Static analysis of different thickness cervical implants using finite element analysis and comparison of results

Abstract

It is known that the apparent difference between the geometric factors and loading conditions in the cervical cage is caused by the limited high pressure and thus the collapse of the adjacent vertebral body of the cage, leading to clinical problems such as vertebral body rupture, bone loss, stability and fusion failure. Numerous techniques and methods with advantages and disadvantages are applied for these clinical problems. But the cost of spine testers and biomechanical spine testing is a time-consuming process, and other alternatives and end-to-end analysis of implants are worthwhile and necessary to develop. The aim of this study is to calculate the equivalent stretching and deformation of cervical cage implants of different thicknesses with the Finite Element Static Analysis models to quantitatively evaluate the tendency of collapse in clinically encountered conditions. In this context, PEEK (polyether ketone) has been chosen as a material because of the incentive results in recent years with the use of integrated screws and cages in a select group of patients. A force of 100 N was applied to the upper surface of the implant in accordance with the standards and the lower surface of the implant model was defined as a fix support. As a result of the analysis made on 3 different models with different thicknesses, the total deformation on the 5.0 mm, 6.0 mm and 7.0 mm systems was 0.073161 mm; 0.032413 mm; 0.025319 mm respectively, and the equivalent stresses was 47.722 MPa; 24.126 MPa and 20.43 MPa respectively. These values were found to be smaller than the yield strength of the material used (165 MPa), and as predicted, the maximum deformation of the model and the decrease in equivalent stress were observed to decrease. In addition, there are places where there is a singular load accumulation on the design, which in turn has confirmed that the use of costly and time-consuming testing processes and finite element analysis to avoid faulty production is appropriate.