[Application of distraction osteogenesis in severe maxillary hypoplasia secondary to cleft palate].

OBJECTIVE: To evaluate the effect of distraction osteogenesis in correction of severe undeveloped maxilla secondary to cleft palate and to evaluate the selection of distraction modality.

METHODS: Distraction osteogenesis was performed upon 8 patients, 6 males and 2 females, aged 11 to 25 years, one with incomplete cleft palate, 4 with unilateral complete left palate, and 3 with bilateral complete cleft palate, all accompanied with severe maxillary hypoplasia. The 7 adult patients were treated by modified high-stepped Le Fort I osteotomy, the other patient, a child, was treated by Le Fort I osteotomy followed by rigid external distraction. X-ray films of skull in lateral, frontal, or panoramic positions, and X-ray film of temporomandibular joint in Schiller's position were taken pre- and postoperatively. In model surgery the accurate distraction distance was measured and the direction of distraction designed. Orthodontic therapy was started immediately after the distraction was completed and the distractor was removed after a period of 4 months' consolidation.

RESULTS: The designed distraction was achieved in a11 8 patients. Except in one case with a bone defect 1 cm x 0.5 cm at the osteotomy line in the lateral wall of the right maxillary sinus, dense new bone was formed in the area of distraction in the other cases. The postoperative occlusal relationship was good and stable. No infection and other complication was found. During an average of 20 months' follow-up, the maxilla and occlusion were stable, and no relapse was found. The distance of forward distraction of the maxilla reached an average of l2 mm (5 approximately 15 mm). The SNA angle increased from 71 degree on average preoperatively to an average of 79 degree postoperatively. Both the facial appearance and occlusal relationship returned to normal in a11 the patients.

CONCLUSION: Without need of bone grafting and with a stable effect and little influence on platatopharyngeal competence, distraction osteogenesis is an effective method of correcting maxillary hypoplasia secondary to cleft palate and is worthy of spreading.