Metal vs PEEK: Material ConsiderationsTitanium Coating in vitro Evaluation Assays: o Cell...
Transcript of Metal vs PEEK: Material ConsiderationsTitanium Coating in vitro Evaluation Assays: o Cell...
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Metal vs PEEK:Material Considerations
Calusa Ambulatory Spine ConferenceNovember 12, 2016Boyle C. Cheng, PhD
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Disclosure
• Research Funding
• Aesculap
• Alphatec Spine
• Globus
• K2M
• Medtronic
• OrthoKinematics
• Ratchiotek
• SI-Bone
• Stryker Spine
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Healthcare Providers
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Election Year
• Step 1: Cut out ear slots• Step 2: Cut out deflector• Step 3: Place over earlobes
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Anterior Column Support:Devices Bone Implant Interface
Courtesy: Scott Webb
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WALKER, JASON - 2/23/2012 15:27; !S_72110Spine - Lumbar 4V
Image Page 1
WALKER, JASON - 960606864DOB: 8/13/1973 038YExam: !S_721102/23/2012
Fondren Orthopedic Group,LLPAcquired: S
TECH, *2/23/2012 3:28:48 PM
Laterality: U
Ser 2(1) Img 11972 x 2414 x 12
Zoom: 5.2:1True Size: 65%W 4095 L 2047W 4095 L 2047Compress: 2:1
Plain Film X-Rays of PEEK Interbody Implants
Titanium
Screws
Titanium
Screws
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Sheep #3987mm cTDR @ 6mos.
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Device Failure
Migration and Expulsion
Moatz B and Tortolani, Cervical disc arthroplasty: Pros and consJ Surg Neurol Int 2012, 3:216
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Government Accountability Office: January 2009
• FDA submission through the 510(k) process between 2003-2007• Class I and II devices, 13,199
submissions (90% cleared)• Class III devices, 342
submissions were submitted with only 228 cleared (67%)
• For class III PMA submissions, 217 original and 784 supplemental, 78% and 85%, respectively, were approved
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Ti Surfaces
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Additive Manufacturing
Dental Implant Screw
3D Printing - not just for
plastics, can also print implantable
metal materials (e.g. CoCr &
Ti6Al4V).
Successive layers of materials
are laid down under computer
control.
Can be almost any shape or
geometry.
Porosity / open structure ideal
for boney apposition.
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Competitive Interbody Products
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Biomechanical Goal of the Bone Implant Interface
• Clinical relevance– Reduce instability of
pathologic FSU (< ROM)
• Interface design rational– Provides immediate
stabilization and fixation
– Allows device to perform as intended
• Metric– Interface
– Pullout strength
Bone Implant Interface
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Biomechanical Testing:Pullout Strength
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Good Idea?
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Essential Components of Arthrodesis
• Ti
• PEEK
• collagen
• osteoblasts
• osteoclasts
• BMP’s
• PDGF
Matrix Cells
GrowthFactors
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Titanium vs. PEEK: in vitro Evaluation
Objective: Evaluate the effect of the titanium coating on the in vitro adhesion, proliferation and
differentiation of bone-forming cells as compared to non-coated PEEK surfaces.
Substrates: Tissue culture plastic Titanium PEEK
Cells: Human MG-63 osteoblast-like osteosarcoma cells. 15mm diameter discs,10,000 cell/cm2.
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Titanium Coating in vitro EvaluationAssays:
o Cell Adhesion/Proliferation Assay: Cells seeded onto tissue culture plastic or disc substrates in 24
well plates in complete media containing serum at 37° C, 5% CO2 until confluent (n=12 per
surface).
o Cell Differentiation Assays: Transcriptional and translational analyses
• Alkaline Phosphatase (ALP) activity, chromogenic assay.
• qRT-PCR Analysis: osteoblast differentiation genes including
type I collagen, osteocalcin, ALP, BSP, BMP-2.
