Healing of critical-size segmental defects in rat femora using strong porous bioactive glass scaffolds

The repair of structural bone defects such as segmental defects in the long bones of the limbs is a challenging clinical problem. In this study, the capacity of silicate (13-93) and borate (13-93B3) bioactive glass scaffolds (porosity = 47–50%) to heal critical-size segmental defects in rat femurs was evaluated and compared with autografts. Defects were implanted with 13-93 and 13-93B3 scaffolds with a grid-like microstructure (compressive strength = 86 MPa and 40 MPa, respectively), 13-93B3 scaffolds with an oriented microstructure (compressive strength = 32 MPa) and autografts using intramedullary fixation. Twelve weeks post-implantation, the defects were harvested and evaluated using histomorphometric analysis. The percentage of new bone in the defects implanted with the three groups of glass scaffolds (25–28%) and the total von Kossa-positive area (32–38%) were not significantly different from the autografts (new bone = 38%; von Kossa-positive area = 40%) (p > 0.05). New blood vessel area in the defects implanted with the glass scaffolds (4–8%) and the autografts (5%) showed no significant difference among the four groups. New cartilage formed in the 13-93 grid-like scaffolds (18%) was significantly higher than in 13-93B3 grid-like scaffolds (8%) and in the autografts (8%) (p = 0.02). The results indicate that these strong porous bioactive glass scaffolds are promising synthetic implants for structural bone repair.