Computer-aided surgery in distraction osteogenesis of the maxilla and mandible

When using unidirectional intraoral distraction devices, it is desirable to be able to determine the final position of the bone fragment after the dis traction procedure. However, additional constraining forces from adjacent t issues render the prediction of the distraction direction difficult. We hav e utilised computer-aided surgery in three patients for intraoperative cont rol of the distraction direction. In one cleft palate patient, suffering fr om maxillary hypoplasia and anterior open bite, a modified Le Fort I osteot omy and maxillary distraction was performed. Despite a ventrocaudal positio n of the distraction device, intraoperative computer visualisation showed a n unfavourable caudal vector of distraction without any anterior movement. The final result confirmed the direction indicated by the computer. Maxilla ry advancement remained insufficient. In two patients suffering from mandib ular hypoplasia, intraoperative assessment revealed a favourable direction of distraction. The distraction procedure led to a satisfactory result in b oth cases. Computer-aided surgery is helpful in assessing the vector of dis traction intraoperatively, making the result of the distraction procedure m ore predictable and allowing instant correction by adequate reapplication o f the device.