Evaluation of the biocompatibility of a hydroxyapatite-CaTiO3 coating in vivo

Objective: This study was designed to evaluate the biocompatibility and osteointegrative activity of hydroxyapatite (HA)-CaTiO3, titanium substrate, traditional HA coating and CaTiO3 coating via an animal experiment. Method: Four types of screws (type 1: coated with HA; type 2: coated with CaTiO3; type 3: coated with HA-CaTiO3; type 4: untreated titanium screws) were implanted into femur bone of 48 New Zealand rabbits. Histological and mechanical investigations were employed at the end of 2, 4, 8 and 12 weeks to evaluate the material osteointegration. Results: (1) All of the experimental rabbits were healthy during the experiment process. (2) Histological investigation showed fully regenerated and well integrated bone tissue surrounding the screws coated with HA, HA-CaTiO3 and CaTiO3. (3) Mechanical investigation showed that the bonding strength of HA-CaTiO3 coating was significantly higher than that of CaTiO3 coating or titanium materials without coating, but was lower than those coated with HA. Conclusion: HA-CaTiO3 coating possesses similar admirable biocompatibility and osteointegration activity with HA coating, indicating a promising coating material for implants in orthopedics.