Condyle as the point of rotation for 3-D planning of distraction osteogenesis for hemifacial microsomia.

AIM The purpose of this study is to present an exact simulation method for mandibular rotational movement in distraction osteogenesis for hemifacial microsomia. METHODS Three-dimensional (3-D) surgery simulation software programmes (V-Works and V-Surgery; Cybermed, Seoul, Korea) were used, based on 3-D CT data in addition to the conventional data, which included facial photography, panoramic radiograph, cephalogram, and dental models. After measuring the mandibular deficiency (horizontal and vertical) from a 3-D model reconstructed using the software, the angulation of the distraction device to the mandibular border (posterior or inferior) was determined. The rotation axis in the V-Works simulation was defined as the line perpendicular to the plane made by condylion and the distraction vector location on the mandible. The mandible moves along the plane around this rotational axis during distraction. After the 3-D simulation with the software programme, mock surgery on a rapid prototyping model was performed. This planning method was applied to models of two hemifacial microsomia patients. RESULTS With this protocol, it was possible to simulate the rotational movement of the mandible on the axis passing through the condylar head of the unaffected side. CONCLUSION The sequential planning procedure presented in this paper is considered to be helpful in performing effective preoperative simulation of distraction osteogenesis for hemifacial microsomia.