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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
IMG/FigFlo1.png IMG/FigFlo2.png

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
IMG/FigFlo3.png IMG/FigFlo4.png

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.