Combining 3D Printing and Cryostructuring to Tackle Infection and Spine Fusion

Low back pain is among the main issues in vertebral orthopaedics. Intervertebral disk degeneration can be severe, up to requiring the replacement of the damaged disk by substitutes to achieve spine fusion. Disk removal results in critical size defects, so fusion does not occur naturally, but synthetic bone grafts are needed. Since the surgical procedure is time-consuming, high infection rates occur. Hence, in spine fusion, bone regeneration enhancement and infection prevention are needed. Here, a new dual-component system is proposed, to tackle both issues at one time. To enable spine fusion, 3D extrusion-based printing is employed to develop coherent custom magnesium phosphate (CaMgP)-based cages. The 3D-printed scaffolds are hardened, and the structural properties are evaluated to be within the ranges of physiological bone. To prevent infection, an in-house ice-templating device is employed in combination with a 3D-printed ceramic scaffold, to develop tailored porous alginate structures loaded with vancomycin. Results show that CaMgP can be printed into complex geometries and that the geometry influences the pore orientation during ice-templating. These structures loaded with vancomycin have antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) strains. The development of a 3D composite structure to achieve both bone regeneration and infection prevention is obtained. 3D printing of magnesium-phosphate (CaMgP) for custom-shaped spinal cages is performed and combined with porous structures generated by novel ice-templating technique. Pore morphology is affected by the 3D printed geometry and the efficacy of loaded antibiotic drug against bacteria strains is demonstrated. image