Department of Mechanical Engineering

Develop a Parametric model of a child’s spine to model scoliosis.

Student name: Valentin Ioan DascalescuStudent number: X00097718

Supervisor: Tony Tansey ( Interim Report)

Introduction:

The main objective of this project is to develop a

parametric model framework of the human spine based on a

command file system by combining different modelling

technics with vertebra and spine parameters which are

deduced from existing anthropometric data bases .

Secondary objective will be completing a conclusive

literature review of relevant scientific journals and peer reviewed papers that will,

provide a better understanding of the project and, generate a guide for the completion of it.

Project Objectives:

Literature review:

In vitro, in vivo and in silico

methodologies.Anatomy of the

spine.

Anatomy of the vertebrae

Modelling techniques.

Medical imaging

methods.

Existing models of the human spine and vertebra.

Anthropometric data base. Validation

• Obtaining vertebra dimensions from computer tomography (CT) scans.• A precise segmentation of a full vertebra from a CT scan is a challenging process and it is affected by various factors

such as: complex anatomical structure, unclear object boundaries, similar structures in near vicinity and degenerative deformities

• (images: Akyokus, Meram, Konya, Turkey : Journal of Craniovertebral Junction&Spine, 2015, Vol. 6. )

Modelling the Scoliotic spine:

Modelling from stereo lithography (STL) type file:

Based on the knowledge obtained from the literature review, it was decided to model the geometry of the parametric vertebrae from STL files using primitives such as: circles, ellipses and cylinders. The resulting models are very close approximation of the vertebrae.

STL file

Solid model

Parameterization Process of the

vertebrae in PTC Creo

1. Vertebra height is obtained from

subtracting the hip height from the

shoulder height and dividing by the

number of vertebrae. Data is selected from http://dined.io.tudelft

.nl/en

2. Using Panjabi et all 1911,1992 data sets,

together with published data, the main parameters of the vertebrae are

identified.

3. Using assumptions and critical

parameters the correlating relations between the main

vertebra regions are formulated.

4. New parametric vertebrae are

generated. They have a direct linear

relation to the master vertebra

model.

Picture of the vertebra here

Geometry control by parameterisation

Parameterisation of the master vertebrae:

• When using a CAD type software, a geometry entity can be defined by dimensions.

• In parametric modelling is the dimensions that drive, define, the geometry.

• The advantage is that, once the key elements of a geometry entity are captured in the drawing, they could all be related to each other or to a driving parameter, so that later on, the geometry could by altered or modified by changing that respective parameter

• http://dined.io.tudelft.nl/en/database/introduction.

• The most in-depth and complete resource of data is provided by the Panjabi et all

• “Thoracic Human Vertabrae- Quantitative 3-Dimensional Anatomy,. Spine. August, 1991, Vol. 16.”

Parameters and relations:

Nomenclature of vertebra defining parameters Spine Deformity. November, 2013, Vol. 1, 6.

Parameters prediction formulae (M. Haghpanahi, M. Javadi,. December, Narmak Ave., Tehran, Iran : Science Direct, 2011. )

Panjabi et all Spine 1992

Data collection Datasets were compiled by direct measuring and by statistical analysis such as linear regression, mean

and standard deviation

Lengths of the thoracic, lumbar and combined spine lengths by age with minimums and maximums

(Normal growth of the spine and skeletal maturation, Seminars in spine surgery 2015).

Project progress so far (15/12/2015)

Future course of action:Create

parameterised vertebrae for cervical and

thoracic region.

Create equation of the spine.

Assemble the spine model.

Create method which allows for

angular adjustment.

Model validation against in vitro

data.Finish writing the

report.Analysis.Output

calculations sheet.

Output sectioned assembly sheet.

Output drawings with angular adjustment.

Thank you for your attention! Any questions ?