Enhanced Biocompatibility and Osseointegration of Calcium Titanate Coating on Titanium Screws in Rabbit Femur

This study aimed to examine the biocompatibility of calcium titanate（CaTiO_3） coating prepared by a simplified technique in an attempt to assess the potential of CaTiO_3 coating as an alternative to current implant coating materials. CaTiO_3-coated titanium screws were implanted with hydroxyapatite（HA）-coated or uncoated titanium screws into medial and lateral femoral condyles of 48 New Zealand white rabbits. Imaging, histomorphometric and biomechanical analyses were employed to evaluate the osseointegration and biocompatibility 12 weeks after the implantation. Histology and scanning electron microscopy revealed that bone tissues surrounding the screws coated with CaTiO_3 were fully regenerated and they were also well integrated with the screws. An interfacial fibrous membrane layer, which was found in the HA coating group, was not noticeable between the bone tissues and CaTiO_3-coated screws. X-ray imaging analysis showed in the CaTiO_3 coating group, there was a dense and tight binding between implants and the bone tissues; no radiation translucent zone was found surrounding the implants as well as no detachment of the coating and femoral condyle fracture. In contrast, uncoated screws exhibited a fibrous membrane layer, as evidenced by the detection of a radiation translucent zone between the implants and the bone tissues. Additionally, biomechanical testing revealed that the binding strength of CaTiO_3 coating with bone tissues was significantly higher than that of uncoated titanium screws, and was comparable to that of HA coating. The study demonstrated that CaTiO_3 coating in situ to titanium screws possesses great biocompatibility and osseointegration comparable to HA coating.