Enhanced osteointegration of orthopaedic implant gradient coating composed of bioactive glass and nanohydroxyapatite.

We conducted histologic and histomorphometric studies to evaluate the osteointegration of gradient coatings composed of bioactive glass and nanohydroxyapatite (BG-nHA) on titanium-alloy orthopaedic implants and surrounding bone tissue in vivo. Titanium-alloy implants with a gradient coating (gradient coating group), uncoated implants (uncoated group), and implants with a conventional hydroxyapatite (HA) coating (HA coating group) were randomly implanted in bilateral femoral condyles of 36 male New Zealand rabbits. The bone-implant contact at 12 and 24 weeks and the new bone volume in the notch created for observing bone ingrowth at 4, 12, and 24 weeks were found greater in the gradient coating group than those in both the uncoated group and the HA coating group (p < 0.05). Fluorescence micrographs showed active osteogenesis in the gradient coating group at 4 weeks after implantation. These findings indicated that BG-nHA gradient coatings could enhance the osteointegration of orthopaedic implant.