Design And Biomechanical Study Of Anatomic Fixation-plate And Block In Open Wedge High Tibial Osteotomy

Open-wedge high tibial osteotomy(OWHTO)is one of the common surgical treatments for medial unicompartmental knee osteoarthritis.The core of OWHTO is to maintain the correct osteotomy angle by using a reasonable fixation system.Although many fixation systems have been developed and applied,complications such as tibial fracture,fracture of fixation plate and delayed or nonunion of osteotomy incisionafter OWHTO have been plaguing patients and doctors,seriously hindering the development of OWHTO technology.The unreasonable design of the fixation system is still an important reason for the clinical failure of OWHTO.In this study,the finite element model of OWHTO fixation system was constructed based on the finite element method.Based on the finite element modeling method reported in the literature,the finite element model of the OWHTO fixation system was constructed,and the reliability of the existing modeling method was indirectly verified by comparing with the literature report.Considering the individualized tibial material assignment method and the tibial load condition in actual walking gait,a more reasonable finite element modeling method for individualized OWHTO fixation system was proposed.respectively.Studies had shown that knee joint force and joint movement affect the stress distribution of the fixation system and the tibia and the micromotion of the osteotomy gap.Therefore,the individualized OWHTO finite element modeling method was recommended to evaluate the biomechanical properties of the fixation system,which provided a technical means for the subsequent design and development of the OWHTO fixation system.On the basis of summarizing the design and clinical problems of the existing OWHTO fixation system,a new anatomicalfixation plate design was proposed.The biomechanical properties of the fixation plate were evaluated by finite element method.The effects of the design parameters of the length,width and thickness and materials of the fixation plate on the biomechanics of OWHTO fixation system were studied.Therefore,the new anatomical fixation plate improved the biomechanical properties of the fixation system.In the design of the anatomical fixation plate,the influence of thickness should be given priority,and titanium alloy or magnesium alloy materials were recommended.Considering the influence of the fixation system introducing filling block on the design and fixation effect of OWHTO,an individualized anatomical block was designed.The effects of geometric shape,filling position,material and porosity of the block on the biomechanics of OWHTO fixation system were studied.After the introduction of the block,the stability of the osteotomy area increased.The thickness of the fixation plate could be reduced from 3 mm to2.25 mm.Therefore,the introduction of the block in the OWHTO fixation system not only provided a better fixation effect,but also helped to optimize the design of the fixation plate.The results of the parametric study in this thesis was helpful to promote the design of anatomical fixation plate + blocks,and had essential significance in clinical application for clinicians to choose a reasonable fixation system.