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Cambre Kelly1 Nathan Evans2 Cameron Irvin2 Savita Chapman2 Ken Gall1 David Safranski3

1, Duke University, Durham, North Carolina, United States
2, Georgia Institute of Technology, Atlanta, Georgia, United States
3, Medshape, Atlanta, Georgia, United States

As the manufacturing of medical devices via additive manufacturing (3D Printing) continues to increase, better understanding of structure-function relationships of microarchitecture and surface topography are needed. Selective laser melting (SLM) of Ti-6Al-4V of implants with interconnected porosity have become widespread in orthopedic and other load bearing applications where porous structures encourage bony ingrowth and the stiffness of the implant can be tuned to reduce stress shielding. SLM allows high resolution control over design, including the ability to introduce porous surfaces or regions with spatial variations in pore size, shape, and connectivity. Investigation of the effect of construct microarchitectural design and surface topography on mechanical behavior of 3D printed Ti-6Al-4V showed a dominating effect of porosity on monotonic and fatigue behavior as compared to solid samples. Irrespective of surface treatment and resulting surface roughness, the fatigue strength of 3D printed samples containing bulk or surface porosity was approximately 20% to 25% of the ultimate tensile strength of identical printed porous material. For the vast range of microarchitectures which can be fabricated to tune construct porosity and resulting stiffness, creation of predictive models of fatigue behavior based on monotonic properties would allow for rapid iteration of design for devices with microarchitecture specified not only to patient anatomy, but also bone quality and loading profiles for tailored reduction of stress shielding.

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