Transport distraction osteogenesis for closing full-thickness calvarial defects in sheep

To prove the hypothesis that transport distraction osteogenesis can be applied to the skull to close critical-size calvarial defects.

A sheep model was developed to investigate this hypothesis. In four sheep, bilateral parietal bone windows were created and adjacent osteotomies performed. On the tested side, an adjacent bone segment was transported into the defect. The contralateral side was left untreated as a control.

After completion of the distraction and consolidation period, a computed tomography study was performed, and the animals were sacrificed. The newly formed bone was examined macroscopically and histologically.

A successful closure of the defect with transport distraction was achieved in all of the animals. The control side healed spontaneously in one (younger) sheep but did not heal in the other three animals. The closure of the bony defect with transport distraction was evident macroscopically as well as on the computerized tomography. Microscopic examination showed new healthy bone formation on the treated side.

We conclude that transport distraction is an effective tool in closing full-thickness calvarial defects in adult sheep. Further investigation is needed before applying this promising technique in humans.