels were the lowest at the age of 40-49 years in both men [2.55 ng/ml (95% CI = 1.96-3.13 ng/ml)] and women [1.57 ng/ml (95% CI = 1.12-2.03 ng/ml)]; in patients younger than 49 years, they decreased with age; then over 50 years, they quickly increased. Furthermore, we found that a higher ucOC level was correlated with lower BMD values at the lumbar spine (men, r = -0.128, p = 0.013; women, r = -0.321, p < 0.001), femoral neck (men, r = -0.095, p = 0.062; women, r = -0.260, p < 0.001), and total hip (men, r = -0.123, p = 0.015; women, r = -0.209, p < 0.001) and higher P1NP (men, r = 0.307, p < 0.001; women, r = 0.239, p < 0.001) and β-CTX (men, r = 0.169, p = 0.001; women, r = 0.354, p < 0.001) levels in both men and women. Furthermore, we also showed that a 1 - SD increase in ucOC was associated with an odds ratio (OR) of 1.63 and 1.70 for having osteopenia or osteoporosis in men and women, respectively (men, 95% CI = 1.25-2.13, p = 0.004; women, 95% CI = 1.19-2.42, p = 0.004).

CONCLUSIONS

We first revealed the profile of serum ucOC levels according to gender and age in the Chinese population and demonstrated the associations of ucOC with BMD and BTMs and the risk of prevalent osteopenia or osteoporosis. Our findings provide a clue to elucidate the function of ucOC in bone metabolism.

Association of osteopenia and osteoporosis with higher rates of pseudarthrosis and revision surgery in adult patients undergoing single-level lumbar fusion

OBJECTIVE

Patients with osteopenia or osteoporosis who require surgery for symptomatic degenerative spondylolisthesis may have higher rates of postoperative pseudarthrosis and need for revision surgery than patients with normal bone mineral densities (BMDs). To this end, the authors compared rates of postoperative pseudarthrosis and need for revision surgery following single-level lumbar fusion in patients with normal BMD with those in patients with osteopenia or osteoporosis. The secondary outcome was to investigate the effects of pretreatment with medications that prevent bone loss (e.g., teriparatide, bisphosphonates, and denosumab) on these adverse outcomes in this patient cohort.

METHODS

Patients undergoing single-level lumbar fusion between 2007 and 2017 were identified. Based on 1:1 propensity matching for baseline demographic characteristics and comorbidities, 3 patient groups were created: osteopenia (n = 1723, 33.3%), osteoporosis (n = 1723, 33.3%), and normal BMD (n = 1723, 33.3%). The rates of postoperative pseudarthrosis and revision surgery were compared between groups.

RESULTS

The matched populations analyzed in this study included a total of 5169 patients in 3 groups balanced at baseline, with equal numbers (n = 1723, 33.3%) in each group: patients with a history of osteopenia, those with a history of osteoporosis, and a control group of patients with no history of osteopenia or osteoporosis and with normal BMD. A total of 597 complications were recorded within a 2-year follow-up period, with pseudarthrosis (n = 321, 6.2%) being slightly more common than revision surgery (n = 276, 5.3%). The odds of pseudarthrosis and revision surgery in patients with osteopenia were almost 2-fold (OR 1.7, 95% CI 1.26-2.30) and 3-fold (OR 2.73, 95% CI 1.89-3.94) higher, respectively, than those in patients in the control group. Similarly, the odds of pseudarthrosis and revision surgery in patients with osteoporosis were almost 2-fold (OR 1.92, 95% CI 1.43-2.59) and > 3-fold (OR 3.25, 95% CI 2.27-4.65) higher, respectively, than those in patients in the control group. Pretreatment with medications to prevent bone loss prior to surgery was associated with lower pseudarthrosis and revision surgery rates, although the differences did not reach statistical significance.

CONCLUSIONS

Postoperative pseudarthrosis and revision surgery rates following single-level lumbar spinal fusion are significantly higher in patients with osteopenia and osteoporosis than in patients with normal BMD. Pretreatment with medications to prevent bone loss prior to surgery decreased these complication rates, although the observed differences did not reach statistical significance.

Differences in Physical Activity and Sedentary Behavior Patterns of Postmenopausal Women With Normal vs. Low Total Hip Bone Mineral Density

