Spine implant materials and surface characteristics are popular topics among engineers and surgeons. How do surface technologies relate to spine implants and bone integration and fusion? What are the pros and cons of various materials and surfaces? In this interactive session, members of industry and academia reviewed and presented research related to use of
• porous plasma spray coating,
• porous PEEK, and
• additive manufactured titanium in spinal devices.
Giftedness: Understanding Everyday Neurobiology for Self-Knowledge
Spine Implants: Porous Coatings vs. Porous Materials vs. Additive Manufacturing
1.
2. Jason Cianfrani, VP of Product Development
Camber Spine and The Institute of Musculoskeletal Science and Education
BSME Clemson University
Additive Manufactured Titanium
Geometric and Surface Design Considerations
3. Electron Beam Melting
• More parts per build, less detail
Direct Metal Laser Sintering / Melting
• Less parts per build, more detail
Additive Manufactured Titanium
Types of Manufacturing
Osseointegration of Coarse and Fine Textured Implants Manufactured by Electron Beam Melting and Direct Metal Laser
Sintering, Ruppert et al.
Surface roughness and directional fatigue behavior of as-built EBM and DMLS Ti6Al4V, Nicoletto et al
4. Open Geometric Matrix – macro pores with optimized surface texture; graft can be packed
throughout the cage. SPIRA surface topography is modelled using software, centered
around 500 microns.
Additive manufacturing advantages as compared to traditional PEEK and machined metal cages:
• More boney ongrowth and ingrowth
• Maybe faster mechanical fusion?
• Bone doesn’t have to grow completely through the implant
• Concept of ‘grip growth’
• Better patient outcomes! Pain free faster!!
Additive Manufactured Titanium
Commercially Available Styles of Implant Geometry
CAD input vs machine type vs layer thickness
5. Additive Manufactured Titanium
Commercially Available Styles of Implant Geometry – Design Considerations
Easy to
Model in
CAD
IP Risk
Utilizes
complex
additive
capabilities
Larger Graft
Bed - More
Graft
Fatigue and
Impact
Strength
Micropore
Size Control
Surface
Topography
Control
Modulus
Control
Trabecular
Matrix
Yes Medium Yes No ? Yes No Yes
Honeycomb
Lattice
Structure
Yes Low No No ? Yes No No
Open
Geometric
Matrix
No High Yes Yes Yes No Yes Yes
Optimization
6. IMSE Studies in Progess:
Effects of surface topography on cell characterization and gene expression
• Looking at 6 different surface designs
Sheep Study – in progress, SPIRA cages vs. PEEK control
• Early timepoints – 6 weeks, 12 weeks
Additive Manufactured Titanium
Active Studies – IMSE with Camber Spine
7. • Additive manufactured titanium offers a variety of design options to
designers and clinicians
• Two types of additive manufacturing to choose from depending on
design and production requirements
• Current IP can be a limitation for new designs
• We are in the early days of development and there is significant
room for optimization
• More studies are required to validate current hypotheses and move
implant development to the next level
Additive Manufactured Titanium
Summary and Conclusions
9. Porous PEEK
Ken Gall, PhD
Professor and Chair
Mechanical Engineering and Materials Science
Financial Conflict:
10. Porous PEEK Interbody Devices For ACDF and TLIF/PLIF
Mimics Bone1,2
• Fully interconnected
• ~1mm in-growth depth
• >60% porosity
• 300-400µm pore size
Bone Porous PEEK
1Evans NT, Torstrick FB, Lee CSD, et al. High-strength, surface-porous poly-ether-ether-ketone for load-bearing orthopedic implants. Acta Biomater 2015;13:159-67
2Evans NT, Torstrick FB, Safranski DL, et al. Local deformation behavior of surface porous polyether-ether-ketone. J Mech Behav Biomed Mater 2017;65:522-32.
Wicking Capability
The only interbody Porous PEEK devices to achieve FDA clearance, promote bone in-growth,
and maintain mechanical and imaging properties of PEEK.1,2
11. Investigations into Effect of Topography on PEEK – All Data on Smooth PEEK
Smooth PEEK Porous Titanium
Smooth PEEK Rough Titanium
12. 1 cm
Implant
Side
View
Top
View
Surgery
8 weeks0 Timeline
Smooth PorousRough
µCT (n = 12)
Histology (n = 4)
Biomechanics (n = 8)
PEEKTitanium
Surface Topography
SurfaceMaterial
Nano-scale TiO2 coating
• ~30 nm thickness
• Atomic Layer Deposition (ALD)
• All titanium implants have TiO2
surface
Torstrick BF et al. In vivo effect of surface topography and chemistry on PEEK and titanium implant osseointegration. Proc of Ortho Res Soc. 2018.
