Three-dimensional preoperative design of distraction osteogenesis for hemifacial microsomia

The purpose of this research was to simulate mandibular movement calculated from three-dimensional computed tomography (CT) data to determine the linear distractor position to correct mandibular deformities in a series of patients with hemifacial microsomia (HFM). Preoperative CT scans from 6 HFM patients were obtained and imported into a CT-based software program (Mimics) to produce three-dimensional images and data. After measurement of the mandibular deficiency in 3 dimensions (horizontal and vertical), the angle between the distraction device and the ramus was determined by a geometric calculation, and then the surgery was performed on the three-dimensional model constructed using the rapid prototyping technique. This planning method was finally used in the treatment of 6 HFM patients. The HFM was corrected, and a symmetrical facial contour obtained without any complications in these 6 patients. The results matched the expectation before surgery that the distractor elongation would range from 18 to 22 mm. The distraction tracing model fitted the actual postdistraction tracing to within 2 mm. The preoperative design and three-dimensional modeling technique are considered to be helpful in enhancing the predictability and improving the outcome of the treatment of distraction osteogenesis.