Purpose: Recent evidence suggests that sedentary behavior (SB) may be associated with bone health. This study compares free-living physical activity (PA) and SB distribution patterns of postmenopausal women with normal vs. low total hip bone mineral density (BMD). Methods: Sixty nine post-menopausal women [mean (min-max) age: 61 (46-79) years] wore ActiGraph GT3X+ activity monitors on the bilateral ankles for 7 days in free-living. Participants were split into two groups: those with normal hip BMD (T-scores ≥-1.0; N = 34) and those with low hip BMD (T-scores <-1.0; N = 35) as defined by the World Health Organization. Daily active time, step counts, sedentary time, sedentary break number, and median sedentary bout length were estimated from ankle acceleration data. The distribution and accumulation patterns of time spent in sedentary bouts, sedentary breaks, and stepping bouts, and sedentary break and stepping bout lengths' variability were also investigated. Group differences were assessed using two-sampled t-tests and Mann-Whitney U-tests with significance levels of 0.5. Results: Significant between group differences (p < 0.05) were in total daily active time [median (IQR): 257 (209-326) vs. 249 (199-299) min], step count [14,188 (10,938-18,646) vs. 13,204 (10,337-16,630) steps], sedentary time [669 (584-731) vs. 687 (615-753) min], and sedentary break number [93 (68-129) breaks vs. 88 (64-113) breaks], as well as median sedentary bout length [15.1 (11.9-22.1) vs. 15.8 (12.1-24.9) min]. Participants' sedentary bouts were found to be power law distributed with 52% of sedentary time occurring in bouts ≥20 min for the normal BMD group, and 58% for the low BMD group. Significant differences were observed between groups in sedentary bouts' and sedentary breaks' power distribution exponents (p < 0.0001) and patterns of sedentary and stepping time accumulation using the Gini index (p ≤ 0.0014). Variability was significantly lower for sedentary break and stepping bout lengths for the low BMD group (p ≤ 0.0001). Participants with lower hip BMD have longer sedentary bouts with shorter and less complex activity bouts compared to participants with normal hip BMD. Conclusion: The results suggest healthier hip BMD may be associated with PA distributed more evenly throughout the day with shorter sedentary bouts. PA distribution should be considered in exercise-based bone health management programs.

A comparative overview of metatarsal stress fractures in premenopausal and postmenopausal women: our single-centre experience with eighty-one patients

PURPOSE

To compare the demographic, clinical, and laboratory features of metatarsal bone stress fractures encountered in premenopausal and postmenopausal women.

METHODS

This retrospective study was carried out in the orthopaedics and traumatology department of our tertiary care centre. Data were collected from the hospital records of a total of 81 women (average age 42.65 ± 12.97) allocated in premenopausal (n = 36) and postmenopausal (n = 45) groups. These two groups were compared in terms of age, body mass index, side, and level of the metatarsal stress fracture, serum levels of vitamin D, duration of complaint and treatment, and T-scores of femur and vertebra as measured by dual-energy X-ray absorptiometry.

RESULTS

The average body mass index (BMI) was 27.00 ± 2.49 kg/m² (range 21.8 to 31.2). The right side was involved in 44 cases (54.3%), while the left side was affected in 37 patients. DXA T-scores were significantly high for group 2 for both femur and vertebra (p < 0.001 for both). Two groups did not exhibit any significant differences in terms of BMI, side of the stress fracture, level and location of the fracture, seasonal distribution, smoking habits, comorbidities, serum levels of vitamin D, durations of complaints, and treatment.

CONCLUSION

Our results indicated that there was no difference between 2 groups in terms of serum vitamin D levels; however, postmenopausal women had higher T-scores of femur and vertebra. Identification of patients under higher risk for stress fractures and elucidation of the possible role of menopause necessitate further controlled, randomized trials on larger series.

Outcomes of Total Hip Arthroplasty in Patients With Acetabular Protrusio

Background:

Acetabular protrusio (AP) is associated with distorted anatomic landmarks and insufficient bone stock that increases complexity of total hip arthroplasty (THA). This study used a large national database to compare outcomes after THA in patients with and without AP.

Methods:

The Nationwide Readmissions Database was used to identify patients with and without AP who underwent THA from 2010 to 2014. Primary outcomes analyzed included complications during index hospitalization and within 90 days of THA.

Results:

Propensity score matching generated 4,395 patients without AP and 4,603 patients with AP. Patients with AP were older (68.1 versus 65.2 years, P < 0.0001), more predominantly women (82.1% versus 55.9%), and had more medical comorbidities as measured by the Elixhauser Comorbidity Index (2.29 versus 1.89, P < 0.0001). Patients with AP had an increased risk of requiring bone graft (odds ratio [OR] = 47.97, 95% confidence interval [CI]: 14.27 to 161.22), receiving a blood transfusion (OR = 1.90, 95% CI: 1.57 to 2.29), and suffering a periprosthetic fracture (OR = 2.56, 95% CI: 1.10 to 5.97) within 90 days of THA. Length and cost of index hospitalization were greater for patients with AP (5.0 versus 4.3 days, P = 0.002; $19,211.88 versus $27,736.30, P < 0.0001).

Conclusion:

Given the current emphasis on hospital cost optimization, it is important to ensure that patients with AP are managed appropriately. Attention should be placed on comprehensive preoperative planning and postoperative monitoring in this population.

Spectroscopic Methods Used in Implant Material Studies

It is recognized that interactions between most materials are governed by their surface properties and manifest themselves at the interface formed between them. To gain more insight into this thin layer, several methods have been deployed. Among them, spectroscopic methods have been thoroughly evaluated. Due to their exceptional sensitivity, data acquisition speed, and broad material tolerance they have been proven to be invaluable tools for surface analysis, used by scientists in many fields, for example, implant studies. Today, in modern medicine the use of implants is considered standard practice. The past two decades of constant development has established the importance of implants in dentistry, orthopedics, as well as extended their applications to other areas such as aesthetic medicine. Fundamental to the success of implants is the knowledge of the biological processes involved in interactions between an implant and its host tissue, which are directly connected to the type of implant material and its surface properties. This review aims to demonstrate the broad applications of spectroscopic methods in implant material studies, particularly discussing hard implants, surface composition studies, and surface-cell interactions.

