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

Abstract

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=86MPa and 40MPa, respectively), 13-93B3 scaffolds with an oriented microstructure (compressive strength=32MPa) 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.