Effect of Surgical Fit on Integration of Cancellous Bone and Implant Cortical Bone Shear Strength for a Porous Titanium

Porous scaffold dowels of Ti6Al4V were prepared and implanted into cancellous and cortical bone sites in adult sheep. Cancellous implants were examined under gap, line-to-line, and press-fit conditions, whereas line-to-line implantation was used in cortical sites. Cortical shear strength increased significantly with time and reached 26.1 ± 8.6 MPa at 12 weeks, accompanied by a concomitant increase in bone integration and remodeling. In cancellous sites, bone integration was well established at 4 and 12 weeks under conditions of press-fit and line-to-line match between implant and surgical defect. New bone growth was also found in the gap conditions, although to a lesser extent. These findings suggest that the porous Ti6Al4V could prove an effective scaffold material for uncemented fixation in cortical and cancellous sites.