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Optimization of Load Distribution at the Bone-Implant Interface in Porous Coated Implants ''A Micromechanical Study Using FEM'

Tahani, Masoud | 1997

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55603 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Katoozian, Hamid Reza; Ahmadian, Mohammad Reza; Zohoor, Hassan
  7. Abstract:
  8. Loosening and gap opening at the bone-implant interface depends on several physiological and mechanical factors such as bone remodeling, stress concentration, and variation in load transfer pathway. Since fracture of orthopedic material at the interface is one of the major failure mode of total joint implants, this study focused on the micromechanical behavior of the interface. Using a two-dimensional FE model, with pure compressive, tensile, and shearing forces applied on bone or cement, ratio of the stress at the interface to the applied stress has been calculated. Stress distribution was considered as a function of porosity,angle of bead contact to surface, as well as size of bead for two different states: replacement with cement( cemented) and without cement(non-cemented). This study shows that at the all contact angles, stress distribution is more uniform and the maximum stress in bone and cement is reduced with reduction in porosity. In the case of compressive and shearing loading in a given porosity, increasing the contact angle,causes more uniform stress distribution, and less maximum stress in bone or cement.However, in the case of tensile loading, reduction of contact angle, causes more uniform stress distribution in bone. The greater bead diameter in radial direction of bone, modifies stress distribution for any loading type in a cementless implant. However, with a cemented implant, variation of maximum stress in compressive loading differs from the one in shear loading. Effects of different coating materials in cementless implant is negligible, although in a cemented implant, reduction in modulus of elasticity of coating, results more uniform stress distribution and lower maximum stress
  9. Keywords:
  10. Artificial Joint ; Porous Implants ; Bone ; Glue ; Orthopedic Surgery ; Bone-Implant Attachment ; Micromechanical Modeling

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