Image-based 3D planning of maxillofacial distraction procedures including soft tissue implications

Abstract

Osteodistraction, a technique for new bone formation by the gradual separation of bony fragments, is a possible treatment for dysplasia of the maxillofacial skeleton. However, preoperative assessment of the optimal distraction direction, of the osteotomy trajectory, and of the influence of this procedure on the outlook of a patient, is difficult to assess preoperatively. We report on an 3D image-based planning system for osteodistraction. Basically we adhere to a scene-based approach in which image derived visualizations and additional 3D structures are co-presented and manipulated. Osteotomy simulation with user-defined cutting trajectories, virtual distraction employing biomechanical models specific to the distraction type and evaluation tools based on a cephalometric reference frame, are available in our planning environment. According to the surgeon’s findings, different choices can be redone in order to optimize the therapy. To account for soft tissue implications, skin tissue deformations are calculated using a finite element elastic model based on tetrahedral elements. We report on results in the field of unilateral mandibular distraction. A detailed overview of the planning procedure is given by a case study.