Quality over quantity: skeletal loading intensity plays a key role in understanding the relationship between physical activity and bone density in postmenopausal women

OBJECTIVE

Increasing physical activity (PA) is regularly cited as a modifiable target to improve health outcomes and quality of life in the aging population, especially postmenopausal women who exhibit low bone mineral density (BMD) and high fracture risk. In this cross-sectional study, we aimed to quantify real-world PA and its association with BMD in postmenopausal women.

METHODS

Seventy postmenopausal women, aged 46 to 79 years, received a dual-energy X-ray absorptiometry scan measuring total hip BMD and wore bilateral triaxial accelerometers on the ankles for 7 days to measure PA in their free-living environment. Custom step detection and peak vertical ground reaction force estimation algorithms, sensitive to both quantity and intensity of PA, were used to calculate a daily bone density index (BDI) for each participant. Multiple regression was used to quantify the relationship between total hip BMD, age, step counts, and mean BDI over the span of 7 days of data collection.

RESULTS

All participants completed the full 7 days of PA monitoring, totaling more than 7 million detected steps. Participants averaged 14,485 ± 4,334 steps daily with mean peak vertical ground reaction force stepping loads of 675 ± 121 N during daily living. Across the population, total hip BMD was found to be significantly correlated with objective estimates of mean BDI (r = 0.44), as well as participant age (r = 0.285).

CONCLUSION

Despite having higher-than-expected PA, the low stepping loads observed in this cohort, along with half of the participants having low BMD measures, underscores the need for PA intensity to be considered in the management of postmenopausal bone health.

Osseous Manifestations of Primary Hyperparathyroidism: Imaging Findings

Primary hyperparathyroidism is a systemic endocrine disease that has significant effects on bone remodeling through the action of parathyroid hormone on the musculoskeletal system. These findings are important as they can aid in distinguishing primary hyperparathyroidism from other forms of metabolic bone diseases and inform physicians regarding disease severity and complications. This pictorial essay compiles bone-imaging features with the aim of improving the diagnosis of skeletal involvement of primary hyperthyroidism.

Serum Proteomic Analysis Reveals Vitamin D-Binding Protein (VDBP) as a Potential Biomarker for Low Bone Mineral Density in Mexican Postmenopausal Women

Osteoporosis is a skeletal disease mainly affecting women over 50 years old and it represents a serious public health problem because of the high socioeconomic burden. This disease is characterized by deterioration of bone microarchitecture, low bone mineral density (BMD), and increased risk of fragility fractures. This study aimed to identify serum useful proteins as biomarkers for the diagnosis and/or prognosis of osteoporosis and fracture risk. We collected 446 serum samples from postmenopausal women aged ≥45 years old. Based on the BMD measurement, we classified the participants into three groups: osteoporotic, osteopenic, and normal. In an initial discovery stage, we conducted a proteomic approach using two-dimensional differential gel electrophoresis (2D-DIGE). The peptides into the spots of interest were identified through matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF/TOF). Enzyme-linked immunosorbent assay (ELISA) was performed to validate the proteins of interest. We identified 27 spots of interest when comparing low BMD versus normal BMD postmenopausal women. Based on their relevance in bone metabolism, we analyzed three proteins: ceruloplasmin (CP), gelsolin (GSN), and vitamin D-binding protein (VDBP). Our results demonstrated that low serum VDBP levels correlate with low BMD (osteopenic and osteoporotic). Therefore, VDBP could be considered as a novel, potential, and non-invasive biomarker for the early detection of osteoporosis.

Assessment of gait kinetics in post-menopausal women using tri-axial ankle accelerometers during barefoot walking

BACKGROUND

Physical activity (PA) interventions, designed to increase exposure to ground reaction force (GRF) loading, are a common target for reducing fracture risk in post-menopausal women with low bone mineral density (BMD). Unfortunately, accurate tracking of PA in free-living environments and the ability to translate this activity into evaluations of bone health is currently limited.

RESEARCH QUESTION

This study evaluates the effectiveness of ankle-worn accelerometers to estimate the vertical GRFs responsible for bone and joint loading in post-menopausal women at a range of self-selected walking speeds during barefoot walking.

METHODS

Seventy women, at least one year post-menopause, wore Actigraph GT3X + on both ankles and completed walking trials at self-selected speeds (a minimum of five each at fast, normal and slow walking) along a 30 m instrumented walkway with force plates and photocells to measure loading and estimate gait velocity. Repeated measures correlation analysis and step-wise mixed-effects modelling were performed to evaluate significant predictors of peak vertical GRFs normalized to body weight (pVGRFbw), including peak vertical ankle accelerations (pVacc), walking velocity (Vel_w) and age.

RESULTS

A strong repeated measures correlation of r = 0.75 (95%CI [0.71-0.76] via 1000 bootstrap passes) between pVacc and pVGRFbw was observed. Five-fold cross-validation of mixed-model predictions yielded an average mean-absolute-error (MAE[95%CI]) and root-mean-square-error (RMSE) rate of 5.98%[5.61-6.42] and 0.076 [0.069-0.082] with a more complex model (including Vel_w,) and 6.80%[6.37-7.54] and 0.087BW[0.081-0.095] with a simpler model (including only pVacc), when comparing accelerometer-based estimations of pVGRFbw to force plate measures of pVGRFbw. Age was not found to be significant.

