Design for Additive Manufacturing and Finite Element Analysis of Fe-Mn Biodegradable Fracture Fixation Plate with Varying Porosity Levels

Fracture fixation plates are osteosynthesis implants used to fix fractured bones in a human body. They are either left in the body or required to be removed after a bone healing period of 3–6 months. Recent trends focus on developing iron (Fe) based porous biodegradable implants eliminating the need for revision surgery. However, Fe alloys in their porous state are prone to a higher rate of corrosion resulting in detrimental mechanical properties. This study proposes a design strategy to develop fracture fixation implants mimicking natural cortical bone, i.e., targeting to possess enough structural strength with a minimal level of porosity. Three fixation plates each with 5, 10, and 15% porosity are developed having a gyroid lattice structure of Triply Periodic Minimal Surface designs. Four-point bending simulation is performed on Ansys to characterize the mechanical properties of the designed implants. Results show a decreasing trend of bending strength and flexural stiffness with higher porosity, but still relevant for fixation of fractured sites at different regions. The bending properties of developed implants are compared with USFDA’s proposed performance criteria, which shows 5% porous implants capable of all load-bearing extremities, whereas implants having 10 and 15% porosity are deemed to be suitable for tibia and humerus fixation.