Papers by Keyword: Trabecular Bone

Abstract: Trabecular bone undergoes changes in its morphology when subjected to external loading. This paper analyses changes in morphological parameters of individual trabeculae (trabecular thickness and bone volume fraction) in response to loadings at different directions: 0°, 20°, 45°, 70° and 90°. It was found that increase in the load incline caused increase in trabecular thickness and bone volume fraction. In addition, the equilibrium-state trabeculae obtained from adaptation to load at 90° (shear loading) had the highest axial and lateral stiffnesses, as compared to trabecular geometries obtained from other loading scenarios.

Abstract: Hydroxyapatite (HA) ceramic scaffolds are commonly used as bone graft substitutes. Design of such scaffolds is a challenge to improve biological properties and extend the applications of HA ceramics in the field of bone tissue engineering. In this work, we investigated the processing and the in vitro properties of HA ceramic scaffolds mimicking human trabecular bone architecture. Samples of human tibial trabecular bone were collected (University Hospital Center of Limoges) and scanned by X-Ray μ-computed tomography (μ-CT) to generate 3D model database. From this computer-aided design, HA ceramic scaffolds were shaped layer-by-layer by additive manufacturing using laser stereolithography (SLA). Then, green parts were sintered to obtain dense ceramic scaffolds. The shaped parts were compared to the model (wall thickness, size, and geometry of the porous network) using image analysis. A good agreement was found. Only small differences were detected due to a light overpolymerization or to some unprinted very small details that were not linked to a polymerized area of the previous layer. Due to part shrinkage during sintering a magnifying factor has to be applied to the scanned CAO model to match the real dimensions of the trabecular bone sample. Human mesenchymal stem cell (hMSC) cultures were performed to investigate the biological properties of these scaffolds (cell attachment and proliferation of hMSC). These preliminary biological evaluations show the good biocompatibility and cell adhesion of the HA substitute. This work evidences the efficiency of SLA to produce ceramic scaffold architectures mimicking that of the natural trabecular bone with promising biological behavior.

Abstract: The histomorphometry of the rabbit bone tissue from the lower jaw was done. Authors hypothesized that local enhancement with biphasic calcium phosphate ceramic materials in the femur trochanter major area increase the trabecular bone volume outside the implantation zone in vivo. Twenty-two California female rabbits were included in this study and were divided into four groups. Four healthy rabbits composed a control group (A group), while other eighteen underwent ovariectomy. Bone defects were created in femur trochanter major region. Sham surgery group (B group) consisted of four female rabbits with osteoporosis and bone defect, but no biomaterials were implanted. In C group (seven rabbits) created defects were filled with granules of biphasic calcium phosphate ceramic (hydroxyapatite (HAP) and tricalcium phosphate (TCP) 30/70); in D group (seven rabbits) defects were filled with the same granules (HAP/TCP 30/70) together with strontium (5% by mass). Twenty-two bone samples were taken from lower jaw premolar region. Trabecular bone area was measured using Image Pro Plus 7 program, where three equal fields (0.975 mm²) of view were at random chosen in all bone samples. Results have shown that the trabecular bone area in A group was 0.201 mm² (0.176-0.233), which is statistically significantly higher (p <0.0001) than in B group 0.127 mm² (0.118 – 0.149), C group 0.136 mm² (0.108 – 0.166) and D group 0.135 mm² (0.126 – 0.164), respectively. Statistically significant differences between B, C and D groups were not found (p > 0.05).

Abstract: Trabecular bone, widely presented in the ends of long bones and chine, is a typically porous structure which provides a multifunction such as light weight, undertaking load, impact energy buffer and hosting marrow cells. The structure of trabecular is a dominant factor for the strength of cancellous bone. The prediction of the trabecular bone’s mechanical properties depending on the trabecular structure is very useful for the diagnosis and treatment of osteoporosis. The object of this study is to establish a relationship between the mechanical properties and topological, morphological parameters of trabecular bone. The 50 3-D data of cancellous bone are selected from the CT images of three caput femurs and disposed in BoneJ, through which the BV/TV, SMI and genus parameters of each samples are obtained. The deformation behaviors of trabecular bone are simulated in ABAQUS through uniaxial compression on the 3-D model derived from stack images. Then linear-regression analyses are conducted on the BV/TV, genus, SMI and apparent Young’s modulus, resulting a high correlation (R^2=0.84) between the Young’s modulus and the hybrid parameter derived from SMI and normalized genus, corresponding to morphological and topological parameter of the samples respectively. The result indicates that it’s promising to establish the relationship between mechanical properties of trabecular bone and their topological and morphological parameters.

