A low-temperature biomimetic calcium phosphate surface enhances early implant fixation in a rat model

The present study demonstrates increased early mechanical fixation of titanium implants coated with a new biomimetic apatite surface in a rat model. Male Sprague- Dawley rats received unilateral femoral medullary implants for periods of 1- 4 weeks. The strength of fixation of the implant to the host bone increased more rapidly in the group receiving apatite-treated implants compared with the control group as evidenced by the apatite group's 21-fold greater fixation strength at 1 week (p 0.009), 4-fold greater fixation strength at 2 weeks (p 0.041), and 2-fold greater fixation strength at 4 weeks (p 0.093) compared with the control. Fixation strength was correlated with bone-implant contact as determined from micro computed tomography assessment of the specimens (r 2 0.338, p 0.011 in the control group and r 2 0.543, p 0.001 in the apatite group). Furthermore, for a given amount of bone-implant contact, the fixation strength was higher in the apatite group than in the control group (p 0.011), suggesting that the bone formed a stronger bond to the apatite coating than to the titanium. This difference in bonding strength accounted for the difference in mechanical behavior. © 2004 Wiley Period- icals, Inc. J Biomed Mater Res 70A: 66 -73, 2004