Background: Cranioplasty in children is difficult because autologous bone is limited. To expand the calvarial donor site, surgeons have used bone dust harvested with a power drill and particulate bone taken with a bit and brace. The purpose of this study was to compare bone dust and particulate bone for inlay cranioplasty.
Methods: A critical-size defect was made in the parietal bone of rabbits and managed in three ways: group I (n = 5), no implant; group II (n = 6), bone dust implant; and group III (n = 6), particulate graft implant. Bone dust and particulate graft were obtained using a power burr or brace and bit, respectively. Bone dust and particulate graft volume was calculated using a micrometer. Computed tomography was performed 4, 8, and 16 weeks after cranioplasty to determine ossification; histology also was studied.
Results: The average volume of particulate bone fragments (6.2 × 10 mm) was 344-fold greater than bone dust particles (1.8 × 10 mm) (p < 0.0001). Four weeks postoperatively, the filled volume of the experimental defect was 6.8 ± 4.9 percent in group I, 8.4 ± 7.4 percent in group II, and 43.0 ± 7.2 percent in group III. Eight weeks postoperatively, the filled volume was 22.3 ± 3.9 percent in group I, 29.1 ± 6.7 percent in group II, and 80.0 ± 8.9 percent in group III. Sixteen weeks postoperatively, the defect was closed 38.6 ± 11.1 percent in group I, 41.3 ± 11.2 percent in group II, and 99.3 ± 1.5 percent in group III (p < 0.0001).
Conclusions: Particulate bone graft ossifies full-thickness cranial defects. Bone dust is ineffective and resorbs, possibly because of its smaller particle size and/or thermal injury during harvesting. Particulate graft, and not bone dust, is suitable for inlay cranioplasty.