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Modeling and Analysis of Angular Mis-alignments of Lower Extremity and Prediction of the Results of Osteotomy Surgery

Iravani Mohammad Abadi, Mina | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48229 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Farahmand, Farzam; Hoviattalab, Maryam
  7. Abstract:
  8. Varus-valgus deformity is the improper alignment of lower extremities, which results in the increment of the local stress within the cartilage and the consequent alteration of the performance mechanism of the soft tissues around the knee joint. This accounts for changes within the movement pattern and thus further deformities, which, when continued, can lead to more serious damage in the form of osteoarthritis. The aforementioned cycle can be prevented through the conduction ofosteotomy; a surgical procedure in which the addition or removal of a bone wedge can correct the improper alignment. The correct design and conduction of osteotomy in terms of the location, angle, and size of the correcting wedge is essential to ensure the successful correction of the weight load direction as well as the reduction of stress. The efficiency of the type and method of the osteotomical surgery is still under debate. Development of an accurate and efficient method for the design and conduction of this surgical procedure is thus highly desirable. The prime objective of the current study was to develop an appropriate model for osteotomy, distinguishing the effective biomechanical factors within the surgery. This model was to reflect the post-operative performance mechanism as well as the anatomical configuration of the joint. Within this frame, we developed a subject-specific three-dimensional model of the knee joint based on the MRI technique. Then, conducting a parametric study, we investigated the accuracy of the surgical procedure for the correction of the mechanical axis, as well as the impact of the ligament hardness upon the alteration of the mechanical axis. The results of the research demonstrated that the increase of the varus angle results in a significant increment of the force within the LCL ligament. This can in long run bring about structural and behavioral changes of the LCL, and can even propel the knee joint to its former unaligned position. Furthermore, in contrast to the conventional surgical assumptions, the correction of the mechanical axis does not correct the loading axis caused by the daily activities. The presentresearch opens door to further opportunities to enhance the accuracy of this model and to exploit the obtained results within the context of medical and surgical perspectives
  9. Keywords:
  10. Arthroscopic Surgery ; Finite Element Analysis ; Subject-Specific Model ; Lower Limbs ; Knee Modelling ; Varus-Valgus Deformity

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