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