Reharvested Cranial Particulate Bone Graft Ossifies Inlay Calvarial Defects

Particulate bone graft (PBG) heals calvarial critical-size defects and is procured from the cranium with a hand-driven bit and brace. The donor sites ossify, and thus PBG potentially could be reharvested from the original areas. The purpose of this study was to determine if PBG obtained from a healed donor site is effective for inlay cranioplasty. A 17 x 17-mm critical-size defect was created in the parietal bones of 8 rabbits and treated with either no implant (group 1) or PBG harvested from the frontal bone (group 2). In 4 animals (group 3), a parietal defect was not created initially; PBG was harvested from the frontal bone and then discarded. Sixteen weeks later after the PBG donor sites had healed, a 17 x 17-mm parietal defect was made and filled with PBG reharvested from the previous donor area. Animals underwent micro-computed tomography 16 weeks after inlay cranioplasty. Critical-size defects in controls (group 1) exhibited partial ossification (35.1% +/- 10.5%) compared with those treated with PBG (group 2) (99.1% +/- 1.5%) or reharvested PBG (group 3) (99.3% +/- 1.5%) (P = 0.02). No difference was found between groups 2 and 3 (P = 0.69). Bony thickness was similar in defects implanted with PBG (1.8 mm +/- 1.1 mm) or reharvested PBG (2.1 mm +/- 0.5 mm) (P = 0.68). Particulate bone graft reharvested from healed donor sites ossifies inlay cranial defects. Because the donor area for PBG is of partial thickness and less than critical size, reparative osteogenesis theoretically allows an unlimited supply of autologous bone for inlay cranioplasty using PBG.