iceos: nov. 19 th – nov. 20 th 2015 1 École polytechnique of montreal (canada) 2 sainte-justine...
TRANSCRIPT
ICEOS: Nov. 19th – Nov. 20th 2015
1 École Polytechnique of Montreal (Canada)2 Sainte-Justine Research Hospital Center (Canada)
3 Faculty of Dentistry, University of Montreal (Canada)4 École des Mines de Saint-Étienne (France)
Presenting author
1,2MÉNARD A-L, 2GRIMARD G, 1,2,4MASSOL E, 2LONDONO I, 2,3MOLDOVAN F, 1,2VILLEMURE I
Static versus Dynamic Compression Applied and Subsequently Removed on Growing Rat
Tails: Effects on Intervertebral Discs
2
Intro
M&MResults
Discussion
Disclosures
Authors Disclosure Information a. Consultantb. Stock/Shareholder
Presenter: Anne-Laure Ménard No Relationships
Co-Authors: Guy Grimard (a,b) Emovi, IncÉlise Massol No RelationshipsIrène Londono No Relationships Florina Moldovan No RelationshipsIsabelle Villemure No Relationships
Presenter: Anne-Laure Ménard No Relationships
Co-Authors: Guy Grimard (a,b) Emovi, IncÉlise Massol No RelationshipsIrène Londono No Relationships Florina Moldovan No RelationshipsIsabelle Villemure No Relationships
3
Clinical context: fusionless devices
Research evidence: compression on the disc Mechanical loading:
• Causing factor of disc degeneration (Aronsson et al., 2011)
Disc degeneration: • disc height (Wuertz et al., 2009)
• proteoglycan in the nucleus (Sivan et al., 2014)
Compression-based fusionless devices (Skaggs et al., 2013) Span the intervertebral disc Can possibly be removed following spinal correction
(Hunt et al., 2010)
Intervertebral disc integrity in young growing individuals after physiological compression removal ?
Intro
M&MResults
Discussion
4
Clinical research question
4
Staples : compression Growth plate (GP)
(*) Is the intervertebral disc still healthy ?
RESEARCH QUESTION
Intro
M&MResults
Discussion
Intervertebral disc
Fusionless approaches
Growth
Device removal
(*)
5
Hypothesis & Objectives
5
OBJECTIVES
To assess and compare the effects of subsequently applying and removing static/dynamic compression on the intervertebral disc:
(1) Structure: disc height(2) Composition: nucleus proteoglycan content
Intro
M&MResults
Discussion
HYPOTHESIS
Dynamic compression better preserves long-term disc integrity and functionality
In vivo protocol: rat tail
Growth modulation Growth resumption?
28 43 53Rat age in Days
Loading (15 days) No loading (10 days)
Surgery
6
Cd7
Cd7
Proximal Distal
Cd7
Cd7
Control (n = 6)
Sham(n = 6)
Static(n = 6)
Dynamic(n = 6)
StaticCompression
DynamicCompression
Intro
M&MResults
Discussion
(inspired by Walsh et al., 2004 ; Cancel et al., 2009 ; Valteau et al., 2011)
Micro-loading deviceDissection of4-week group
Dissection of2-week group
Dissection & measures
7
Intervertebral disc height
Intro
M&MResults
Discussion
Analyzed discs
Cd4 Cd5 Cd6 Cd7 Cd8
D45 D78
Collecting tissus
3D reconstruction of ex-vivo samples using microCT images
Disc height = mean value of six images cut through vertebra
Intervertebral disc measurements
Safranine-O staining (2.5X)Intensity level (ImageJ software)
8
Proteoglycan content in the nucleus
(Nb pixels) proteoglycanProteoglycan =
(Nb pixels) nucleus
Intro
M&MResults
Discussion
Nucleus/Annulus proportion: stereological method (Griffiths, 1993)
(Nb points) nucleusProportion =
(Nb points) annulus
Toluidine blue staining (2.5X)Grid (Gimp) + cell counter (ImageJ)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Intervertebral disc height
9
Both static and dynamic compressions disc height
Summary
Intro
M&MResults
Discussion
Disc height D78 normalized with D45 [μm/μm]
* **
4-week group2-week group
p = 0.056 & p = 0.052
One-way ANOVA, Tukey post-hoc comparisons, *p < 0.05 and **p < 0.01
Control ShamStatic Dynamic
Cd4 Cd5 Cd6 Cd7 Cd8
D78
Intervertebral disc composition
10
No difference observed for nucleus/annulus proportion After loading removal, proteoglycan for static but remained for dynamic
Intro
M&MResults
Discussion
Nucleus/Annulus proportion of D78 [μm/μm] Proteoglycan content in the nucleus for D78
2-week group 4-week group0.00
0.20
0.40
0.60
0.80
1.00
1.20
One-way ANOVA, Tukey post-hoc comparisons, **p < 0.01
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50 **
2-week group 4-week group
**
Summary
Control ShamStatic Dynamic
Discussion
11
Intro
M&MResults
Discussion
Limitations One range of loading (magnitude/frequency) Rat discs: conservative model with more notochordal cells, therefore
better adaptation capabilities
Future work Inflammatory pathways within disc
Physiological loading range Magnitude below 1.0MPa &
frequency above 0.01Hz and below 1.0Hz preserve disc integrity (Iatridis et al., 2006)
Dynamic loading: preserve nucleus PG content even following compression removal
PG in the nucleus
COMPRESSION2-week group
REMOVING COMPRESSION4-week group
STAT
ICDY
NAM
IC
Funding & References
12
Intro
M&MResults
Discussion
Hunt KJ, Braun JT, Christensen BA. The Effect of Two Clinically Relevant Fusionless Scoliosis Implant Strategies on the Health of the Intervertebral Disc. Spine 2010;35: 371-7.
Aronsson DD, Stokes IAF. Nonfusion Treatment of Adolescent Idiopathic Scoliosis by Growth Modulation and Remodeling. J Pediatr Orthop 2011;31: S99-106.
Wuertz K, Godburn K, MacLean JJ, Barbir A, Stinnett Donnelly J, Roughley PJ, Alini, M, Iatridis JC. In Vivo Remodeling of Intervertebral Discs in Response to Short- and Long-Term Dynamic Compression. J Orthop Res 2009;27: 1235-42.
Sivan SS, Wachtel E, Roughley PJ. Structure, Function, Aging and Turnover of Aggrecan in the Intervertebral Disc. Biochimica et Biophysica Acta 2014;1840: 3181-9.
Walsh AJ, Lotz JC. Biological Response of the Intervertebral Disc to Dynamic Loading. J Biomech 2004;37: 329-37. Cancel M, Grimard G, Thuillard-Crisinel D, Moldovan F, Villemure I. Effects of In Vivo Static Compressive Loading on
Aggrecan and Type II and X Collagens in the Rat Growth Plate Extracellular Matrix. Bone 2009;44: 306-15. Valteau B, Grimard G, Londono I, Moldovan F, Villemure I. In Vivo Dynamic Bone Growth Modulation is Less Detrimental
but as Effective as Static Growth Modulation. Bone 2011;49: 996-1004. Griffiths G. Quantitative Aspects of Immunocytochemistry. In Fine Structure Immunocytochemistry. 1993: 371-445. Iatridis JC, MacLean JJ, Roughley PJ, Alini M. Effects of Mechanical Loading on Intervertebral Disc Metabolism In Vivo. J
Bone Joint Surg Am 2006;88: 41-46.
Funding sources:
References: