The approach to obtain the anatomical and FE model of the rib cage

Presented by Krzysztof Rechowicz

on 05/07/2008

Krzysztof Rechowicz 2

Pectus Excavatum Congenital chest wall

deformity; Displacement of the

sternum toward the spine;

Different types of deformity;

Krzysztof Rechowicz 3

The Nuss procedure

Krzysztof Rechowicz 4

3D scanner

Wand

Styllus

Tracker

PU

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3D Printing

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Goals and Objectives: Finding the proper way to create the 3D virtual

and then FE model of a the rib cage; Methodology of segmenting the rib cage with the

cartilage; The registration between the cartilage and the

skin surface in order to locate points to apply loads;

Application of 3D scanning; Application of rapid prototyping; Discussion about requirements for FEM; Related work; Future work;

Krzysztof Rechowicz 7

Motivation A stage in the Pectus Excavatum project; Little literature about the rib cage

segmentation; Investigation of the mechanical properties

of the PE cartilage; Results will be used to create a guide for

the optimization of the Nuss procedure; Eventually, the surgery simulator is

planned to be developed;

Krzysztof Rechowicz 8

General description of the procedureCT rib cage model with manually identified DCPs

CT skin surface model with DCPs (from extruded rib cage)

Actual DCP data

Laser skin surface scan

Merged DCP data and CT skin surface

Corrected

FEA Model

Merged DCP data and CT rib cage

Compare

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The rib cage segmentation w/out the cartlige

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The rib cage segmentation with cartlige using Chebyshev’s Rule

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Registration between the rib cage and the skin surface

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Surface skin scan

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3D Physical Models

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3D CAD Model of the PE rib cage

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3D CAD Model of the cartlige

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Assumptions and requirements for the FEM Geometric modeling of the other tissue that is

connected to the sternum, costal cartilage, and ribs would be more problematic than modeling of than the rib cage itself;

Using constraints and boundaries to represent other organs;

3D FEM is to complicated; 2-1/2 FEM might be a good start - a single set of

costal cartilages and a corresponding section of the sternum in the axial plane;

Krzysztof Rechowicz 17

Related work Awrejewicz and Luczak; Simplified model based

on an anatomy atlas; Impacts due to

accidents; Frontal impacts to the

chest after the Nuss procedure;

Not deformed;

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Related work Dr. Kelly; FEA of the sternum; Correlation of stress patterns within the

sternum with bone growth centers;

Krzysztof Rechowicz 19

Future work Obtaining input data to FEM; Use pre and postoperative surface scans in a shape

analysis for objective improvement of chest symmetry and displacement/replacement;

Use pre and post surface scans in a shape analysis of aesthetic improvement which will obtain an objective measurement of closeness to a norm;

Develop a methodology for automatic classification into cup vs saucer, Haller index range, length (long vs short), torsion, symmetry, and slope;

Parameterized 3D CAD model; A guide for the Nuss procedure optimization; Using 3D physical models to train doctors;