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SlicerSOFA simulation for predicting soft tissue restoration after orbital fracture repair

Key Investigators

• Chi Zhang (Texas A&M College of Dentistry, USA)
• Andrew Read-Fuller (Texas A&M College of Dentistry, USA)
• Rafael Palomar (NTNU / OUH, Norway)
• Paul Baksic (INRIA, France)
• Steve Pieper (Isomics Inc., USA)

Project Description

Orbital fractures are typically caused by blunt-force trauma. Fracture repair frequently requires placing a titanium plate to reconstruct bony orbit and restore tissue position and function from disturbed conditions, such as enophthalmos (“sunken eye”) and muscle entrapment & conformational changes.

This project aims to develop a reproducible patient-specific SOFA/SlicerSOFA FEM simulation workflow to predict orbital soft tissue restoration after fracture repair using a preformed titanium plate.

The simulation processes span across multiple scenes from retracting orbital tissue to place a plate and then let the tissue fall onto the plate. The only deformable object is a unified multi-material orbital tissue mesh. Tetrahedrons inside different tissue regions to assign with different material properties. The retracting tool, plate, and bony orbit are all simulated as rigid bodies.

Major simulation steps are:

1. Tissue retraction to create a gap for plate placement
2. Plate placement
3. Tissue restoration by falling onto the plate

Objective

The main objective is to streamline workflow reproducibility and improve efficiency for patient-specific simulation:

1. Streamlining setting & simplifying constraints and boundary conditions for patient-specific simulation, including bone-tissue attachment, collision simplification, retracting moving trajectories and retraction stages, etc.
2. Tracking, quantifying, and visualize tissue position and shape change.
3. Use Slicer methods to facilitate simulation setup, smooth transitions across multiple scenes, outcome visualization, and parameter tuning.

Approach and Plan

Implement Slicer methods to:

1. Streamline scene setup and interaction, such as tissue bone attachment, syncing the interactive transform with the SOFA controller, retraction trajectories, and collision regions
2. Track and visualize tissue deformation, such as using TPS, grid transform, and mark up-based methods.
3. Facilitate performance tracking and parameter tuning & method selection in SlicerSOFA (e.g., exploring using AI agents)
4. Initiate creating a Slicer module based on SlicerSOFA.

Progress and Next Steps

1. Describe specific steps you have actually done.

Illustrations

Standard surgical process that retracted orbital tissue to create a gap for plate placement.

Fat herniation and inferior rectus muscle conformational changes in floor fx

Create a multi-material mesh from a combined orbital tissue surface model from segmentations using Gmsh.

Orbital tissue attachment points at the superior surface set up in Slicer and visualized in SOFA

Simulation of tissue retraction using plane models in SOFA (skull hidden) and the same process in Slicer SOFA. The left picture shows one plane holds one area of the tissue to enable another plane for further retraction.

Tissue restoration onto the plate

Tracking and visualizing globe & inferior rectus changes after restoration (not very accurate though):

Background and References

No response