Biology of grit-blasted titanium alloy implants.

This study describes the biologic integration of grit-blasted titanium alloy (Ti-6A1-4V) implants that were press fit into the distal femoral canal of young adult rabbits and evaluated by histologic, histomorphometric, and biomechanical methods. Polished and aluminum oxide grit-blasted (4.2 +/- 0.7 microns surface roughness) solid implants were compared with titanium fibermetal implants. Nondecalcified cross sections were studied by histology, histomorphometry, and electron microscopy in the backscatter mode at 3, 6, and 12 weeks after implantation. Pullout strength was measured at 12 weeks. Data were analyzed by analysis of variance and post-hoc Student-Newman-Keuls and Scheffe's tests. The blasted implants had significantly more bone intimately in contact with the implant surface (31%) than the fibermetal (17%), or solid polished implants (15%). By 3 weeks, woven bone had formed directly on the surface of the blasted implants, whereas there was a discrete space between woven bone and the other implants. Active remodeling of bone was shown by fluorochrome uptake at the surface of the blasted implants at 12 weeks after implantation. The strength of fixation of blasted and fiber-metal implants was significantly greater than polished implants at 12 weeks after implantation. Direct attachment of newly formed bone onto the blasted implant surface was confirmed by backscatter electron microscopy. The results of this study indicate that grit-blasted titanium surfaces provide an excellent surface for bone implant integration.