SIGNIFICANCE

This study is the first to show a strong relationship among ankle accelerometry data and high fidelity lower-limb loading approximations in post-menopausal women. The results provide the first steps necessary for estimation of real-world limb and joint loading supporting the goals of accurate PA tracking and improved individualization of clinical interventions.

Skeletal changes through the lifespan--from growth to senescence

Age-related fragility fractures are an enormous public health problem. Both acquisition of bone mass during growth and bone loss associated with ageing affect fracture risk late in life. The development of high-resolution peripheral quantitative CT (HRpQCT) has enabled in vivo assessment of changes in the microarchitecture of trabecular and cortical bone throughout life. Studies using HRpQCT have demonstrated that the transient increase in distal forearm fractures during adolescent growth is associated with alterations in cortical bone, which include cortical thinning and increased porosity. Children with distal forearm fractures in the setting of mild, but not moderate, trauma also have increased deficits in cortical bone at the distal radius and in bone mass systemically. Moreover, these children transition into young adulthood with reduced peak bone mass. Elderly men, but not elderly women, with a history of childhood forearm fractures have an increased risk of osteoporotic fractures. With ageing, men lose trabecular bone primarily by thinning of trabeculae, whereas the number of trabeculae is reduced in women, which is much more destabilizing from a biomechanical perspective. However, age-related losses of cortical bone and increases in cortical porosity seem to have a much larger role than previously recognized, and increased cortical porosity might characterize patients at increased risk of fragility fractures.

Osteoporosis risk prediction using machine learning and conventional methods

A number of clinical decision tools for osteoporosis risk assessment have been developed to select postmenopausal women for the measurement of bone mineral density. We developed and validated machine learning models with the aim of more accurately identifying the risk of osteoporosis in postmenopausal women, and compared with the ability of a conventional clinical decision tool, osteoporosis self-assessment tool (OST). We collected medical records from Korean postmenopausal women based on the Korea National Health and Nutrition Surveys (KNHANES V-1). The training data set was used to construct models based on popular machine learning algorithms such as support vector machines (SVM), random forests (RF), artificial neural networks (ANN), and logistic regression (LR) based on various predictors associated with low bone density. The learning models were compared with OST. SVM had significantly better area under the curve (AUC) of the receiver operating characteristic (ROC) than ANN, LR, and OST. Validation on the test set showed that SVM predicted osteoporosis risk with an AUC of 0.827, accuracy of 76.7%, sensitivity of 77.8%, and specificity of 76.0%. We were the first to perform comparisons of the performance of osteoporosis prediction between the machine learning and conventional methods using population-based epidemiological data. The machine learning methods may be effective tools for identifying postmenopausal women at high risk for osteoporosis.

The effect of age on the changes in bone mineral density and osteoporosis detection rates in Han Chinese men over the age of 50

OBJECTIVE

To examine the relationship between age and BMD at different skeletal sites and osteoporosis (OP) detection rates in Han Chinese men over 50 years and to assess the diagnostic value of the OSTA.

METHODS

A retrospective analysis of 1488 men over 50 was carried out and group comparisons were made.

RESULTS

BMDs at total hip and femoral neck decreased with age (p < 0.01) and were negatively correlated with age by liner correlation analysis (r = -0.36, -0.30; p all <0.05). The detection rates of OP and osteopenia were 10.08% and 43.21% respectively, which increased with age, and significantly higher among over 70 years old than under 70 individuals (47.75% versus 35.56%; 14.88% versus 1.99%; p all <0.01). The detection rate at the femoral neck was similar to the overall detection rate. Sensitivities of OSTA index at a cutoff value of -1 and -4 were 87.33% and 52.0% respectively, and the specificities were 56.20% and 87.59%.

CONCLUSION

BMDs at femoral neck and total hip decrease with age. Detection rates of OP increase with age. Bilateral femoral neck BMD measurement can improve detection rates of OP. OSTA is a useful screening tool for OP in Han Chinese men over 50 years.

Distinct actions of akt1 on skeletal architecture and function

Skeletal integrity is dependent on the coordinated actions of bone-forming osteoblasts and bone-resorbing osteoclasts, which recognize and respond to multiple environmental inputs. Here we have studied the roles in bone development and growth of Akt1 and Akt2, two closely related signaling proteins, by evaluating mice lacking either of these enzymes. Global deficiency of Akt1 but not Akt2 caused a reduction in whole body and femoral bone mineral density, in femoral cortical thickness and volume, and in trabecular thickness in both males and females when measured at 20-weeks of age, which was reflected in diminished femoral resistance to fracture. Haplo-deficiency of Akt1 in male mice also decreased femoral cortical and trabecular skeletal parameters, and reduced bone strength. Cell-based studies showed that genetic Akt1 deficiency diminished the rate of proliferation of osteoblast progenitors and impaired osteoclast differentiation in primary culture but that loss of Akt2 did not. Our results demonstrate differential effects of Akt1 and Akt2 on skeletal maturation and architecture through actions on both osteoblast and osteoclast precursors.

