Porosity and pore design influence on fatigue behavior of 3D printed scaffolds for trabecular bone replacement

• Published in: Journal of the mechanical behavior of biomedical materials Vol. 117; p. 104378
• Main Authors: Baptista, R., Guedes, M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.05.2021
• Subjects: 3D printing; Bone tissue engineering; Cancellous Bone; Compressive Strength; Fatigue; Materials Testing; Numerical simulation; Porosity; Printing, Three-Dimensional; Scaffolds; Tissue Engineering; Tissue Scaffolds; Fatigue; Numerical simulation; Bone tissue engineering; Scaffolds; 3D printing
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2021.104378

Polymeric scaffolds provide several advantages when compared with other bone replacement and regenerating techniques. Namely, when compared with the current gold standard, bone autografts, there is no shortage of supply nor donor site morbidity. Contrarily to metallic implants, their mechanical properties are similar to those of cortical bone and they are biodegradable, therefore stress shielding is not expected to occur, and they will be gradually replaced by new bone tissue. Yet, there are still several challenges to overcome. After implantation scaffolds are subjected to dynamic loads, thus understanding polymeric scaffolds’ fatigue behavior plays a major role on the design of better products. In this work PLA scaffolds were manufactured using 3D printing with optimized parameters. A total of six configurations were tested under static and dynamic load conditions. Static compression testing and numerical simulation showed good correlation. Numerical simulation provided a viable resource for scaffold design and innovation. Four different low-cycle fatigue loads were applied, during 3600 cycles with a frequency of 0.25 Hz. While under dynamic conditions, with a maximum stress of 24 MPa and R = 0.1, the apparent compressive modulus reached 973 MPa, due to pore collapse. Even after 3600 cycles no significant fatigue damage mechanisms were found on low porosity scaffolds, rendering them useful for trabecular bone replacement under dynamic conditions. [Display omitted] •Commercially available FDM 3D printer and PLA filament were used to manufacture two different geometry scaffolds.•Scaffolds were compatible with trabecular bone replacement in terms of both monotonic and low cycle fatigue properties.•Filament offset distance influenced scaffold porosity, filament width, pore size and mechanical properties.•SEM morphology analysis was used to create scaffolds' numerical models, that improved mechanical behavior assessment.•Orthogonal scaffold design showed improved mechanical properties, that can be tailored using filament offset distance.