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Background: Inlay cranioplasty in children is difficult because autologous bone is limited. Cranial particulate bone graft effectively closes defects when placed over normal dura. The purpose of this study was to determine if particulate bone graft will heal when used for secondary cranioplasty over scarred dura.
Methods: A 17mm x 17mm critical-sized defect was made in the parietal bone of 12 rabbits and allowed to heal. Sixteen weeks post-operatively the 17mm x 17mm critical-sized defect was recreated and managed in two ways: Group I (no implant) (n=6) and Group II (particulate bone graft) (n=6). Particulate graft was obtained using a brace and bit from the frontal bone and placed over the scarred dura. Gross analysis and micro-computed tomography were performed 16 weeks following the cranioplasty to determine the: (1) area of critical-sized defect ossification and (2) thickness of the healed bone graft.
Results: Critical-sized defects treated with particulate bone graft grossly exhibited superior ossification (96.0%; range, 86.5%-100%) compared to those managed without an implant (49.9%; range, 42.6%-54.6%) (p<0.0001). MicroCT examination showed critical-sized defects treated with particulate bone graft healed 91.1% (range, 79.0-97.2%) of the area, while control defects demonstrated inferior ossification 56.9% (range, 40.0-68.3%) (p<0.0001). Critical-sized defects treated with particulate bone graft exhibited thinner bone (2.42mm; range, 1.69-3.30mm) compared to the normal adjacent parietal cranium (4.33mm; range, 3.28-6.20mm) (p<0.0001).
Conclusions: Particulate bone graft ossifies inlay calvarial defect area over scarred dura, although the bone is thinner than the normal cranium. Clinically, particulate bone graft may be efficacious for secondary inlay cranioplasty.