ORCID

https://orcid.org/0009-0009-6433-0301

Degree

Bachelor of Science (B.S.)

Major(s)

Mechanical Engineering

Document Type

Immediate Open Access

Abstract

The customization, characterization, and development of biomedical implants through additive manufacturing (AM) and finite element methods (FEM) becomes imperative to the success of surgical operations and long-term patient satisfaction. To combat stiffness mismatches and prevent stress shielding between implant and bone tissue, lattice structures can be implemented within bone implant design to reduce the effective Young’s modulus (EYM) of the implant and to promote osteointegration within bone tissue. Lattice structures are highly customizable, three dimensionally repeated patterned unit cells that can be manipulated to mimic the porous nature of bone tissues to increase implant-bone interface longevity. The study presents the design and topological optimization of diamond lattice-integrated post lumbar interbody fusion (PLIF) cages, tailored for fabrication via laser powder bed fusion (L-PBF). The use of L-PBF enables the precise and reproducible fabrication of complex geometries, allowing for the creation of lattice integrated implants with controlled macroscopic porosity (MP) and mechanical properties. Conventional PLIF cages created from traditional manufacturing techniques are typically solid structures with limited porosity, which can lead to implant subsidence, screw loosening, and adjacent segment degradation. By implementing cellular lattice structures within implant design, the study aims to enhance implant MP while maintaining structural integrity, ultimately improving the implant’s biomechanical compatibility with surrounding bone tissue while addressing critical limitations of traditional PLIF cages. In addition, the approach demonstrates the limitations of the intra-lattice propagation. Within this study, six PLIF cage prototypes with varying MP, up to 79%, were computationally designed and evaluated with FEM. Models with a greater number of cellular lattice structures were the most MP and had the greatest increase in surface area when compared to a non-porous PLIF cage ii design. Preliminary computational testing demonstrated that the most MP lattice integrated cage design and a non-porous PLIF cage maintained peak von Mises stresses of 1.625 MPa and 0.0143 MPa, respectively, under physiological compressive loads. Each of these values were well below the yield strength of Ti-6Al-4V, confirming mechanical viability.

DOI

https://doi.org/10.54718/MZET2821

Date Defended

4-22-2025

Thesis Director

Matthew Priddy

Second Committee Member

Lauren Priddy

Third Committee Member

Thomas Anderson

Rights Statement

"Design and Optimization of Lattice-Integrated PLIF Cages Using Additive Manufacturing and Finite Element Modeling", Copyright 2025 by Olivia Draughn. All rights reserved. Note that in addition to my own works of authorship, this thesis may contain and provide citations to third party content. If your use goes beyond fair use, you would need to contact those rights holders for additional licensing/permissions.

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