Assessment of trabecular bone score (TBS) in overweight/obese men: effect of metabolic and anthropometric factors

The "trabecular bone score" (TBS) indirectly explores bone quality, independently of bone mineral density (BMD). We investigated the effects of anthropometric and metabolic parameters on TBS in 87 overweight/obese men. We assessed BMD and TBS by DXA, and some parameters of glucose metabolism, sex-and calciotropic hormone levels. Regression models were adjusted for either age and BMI, or age and waist circumference, or age and waist/hip ratio, also considering BMI >35 (y/n) and metabolic syndrome (MS) (y/n). Correlations between TBS and parameters studied were higher when correcting for waist circumference, although not significant in subjects with BMI >35. The analysis of covariance showed that the same model always had a higher adjusted r-square index. BMD at lumbar spine and total hip, fasting glucose, bioavailable testosterone, and sex hormone-binding globulin are the only covariates having a significant effect (p 35 on TBS values or significant interaction terms between each covariate and either BMI >35 or the presence of MS. Obesity negatively affected TBS, despite unchanged BMD. Alterations of glucose homeostasis and sex hormone levels seem to influence this relationship, while calciotropic hormones have no role. The effect of waist circumference on TBS is more pronounced than that of BMI

Higher fracture prevalence and smaller bone size in patients with hEDS/HSD-a prospective cohort study

Increased fracture risk in patients with Ehlers-Danlos syndromes has been reported, but the reasons for it are incompletely understood. We aimed to investigate possible determinants of this increased risk and found that hEDS/HSD patients present with a cortical bone size deficit compared with control subjects, possibly related to lower mechanical loading. Introduction The Ehlers-Danlos syndromes (EDS) comprise a group of heritable connective tissue disorders caused by defects in the biosynthesis, secretion, and/or organization of fibrillar collagens which might impair bone strength. Our aim was to compare fracture prevalence, volumetric and areal bone mineral density (BMD), bone geometry, muscle size and the muscle-bone interaction, body composition and longitudinal changes therein between patients with hypermobile EDS (hEDS) or hypermobility spectrum disorder (HSD), and healthy control subjects. Methods Cross-sectional data comprised 39 female hEDS/HSD patients (age 41 +/- 11 years) and 43 age-matched controls. After 8 years, 27 hEDS/HSD and 17 control subjects were re-evaluated. Tibial trabecular and cortical volumetric BMD, bone mineral content (BMC), cortical bone geometry, and lower leg muscle cross-sectional area (CSA) were measured using pQCT. Body composition, areal BMD, and BMC were determined by DXA. Results At baseline, patients with hEDS/HSD presented with a smaller cortical bone area, smaller cortical thickness and muscle CSA, and a higher fracture prevalence than control subjects (all p < 0.05). No differences in areal or volumetric BMD were found. Longitudinally, muscle CSA decreased in both groups and muscle density decreased in the hEDS/HSD group (p < 0.001) whereas all bone parameters remained unchanged. Conclusion hEDS/HSD patients have a cortical bone size deficit compared with controls, possibly contributing to their increased fracture risk. They presented with decreased muscle CSA but normal bone/muscle area ratio, suggesting that this bone size deficit is likely secondary to decreased mechanical loading. Further, there were no arguments for accelerated bone loss in hEDS/HSD subjects

Influence of vitamin D on biomechanical microstructure and properties of patients with hip fracture.

