Optimization of curvilinear mandible distraction using 3-dimensional computer-simulated modeling

Multi-vector distraction osteogenesis has been described for use in the reconstruction of complex mandible deformities. Using 3-dimensional computer simulation, the location of the osteotomy and arc of the device can be predetermined, allowing for precise planning and determination of end points. Here, we discuss our experience using this technique and propose methods to optimize outcomes and minimize discrepancies in the projected results.

Three patients who underwent curvilinear mandible distraction and preoperative computer-simulated planning are described. After simulation to determine level of osteotomy and arc of the curvilinear distractor device, design-specific guides were constructed. Intraoperatively, custom guides were used to precisely perform the osteotomy and for placement of each distractor. After the completion of distraction and device removal, the correlation of distraction end points, occlusion, and the volumes of the mandibles were analyzed.

A vertical difference of 2.6 mm (shorter) from the proposed final position and an 8-mm sagittal difference (under correction) were seen in the first patient. In the second patient, the final position had a vertical difference of 5.7 mm (shorter) and a sagittal difference of 14 mm (undercorrected). In the third patient, after first simulating anterior rotation of the condyle before osteotomy and vector design, the final and simulated end points differed approximately 0.6 mm vertically (shorter) and 4.3 mm sagittally (undercorrected)

Preoperative 3D simulation and planning is a useful adjunct in curvilinear mandible distraction; however, the forces of the muscles of mastication and the restrictive soft tissue envelope must be accounted for in the design to achieve precise end results.