Osteoporosis risk prediction for bone mineral density assessment of postmenopausal women using machine learning

PURPOSE

A number of clinical decision tools for osteoporosis risk assessment have been developed to select postmenopausal women for the measurement of bone mineral density. We developed and validated machine learning models with the aim of more accurately identifying the risk of osteoporosis in postmenopausal women compared to the ability of conventional clinical decision tools.

MATERIALS AND METHODS

We collected medical records from Korean postmenopausal women based on the Korea National Health and Nutrition Examination Surveys. The training data set was used to construct models based on popular machine learning algorithms such as support vector machines (SVM), random forests, artificial neural networks (ANN), and logistic regression (LR) based on simple surveys. The machine learning models were compared to four conventional clinical decision tools: osteoporosis self-assessment tool (OST), osteoporosis risk assessment instrument (ORAI), simple calculated osteoporosis risk estimation (SCORE), and osteoporosis index of risk (OSIRIS).

RESULTS

SVM had significantly better area under the curve (AUC) of the receiver operating characteristic than ANN, LR, OST, ORAI, SCORE, and OSIRIS for the training set. SVM predicted osteoporosis risk with an AUC of 0.827, accuracy of 76.7%, sensitivity of 77.8%, and specificity of 76.0% at total hip, femoral neck, or lumbar spine for the testing set. The significant factors selected by SVM were age, height, weight, body mass index, duration of menopause, duration of breast feeding, estrogen therapy, hyperlipidemia, hypertension, osteoarthritis, and diabetes mellitus.

CONCLUSION

Considering various predictors associated with low bone density, the machine learning methods may be effective tools for identifying postmenopausal women at high risk for osteoporosis.

Increased vertebral morphometric fracture in patients with postsurgical hypoparathyroidism despite normal bone mineral density

BACKGROUND

The mechanism behind parathyroid hormone (PTH) activation of bone remodeling is intimately dependent on the time of exposure of bone cells to hormone levels. Sustained high PTH levels trigger catabolism, while transitory elevations induce anabolism. The effects of hypoparathyroidism (PhPT) on bone are unknown. The objective was to study the impact of PhPT on bone mineral density (BMD), on the frequency of subclinical vertebral fracture and on mandible morphometry.

METHODS

The study comprised thirty-three postmenopausal women, 17 controls (CG) and 16 with PhPT (PhPTG) matched for age, weight and height. Bone mineral density (BMD) of lumbar spine, total hip and 1/3 radius, radiographic evaluation of vertebral morphometry, panoramic radiography of the mandible, and biochemical evaluation of mineral metabolism and bone remodeling were evaluated in both groups.

RESULTS

There were no significant differences in lumbar spine or total hip BMD between groups. There was marked heterogeneity of lumbar spine BMD in PhPTG (high = 4, normal = 9, osteopenia = 1, and osteoporosis = 2 patients). BMD was decreased in the 1/3 radius in PhPTG P < 0.005). The PhPTG group exhibited an increased frequency of morphometric vertebral fractures and decreased mandible cortical thickness.

CONCLUSION

The study suggests that vertebral fragility occurs in PhPT despite normal or even high BMD. The current results encourage further studies to evaluate the use of panoramic radiography in the identification of osteometabolic disorders, such as PhPT and the development of a more physiological treatment for PhPT.

Efficacy of intravenous zoledronic acid in the prevention and treatment of osteoporosis: a meta-analysis

OBJECTIVE

To compare the effect of zoledronic acid in treatment and prevention of osteoporosis with placebo.

METHODS

Random control trials regarding zoledronic acid in treatment of osteoporosis were retrieved by selecting Medline, EMbase and Pubmed databases till April 2012. The RevMan software was used for all of the statistical analysis.

RESULTS

A total of 9 trials were included in this meta-analysis. The pooled effect showed that zoledronic acid could increase the bone mineral density by 2.98 times compared with placebo, and reduce the rate of fracture in patients by 32%. The results should the zoledronic acid intervention had significantly less serious adverse events than controls, and the odds ratio was 0.81 (0.76-0.87). The longer term intervention, more than 12 months intervention, could gain a better prevention effect for osteoporosis (OR, 95%CI for BMD was 3.35, 2.77-3.92; for fracture was 0.67, 0.54-0.82).

CONCLUSIONS

This present study shows that zoledronic acid could be effective approach in the prevention of osteoporosis, and could increase the bone mineral density and reduce the risk of fracture.

Congenic mice provide in vivo evidence for a genetic locus that modulates intrinsic transforming growth factor β1-mediated signaling and bone acquisition

