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Investigating Designs and Additive Manufacturing of Flexible Cellular Cones for Bone Replacement in Revision Total Knee Arthroplasty

Sabokrooz Roozbahani, Fatemeh | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56675 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Farahmand, Farzam; Movahhedy, Mohammad Reza
  7. Abstract:
  8. Flexible cones are one of the latest bone loss treatment methods in the ever-increasing revision total knee arthroplasty. This study is conducted to assess the biomechanical performance of the tibial flexible cellular cones in enhancing the initial stability of the implant system through the analysis of implant micromotion, as well as minimizing stress shielding through the analysis of strain distribution in the bone. The research evaluates the impact of various geometrical variables, including the thickness of the porous wall, the presence, type, width, number, and location of the inner solid wall notches on the spring stiffness and stress distribution of these cones. The research methodology in this step includes finite element analysis and experimental testing of a prototype produced by 3D printing. Then, by determining the range of spring stiffness, a finite element model has been made containing voxel-based bone, cement, tibial component, and the aforementioned cones to estimate the micromotion of bone-cone interface nodes according to the spring stiffness of the cone. In the next step, the mentioned model was implemented assuming a complete osseointegration between the bone and the prosthesis to investigate bone remodeling by comparing the strain energy density distribution in the implanted and intact bone. The obtained results showed that, in general, the presence of radial compressive force on the bone will have a significant positive effect in reducing micromotion and improving the initial stability of the implant, but this positive effect decreases with increasing force, while the improvement of bone regeneration will continue with the increase of radial compressive force. The study suggests that to reduce radial compressive force in the present design to facilitate implant insertion during the operation, while improving initial stability and bone regeneration, a radial compressive force of 300 Newtons gives the best results with a relative improvement of 60% in the percentage of interface nodes with ideal contact and a relative 10% decrease in bone resorption
  9. Keywords:
  10. Porous Titanium ; Spring Stiffness ; Micromotion ; Osseointegration ; Stress Shielding ; Knee Joint ; Additive Manufacturing

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