Scientific Highlight: Development of porous Mg scaffolds for bone growth by additive manufacturing

Mg is a biocompatible and biodegradable metal with osteopromotive capabilities that is beginning to be used for bone repair and fixation in biomedical applications.

Mg elastic modulus and density are closer to bone than those of other metallic alloys used in  biomedical applications (stainless steel, Ti), limiting stress shielding effects. Moreover, the controlled degradation of Mg allows the progressive transfer of load to the new tissue and eliminates problems associated with the long term presence of metallic implants within the body.
Further biomedical applications of Mg are envisaged through the fabrication of porous Mg scaffolds for tissue engineering. In particular, selective laser melting of Mg alloys can be used to manufacture patient-specific porous scaffolds with geometries optimised for better mechanical support, osteoblast integration and vascularisation of the new tissue. 

Meotec GmbH and IMDEA Materials Institute are collaborating to fully optimize the microstructure of Mg scaffolds manufactured by this technique through the application of thermo-mechanical treatments, coatings and topology optimization strategies. In particular, solution heat-treatments in combination with plasma electrolytic oxidation can be used to tailor the degradation resistance of the scaffolds in simulated body fluids so they can match tissue growth and provide enough mechanical strength during the whole healing process.

Moreover, finite element simulations of the scaffold can be used to assess the effect of degradation due to corrosion on the mechanical behavior to design patient-specific implants with optimum performance.

Microstructural analysis at different length scales of WE43 Mg alloy cubic porous scaffolds manufactured by selective laser melting. The dimensions of the scaffold at 10 x 10 x 10 mm3. BD stands for the building direction during selective laser melting

Mechanical test of the WE43 Mg porous scaffold within the scanning electron microscope showing the progress of damage during deformation

Microstructure and mechanical properties of porous Mg scaffolds fabricated by additive manufacturing for biomedical applications
M. Li, T. Derra, A. Kopp, J. M. Molina-Aldareguía, J. LLorca. 
TMS 2020, 149th Annual Meeting and Exhibition, San Diego, California, February 2020