What is more important? Surface architecture or material?
13. Porous PEEK Osseointegration is Equivalent to Porous Titanium
*p < 0.05; ^p < 0.01 versus all smooth and rough groups.
(2-Way ANOVA, Tukey, n = 6-8). Mean ± SE.
Effect Effect Size (ω2) p-value
Topography 65% <0.001
Chemistry 6% <0.01
Interaction 1% 0.17
Smooth Rough Porous
0
20
40
60
PEEK
Titanium
Force(N)
^ ^
*
Pull-out StrengthSmooth PorousRough
PEEKTitanium
Bone Nuclei
Osteoid / Soft tissue
Sanderson’s Rapid Bone Stain
+ Van Gieson
Torstrick BF et al. In vivo effect of surface topography and chemistry on PEEK and titanium implant osseointegration. Proc of Ortho Res Soc. 2018.
14. 1Evans NT, Torstrick FB, Lee CS, et al. High strength surface-porous polyether-ether-ketone for load bearing applications. Acta Biomater 2015;13:159-67.
Torstrick FB, Lin ASP, Gall K, et al. Porous PEEK improves the bone-implant interface compared to plasma-sprayed titanium coating in PEEK: in vitro and in vivo analysis. Orthopaedic Research Society (ORS) Annual Meeting; March 2017; San Diego, CA.
Rat Femoral Segmental Defect1
Smooth PEEK
Porous PEEK
Fibrous
Tissue
Bony
In-growth
Bone
Smooth PEEK
Histology at 6 Wks Post-op1
Bone
Porous PEEK
X-ray at 6 Wks Post-op1
Smooth PEEK
Porous PEEK
Smooth PEEKPorous PEEK
Smooth PEEK
Porous PEEK
MicroCT at 6 Wks Post-op1
Porous PEEK Promotes Bone In-growth as Strong as Bone
15. Porous PEEK Promotes Bone In-growth as Strong as Bone
1Evans NT, Torstrick FB, Lee CS, et al. High strength surface-porous polyether-ether-ketone for load bearing applications. Acta Biomater 2015;13:159-67.
Torstrick FB, Lin ASP, Gall K, et al. Porous PEEK improves the bone-implant interface compared to plasma-sprayed titanium coating in PEEK: in vitro and in vivo analysis. Orthopaedic Research Society (ORS) Annual Meeting; March 2017; San Diego, CA.
Rat Femoral Segmental Defect1
Torsional Strength at 12 Wks Post-op2
X-ray at 6 Wks Post-op1
Smooth PEEK
Porous PEEK
Smooth PEEKPorous PEEK
19. Plasmapore® XP
Marriage of PEEK material properties, radiolucency & titanium osseointegration
PEEK Optima®
Provides device structure, appropriate elastic modulus
and radiolucency
PVD Titanium 3-5 µm
Adhesion layer to facilitate bonding of VPS Titanium to PEEK
VPS Titanium 60-150 µm
Porous osseoconductive substrate
Plasmapore ® XP : PEEK interbody devices
coated with a composite Titanium layer
20. Surface Characterization
Plasmapore ® XP presents complex nano & micro features
60 to 150 µm; determined by cross-sectional imaging at 50xThickness
35 to 60% & 25 to 150 µm; determined by cross-sectional
imaging at 50x
Porosity
22.94 µm with a Standard Deviation of 0.98 µmRa
136.49 µm with a Standard Deviation of 6.25 µmRz
22. Implant:Tissue Interface
Biochemical & cellular activity result in improved new bone formation & apposition
PEEK Plasmapore® XP
H&E Straining
Inflammation
New Bone
Fibrosis
Bony Apposition
23. Ex Vivo Pull Out Strength Evaluation
Plasmapore XP demonstrates significantly improved fixation at 12 & 24 weeks
PEEK Plasmapore® XP
24. Summary
Plasmapore® XP enables osseointegration behavior from biochemical to tissue processes
Plasmapore XP drives increase
in markers for osteogenic
differentiation in vitro
Plasmapore XP increases
expression of osteogenic
growth factors in vitro
Plasmapore XP increases
new bone growth and
apposition in vivo
Plasmapore XP
significantly increases
fixation strength ex vivo