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A Micromechanical Approach to the Fracture of Femoral Bone during Total Hip Arthroplasty: A Threshold for the Maximum Allowable Press-Fit
, M.Sc. Thesis Sharif University of Technology ; Mohammadi Shoja, Hossein (Supervisor)
Abstract
The principle of micromechanics has been used to determine the maximum allowable press-fit for the hip stem during total hip arthroplasty. A 2D parametric solution has been presented. Bone and stem cross sections are modeled parametrically with respect to their geometry and mechanical properties. Surrounding soft tissue is also modeled and all the participating materials are considered as linear isotropic. Drucker-Prager fracture criterion is used to interpret the fracture phenomenon which is considered as both strain- and stress-state fracture. Considering presence of a thin layer of cancellous bone in the model caused a significant increase in results in comparison with previous numerical...
Design and Manufacturing of Gradient Cellular Tibial Stem for Total Knee Replacement
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor) ; Bahrami Nasab, Marjan (Co-Supervisor)
Abstract
Loosening of uncemented tibial component is one the most common causes of total knee prosthesis failure which is a result of short-term factors such as instability and incomplete osseointegration as well as long-term factors such as peri-prosthetic stress shielding and bone atrophy. Porous cellular structures for tibial stem have been considered as a solution to this problem. This project is aimed to achieve an optimal gradient porous cellular design of tibial stem that in addition to sufficient mechanical strength, provides a perfect osseointegration and prevents bone resorption by incorporating appropriate porosity size, small micro-motion and favorable stress distribution on bone. A...
Investigating Designs and Additive Manufacturing of Flexible Cellular Cones for Bone Replacement in Revision Total Knee Arthroplasty
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
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...