DOI: https://doi.org/10.15674/0030-59872019442-49

Mathematical modelling of a new implant for interbody lumbar spinal fusion

Mykola Korzh, Volodymyr Kutsenko, Andrey Popov, Oleg Veretelnik, Iryna Timchenko, Mykola Gnyrya, Mykola Tkachuk, Mykola Tkachuk

Abstract


Objective: using mathematical modeling with the finite element method to develop a model of the interbody implant with an additional fastening element and to evaluate the stress-strain state of the system «vertebral body – implant». Methods: models were designed in SolidWorks software. Two designed schemes with implants were developed and studied: 1) titanium cylindrical; 2) titanium cylindrical with an additional fastening element — a spike. The condition of the Ist stage of the study is the absence of movements of the elements of the contact pair «implant – vertebral body», the IInd — a small relative slip between them with zero friction. Bending loads on the segment were created. Re­sults: the application of an additional fastener significantly in­creases the rigidity of the entire system. Redistribution of stresses occurs with their decrease in the implant with an additional fastening element by 30 % than without it. The equivalent stresses of cortical tissues for the first and second calculation schemes of the first stage of the study turned out to be close in values, the difference is 2 %. For stage II, the difference was 43 %, higher stresses were observed in the case of implant with a spike. Contact pressure indices in models with two types of implants in the absence of movements in the «implant – vertebral body» system are close, the difference is 5 %. In the case of modeling of a small relative slip between them with zero friction (stage II), the difference in values rises up to 54 %, and the lower pressure corresponds to the implant model with a spike. Conclusions: the use of an improved design of the interbody implant with an additional fastening element in the form of a spike is more effective to achieve stabilization in the system of the «vertebral body – implant» compared with a conventional cylindrical implant.


Keywords


finite element models; interbody spinal fusion; implant; vertebrae body; stress-strain state contact pressure

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Copyright (c) 2020 Mykola Korzh, Volodymyr Kutsenko, Andrey Popov, Oleg Veretelnik, Iryna Timchenko, Mykola Gnyrya, Mykola Tkachuk, Mykola Tkachuk

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