Valorar niveles séricos de 25-hidroxivitamina D -25(OH)D-, hormonas con influencia sobre el metabolismo óseo (parathormona -PTH- y factor de crecimiento insulínico -IGF-I-), marcadores de remodelado óseo (MRO) (telopéptido carboxilo-terminal del colágeno tipo I -β-CTX- y propéptido aminoterminal del procolágeno tipo I -PINP-), densidad mineral ósea (DMO), microestructura y biomecánica de cuello de fémur, en pacientes con fractura de cadera osteoporótica (OP) vs. pacientes artrósicos (OA). Material y métodos: Estudio observacional transversal de 29 pacientes OP y 14 OA, edad ≥50 años. Cuantificamos niveles séricos hormonales y MRO (inmunoensayo), DMO de cadera (DXA), microestructura (micro-CT) y biomecánica (ensayos de compresión uniaxial, sistema IGFA). Análisis estadístico (SPSS 20.0.) Resultados: Los pacientes OP presentaron niveles inferiores de 25(OH)D (p=0,02) y DMO de cadera (p<0,05), y superiores de PTH (p=0,029) y de β-CTX (p=0,04). Los niveles de 25(OH)D se correlacionaron positivamente con IGF-I (p=0,04) y negativamente con β-CTX (p=0,003). Los valores de PTH se correlacionaron negativamente con DMO de cadera (p=0,0005) y positivamente con la separación trabecular (Tb.Th) (p=0,006). Los pacientes con niveles de 25(OH)D <20 ng/mL presentaron niveles mayores de β-CTX (p=0,006), menores de IGF-I (p=0,007) y Tb.Th (p=0,04). Conclusiones: Los niveles de vitamina D son bajos en población anciana, sobre todo en pacientes con fractura de cadera osteoporótica. Además, en estos pacientes existen niveles elevados de PTH y MRO y descendidos de DMO. Los pacientes cuyos niveles de 25(OH)D son inferiores a 20 ng/mL presentan un remodelado óseo más elevado, con menores niveles de IGF-I y alteraciones de la estructura ósea (Tb.Th) que puedan estar en relación con un mayor riesgo de fracturas.To assess serum levels of 25-hydroxyvitamin D-25 (OH) D-hormones with influence on bone metabolism (parathormone -PTH- and insulin-like growth factor (IGF)-I), bone remodeling markers (BRM) (carboxy-terminal telopeptide of collagen type I-β-CTX- and amino-peptide pro-peptide of procollagen type I -PINP), bone mineral density (BMD), microstructure and biomechanics of the femoral neck, in patients with osteoporotic hip fracture (OH) versus arthritic patients (OA). Material and methods: A cross-sectional observational study of 29 OH and 14 OA, age ≥50 years. We quantified hormonal serum levels and BRM (immunoassay), hip BMD (DXA), microstructure (micro-CT) and biomechanics (uniaxial compression tests, IGFA system). Analysis (SPSS 20.0.) Results: OH patients had lower levels of 25(OH)D (p=0.02) and hip BMD (p<0.05), and higher PTH (p=0.029) and β-CTX (p=0.04). Levels of 25(OH)D correlated positively with IGF-I (p=0.04) and negatively with β-CTX (p=0.003). The PTH values were correlated negatively with hip BMD (p=0.0005) and positively with trabecular thickness (TbTh) (p=0.006). Patients with 25(OH)D <20 ng/mL presented higher levels of β-CTX (p=0.006), lower IGF-I (p=0.007) and TbTh (p=0.04). Conclusions: Vitamin D levels are low in the elderly population, especially in patients with osteoporotic hip fracture. These patients also presented raised levels of PTH and BRM and descended from BMD. Patients whose 25(OH)D levels are below 20 ng/mL present higher bone remodeling, with lower levels of IGF-I and alterations of the bone structure (TbTh) that may be linked to a greater risk of fractures

Cancellous bone and theropod dinosaur locomotion. Part I—an examination of cancellous bone architecture in the hindlimb bones of theropods

This paper is the first of a three-part series that investigates the architecture of cancellous (‘spongy’) bone in the main hindlimb bones of theropod dinosaurs, and uses cancellous bone architectural patterns to infer locomotor biomechanics in extinct non-avian species. Cancellous bone is widely known to be highly sensitive to its mechanical environment, and has previously been used to infer locomotor biomechanics in extinct tetrapod vertebrates, especially primates. Despite great promise, cancellous bone architecture has remained little utilized for investigating locomotion in many other extinct vertebrate groups, such as dinosaurs. Documentation and quantification of architectural patterns across a whole bone, and across multiple bones, can provide much information on cancellous bone architectural patterns and variation across species. Additionally, this also lends itself to analysis of the musculoskeletal biomechanical factors involved in a direct, mechanistic fashion. On this premise, computed tomographic and image analysis techniques were used to describe and analyse the three-dimensional architecture of cancellous bone in the main hindlimb bones of theropod dinosaurs for the first time. A comprehensive survey across many extant and extinct species is produced, identifying several patterns of similarity and contrast between groups. For instance, more stemward non-avian theropods (e.g. ceratosaurs and tyrannosaurids) exhibit cancellous bone architectures more comparable to that present in humans, whereas species more closely related to birds (e.g. paravians) exhibit architectural patterns bearing greater similarity to those of extant birds. Many of the observed patterns may be linked to particular aspects of locomotor biomechanics, such as the degree of hip or knee flexion during stance and gait. A further important observation is the abundance of markedly oblique trabeculae in the diaphyses of the femur and tibia of birds, which in large species produces spiralling patterns along the endosteal surface. Not only do these observations provide new insight into theropod anatomy and behaviour, they also provide the foundation for mechanistic testing of locomotor hypotheses via musculoskeletal biomechanical modelling

An approximate model for cancellous bone screw fixation

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2013 Taylor & Francis.This paper presents a finite element (FE) model to identify parameters that affect the performance of an improved cancellous bone screw fixation technique, and hence potentially improve fracture treatment. In cancellous bone of low apparent density, it can be difficult to achieve adequate screw fixation and hence provide stable fracture fixation that enables bone healing. Data from predictive FE models indicate that cements can have a significant potential to improve screw holding power in cancellous bone. These FE models are used to demonstrate the key parameters that determine pull-out strength in a variety of screw, bone and cement set-ups, and to compare the effectiveness of different configurations. The paper concludes that significant advantages, up to an order of magnitude, in screw pull-out strength in cancellous bone might be gained by the appropriate use of a currently approved calcium phosphate cement

Biomechanical Computed Tomography analysis (BCT) for clinical assessment of osteoporosis.

