prof.dr.ir. bart verkerke dr. a.g. veldhuizen · x-ray / echo digitalisatie bepaling stijfheid...

Scoliose-correctie

Prof.dr.ir. Bart VerkerkeDr. A.G. Veldhuizen

Dept of Biomedical Engineering

BMSA 1: Injury, repair, intervention and support

Aim: To realize the development and application of

advanced optical and biochemical diagnostic techniques for

assessment of organ function, and the development of

interventional strategies to assist, repair, or replace injured organs within translational setting.

Approach:

-Development of diagnostic tools and markers-Design of mechanical organ support systems

-Development of transplantation models

-Performance of applied clinical research

-Design and evaluation of interventional strategies

-Product-driven research

BMSA 2: Microbial adhesion and infection

Aim: To determine physico-chemical and biological

mechanisms for the interaction of biological components

with biomaterials surfaces to be applied for infection

prevention by developing technology-based or tissue-engineered solutions for the repair of human function.

Approach:

-Study of mechanisms of biomaterial-related infections

-Development and assessment of adhesion-modifyingcoatings

-Study of molecular mechanisms of biofilm-formation

-Study of biofilm architecture

-Analysis of clinical biofilms-Prevention of biofilm formation

Confocal laser microscopic image

of an ingrowing biofilm on a silicone rubber voice prosthesis (insert)

isolated from a patient

Normothermic liver machine perfusion for

better preservation of organ function before transplantation. Organ function

control is achieved by diagnostic markers/tools and by support systems

Heart assist devices can be used to bridge to transplantation, or to

relieve the heart muscle and

therewith allow it to recover

Confocal laser microscopic image of

an E. coli biofilm on a monofilament surgical polypropylene mesh (insert)

for abdominal wall reconstruction

Examples of innovative implant design: the Groningen temporomandibular joint

prosthesis and a voice-producing prosthesis for laryngectomised patients

(insert)

BMSA 3: Permanent implants for function restoration

Aim: To realise and test permanent implants and diagnostic

instruments for the repair of human function.

Approach:

-Design of innovative implants

-Realization of prototypes of innovative implants-Exploration of potential use of hybrid implants

-Design of diagnostic tools / instruments

-Development of algorithms for analysing complex images

Design of a degradable polyurethane scaffold material with interconnected

pores, and the tissue response to the degrading scaffold (insert)

Clinical evaluation of the tissue response to implants – lens

epithelial cells responding to the presence of an accommodating

intra-ocular lens

BMSA 4: Tissue engineering and scaffold materials

Aim: To realise new strategies for the repair of human

tissues and organs based on (biodegradable) polymers and/or humoral factors and (stem)cells.

Approach:

-Study of cell-scaffold interactions

-Isolation,expansion, differentiation of autologous (stem/progenitor) cells

-Design of innovative, smart, degradable scaffolds

-Study of mechanisms of tissue repair (inflammatory niche)

-Implementation of modulation of inflammation for repair

-Induction of stem cell homing and angiogenesis-Development of a cell-based implantable kidney

-Focus on cardiovascular, renal, bone/cartilage applications

Application of memory metal as a scoliosis correction device.

Scoliosis can be detected by

image analysis algorithms

Scoliose

Scoliose

Scoliose-correctie

Hippocrates(400 BC)

Scoliose-correctie

Boston brace

Scoliose-correctie

Milwaukeebrace

Cotrel-Duboussetsysteem

Harringtonmethode

Scoliose-correctie

Luque systeem

A vd Plaats

Ontstaan van scoliose

alleen als asymmetrie in:

ligamentum flavum en intertransversale ligament

eis: koppeling van laterale verplaatsing en

axiale rotatie

A vd Plaats

Ontstaan van scoliose

-4

-3

-2

-1

0

1

2

3

Sacr L5 L4 L3 L2 L1 T12 T11 T10 T9 T8 T7 T6 T5 T4 T3 T2 T1

Dis

pla

cem

ent [m

m]

-0,2

-0,15

-0,1

-0,05

0

0,05

0,1

0,15

Rota

tion [ra

d]

