Biomechanical evaluation of pedicle screw fixation system in spinal adjacent levels using polyetheretherketone, carbon-fiber-reinforced polyetheretherketone, and traditional titanium as rod materials

In the present study, we compared the biomechanical effects of changing the material properties of the fixation rod on adjacent segments of the spine, with respect to the use of polyetheretherketone (PEEK), carbon-fiber-reinforced (CFR) PEEK, and traditional titanium (Ti) rods. Using a validated intact lumbar finite element model for L2-L5, interbody fusion models for L3-L4 in one-level and L3-L5 in two-levels were developed using rod materials with three different stiffness values. The highest and lowest disc pressure increments and facet joint contact forces were found on the adjacent segments with the Ti and PEEK rods fixation systems, respectively. However, there was no difference in values for disc pressure and contact force in the facet joint between PEEK and CFR-PEEK. CFR-PEEK is a better alternative for fixation rod material for spinal fusion compared to PEEK and Ti. CFR-PEEK rod systems reduce the risk of pedicle screw breakage compared to PEEK.