The surgeon general of the USA defines osteoporosis as "a skeletal disorder characterized by compromised bone strength, predisposing to an increased risk of fracture." Measuring bone strength, Biomechanical Computed Tomography analysis (BCT), namely, finite element analysis of a patient's clinical-resolution computed tomography (CT) scan, is now available in the USA as a Medicare screening benefit for osteoporosis diagnostic testing. Helping to address under-diagnosis of osteoporosis, BCT can be applied "opportunistically" to most existing CT scans that include the spine or hip regions and were previously obtained for an unrelated medical indication. For the BCT test, no modifications are required to standard clinical CT imaging protocols. The analysis provides measurements of bone strength as well as a dual-energy X-ray absorptiometry (DXA)-equivalent bone mineral density (BMD) T-score at the hip and a volumetric BMD of trabecular bone at the spine. Based on both the bone strength and BMD measurements, a physician can identify osteoporosis and assess fracture risk (high, increased, not increased), without needing confirmation by DXA. To help introduce BCT to clinicians and health care professionals, we describe in this review the currently available clinical implementation of the test (VirtuOst), its application for managing patients, and the underlying supporting evidence; we also discuss its main limitations and how its results can be interpreted clinically. Together, this body of evidence supports BCT as an accurate and convenient diagnostic test for osteoporosis in both sexes, particularly when used opportunistically for patients already with CT. Biomechanical Computed Tomography analysis (BCT) uses a patient's CT scan to measure both bone strength and bone mineral density at the hip or spine. Performing at least as well as DXA for both diagnosing osteoporosis and assessing fracture risk, BCT is particularly well-suited to "opportunistic" use for the patient without a recent DXA who is undergoing or has previously undergone CT testing (including hip or spine regions) for an unrelated medical condition

High-Impact Mechanical Loading Increases Bone Material Strength in Postmenopausal Women-A 3-Month Intervention Study.

Bone adapts to loading in several ways, including redistributing bone mass and altered geometry and microarchitecture. Because of previous methodological limitations, it is not known how the bone material strength is affected by mechanical loading in humans. The aim of this study was to investigate the effect of a 3-month unilateral high-impact exercise program on bone material properties and microarchitecture in healthy postmenopausal women. A total of 20 healthy and inactive postmenopausal women (aged 55.6 ± 2.3 years [mean ± SD]) were included and asked to perform an exercise program of daily one-legged jumps (with incremental number, from 3×10 to 4×20 jumps/d) during 3 months. All participants were asked to register their performed jumps in a structured daily diary. The participants chose one leg as the intervention leg and the other leg was used as control. The operators were blinded to the participant's choice of leg for intervention. The predefined primary outcome was change in bone material strength index (BMSi), measured at the mid tibia with a handheld reference probe indentation instrument (OsteoProbe). Bone microstructure, geometry, and density were measured with high-resolution peripheral quantitative computed tomography (XtremeCT) at the ultradistal and at 14% of the tibia bone length (distal). Differences were analyzed by related samples Wilcoxon signed rank test. The overall compliance to the jumping program was 93.6%. Relative to the control leg, BMSi of the intervention leg increased 7% or 0.89 SD (p = 0.046), but no differences were found for any of the XtremeCT-derived bone parameters. In conclusion, a unilateral high-impact loading program increased BMSi in postmenopausal women rapidly without affecting bone microstructure, geometry, or density, indicating that intense mechanical loading has the ability to rapidly improve bone material properties before changes in bone mass or structure. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc

Adaptive Segmentation of Knee Radiographs for Selecting the Optimal ROI in Texture Analysis

The purposes of this study were to investigate: 1) the effect of placement of region-of-interest (ROI) for texture analysis of subchondral bone in knee radiographs, and 2) the ability of several texture descriptors to distinguish between the knees with and without radiographic osteoarthritis (OA). Bilateral posterior-anterior knee radiographs were analyzed from the baseline of OAI and MOST datasets. A fully automatic method to locate the most informative region from subchondral bone using adaptive segmentation was developed. We used an oversegmentation strategy for partitioning knee images into the compact regions that follow natural texture boundaries. LBP, Fractal Dimension (FD), Haralick features, Shannon entropy, and HOG methods were computed within the standard ROI and within the proposed adaptive ROIs. Subsequently, we built logistic regression models to identify and compare the performances of each texture descriptor and each ROI placement method using 5-fold cross validation setting. Importantly, we also investigated the generalizability of our approach by training the models on OAI and testing them on MOST dataset.We used area under the receiver operating characteristic (ROC) curve (AUC) and average precision (AP) obtained from the precision-recall (PR) curve to compare the results. We found that the adaptive ROI improves the classification performance (OA vs. non-OA) over the commonly used standard ROI (up to 9% percent increase in AUC). We also observed that, from all texture parameters, LBP yielded the best performance in all settings with the best AUC of 0.840 [0.825, 0.852] and associated AP of 0.804 [0.786, 0.820]. Compared to the current state-of-the-art approaches, our results suggest that the proposed adaptive ROI approach in texture analysis of subchondral bone can increase the diagnostic performance for detecting the presence of radiographic OA