Comparative effects of scaffold pore size, pore volume, and total void volume on cranial bone healing patterns using microsphere-based scaffolds.

Bony craniofacial deficits resulting from injury, disease, or birth defects remain a considerable clinical challenge. In this study, microsphere-based scaffold fabrication methods were use to study the respective effects of scaffold pore size, open pore volume, and total void volume fraction on osseous tissue infiltration and bone regeneration in a critical size rat cranial defect. To compare the healing effects of these parameters, three different scaffolds types were fabricated: solid 100 microm spheres, solid 500 microm spheres, and hollow 500 microm spheres. These constructs were implanted into surgically created rat calvarial defects. By 90-days post op, results of micro computed tomography (CT) analysis showed that all scaffolds generated similar amounts of new bone which was significantly greater than untreated controls. Interestingly, the spatial distribution of new bone within the defect area varied by scaffold group. MicroCT and histological analysis demonstrated healing restricted to the dural side in the hollow 500 microm group, whereas the solid 500 microm group demonstrated healing along the dural side and within the center of the defect. Solid 100 microm groups demonstrated healing along the dural layer, periosteal layer, and within the center of the defect. These results suggest that pore size and closed void volume may both play important roles in scaffold degradation patterns and associated bone healing. 2008 Wiley Periodicals, Inc.