Reproducibility of Bone Microstructure and Stiffness Measurements in Rats by In Vivo Micro Computed Tomography and Finite Element Analysis

2012 ◽  
Author(s):  
Shenghui Lan ◽  
Abhishek Chandra ◽  
Ling Qin ◽  
X. Sherry Liu
Keyword(s):  
Computed Tomography ◽  
Mechanical Properties ◽  
Finite Element ◽  
Recent Decade ◽  
Micro Computed Tomography ◽  
Element Analysis ◽  
3 Dimensional ◽  
Bone Changes ◽  
Μct Scan

Micro computed tomography (μCT) has been widely used to study 3-dimensional (3D) microstructure of bone specimens. In the recent decade, in vivo μCT scanners have become available to monitor longitudinal bone changes in rodents (1,2). The current in vivo μCT scan can obtain images with an isotropic voxel size up to 10.5 μm, which is high enough for direct 3D bone microstructural analyses. Moreover, based on these high-resolution images, micro finite element (μFE) models can be generated to estimate mechanical properties of bone. Therefore, by using in vivo μCT imaging and μFE analysis techniques, changes in geometry, microstructure, and mechanical properties of rodent bone, in response to either diseases or treatments, can be visualized and quantified over time.

Micro-Computed Tomography to Finite Element Analysis of In Vivo Biodegradable Magnesium-Alloy Screw and Surrounding Bone in Rabbit Femurs

2015 ◽  
Author(s):  
Adrienne F. O. Williams ◽  
Matthew B. A. McCullough
Keyword(s):  
Computed Tomography ◽  
Finite Element ◽  
Mg Alloy ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Element Analysis ◽  
Animal Modeling ◽  
Finite Element Software ◽  
Over Time

Magnesium (Mg) and its alloys are attractive orthopedic biomaterials because of their degradability and mechanical properties, which are similar to bone’s. Characterizing the mechanical changes and interactions of these promising degradable biomaterials and the host environment (bone) is essential to their success in orthopedic devices. The objective of this study was to develop a protocol to evaluate in vivo biodegradable Mg-alloy screws and surrounding new and cancellous bone in rabbit femurs over time, using high resolution micro-computed tomography (micro-CT) images and the finite element method. Micro-CT was used to visually evaluate bone remodeling and degradation of Mg-alloy screws that were implanted in rabbit femoral condyles for 2, 4, 12, 24, 36 and 52 weeks. Over time, the degradation product around the device and the remainder of the intact core was observed. Scans were segmented into bone, degradation/corrosion products and non-degraded device, then reconstructed into 3D volumes. These volumes were meshed and assigned material properties based on CT data. The meshed volumes were exported to finite element software and analyzed in a virtual environment. Several foundational observations were made about animal modeling of in vivo degrading magnesium devices with a micro-CT to FEA protocol.

Tissue Engineered Bone Using Polycaprolactone Scaffolds Made by Selective Laser Sintering

2004 ◽  
Vol 845 ◽  
Author(s):  
J. M. Williams ◽  
A. Adewunmi ◽  
R. M. Schek ◽  
C. L. Flanagan ◽  
P. H. Krebsbach ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Selective Laser Sintering ◽  
Mandibular Condyle ◽  
Computational Design ◽  
Laser Sintering ◽  
Histological Evaluation ◽  
Micro Computed Tomography ◽  
Element Analysis ◽  
Immunocompromised Mice

ABSTRACTPolycaprolactone is a bioresorbable polymer that has potential for tissue engineering of bone and cartilage. In this work, we report on the computational design and freeform fabrication of porous polycaprolactone scaffolds using selective laser sintering, a rapid prototyping technique. The microstructure and mechanical properties of the fabricated scaffolds were assessed and compared to designed porous architectures and computationally predicted properties. Compressive modulus and yield strength were within the lower range of reported properties for human trabecular bone. Finite element analysis showed that mechanical properties of scaffold designs and of fabricated scaffolds can be computationally predicted. Scaffolds were seeded with BMP-7 transduced fibroblasts and implanted subcutaneously in immunocompromised mice. Histological evaluation and micro-computed tomography (μCT) analysis confirmed that bone was generated in vivo. Finally, we have demonstrated the clinical application of this technology by producing a prototype mandibular condyle scaffold based on an actual pig condyle.

Regional vascular mechanical properties by 3-D intravascular ultrasound with finite-element analysis

1997 ◽  
Vol 272 (1) ◽  
pp. H425-H437 ◽  
Author(s):  
M. J. Vonesh ◽  
C. H. Cho ◽  
J. V. Pinto ◽  
B. J. Kane ◽  
D. S. Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Elastic Modulus ◽  
Intravascular Ultrasound ◽  
Regional Distribution ◽  
Optimization Procedure ◽  
Element Analysis ◽  
Dimensionless Variable

A method employing intravascular ultrasound (IVUS) and simultaneous hemodynamic measurements, with resultant finite element analysis (FEA) of accurate three-dimensional IVUS reconstructions (3-DR), was developed to estimate the regional distribution of arterial elasticity. Human peripheral arterial specimens (iliac and femoral, n = 7) were collected postmortem and perfused at three static transmural pressures: 80, 120, and 160 mmHg. At each pressure, IVUS data were collected at 2.0-mm increments through a 20.0-mm segment and used to create an accurate 3-DR. Mechanical properties were determined over normotensive and hypertensive ranges. An FEA and optimization procedure was implemented in which the elemental elastic modulus was scaled to minimize the displacement error between the computer-predicted and actual deformations. The “optimized” elastic modulus (Eopt) represents an estimate of the component element material stiffness. A dimensionless variable (beta), quantifying structural stiffness, was computed. Eopt of nodiseased tissue regions (n = 80) was greater than atherosclerotic regions (n = 88) for both normotensive (Norm) and hypertensive (Hyp) pressurization: Norm, 9.3 +/- 0.98 vs. 3.5 +/- 0.30; Hyp, 11.3 +/- 0.72 vs. 8.5 +/- 0.47, respectively (mean +/- SE x 10(6) dyn/cm2; P < 0.01 vs. nondiseased). No differences in beta between nondiseased and atherosclerotic tissue were noted at Norm pressurization. With Hyp pressurization, beta of atherosclerotic regions were greater than nondiseased regions: 21.5 +/- 2.21 vs. 14.0 +/- 2.11, respectively (P < 0.03). This method provides a means to identify regional in vivo variations in mechanical properties of arterial tissue.

Modeling Dental Implants With Finite Element Analysis and Micro-Computed Tomography

2009 ◽  
Author(s):  
Naomi Tsafnat
Keyword(s):  
Computed Tomography ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Structural Response ◽  
Micro Computed Tomography ◽  
Element Analysis ◽  
Numerical Modeling And Simulation ◽  
Non Destructive ◽  
Digital Nature

X-ray micro-computed tomography (microCT) allows us to construct three-dimensional images of specimens at the micron scale in a non-destructive manner. The digital nature of the microCT images, which are in voxel form, make them ideal candidates for use in numerical modeling and simulation [1]. Finite element analysis (FEA) is a well-known technique for modeling the structural response of a system to mechanical loading, and is most useful in modeling complex systems which cannot be analyzed analytically. MicroCT datasets can be converted into finite element models, directly incorporating both the geometry of the specimen and information about the different materials in it. This method is known as micro-finite element analysis (microFEA). It is especially useful in the study of materials with complex microstructures.

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