Ux

Uy

Uz

Rotx

Roty

Rotz

G Nijenbanning, DJ Wever

• achterblijvende groei spieren + ligamenten

• visco-elastisch gedrag discus, ligamenten

Progressie van scoliose

G Nijenbanning

in FEM geen mm rotatores, mm multifidus, facetgewrichten; discus als balkelement

Progressie van scoliose

LLJ Kamman

• numeriek rigid body model

• initiatie: symm én asymm achterblijven in groei van spieren en ligamenten

• progressie afhankelijk van rek in spieren en ligamenten

echter: discus als bolscharnier; geen facetgewrichten; spieren en ligamenten identiek

Ontstaan, progressie van scoliose

J Cheung

ontstaan door stoornis in

evenwichtssysteem

voorspelling progressie

adhv spinale groei en EMG-ratio

Progressie van scoliose

wervelkolomgeometrie

X-ray / echo

digitalisatiebepaling stijfheid

gebruikersinterface

Numeriekmodel

grafischerepresentatiechirurgisch

resultaat

feedbackexpert-systeem

operatie-strategie

• optimalisatie braces• optimalisatie implantaten• ontstaan van scoliose• progressie van scoliose

Virtuele scoliose-chirurgie

Numeriek model

Model of motion segment

Body-disc-body:

• Based on concave endplates

• Vertebrae: rigid bodies

• Intervertebral disc: annulus and nucleus

Geometry: Panjabi et al.

Intervertebral disc:

Annulus fibrosus

• 2 layers of fibers (double mesh)

+/-30 degrees with local x-axis

• Volume fraction 16%

Nucleus Pulposus

• Incompressible fluid

Model of motion segment

= model.

*=measured in Thoracic region.

Validation body-disc-body

with literature:

• High range in measured stiffness.

• Overall mechanical behavior corresponds well.

• Model is stiff in lateral bending.

Model of motion segment

Facet joints:

• Modeled as surfaces with cartilage in between, with low shear and tension resistance.

• Facet angles determine restricted motions.

• Results: Increase of stress-stiffening (non-linear) behavior in flexion, extension and AP-shear.

Geometry: Panjabi et al.

Model of motion segment

Ligaments:

• Bilinear load-deformation curves: constant throughout spine.

• Tension only.

• 6 ligaments (Lumbar).

Measurements: Chazal et al.

Model of motion segment

Sensitivity analysis

Interpersonaldifferences

Growth

±5%+10%width

±6%+20%depth

±60%+3%height

±12%±13%±55%+23%+43%-3%torsion

±17%±6%±56%+33%+21%-3%lateral

bending

±4%±20%±58%+8%+66%-3%extension

±5%±21%±54%+10%+69%-3%flexion

±3%±6%±66%+6%+19%-3%axial com-

pression

widthdepthheightwidthdepthheight

Interpersonal

differencesGrowth

Geometry of disc and vertebrae have large influence on stiffness

⇒ Growth has influence

⇒ Patient specific data has to be accurate

• Relative size (30-50%) of nucleus has little influence

⇒ No patient-specific data required.

Sensitivity analysis

Influence ligaments & facet joints

Model of motion segment

Lumbar model

Level-specific:

• Geometry vertebra (processes) and disc.

• Wedge angle of vertebrae.

• Facet angles (averaged for left and right).

• Validation with literature: stiffness in flexion too high.

• Theoretical stiffness lumbar level: ¼ of motion segment .

NOT in measurements: protocol or specimen differences?

=> Measurements with same specimen (Iris).

Lumbar model

Motion segment with facet joints in response

to extension loading. The contours represent

the Von Mises stresses, in N/mm2.

Numeriek model

Numeriek model

I Busscher (ism dr Veldhuizen, Orthopedie; prof van Dieën, VUmc)

Stijfheidsmeting

3D visualisatie

X-Rays 3D CT Spine

Template

Individual 3D CT

Spine

2D US Spine

TA Sardjono, KE Purnama

3D visualisatie

Automatische detectie Cobb-hoek

Scannen met ultrageluid

axial sagittal coronal

Scannen met ultrageluid

Scannen met ultrageluid

Scannen met ultrageluid

Scoliose-correctie

Vormgestuurd vs

Krachtgestuurd,

gebruikmakend van visco-elasticiteit

Memory metal

Memory metal

TriaC braceBaat Engineering, Somas, Boston Brace

Scoliose-correctie

G Nijenbanning

geheugenmetalen

correctiesysteemDePuy-Spine

MM Sanders, DJ Wever

Scoliose-correctie

Non-fusie scoliose-correctie

Voordeel:

• Eerder ingrijpen, want groei is mogelijk

• Geen fusie

BMT - De kunst van het beter maken