When preparing patients for orthognatic surgery, one of the major concerns besides the functional outcome is the prediction of the postoperative facial appearance. To satisfy this whish, two-dimensional computer-assisted profile predictions were introduced almost two decades ago. Since several years new software packages are available that allow a three dimensional simulation of the postoperative soft tissue development, but these system have certain disadvantages: research based approaches are mainly time consuming procedures and not applicable in clinical routine, while the commercially available solutions provide unrealistic simulations in delicate facial anatomical regions (e.g. the nose).

In this work, we propose a computationally efficient, bio-mechanically relevant soft-tissue simulation method for cranio-maxillofacial (CMF) surgery. Special emphasis is given to comply with the current clinical workflow. A template-based facial muscle prediction was introduced to avoid laborious segmentation from medical images. In addition, transversely isotropic mass-tensor model (MTM) was applied to realize the directional behavior of facial muscles in short computation time. Finally, sliding contact was incorporated to mimic realistic boundary condition in error-sensitive regions. Mechanical simulation result was compared with commercial finite element software. And retrospective validation study with post-operative scan of four CMF cases was performed.

Conflict of interest: None declared.