MIDFACE ADVANCEMENT BY GRADUAL DISTRACTION

Midface osteotomy was performed on 5 young adult sheep aged 10-12 mont hs. In 4 animals midface advancement by gradual distraction was perfor med using an external device; one animal served as a control. The midf ace was advanced by 2 mm per day for 21 days. The amount of advancemen t was 36 mm in the nasofrontal area and 43 mm on the lateral aspect of the maxilla. After the period of active distraction the midface was m aintained with external fixation for an additional 6 weeks to allow fo r ossification. Radiographs were obtained immediately postoperatively, after 21 days of distraction, and at the end of the 6 week fixation p eriod. New bone formation in the distracted area was obvious radiograp hically, clinically and histologically. In conclusion, midface advance ment by osteotomy and gradual distraction is possible in the sheep mod el and may offer controlled correction of deformity, obviating the nee d for bone grafting.