br Conclusions br Introduction Within

Conclusions

Introduction
Within the content of this study, a literature review is compiled to underline the importance of the investigation, in which the formation of finite chir99021 modeling techniques and mechanical properties, as well as the behavior of bone structures, are examples of materials with complex geometries. Although surface and volumetric mesh generation techniques which are based on CT and MRI data, have been used for a long time, research on developing new algorithms and improved methods is continuously being undertaken to respond to many different types of problem of our day. In this context, Zhang et al.  [1] built up a new algorithm to evaluate adaptive 3D meshes from volumetric image data, and have lately investigated an efficient approach to reconstruct unstructured tetrahedral and hexahedral meshes for mixed domains consisting of heterogeneous materials  [2].
Finite element models working on high resolution sequenced imaging data enable micro-mechanical approaches, and the results of these models are accepted as a gold standard for the calibration of studies using classical continuum FE. Pahr and Zysset  [3] examined the accuracy of a continuum FE model using Micro-FE as the gold standard. In this work, Micro-FE models were evaluated from high-resolution CT images. Eswaran et al.  [4] revealed that Young’s modulus and the density relation, particularly when assigned to the peripheral bone, substantially altered with regression coefficients, but not the degree of correlation between the continuum and Micro-FE predictions of whole-vertebral stiffness. Obviously, reconstruction procedures combined with FEM need rapid and strong software and hardware configurations. Soenke et al.  [5] presented an extensive review of the reconstruction procedures. By the increasing number of the studies related to bone micro architecture, micro structural details gained significant importance in mechanical analysis. Lai et al.  [6] have put forward regional differences in the trabecular bone of human cadavers using the values of bone mass density and details of the micro-architecture. Griffith and Genant  [7] presented a notable study that although bone density has a significant effect on bone strength, it is not sufficient by itself and properties about micro architecture of bone should, especially be taken into consideration regarding bone strength. A study by Chevalier et al.  [8] described that, voxel-based FE models of trabecular bone are combined with mechanical properties of volume fractions, Micro-CT reconstructions, mechanical tests, and sample specific nano indentation experiments for the validation method. In the study of N. Toosizadeh and M. Haghpanahi  [9], forces generated by muscles in different postures of the head were estimated. Furthermore, these muscle forces were also used to estimate internal cervical loads. Consequently, a geometrically accurate nonlinear finite element model of C0–C7 was developed using CT images of the human cervical spine.
A three dimensional parametric model based on CT images of the lower cervical spine was investigated and validated by examining the model with some experimental data by Haghpanahi and Javadi  [10].
On the other hand, analysis results of the model may differ fundamentally due to the data and image processing techniques which have several calculation steps and optional variables. Particularly, resolutions of the slice thickness and parameters of segmentation of the images have an important effect on the reconstruction of voxel based FE models. Slice thickness and image resolution are both noteworthy parameters for simple images. The sensitivity of these parameters cannot be increased afterwards. In spite of the importance of this, a substantial part of the studies may be regarded as new. FE calculations of the apparent modulus were previously stated by Hara et al.  [11] to be strongly affected by the threshold process applied for segmentation of CT data to construct the FE mesh. Furthermore, the moduli are substantially sensitive to error, due to the strong interaction between volume fraction and mechanical properties. In the study of Genant and Jiang  [12], they compared the non-invasive imaging techniques with each other using trabecular bone tissue. The results are quite informative in terms of resolution values which are used during investigation of trabecular bone tissue. The relationship between CT slice intensity and the mechanical properties of porcine vertebral cancellous bone has also been investigated by Teo et al.  [13].