Modelling of fracture risk in degenerated lumbar vertebra

The dissertation presents the numerical modelling of lumbar vertebrae L1 is performed and finite element method is employed. The 3D model has anatomical geometry which is developed using medical images.

In order to define the effect of osteoporosis the static and dynamic problems were formulated. The numerical calculations were performed in aim to figure the stressed state of model in case of physiological loads. Such parameters as tissue apparent density, porosity the thickness of cortical shell, tissue anisotropy were verified. The intervertebral disks were involved in research as well. The mechanical properties of bone tissue were bounded with bone mineral density and trabecular bone score ratios.

The dissertation includes introduction, 3 chapters, general conclusions, references and 7 annexes.

The introduction reveals the investigated problem, importance of the thesis and the object of research and describes the purpose and tasks of the paper, research methodology, novelty, the practical significance of results examined in the paper and defended statements. The introduction ends in presenting the author’s publications on the subject of the dissertation, offering the material of made presentations in conferences and defining the structure of the dissertation.

Chapter 1 revises used literature. The analysis of disadvantages of modern medical diagnostics is presented and the review of numerical bone models and mechanical properties is submitted too. At the end of the chapter, conclusions are drawn and the tasks for the dissertation are reconsidered.

Chapter 2 is focused on theoretical investigation of continuous and trabecular vertebrae model respectively. Bone tissue is modelled as elastoplastic continuum. The finite element method is applied for equation solving during static and dynamic analysis. The statistical Monte-Carlo method is used in order to verify the fracture risk. The correlation between such factors as stress, load and BV/TV ratio is obtained.

Chapter 3 presents the numerical results of performed parametric study, showing the relation between von Mises stress, external load and the level of osteoporosis, which is strongly bounded with porosity level. Also, the validation of the model is perfomed and the numerical results are depicted and discussed. Finally, the discussion results and conclusions are submitted.

8 articles focusing on the subject of the discussed dissertation are published: two articles – in the Clarivate Analytics Web of Science data base, two articles – in the Scopus data base, two – in conference materials and two articles – in the journals quoted by other international data bases. 8 presentations on the subject have been given in conferences at national and international level.

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DOI: https://doi.org/10.20334/2021-006-M