Dynamic behavior and microstructural properties of cancellous bone

The aim of the presented study is to identify some properties of the dynamic behavior of the cancellous bone and to identify the link between this mechanical behavior and the microstructural properties. 7 cylinders of bovine cancellous bone (diameter 41 mm, thickness 14 mm) were tested in quasi static loading (0.001 s-1), 8 in dynamic loading (1000 s-1) and 10 in dynamic loading (1500 s-1) with a confinement system. All the specimens were submitted to imaging before the tests (pQCT) in order to indentify two microstructural properties: Bone Volume / Total Volume ? BV/TV ? and Trabeculae Thickness ? Tb.Th. The behavior of bovine cancellous bone under compression exhibits a foam-type behavior over the whole range of strain rates explored in this study. The results show that for the quasi-static tests only the stresses are correlated with BV/TV. For the unconfined dynamic tests, the yield stress is correlated to BV/TV and the plateau stress to BV/TV and Tb.Th. For the confined tests, only the plateau stress is correlated to BV/TV and Tb.Th. The effect of strain rate is an increase of the yield stress and the plateau stress. The confinement has an effect on the measured values of compression stresses that confirms the importance of marrow flow in the overall behavior

Links between microstructural properties of cancellous bone and its mechanical response to different strain rates.

Not applicabl

Correlations between cancellous bone architecture and its dynamic behaviour

Previous studies showed that in vivo evaluation of the fracture risk of cancellous bone can be assessed by identifying the relationships between its microarchitecture description extracted from clinical imaging and its mechanical properties. The mechanical properties under dynamic loadings (with and without confinement) were obtained and compared to quasi-static ones. The architectural parameters of each specimen were extracted from pQCT images and split into four groups: geometry, topology, connectivity and anisotropy. Results show that architectural parameters are strong determinants of mechanical behaviour for the different applied boundary conditions.http://icills2014.org/wp-content/uploads/2014/01/Marrianne-Prot.pd

Links between mechanical behavior of cancellous bone and its microstructural properties under dynamic loading

Previous studies show that in vivo assessment of fracture risk can be achieved by identifying the relationships between microarchitecture description from clinical imaging and mechanical properties. This study demonstrates that results obtained at low strain rates can be extrapolated to loadings with an order of magnitude similar to trauma such as car crashes. Cancellous bovine bone specimens were compressed under dynamic loadings (with and without confinement) and the mechanical response properties were identified, such as Young's modulus, ultimate stress, ultimate strain, and ultimate strain energy. Specimens were previously scanned with pQCT, and architectural and structural microstructure properties were identified, such as parameters of geometry, topology, connectivity and anisotropy. The usefulness of micro-architecture description studied was in agreement with statistics laws. Finally, the differences between dynamic confined and non-confined tests were assessed by the bone marrow influence and the cancellous bone response to different boundary conditions. Results indicate that architectural parameters, such as the bone volume fraction (BV/TV), are as strong determinants of mechanical response parameters as ultimate stress at high strain rates (p-valueo0.001). This study reveals that cancellous bone response at high strain rates, under different boundary conditions, can be predicted from the architectural parameters, and that these relations with mechanical properties can be used to make fracture risk prediction at a determined magnitude

Prediction of Hip Failure Load: In Vitro Study of 80 Femurs Using Three Imaging Methods and Finite Element Models-The European Fracture Study (EFFECT).

Purpose To evaluate the performance of three imaging methods (radiography, dual-energy x-ray absorptiometry DXA, and quantitative computed tomography CT) and that of a numerical analysis with finite element modeling (FEM) in the prediction of failure load of the proximal femur and to identify the best densitometric or geometric predictors of hip failure load.Supported by the European Commission “Quality of Life And Management of Living Resources Program” (QLK6-CT-2002-02440-3DQCT)

Microstructure et densité de l'os cortical fémoral (variations avec l'âge et la fracture du col)

