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Titanium and its alloys are the most commonly used fixation rod materials in spinal fusion surgery because of their biocompatibility, stability, and endurance. However, titanium may not be the best rod material for patients as it can cause adjacent segment degeneration (ASD), in which the spinal segments adjacent to the instrumented segment or segments experience increased force loading and begin to deteriorate. Through analysis of various studies, polyetheretherketone (PEEK), nitinol, and silicon nitride were found to be possible alternative spinal fusion fixation rod materials. To determine which of these materials is best suited for use as a spinal rod material, the osteointegration, current availability, stiffness, durability, corrosion resistance, and clinical efficacy of each material was analyzed. Although silicon nitride had strong osteointegrative properties, no testing could be found evaluating the material as a spinal fusion rod, indicating its current unavailability. Even though nitinol was determined to have better osteointegrative properties than PEEK, PEEK has an elastic modulus close to bone, a reinforcing material, carbon fiber, that allows for customization of the elastic modulus, no risk of corrosion, and strong clinical results. By implementing PEEK fixation rods in spinal fusion surgeries instead of titanium rods, the incidence of ASD may decrease as well as the risk of rod corrosion.

Publication Date


Subject Major(s)

Biomedical Engineering

Current Academic Year


Faculty Advisor/Mentor

Mary Boyes


Virginia Commonwealth University. Undergraduate Research Opportunities Program

Is Part Of

VCU Undergraduate Research Posters


© The Author(s)

Alternative Spinal Fusion Fixation Rod Materials: Polyetheretherketone, Nitinol and Silicon Nitride