OBJECTIVETo evaluate the 3-D position changes of periorbital structures after midface distraction osteogenesis in patients with Crouzon syndrome.

METHODSThe CT data of 8 cases who had accepted the midface distraction osteogenesis following Le Fort III osteotomy were retrospectively analyzed. The patients were averagely 11.9 years old, and the CT was performed before and one year after operation. After 3-D image reconstruction, a right-hand coordinate system based on the preoperational Frankfurt Plane was then established. The pre- and post-operative positions of the superior orbit point (SOr), inferior orbit point (IOr), median orbit point (MOr), lateral orbit point (LOr), anterior ocularis point (AO), ocularis eyeball point (PO) and the four insertion ocularis rectus were documented and compared. The positions of these marked points in normal controls were also documented and compared with those in patients.

RESULTSAfter midface distraction osteogenesis, the position of AO was not changed significantly on the y-axis and z-axis, but the distance between two AO points on x-axis was reduced by 3.40 mm; IOr moved averagely 12.24 mm on y-axis and 4.25 mm on z-axis, MOr moved averagely 10.11 mm on y-axis and 2.80 mm on z-axis, LOr moved averagely 9.86 mm on y-axis and 2.31 mm on z-axis. The Inferior Rectus attachment moved averagely 3.63 mm on y-axis and 2.98 mm on z-axis. No other significant change was observed on other marked points.

CONCLUSIONSMidface distraction osteogenesis following Le Fort III osteotomy can significantly move the medial, lateral and inferior peri-orbital bone structure anteriorly and inferiorly. The eyeballs have no markedly sagittal position changes after distraction except slight medial, downwards movements and anterior-upwards rotations.