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Designing a Total Knee Replacement to Obtain Minimum Wear on Contact Surfaces and Reduce the Risk of Loosening Using Fgm and Sma

Naghibi Beidokhti, Hamid | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44059 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Ahmadiyan, Mohammad Taghi; Zohoor, Hassan
  7. Abstract:
  8. In recent years, Total Knee Replacement is a highly common surgery. Other than the injuries caused by trauma in accidents among different ages, a need for Total Knee Replacement can arise due to diseases such as Knee Osteoporosis among the elderly which leads to loss of balance in the physiologic properties of knee joint and a failure in load transfer from distal femur to proximal tibia. Currently, the practice of Total Knee Replacement is performed by implanting a mechanical knee between femoral and tibial shafts. Increase in life expectancy of the people with replaced knee, causes the failure of some prostheses due to various factors. Following the failure, a second operation is required to replace the failed component. The factors causing the second surgery to be inevitable include: loosening of the component in bone, infection or bone fracture in proximity of the prosthesis, prosthesis instability, wear in part of the prosthesis and the fracture of the prosthesis. A great deal of research has been focused on deign of mechanical knee and its components. One of the main objectives of all designs is reduction of prostheses weight while enhancing the strength of the components. In the available designs, the applied materials are Titanium alloys and hard low-wear coverings such as ceramic. However, the problematic issue of wear in contact zone, and also the sudden impact load transfer remains an open question demanding more research. The purpose of the current study is to use FGM and SMA materials in the design of TKR in order to minimize the wear between contact surfaces, resulting in a smooth load transition to tibia and minimizing the risk of prosthesis loosening. The current objective is to conform the function of applied materials to the functional physiology of human knee. According to analysis of present thesis, utilizing the FGM in TKR has huge effect on reduction of risk of loosening. Among the proposed models for application of FGM in prostheses, none of them have had a considerable advantage over the others from view point of reduction of loosening. But as far as it has been seen that application of these materials in prostheses has reduced the wear of polyethylene of tibial component, after comparison the reasons, the first proposed FGM model (the linear FGM) was selected. It was revealed that designing the TKR with SMA has reduced the wear in articulation surfaces of polyethylene. It was shown that TKR design with SM alloys, reduces the wear in Polyethylene contact surfaces. The simultaneous use of FG materials and SM alloys did not suggest any advantage over the previously presented designs. Also, its success in reducing the wear was found to be less than SMA and FGM models
  9. Keywords:
  10. Wear ; Shape Memory Alloy ; Total Knee Replacement (TKR) ; Loosening ; Smart Materials

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