Osteoporosis, the most common skeletal disorder, is characterized by low bone mineral density (BMD) and an increased risk of fragility fractures. BMD is the best clinical predictor of future osteoporotic fracture risk, but is a complex trait controlled by multiple environmental and genetic determinants with individually modest effects. Quantitative trait locus (QTL) mapping is a powerful method for identifying chromosomal regions encompassing genes involved in shaping complex phenotypes, such as BMD. Here we have applied QTL analysis to male and female genetically-heterogeneous F(2) mice derived from a cross between C57BL/6 and DBA/2 strains, and have identified 11 loci contributing to femoral BMD. Further analysis of a QTL on mouse chromosome 7 following the generation of reciprocal congenic strains has allowed us to determine that the high BMD trait, which tracks with the DBA/2 chromosome and exerts equivalent effects on male and female mice, is manifested by enhanced osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro and by increased growth of metatarsal bones in short-term primary culture. An insertion/deletion DNA polymorphism in Ltbp4 exon 12 that causes the in-frame removal of 12 codons in the DBA/2-derived gene maps within 0.6 Mb of the marker most tightly linked to the QTL. LTBP4, one of four paralogous mouse proteins that modify the bioavailability of the transforming growth factor β (TGF-β) family of growth factors, is expressed in differentiating MSC-derived osteoblasts and in long bones, and reduced responsiveness to TGF-β1 is observed in MSCs of mice homozygous for the DBA/2 chromosome 7. Taken together, our results identify a potential genetic and biochemical relationship between decreased TGF-β1-mediated signaling and enhanced femoral BMD that may be regulated by a variant LTBP4 molecule.

Osteoporosis related to disease or therapy in patients with cancer

Osteoporosis is a major public health issue in the general population, particularly in postmenopausal women. Patients with cancer may not only be at risk for primary osteoporosis, but for secondary osteoporosis related to cancer therapies-particularly therapies that impair gonadal function, lead to loss of serum estrogen, and negatively affect bone turnover. Normal bone remodeling is influenced by the receptor activator for nuclear kappa-B ligand pathway, calcium, vitamin D, and other nutrition factors, as well as modifiable and nonmodifiable factors. Identifying which patients with cancer are at risk for bone mineral density loss is important and may include patients with breast or prostate cancer, some survivors of pediatric malignancies, and adults with other tumors. Nurses play a major role in identifying those patients and their risk for low-impact fractures, which can have a significant effect on patient morbidity and mortality. Counseling and teaching are central nursing functions, as well as safely administering therapies, particularly bisphosphonates and denosumab.

Bone microstructural changes revealed by high-resolution peripheral quantitative computed tomography imaging and elevated DKK1 and MIP-1α levels in patients with MGUS

Recent population-based studies demonstrate an increased fracture risk with monoclonal gammopathy of undetermined significance (MGUS). The etiology of this increased risk remains unclear, however, because areal bone mineral density (aBMD) measurements by dual-energy x-ray absorptiometry cannot assess bone microstructural properties critical to determining bone quality and strength. To better define the skeletal effects of MGUS, we performed aBMD and high-resolution peripheral quantitative computed tomography volumetric bone mineral density (vBMD) measurements in 50 MGUS patients (20 females, 30 males; mean ± SEM age, 70.5 ± 1.4 years) and 100 matched control subjects. Relative to controls, MGUS patients had decreased aBMD at the femoral neck (P = .05) and total femur (P < .05) but no differences at other sites. In contrast, high-resolution peripheral quantitative computed tomography showed markedly diminished cortical thickness (P < .05) and increased endocortical area (P < .01). Average vBMD (P < .01), cortical vBMD (P < .001), and trabecular thickness (P < .01) were all significantly decreased in MGUS patients, suggestive of impaired bone formation. Serum levels of the Wnt pathway inhibitor Dickkopf-related protein 1 (P < .001) and osteoclast-activating factor MIP-1α (P < .05) also were significantly elevated in MGUS patients. Our data provide the first evidence of altered bone microstructure in MGUS and suggest that cytokines elevated in osteolytic myeloma also may be associated with bone loss in MGUS.

The safety and efficacy of early-stage bi-weekly alendronate to improve bone mineral density and bone turnover in chinese post-menopausal women at risk of osteoporosis

The efficacy and safety of early, low frequency antiresorptive drug intervention for osteopaenia on bone mineral density (BMD) and bone turnover in Chinese post-menopausal women at risk of developing osteoporosis were investigated. A total of 180 women aged 40 - 70 years were enrolled and equally randomized to receive either 70 mg alendronate once every 2 weeks plus 0.5 μg alfacalcidol daily (treatment group) or alfacalcidol 0.5 μg daily alone (control group) for 12 months. In the treatment group, lumbar spine and total hip BMD at 12 months had increased significantly from baseline and compared with the control group. There were also significant reductions in serum levels of the bone turnover biomarkers, bone-specific alkaline phosphatase and C-terminal telopeptide of type I collagen, compared with the control. No serious adverse events were observed in either group and safety profiles were similar. It was concluded that early intervention with 70 mg alendronate once every 2 weeks was safe, well tolerated and more effective than alfacalcidol alone (control) in increasing BMD and reducing bone turnover, and might prevent serious outcomes, such as fragility fractures, reduce rates of adverse effects and improve patient compliance.

