Collagen type I coating stimulates bone regeneration and osteointegration of titanium implants in the osteopenic rat

Purpose: To investigate the effects of titanium implants functionalised with collagen type I (TiColl) on bone regeneration and osteointegration in a healthy and osteopenic rat animal model. Method: TiColl screws were implanted into the femoral condyles of healthy and osteopenic rats and compared with acid-etched titanium (Ti) screws. The osteointegration process was evaluated by a complementary approach combining microtomographic, histological, histomorphometric and biomechanical investigations at four and 12 weeks. Results: The TiColl screw also ensured a greater mechanical stability; the push-out values for TiColl screws increased from four to 12 weeks (+28 %). The energy necessary to detach the bone from the screw was significantly higher for TiColl-functionalised screws in comparison to Ti screws (+23 %) at 12 weeks. Histomorphometric investigation revealed that total bone-to-implant contact was higher in TiColl screws in comparison to Ti screws (P <0.05) and at epiphyseal level, increased bone-to-implant contact was found with TiColl screws in comparison to Ti screws (P <0.05) in an ovariectomy (OVX) condition. A significant increase in the measured total bone ingrowth from four to 12 weeks was detected for both materials, but more significant for the TiColl material (P <0.0005). Finally, bone ingrowth in the TiColl group was significantly higher (P <0.005) in comparison to that of Ti screws in the SHAM condition at metaphyseal level at 12 weeks. Conclusion: The present results showed that TiColl is effective in promoting implant osteointegration even in compromised bone.