Maxillofacial surgery simulation using a mass-spring model derived from continuum and the scaled displacement method.

Purpose: Development of a maxillofacial surgery simulation software capable of predicting a patient's appearance after surgery.
Methods: We have derived a new mass-spring model (MSM) equivalent to a linear finite element (FE) model for cubic elements. In addition, we propose the scaled displacement method as a new method to perform the simulation more realistically.
Results: The average error of eight soft tissue landmarks measured between 0.37 and 2.01 mm except from a landmark that had an error of 4.44 mm; values close to those obtained with the linear FE method. On the other hand, the scaled displacement method allows avoiding punctual stress concentration and bending effects making a much more realistic simulation in the region of the bone cut.
Conclusions: Good results have been achieved with our two proposed methods. In addition, the simple way in which MSM can be parallelized makes it an interesting alternative to FE method.