Development of Bioactive Glass Scaffolds for Structural Bone Repair

The regeneration of large defects in load-bearing bones remains a clinical challenge. Current treatments such as bone autograft, allograft and porous metals have limitations. Bioactive glass is of interest in bone repair because it is bioactive, osteoconductive, converts to hydroxyapatite in vivo, and bonds strongly to hard and soft tissues. However, most previous studies indicated that bioactive glass scaffolds were sub-optimal for structural bone repair because of their low mechanical strength and concerns about their mechanical reliability in vivo. This article provides a review of our recent research in developing strong porous bioactive glass scaffolds to meet the need of repairing structural bone loss. Bioactive glass (13-93) scaffolds with a grid-like microstructure (porosity ~50%; pore width ~300 μm), created using a robotic deposition technique, have compressive strengths comparable to human cortical bone (100-150 MPa), good mechanical reliability in compression (Weibull modulus = 12), and excellent fatigue resistance (fatigue life >10 ⁶ cycles) under compressive loads greater than normal physiological loads. Those strong porous scaffolds have shown the capacity to support new bone formation in osseous defects in a rat calvarial defect model. Eight weeks postimplantation, ~60% of the pore space in the scaffolds was infiltrated with new bone. Based on their mechanical properties and capacity to regenerate bone in osseous defects, these 13-93 bioactive glass scaffolds fabricated by robocasting are promising in structural bone repair.