La fracture ostéoporotique de l'extrémité supérieure du fémur (FESF) est un problème de santé publique en raison de son énorme coût humain et financier. L'os cortical contribue pour 40 à 60 % de la résistance de l'ESF à la fracture, mais sa situation périphérique et sa faible épaisseur le rende difficile à étudier. Nous avons étudié la microstructure et la densité minérale osseuse (DM0) de l'os cortical de la mi-diaphyse fémorale de 163 fémurs d'une collection anthropologique récente, grâce respectivement à des microradiographies avec un système d'analyse d'image semi-automatisé et à un appareil de tomodensitométrie quantitative avec un protocole adapté à la haute résolution. Nous avons ainsi 1/ observé l'évolution de la taille, du nombre et de la répartition des pores avec l'âge, chez les hommes et les femmes, 2/ observé l'évolution de la DM0 avec l'âge, 3/ corrélé la porosité et la DM0. Nous avons également étudié, in vitro, la microstructure, la densité et le module d'élasticité de la corticale du col fémoral chez 16 patientes avec une fracture ostéoporotique du col et chez 16 femmes témoins de même âge, décédées sans fracture, afin de mesurer le lien entre ces paramètres et la fracture du col. Les moyens d'investigation ont été respectivement la microtomodensitométrie 3D par rayonnement synchrotron, la tomodensitométrie quantitative avec le même protocole que précédemment, et l'ultrasonographie. Nous n'avons pas observé de différence significative entre les deux groupes sur les paramètres mesurés, soit en raison d'un biais de sélection de la population témoin, soit en raison de l'absence réelle de différence. Les données obtenues améliorent la connaissance des phénomènes normaux de vieillissement de l'os cortical et des phénomènes liés à l'ostéoporose. Ces connaissances nouvelles pourraient prendre place dans la discussion des stratégies de prévention et de traitement de l'ostéoporose et du risque de fracture de l'extrémité supérieure du fémur.PARIS12-CRETEIL BU Multidisc. (940282102) / SudocSudocFranceF

Dynamic behavior and microstructural properties of cancellous bone

International audienceThe aim of the presented study is to identify some properties of the dynamic behavior of the cancellous bone and to identify the link between this mechanical behavior and the microstructural properties. 7 cylinders of bovine cancellous bone (diameter 41 mm, thickness 14 mm) were tested in quasi static loading (0.001 s-1), 8 in dynamic loading (1000 s-1) and 10 in dynamic loading (1500 s-1) with a confinement system. All the specimens were submitted to imaging before the tests (pQCT) in order to indentify two microstructural properties: Bone Volume / Total Volume – BV/TV – and Trabeculae Thickness – Tb.Th. The behavior of bovine cancellous bone under compression exhibits a foam-type behavior over the whole range of strain rates explored in this study. The results show that for the quasi-static tests only the stresses are correlated with BV/TV. For the unconfined dynamic tests, the yield stress is correlated to BV/TV and the plateau stress to BV/TV and Tb.Th. For the confined tests, only the plateau stress is correlated to BV/TV and Tb.Th. The effect of strain rate is an increase of the yield stress and the plateau stress. The confinement has an effect on the measured values of compression stresses that confirms the importance of marrow flow in the overall behavior

Cortical Bone Mineralization in the Human Femoral Neck in Cases and Controls from Synchrotron Radiation Study

International audienceTo compare the degree and distribution of mineralization in femoral neck cortex from 23 women with hip fractures (age 65–96 years) and 17 female controls (age 72–103 years), we obtained 3D data by synchrotron radiation microtomography (SRμCT). Variables were degree of mineralization of bone (DMB) in total cortex (cDMBSRMEAN), osteons (oDMBSRMEAN), and pure interstitial tissue (intDMBSRMEAN). The cortex on SRμCT images was divided into nine to twelve 50-μm zones from the periosteum to the endosteum; cDMBSRMEAN, oDMBSRMEAN, and intDMBSRMEAN were measured in each zone. We used descriptive statistics and t tests, general linear model analyses to compare DMBSR values across zones and individuals, one-way analysis of variance for within-group comparisons of zones. In patients, the variance of mineral content value was not different than in controls, but mean values of degree of mineralization varied across zones. These cross-sectional data suggest that bone fragility may be related to a greater heterogeneity of the distribution of mineralization in femoral neck cortex

Correlations between cancellous bone architecture and its dynamic behavior

International audienc

Automatic semantic segmentation and detection of vertebras and intervertebral discs by neural networks

International audienc