Section: New Results

Thoracic implant

We are interested in the simulation of elastic tissus deformation in order to simulate the skin deformation due to the pose of a thoracic implant. These implants are used to fill the sternum cavity of patients affected by Pectus Excavatum syndrom. As a first step, we simulated the skin deformation with a single layer elastic model from the real bones, skin and implant geometries imported from STL files. The implant geometry has been designed on-demand by Anatomik Modeling. The single layer elastic model representing an under-skin implant, has been implemented on an octree grid to easily and automatically refine around the different geometries and keep accuracy.

Figure 19. Left: Automatic refinement around a part of the rib cage. Right: Slice of the signed distance fonction from rib cage and skin with automatic refinement

The results obtained were qualitatively validated by Anatomik Modeling. The implant actually lays on the rib cage, under the muscles. The next step will be then to include a multi-layer elasticity model to take into account the muscles and other biological soft tissus.

Figure 20. Left: Skin without implant. Right: Skin simulation with implant under skin

Another problem linked to custom made thoracic implants is the extraction of the so-called surgical plan. It is a critical step necessary to design the implant. This plan corresponds to the surface of the rib cage. To extract it, a mass-spring model has been developed and integrated in a software prototype with a graphical interface. The resulting prototype can be used easily from on any rib cage described by a STL file.