Date of Award

6-2015

Document Type

Open Access

Degree Name

Bachelor of Science

Department

Mechanical Engineering

First Advisor

Glenn Sanders

Language

English

Keywords

cage, porosity, bone, design, RVE

Abstract

This project involved the design of an all-in-one patient-specific lumbar spinal fusion cage using Direct Metal Laser Sintering (DMLS) manufacturing. The cage is zero-profile and does not need the use of supplemental fixation. It was manufactured out of the titanium alloy Ti 6Al-4V using a DMLS rapid prototyping machine from a third party company. The endplates of the cage are patient-specific allowing for a larger surface contact area between the cage and the vertebral bodies than most cages on the market. This fosters a more successful fusion as well as decreases surgery time, effectively decreasing recovery time. Different porosity variations of the design were tested and optimized by conducting a comprehensive analysis on a representative volume element (RVE). The RVE consisted of a one cubic centimeter cube with a non-uniform porosity. The results of the RVE analysis were then applied to the cage porosity. The purpose of optimizing the pores was to achieve an effective modulus of elasticity of approximately the same magnitude of bone (1.5 GPa) as well as to foster bone growth between the bone graft and the vertebral endplates. The final design has an effective modulus of 2.576 GPa and a porosity of 69.939%.

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