3D-printing polylactic acid/hydroxyapatite fracture internal fixation plates for bone repair

Fracture internal fixation plates are the most common implants in internal fixation and have been applied to fix fractures for over a hundred years. Plates of metal material remain the gold standard. However, they are not the ideal bone plate considering the stress shielding induced by the high elastic modulus and biomechanical mismatch with bone. PLA fracture internal fixation plates present the advantages of matching with the elastic modulus of the bone and absorbable properties but are limited by poor toughness and acidic degradation. Degradable bone plates composed of polylactic acid/hydroxyapatite (PLA/HA) composite were prepared by fused deposition modeling, which had higher bending strength and compressive strength than that of pure PLA. The hydrophilicity of PLA/HA composite was improved by the addition of HA, it was beneficial to the adhesion of cells on the surface of the composite. The results of in vitro degradability showed that the addition of HA can effectively neutralize the acidity generated by PLA degradation. Meanwhile, the addition of HA can improve the cell affinity to promote the adhesion and growth of MC3T3-E1 cells on the surface of the composites. Consequently, the PLA/HA composite shows a good potential as a bone plate to fix bone fractures.