• ELISAs: Secreted bone morphogenetic proteins (BMP-2, BMP-
4, BMP-7)
Rationale: Tracking 3 distinct phases of osteoblast maturation
Growth (proliferation):BMP’s
Extracellular matrix development:ALP, Type I Collagen
Mineralization:Osteocalcin
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Cell Activity on Titanium Substrate
80.00
85.00
90.00
95.00
100.00
Average Cell Viability
0.00E+00
5.00E+04
1.00E+05
1.50E+05
2.00E+05
2.50E+05
Cell Y
ield
Average Cell Yield C
ell V
iab
ilit
y
o Lower cell proliferation/growth on Ti
o Consistent with higher level of
differentiation on Ti
o Differentiating cells divide slower
o High cell viability on all surfaces
TC Plastic Titainum PEEK
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Cell Activity on Titanium Coated Implants
0.00E+00
5.00E-04
1.00E-03
1.50E-03
2.00E-03
2.50E-03
AL
P
(ng
/µg
pro
tein
)
Surface
Average Alkaline Phosphatase Activity
*
* p
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Cell Activity on Rough Titanium
Surfaceso Similar results published for roughened titanium surface (acid etched)
compared to smooth titanium or PEEK.
Taken from: Olivares-Navarette et al., The Spine Journal 12 (2012): 265–272.
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Study Design
1. Ovine Model2. Paired Comparison Femora
Implantation1. Treated (Right)2. Control (Left)
3. Implantation1. Survival 12wks (n=5)2. Survival 24wks (n=5)
4. Endpoints1. Local Tissue Tolerance –
Histology2. Bone Implant Interface –
Mechanical Pullout Test
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Implantation*Note Consistent Inteference Fit
*Implant specific reamer
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Histology:Bony Apposition (0.1mm)
Coated
Uncoated
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Histology:New Bone Formation
Stained Histologic Section Analysis of Void
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Representative Pull Out Study
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Bony Apposition
• Histologic confirmed bone apposition (bone within 0.1mm of surface)
– Statistically significant greater at 12wks
• Good immediate stabilization
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New Bone Formation
• New Bone Formation in Surgical Site– New Bone is
statistically significantly greaterat 24wks
• Increased bony ingrowth
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Biomechanics
• Pullout strength significantly greater at 12 and 24wk time points compared to uncoated
• Pullout strength greater compared to initial post op condition
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Confocal Microscopy
Plasmapore XP (24wk ovine specimen)
Red: New BoneBlue: Collagenand MatrixGold: Plasmapore
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Patient 10mos Post-op
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Failure Is Not Uncommon
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Conclusions
• Bone implant interface may dictate the outcome of the device and subsequently the procedure
• Ti coating may increase short term (friction) and long term stability (bony ingrowth and ongrowth) of the FSU
• Fixation and motion preservation devices benefit from strong bone implant interfaces in the interbody space
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Thank you!
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Sheep #3966mm cTDR @ 6 mos.
