Angiogenesis is enhanced by continuous traction in rabbit mandibular distraction osteogenesis

Distraction osteogenesis is a controlled surgical procedure that initiates a regenerative process and uses mechanical strain to enhance the biological responses of the injured tissues to create new bone. To test the hypothesis that high frequency mechanical traction can enhance the angiogenesis in distraction regenerate, we compared the neo-vessel formation and gene expression of the angiogenic mediators between intermittent and continuous distraction osteogenesis.

Eighty adult New Zealand white rabbits were randomly assigned to the continuous and intermittent distraction groups. Unilateral mandibular osteotomy was performed and custom-designed manual-driven or autodriven distractor was bridged over the osteotomy segments. Animals were sacrificed at day-6, day-10, day-14 and day-21 after osteotomy and examined with histology, immunohistochemistry and real-time polymerase chain reaction (PCR).

Histological examination showed a more advanced bone formation in the continuous distraction group associated with significantly increased micro-vascular density and up-regulated mRNA expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF).

We concluded that the high frequency traction provides a proper mechanical environment for angiogenesis contributing to the enhanced bone formation likely to be through up-regulation of the angiogenic mediators.