Abstract: The study deals with the development of highly porous undegradable ceramics based on silicon nitride as potential replacement of trabecular bone. These materials were produced using replication method with polyurethane foams as pore-forming agents to achieve similar porous structure to trabecular bone. Prepared porous ceramics had a bimodal pore structure with macro-pores larger than 200 μm and micro-pores smaller than 1 μm in diameter, which are necessary for tissue ingrowths, cell adhesion, adsorption of biological metabolites and nutrition delivery in organism. The microstructure and local mechanical properties (Young’s modulus and Yield strength) were evaluated and compared with human trabecular bone. Results showed that studied porous materials have satisfactory porosity and pore sizes for trabecular bone replacement. Young’s modulus of bone was 12.6 ± 2.23 GPa and porous silicon nitride samples ranged from 10.9 ± 3.38 GPa to 12.9 ± 1.13 GPa. The values of Yield strength of trabecular bone was determined as 493 ± 30.7 MPa and the values of porous samples varied from 250 ± 19.3 MPa to 558 ± 36.5 MPa. Young’s modulus and Yield strength increase with increasing of the pre-sintering temperature and multiple infiltrations.

Abstract: The bone is a hierarchically structured material with mechanical properties depending on its architecture at all scales. Water plays an important role in the bio-mineralization process and serves as a plasticizer, enhancing the toughness of bone. In this paper, a trabecular bone multiscale model based on finite element analysis was developed to link scales from sub-nanoscopic scale (Microfibril) to sub-microscopic (Lamella) in order to predict the orthotropic properties of bone at different structural level. To identify the orthotropic properties, an inverse identification algorithm is used. Furthermore, the effect of water is incorporated. Good agreement is found between theoretical and experimental results.

Abstract: This paper describes the effect of different radiation-reducing methods of bone modelling on the volume of bone models and structural differences between individual models. Careful analysis of data has enabled to determine which of these methods are the best from a structural point of view. The next step is to compare different methods of bone modelling with regard to potential similarities in strength behaviours of bone models.

Abstract: Morphology of cancellous bone has been studied for years, with researchers always seeking accurate methods to assess the parameters. They also study the importance of cancellous morphology in itself. Despite the amount of previous research, there are currently no reviews on the morphology at different anatomy. This paper evaluate the methods and parameters of cancellous bone morphology at different human anatomy. From 1997 to February 2014 we found the articles published on cancellous bone morphology vary in parameters at different anatomy of human bone. Further, researchers are also interested in finding the precision methods for identifying the parameters of cancellous bone. Both in vitro and in vivo were used in finding the accurate result of cancellous bone parameters whilst also searching the importance of the morphology parameters. The morphology studies are vital due to the direct relation with the mechanical properties of cancellous bone. Based on the morphology data, it is found that the morphology parameters are dissimilar at different human anatomy sites. A variety of methods were used by researchers in identifying the morphology parameters, with each method having its own advantages and disadvantages. This review paper summarises the pros and cons of all methods available, in order to help researchers select the best methods for their future studies.

Abstract: This study aims to investigate the influence of trabecular bone in human mandible bone on the mechanical response under implant load. Three dimensional voxel finite element (FE) model of mandible bone was reconstructed from micro-computed tomography (CT) images that were captured from bone specimen. Two FE models were developed where the first consists of cortical bone, trabecular bone and implants, and trabecular bone part was excluded in the second model. A static analysis was conducted on both models using commercial software Voxelcon. The results suggest that trabecular bone contributed to the strength of human mandible bone and to the effectiveness of load distribution under implant load.

Abstract: This study presents a prediction of apparent elastic moduli of vertebral trabecular bone using the homogenization method. A micro-finite element (FE) model of trabecular bone was reconstructed from a sequential of cross-section micro-CT image by converting bone voxels to brick elements. Eight regions of interest (ROIs) were extracted from two lumbar vertebra bone specimens of healthy and osteoporotic. The homogenization method and finite element method was employed to analyze the microscopic trabecular bone. Bone tissue property was modeled as orthotropy material considering the biological apatite (BAp) crystallite orientation. This research focuses on the effect of morphological difference between healthy and osteoporotic bones to the apparent elastic moduli. The change of degree of anisotropy was also discussed. Comparison of the calculated Youngs moduli in vertical axis with Keyak et al.s experimental result showed good agreement and proved the reliability of the numerical model.