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Surgical Grade Materials
Light alloys (Al-alloys.) Parts for Instruments und Devices,
Containers, Motors
Precious Metals (Ag, Au) Probes, Canulas
Nickel alloys Components for MIS-tube instruments
Vacuum cast-Stellite Parts for HM- scissors, Co-Basis + Cr, W,
C, Ta, Mn, Fe min 60 HRC hardness
Ceramics Al2O3 / ZrO2 used for HF-Surgery
Non Ferrous Metals, Special Alloys, Ceramics
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Polymers used in Medical Devices
Polymers
Thermoplastics (PE; PEEK, PTFE; PVC; POM; PMMA; PP; …)
Elastomers Thermosetting
(Si Rubber, NBR; …) Thermoplastic
(SEBS; TPU; NBR/PP…)
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Metals
Orthopaedic & Spine Implants
Pure Titanium
Titanium Alloys
Stainless Steel
CoCr- Alloys
Tantalum
Nitinol
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Complex Geometries for Machining
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Polymers
UHMW Polyethylene
PEEK
PMMA
Polyurethane Carbonate
Hydrogels
Silicone
Polyhydroxy Acids
Orthopaedic & Spine Implants
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Anterior Column Interbody Device w/
Integrated Supplemental Fixation
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The Same Old Story…
• Designer meets technology
• They fall in love
• Many new products designed with new technology• e.g., early 20th century,
radium was a new technology
• Discovered by Madam and Pierre Curie in 1898
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Products Designed w/ Radium
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Materials Technology: Design Factors
Component Design Changes
• Rigid Devices
– Cage Thickness Changes
– Corpectomy to Interbody Shift
• Material Choices
– Titanium CP
– Titanium Alloy
– Allograft
– Polyetheretherkeytone (PEEK)
Construct Design Philosophy Changes
• Compliant Mechanisms– Charite
– Activ L
• Combined Mechanisms– FSU
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Surface Material Technology
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Essential Components of Arthrodesis
• Ti
• PEEK
• collagen
• osteoblasts
• osteoclasts
• BMP’s
• PDGF
Matrix Cells
GrowthFactors
-
Titanium vs. PEEK: in vitro Evaluation
Objective: Evaluate the effect of the titanium coating on the in vitro adhesion, proliferation and
differentiation of bone-forming cells as compared to non-coated PEEK surfaces.
Substrates: Tissue culture plastic Titanium PEEK
Cells: Human MG-63 osteoblast-like osteosarcoma cells. 15mm diameter discs,10,000 cell/cm2.
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Titanium Coating in vitro EvaluationAssays:
o Cell Adhesion/Proliferation Assay: Cells seeded onto tissue culture plastic or disc substrates in 24
well plates in complete media containing serum at 37° C, 5% CO2 until confluent (n=12 per
surface).
o Cell Differentiation Assays: Transcriptional and translational analyses
• Alkaline Phosphatase (ALP) activity, chromogenic assay.
• qRT-PCR Analysis: osteoblast differentiation genes including
type I collagen, osteocalcin, ALP, BSP, BMP-2.
• ELISAs: Secreted bone morphogenetic proteins (BMP-2, BMP-
4, BMP-7)
Rationale: Tracking 3 distinct phases of osteoblast maturation
Growth (proliferation):BMP’s
Extracellular matrix development:ALP, Type I Collagen
Mineralization:Osteocalcin
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Cell Activity on Titanium Substrate
80.00
85.00
90.00
95.00
100.00
Average Cell Viability
0.00E+00
5.00E+04
1.00E+05
1.50E+05
2.00E+05
2.50E+05
Cell Y
ield
Average Cell Yield C
ell V
iab
ilit
y
o Lower cell proliferation/growth on Ti
o Consistent with higher level of
differentiation on Ti
o Differentiating cells divide slower
o High cell viability on all surfaces
TC Plastic Titainum PEEK
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Cell Activity on Titanium Coated Implants
0.00E+00
5.00E-04
1.00E-03
1.50E-03
2.00E-03
2.50E-03
AL
P
(ng
/µg
pro
tein
)
Surface
Average Alkaline Phosphatase Activity
*
* p
-
Cell Activity on Rough Titanium
Surfaceso Similar results published for roughened titanium surface (acid etched)
compared to smooth titanium or PEEK.
Taken from: Olivares-Navarette et al., The Spine Journal 12 (2012): 265–272.
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Cell-Biomaterial Interaction:
Harnessing the power
Spiro| Biologics
Medical Device Surface Modification Technology
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Design Iteration: Utilizing a Hybrid Material Design
• Patients
• Surgeon recognized need
• Manufacturer
• Coating expertise
• Regulatory Agency
• FDA
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Other Radium Based Products
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Failure Ti Coated PEEK
• Material Considerations• PEEK is radiolucent
• PEEK is also less stiff and thus, decreases risk of subsidence
• Ti is stiffer
• Ti makes for excellent bone implant interface
• Additional consideration for hybrid designs
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Additional Research: in vivo AND biomechanical studies
in vivo Animal Study Biomechanical Studies
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Histology:New Bone Formation
Stained Histologic Section Analysis of Void
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Biomechanics
• Pullout strength significantly greater at 12 and 24wk time points compared to uncoated
• Pullout strength greater compared to initial post op condition
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CautionNuclear Medicine:Chemotherapeutic Agent
Suppository
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Conclusions
• Different material substrates illicit different
cellular responses
• Bone implant interface may dictate the
success of the device and subsequently
the procedure.
