Direct Computation of Nonlinear Soft-Tissue Deformation

A method for computing nonlinear soft–tissue deformation caused by simulated surgical procedures is presented. A mass–spring system is used to model patient individual soft–tissue. Instead of simulating dynamic behaviour, the introduced approach directly estimates the rest position of the system. Very fast and robust nonlinear soft–tissue deformation is computed using an optimization approach. The multi–layer soft–tissue model considers features like skin turgor and gravity. The model takes into account the nonlinear stress– strain relationship of soft–tissue and the fact that soft–tissue is almost incompressible due to its liquid components. The approach to soft–tissue deformation is part of an integrated system for craniofacial surgical simulation. The system is capable of simulating bone cutting and bone realignment with integrated interactive collision detection. Furthermore, soft–tissue deformation and cutting due to the application of surgical instruments can be visualized.