Computer-based Simulation of Facial Flap and Cleft Lip Reconstruction Using Multiresolution Physics.

Computer-based simulation of complex local flap reconstructions of the face requires very high-density finite elements to render accurately due to the intricate incision designs frequently used. This is particularly true in detailed cleft lip/nose repairs. If the entire anatomic model is embedded in a high-resolution solid lattice, the element count becomes so high that simulator performance is very slow, even on a high-performance workstation. This article introduces a simulator in which the model is initially presented at a low, but acceptable physical resolution. As the surgeon operates on the model, only the areas impacted are recut at very high resolution. This surgical subvolume is then merged back into the rest of the model. The dramatic reduction in finite element count results in a surgical simulation program that is quite fast, even on a modest personal computer. This article presents examples of this simulator used in a variety of facial flap and cleft lip reconstructions. Future uses in plastic surgery for patient-specific simulation, education, and illustration are discussed. The simulator is available as free, open-source software.