• Designs that incorporate different
materials may impact clinical outcomes
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Thank you!
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Axial Pullout Strength of a Plasmapore XP Coated PEEK Implants in Sheep: A Comparative Biomechanical Survival Study
Aesculap Spine DaysMarch 2, 2014
Boyle C. Cheng, PhD
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Disclosure
• Research Funding
• Aesculap
• Alphatec Spine
• Globus
• Medtronic
• OrthoKinematics
• Rachiotek
• Stryker Spine
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Co-Authors
• D. Cook
• A. Flintrop
• D. Lemesh
• C. Winiarski
• H. Aberman
• C. Wing
• B. Spiro
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Many New Technological Advances
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Devices Dependent upon the Bone Implant Interface
Courtesy: Scott Webb
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Failure Is Not Uncommon
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Device Failure
Migration and Expulsion
Moatz B and Tortolani, Cervical disc arthroplasty: Pros and consJ Surg Neurol Int 2012, 3:216
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Ti Coating: Plasmapore
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Biomechanical Goal of the Bone Implant Interface
• Clinical relevance– Reduce instability of
pathologic FSU (< ROM)
• Interface design rational– Provides immediate
stabilization and fixation
– Allows device to perform as intended
• Metric– Interface
– Pullout strength
Bone Implant Interface
-
Biomechanical Testing:Pullout Strength
-
Good Idea?
-
Study Design
1. Ovine Model2. Paired Comparison Femora
Implantation1. Treated (Right)2. Control (Left)
3. Implantation1. Survival 12wks (n=5)2. Survival 24wks (n=5)
4. Endpoints1. Local Tissue Tolerance –
Histology2. Bone Implant Interface –
Mechanical Pullout Test
-
Implantation*Note Consistent Inteference Fit
*Implant specific reamer
-
Representative Pull Out Study
-
Histology:New Bone Formation
Stained Histologic Section Analysis of Void
-
Histology:Bony Apposition (0.1mm)
Coated
Uncoated
-
Bony Apposition
• Histologic confirmed bone apposition (bone within 0.1mm of surface)
– Statistically significant greater at 12wks
• Good immediate stabilization
-
New Bone Formation
• New Bone Formation in Surgical Site– New Bone is
statistically significantly greaterat 24wks
• Increased bony ingrowth
-
Biomechanics
• Pullout strength significantly greater at 12 and 24wk time points compared to uncoated
• Pullout strength greater compared to initial post op condition
-
Confocal Microscopy
Plasmapore XP (24wk ovine specimen)
Red: New BoneBlue: Collagenand MatrixGold: Plasmapore
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Patient 10mos Post-op
-
Anterior Column Interbody Device w/
Integrated Supplemental Fixation
-
Failure Is Not Uncommon
-
Conclusions
• Bone implant interface may dictate the outcome of the
device and subsequently the procedure
• Ti coating may increase short term (friction) and long
term stability (bony ingrowth and ongrowth) of the FSU
• Fixation and motion preservation devices benefit from
strong bone implant interfaces in the interbody space
-
Thank you!
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Foundation for Bony Ongrowth and Ingrowth: Mechanotransduction
• CaSO4
• CaPO4
• collagen
• osteoblasts
• marrow
• periosteum
• BMP’s
• PDGF
Matrix Cells
GrowthFactors
Essential Components for Mechanotransduction
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Too Much Complex Math…
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Performance Metrics (2011)
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Failure Is Not Uncommon
• Gary Hart (Gary Warren Hartpence)• Senator from CO
• 1975-1987
• 1988 Democratic Party Presidential Nominee
• 20 pt lead prior to picture
• ‘Monkey Business’