[Optimizing orthodontic treatment in patients taking bisphosphonates]

Bisphosphonates have unique pharmacological characteristics unlike those of any other drug group. Millions of adults take oral bisphosphonates for long-term treatment of osteoporosis and osteopenia; some of these people will most likely also seek orthodontic treatment. Adverse dental effects from bisphosphonates have been reported, including decreased tooth movement, impaired bone healing, and osteonecrosis in the mandible and the maxilla. Osteonecrosis has been rarely observed after bisphosphonate use for osteoporosis. However, adverse drug effects might occur more frequently in orthodontic patients, and they would probably be noted before the end-stage pathology of osteonecrosis. Adverse effects during orthodontic treatment, including decreased tooth movement, could last for years after the drug therapy is stopped. Successful orthodontic treatment requires optimal bone healing to prevent excessive tooth mobility. Bisphosphonates appear to have two bone elimination rates - a fast elimination of weeks from the bone surface and a slow elimination of years after incorporation into the bone structure. This article presents methods to clinically and radiographically monitor orthodontic patients who are taking oral bisphosphonates. Efforts to minimize adverse effects and optimize orthodontic procedures with physician-approved drug holidays are discussed. The orthodontic treatment results of three patients who received bisphosphonate therapy are reported.

Association of hip strength estimates by finite-element analysis with fractures in women and men

Finite-element analysis (FEA) of quantitative computed tomography (QCT) scans can estimate site-specific whole-bone strength. However, it is uncertain whether the site-specific detail included in FEA-estimated proximal femur (hip) strength can determine fracture risk at sites with different biomechanical characteristics. To address this question, we used FEA of proximal femur QCT scans to estimate hip strength and load-to-strength ratio during a simulated sideways fall and measured total hip areal and volumetric bone mineral density (aBMD and vBMD) from QCT images in an age-stratified random sample of community-dwelling adults age 35 years or older. Among 314 women (mean age ± SD: 61 ± 15 years; 235 postmenopausal) and 266 men (62 ± 16 years), 139 women and 104 men had any prevalent fracture, whereas 55 Women and 28 men had a prevalent osteoporotic fracture that had occurred at age 35 years or older. Odds ratios by age-adjusted logistic regression analysis for prevalent overall and osteoporotic fractures each were similar for FEA hip strength and load-to-strength ratio, as well as for total hip aBMD and vBMD. C-statistics (estimated areas under ROC curves) also were similar [eg, 0.84 to 0.85 (women) and 0.75 to 0.78 (men) for osteoporotic fractures]. In women and men, the association with prevalent osteoporotic fractures increased below an estimated hip strength of approximately 3000 N. Despite its site-specific nature, FEA-estimated hip strength worked equally well at predicting prevalent overall and osteoporotic fractures. Furthermore, an estimated hip strength below 3000 N may represent a critical level of systemic skeletal fragility in both sexes that warrants further investigation.

Determining whether women with osteopenic bone mineral density have low, moderate, or high clinical fracture risk

OBJECTIVE

Most low-trauma fractures occur among women with osteopenic bone mineral density (BMD), a population considered to have moderate absolute fracture risk. Our purpose was to refine the fracture risk prediction in women with osteopenic BMD to determine the subgroups at lowest and highest risk.

METHODS

We included 2,588 women aged 50 to 90 years with osteopenic BMD (femoral neck BMD between -1 and -2.5) participating in the Canadian Multicentre Osteoporosis Study, an ongoing prospective cohort study of randomly selected Canadians. Baseline variables, in addition to known risk factors, age, and BMD, were considered for inclusion in a model for the prediction of 5-year absolute risk of low-trauma fracture. Models were derived using logistic regression and assessed by the Bayesian Information Criterion.

RESULTS

We found an increased fracture risk among those with lower BMD (odds ratio [OR], 1.53; 95% CI, 1.06-2.21) for each decrease in femoral neck T score (eg, from -1 to -2), those with prior low-trauma fracture (OR, 2.06; 95% CI, 1.46-2.92), those with self-reported worse general health (OR, 1.35; 95% CI, 1.15-1.59) for each lower category (categories: excellent, very good, good, fair, poor), and those with height loss (OR, 1.44; 95% CI, 1.16-1.90) for each 5-cm difference between current and maximal height. The new model had yielded a better risk stratification than did a model with World Health Organization risk factors.

CONCLUSIONS

Including risk factors such as general health and height loss can be used to provide a highly effective assessment of fracture risk among women with osteopenic BMD.

Independent external validation of nomograms for predicting risk of low-trauma fracture and hip fracture

BACKGROUND

A set of nomograms based on the Dubbo Osteoporosis Epidemiology Study predicts the five- and ten-year absolute risk of fracture using age, bone mineral density and history of falls and low-trauma fracture. We assessed the discrimination and calibration of these nomograms among participants in the Canadian Multicentre Osteoporosis Study.

METHODS

We included participants aged 55-95 years for whom bone mineral density measurement data and at least one year of follow-up data were available. Self-reported incident fractures were identified by yearly postal questionnaire or interview (years 3, 5 and 10). We included low-trauma fractures before year 10, except those of the skull, face, hands, ankles and feet. We used a Cox proportional hazards model.

RESULTS

Among 4152 women, there were 583 fractures, with a mean follow-up time of 8.6 years. Among 1606 men, there were 116 fractures, with a mean follow-up time of 8.3 years. Increasing age, lower bone mineral density, prior fracture and prior falls were associated with increased risk of fracture. For low-trauma fractures, the concordance between predicted risk and fracture events (Harrell C) was 0.69 among women and 0.70 among men. For hip fractures, the concordance was 0.80 among women and 0.85 among men. The observed fracture risk was similar to the predicted risk in all quintiles of risk except the highest quintile of women, where it was lower. The net reclassification index (19.2%, 95% confidence interval [CI] 6.3% to 32.2%), favours the Dubbo nomogram over the current Canadian guidelines for men.

