Reconstruction of calvarial bone defects using an osteoconductive material and post-implantation hyperbaric oxygen treatment

We have developed a biodegradable, malleable, osteoconductive material for calvarial bone defect reconstruction, and evaluated the extent of new bone formation in rabbits after its implantation followed by hyperbaric oxygen (HBO) treatment. Critical-sized calvarial bone defects (15 mm in diameter) were created in 40 New Zealand white rabbits, and reconstructed using the osteoconductive material. Twenty rabbits were given 30 sessions of intermittent HBO treatment (pure oxygen at 2.4 atmospheric absolute pressure (ATA) for 90 min) after surgery; the others, without HBO treatment, served as controls. Sequential fluorescent labeling was performed after surgery. The animals were euthanized 3 months after surgery and bone specimens were subjected to microradiographic, histological, and histomorphometric evaluations. The results demonstrate that there was significantly more new bone formation in the HBO group compared with the controls (microradiogram: 85.2±4.2% vs. 32.5±2.2% of the original bone defect, histomorphometry: 70.2±3.4% vs. 30.8±2.4% of the original bone defect, p<0.05), and sequential florescent labeling demonstrated coalescence of the active mineralization elements in the HBO group. The use of this novel material with HBO treatment may offer an alternative to autogenous bone grafting or methyl methacrylate for calvarial bone defect reconstruction.