Biomechanical Effects of the Implant Designed for Posterior Dynamic Stabilization of the Lumbar Spine (L4-L5): A Finite Element Analysis Study

Abstract

This study aims to design a new pedicle-screw-based posterior dynamic stabilization (DS) implant, which can help stabilize the spine normally, using the finite element (FE) method, and to determine and compare its biomechanical effects. Four different implant and device components that maintain the range of motion (ROM) within the standard limits were created with the SOLIDWORKS program, and the ABAQUS CAD simulation program and MATLAB program were used together to calculate the range of motion. In all devices, some rods connect L4-L5 vertebrae and are connected with screws, screws placed in the spines, and pins and nuts that complete the connection of the screws with the rod. Based on computed tomography scan data, robust and different implant-treated models of the lumbar spine were simulated under physiological loading conditions. For all designed devices, the range of motion was measured in axial rotation, lateral bending, and flexion-extension directions, and adjacent level effect and restoration percentages were calculated in all directions. With the iterations in the design of the implant parts, an acceptable 70% restoration percentage in the movement of the spine with the implant has been tried to be achieved in all directions. With the device whose optimum data were obtained, 58% for flexion, 70% for extension, 67%, and 52% for lateral bending and axial rotations, respectively, were achieved. It can be said that the pedicle-screw design realized with this study will be applicable after successful experimental validation and clinical trials.

Keywords

• finite element method
• lumbar spine
• posterior dynamic stabilization
• range of motion
• restoration