Strategic Uniaxial Macropore Sizing for Honeycomb-Structured Scaffolds for Enhanced Bone Reconstruction in Segmental Bone Defects

Segmental bone defects often present as new irregularly growing bones that fail to bridge gaps. Optimizing the scaffold design for direct bone growth can enhance bone defect reconstruction. We evaluated three carbonate apatite honeycomb-structured scaffolds with uniaxial macropores of 280, 440, and 640 μm (labeled P280, P440, and P640, respectively) implanted into critical-sized ulnar defects in rabbits. The scaffold performance was assessed at 4 and 12 weeks postimplantation. P280 formed small volumes of oriented bone, which decreased the bone strength. P440 formed large volumes of oriented bone and restored bone strength. Meanwhile, P640 formed abundant volumes of disorganized bone and failed to enhance bone strength. The 440 μm macropores effectively guided new bone and enhanced the bone strength. These findings suggest that the macropore size is crucial for designing scaffolds for effective segmental bone defect reconstruction.