Three-dimensional simulation and prediction of craniofacial surgery.

The treatment of patients with complex facial deformities is one of the most challenging multidisciplinary tasks in plastic surgery. Due to advancements in medical technology and surgical techniques in the last 20 years correction of severe malformations has become possible and is performed by highly specialized teams frequently in a single operation. Recent developments in three-dimensional (3-D) imaging techniques have already greatly facilitated diagnosis of complex craniofacial deformities. Computer-based simulation methods for surgical procedures that are based on imaging data have the potential to improve surgical treatment by providing the ability to perform 'virtual surgery' preoperatively and thus reduce patient risk and morbidity intraoperatively. A method is presented for interactive computer-assisted craniofacial plastic surgery planning and visualization, especially simulation of soft tissue changes using an experimental Craniofacial Surgery Planner. The system computes non-linear soft-tissue deformation because of bone realignment. It is capable of simulating bone cutting and bone realignment with integrated interactive collision detection. Furthermore, soft-tissue deformation and cutting due to surgical instruments can be visualized. Simulation processes are based on an individual patient's preoperative 3-D computed tomography and on a 3-D, photo-realistic model of the patient's preoperative appearance obtained by a laser range scanner. Very fast and robust prediction of non-linear soft-tissue deformation is computed by optimizing a non-linear cost function.