Distraction Osteogenesis For Correction Of Cleft Palate

Distraction Osteogenesis (DO) is a new surgical technique to reform malformation or defect by lengthening and widening the bone ,in which certain distraction force is produced to the bone which is cut but kept periosteum and soft tissues attachment and blood supply. The bone and soft tissue of hard palate were repaired simultaneously through DO technique in our study, which aimed at exploring a new method to treat cleft palate, making the perfect functional repairing of this kind of malformation possible.A complete perforative cleft (8x30mm2) was established surgically in the experimental animals to simulate the cleft palate in human beings. The cleft couldn't be cured because the dimension of the cleft was much larger than the thickness of the hard palate. Previous studies had showed that this kind model would be stable and become a reliable model to repair the cleft palate.The self-devised distraction equipment made of pure titanium was used and the pure micro-screw was applied for fixation. At the same time of the surgical establishment of cleft palate model, the distraction device was fixed stably. The interval period after operation was 12 days, and the suture was split on the tenth day, finding the wound had been cured and the distraction device had been stable. On the thirteenth day, the distraction was carried out with the frequency of 2 times a day and with the rate of 0-3mm once. On the fifteenth day the cleft was closed and the stage of distraction came to be stable. The animals were killed in the second, sixth, and tenth week respectively. Every 2 week in the stationary phase, tetracycline was intramuscularly injected 25mg/kg.General specimen showed that the cleft had been closed completely and the marginal mucous membrane of the cleft had been healed by necrosis and fusion from continuous force. X-ray showed that new bonewas formed in the distraction zone, which extended from the distraction direction. The bony specimen showed that the cleft had been closed by new bone and the margin of both sides had fused into a whole. But the new bone was a little thinner than the normal. The back of hard cleft has resumed to the previous form. Histology and tetracycline fluorescent marker showed that on the second week the distraction zone was filled with fibers arrayed from the distraction direction, within which a lot of fibroblast and osteoblast was found. The dispersal fluorescent zone was observed at the edge of bone. On the sixth week, osteogenesis occurred actively, and the new bone trabecula extended from the distraction direction, within which osteoid tissue and wide fluorescent zone were found. On the tenth week, much maturer bone trabecula had generated and calcium salts had deposit largely. Mature Harvard' s system had formed. During that period, the formation of new bone occurred actively and fluorescent zone became narrow and discontinuous.The results of our study showed that it is possible to complete the repairing of cleft palate by DO technique. The formation of new bone belongs to intramembrane osteogenesis. During different period, the degree of calcification has been different. The final reformation of new bone tissue finished the repairing of hard palate defect.