INTERPRETATION

The published nomograms provide good fracture-risk discrimination in a representative sample of the Canadian population.

Vitamin D in health and disease: current perspectives

Despite the numerous reports of the association of vitamin D with a spectrum of development, disease treatment and health maintenance, vitamin D deficiency is common. Originating in part from the diet but with a key source resulting from transformation by exposure to sunshine, a great deal of the population suffers from vitamin D deficiency especially during winter months. It is linked to the treatment and pathogenesis and/or progression of several disorders including cancer, hypertension, multiple sclerosis, rheumatoid arthritis, osteoporosis, muscle weakness and diabetes. This widespread deficiency of Vitamin D merits consideration of widespread policies including increasing awareness among the public and healthcare professionals.

Diagnosis and treatment of osteopenia

Osteopenia is a term to define bone density that is not normal but also not as low as osteoporosis. By definition from the World Health Organization osteopenia is defined by bone densitometry as a T score -1 to -2.5. There are many causes for osteopenia including calcium and vitamin D deficiency and inactivity. Genetics plays an important role in a person's bone mineral density and often Caucasian women with a thin body habitus who are premenopausal are found to have osteopenia. Correction of calcium and vitamin D deficiency and walking 3 to 5 miles a week can often improve bone density in the hip and spine. There are a variety of pharmaceutical agents that have been recommended for the treatment of osteopenia and osteoporosis including hormone replacement therapy, selective estrogen receptor modulator therapy, anti-resorptive therapy. In addition patients with osteoporosis who have failed anti-resorptive therapy can have a significant improvement in their bone density with anabolic therapy.

Novel insights into the relationship between diabetes and osteoporosis

Only three decades ago adipose tissue was considered inert, with little relationship to insulin resistance. Similarly, bone has long been thought of purely in its structural context. In the last decade, emerging evidence has revealed important endocrine roles for both bone and adipose tissue. The interaction between these two tissues is remarkable. Bone marrow mesenchymal stem cells give rise to both osteoblasts and adipocytes. Leptin and adiponectin, two adipokines secreted by fat tissue, control energy homeostasis, but also have complex actions on the skeleton. In turn, the activities of bone cells are not limited to their bone remodelling activities but also to modulation of adipose cell sensitivity and insulin secretion. This review will discuss these new insights linking bone remodelling to the control of fat metabolism and the association between diabetes mellitus and osteoporosis.

Osteopenia and endothelin-1-mediated vasconstrictor tone in postmenopausal women

Low bone mineral density is highly prevalent in postmenopausal women. Osteopenia in postmenopausal women is a predictor of adverse cardiovascular events. A potential mechanism contributing to the increased cardiovascular risk in postmenopausal women with osteopenia is endothelial vasomotor dysfunction. Endothelin (ET)-1 is a potent vasoconstrictor peptide that is associated with endothelial vasomotor dysfunction and increased cardiovascular risk. Currently, there is no information on osteopenia and ET-1 vasoconstrictor activity in postmenopausal women. We tested the hypothesis that ET-1 mediated vasoconstrictor activity is greater in postmenopausal women with osteopenia compared with those without. Forearm blood flow responses to intra-arterial infusion of BQ-123 (100 nmol/min for 60 min), a selective ET(A) receptor antagonist, were determined in postmenopausal women: 10 with osteopenia (age: 56+/-1 yr, lumbar spine T-score between -1.5 and -2.5) and 12 without osteopenia (age: 60+/-2 yr, T-score>-1.5). In women with osteopenia, forearm blood flow increased approximately 25% (P<0.05) in response to BQ-123. However, in the women without osteopenia, resting forearm blood flow was not significantly changed. In conclusion, these results suggest that osteopenia is associated with greater ET-1-mediated vasoconstrictor tone. Increased ET-1 vasoconstrictor activity may contribute to the elevated cardiovascular risk in postmenopausal women with osteopenia.

Evolution of the calcium paradigm: the relation between vitamin D, serum calcium and calcium absorption

Osteoporosis is the index disease for calcium deficiency, just as rickets/osteomalacia is the index disease for vitamin D deficiency, but there is considerable overlap between them. The common explanation for this overlap is that hypovitaminosis D causes malabsorption of calcium which then causes secondary hyperparathyroidism and is effectively the same thing as calcium deficiency. This paradigm is incorrect. Hypovitaminosis D causes secondary hyperparathyroidism at serum calcidiol levels lower than 60 nmol/L long before it causes malabsorption of calcium because serum calcitriol (which controls calcium absorption) is maintained until serum calcidiol falls below 20 nmol/L. This secondary hyperparathyroidism, probably due to loss of a "calcaemic" action of vitamin D on bone first described in 1957, destroys bone and explains why vitamin D insufficiency is a risk factor for osteoporosis. Vitamin D thus plays a central role in the maintenance of the serum (ionised) calcium, which is more important to the organism than the preservation of the skeleton. Bone is sacrificed when absorbed dietary calcium does not match excretion through the skin, kidneys and bowel which is why calcium deficiency causes osteoporosis in experimental animals and, by implication, in humans.