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Design, Construction and Experimental Study of the 3D Bending Device for spinal Column Stabilizing Rods

Hashami Najafabadi, Ali | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55982 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Durali, Mohammad; Farahmand, Farzam
  7. Abstract:
  8. Deformity is one of the common diseases of the spine. For example, in the case of scoliosis, which is a three-dimensional deviation in the spine, the prevalence of 2% to 32% among adults has been reported [1]. In case of severe deformity, surgical methods are usually used to correct it. In surgical methods, rods with appropriate curvature are placed next to the spine and the deviation is completely or partially corrected by connecting the vertebrae to said rods. In general, the curvature of the rods is determined based on the clinical indicators of the patient, the tissue fault strength, the stiffness of the soft tissues, the movement limitation of the vertebrae and the level of spinal cord deformation during surgery. Various methods have been provided for this purpose but the major challenge in this field is to create this curvature, which can be very complex three-dimensional bends. The use of manual bending methods often lacks sufficient efficiency and accuracy for this purpose. In addition, it can cause a strong decrease in rod’s mechanical strength due to the local bending of the rod. Accordingly, the development of a method that is able to create complex curves in the spinal stabilization rods in a continuous and uniform curve is considered. The purpose of this project is to design and manufacture a device for bending spine stabilizer rods, based on the free bending method. This device provides the possibility of creating uniform and continuous three-dimensional bends for different curves without the need to change the bending die. During this project, first, necessary studies were done to understand the anatomy of the vertebral column, its types of abnormalities, evaluation systems and classification of these abnormalities, literature and commercial and laboratory samples provided for this issue. Then, according to the goals and design considerations, various conceptual designs for the device were presented and after evaluation and scoring based on design considerations, the best conceptual design was determined. Then, the free bending process analyzed with using of a finite element model, checking the parameters affecting the results and finally optimizing the process and parts used in the device. In the following, the conceptual design was presented based on the results of the simulation, and after the design of the machine components, an operational example of the device was presented. In the next step, the drawings of the device were completed and finally the device was built according to the design. Finally, the performance of the device was experimentally evaluated and its efficiency and ability to create uniform three-dimensional bends were examined
  9. Keywords:
  10. Scoliosis ; Free Bending ; Continuous Three-Dimensional Bending ; Spinal Deformity ; Mechanical Strength

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