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Additive manufacturing (bioabsorbable) metal implants for orthopaedic applications Holger Jahr University Hospital RWTH Aachen University [email protected], [email protected] 3D Medical Conference Maastricht, 2018-01-31 1

Transcript of Additive manufacturing (bioabsorbable) metal implants for ... · Additive manufacturing...

Page 1: Additive manufacturing (bioabsorbable) metal implants for ... · Additive manufacturing (bioabsorbable) metal implants for orthopaedic applications Holger Jahr University Hospital

Additive manufacturing

(bioabsorbable) metal implants for

orthopaedic applications

Holger Jahr

University Hospital

RWTH Aachen University

[email protected], [email protected]

3D Medical Conference Maastricht, 2018-01-31 1

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SLS / SLM / DMP

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Critical size bone defects

3 cm

6 cm

5 cm

5 cm

Clinical problem

Calori et al., Injury 2011:S56 3

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http://en.wikipedia.org/

2.5 million graftings 1, 2

Clinical impact

8-39 % 1

1 van der Stok et al., Acta Biomater. 2011, “Bone substitutes in The Netherlands” 2 Calori et al., Injury 2011:S56 4

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Porosity Pore size "Strength" (MPa)

(%) (mm) Compress. Young's Tensile

Bone N.D. N.D. 70-280 ± 1-10,000 ± 65

(Tri-)calcium salts 30-90 2-1360 1-55 3.6-3,100 4.5

Bioactive glass 1 N.D. 91-179 6,400 52

Fibrin clot N.D. N.D. << 1 0.0015 ± N.D.

"hydrogels" N.D. N.D. N.D. ± N.D. ± N.D.

Ti alloys - - N.D. 120,000 ± 800

Bone graft substitutes

.

.

van der Stok et al., Acta Biomater. 2011, “Bone substitutes in The Netherlands” Weisel, Biophys. Chem. 2004: 267-76

Gibbs et al., J Tissue Eng Regen med 2014

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Porous anatomically shaped implant

Ti6Al4V powder

(ASTM B348, grade 23)

van der Stok et al., 2013, 2015

Amin Yavari et al. 2013, 2014

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In vivo model

Surgery

Follow-

up

µ-CT reconstruction X-ray

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Surface functionalization

Implant treatment:

• 5 M NaOH, 60°C, 24 h

• H2O, 40°C, 24 h

• 0.5 M HCl, 40°C, 24 h

• 600°C, 5°C/min

• 600°C, 60 min

• passive cooling

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• coatings

• cell attachment

• anti-microbial

• drug release systems

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Ti64 scaffold + biogel e

mp

ty

Fib

rin

+ B

MP

2

Ge

lati

n +

BM

P2

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Torsion strength

Empty Fibrin Contralateral

+ BMP2 ctrl

10 van der Stok et al., eCM 2015

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Ideal solution

• Osteoinductive (actively stimulates bone formation)

• Osteoconductive (allows colonization / vascular ingrowth = porosity)

• Osteogenic (presence of bone-forming cells)

Bone Morphogenetic protein (e.g. BMP-2)

e.g.

(B)MSCs

PDCs

• high porosity

• bio-functionalized

calcium- P

metals (e.g. Ti)

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SLM product portfolio

Substrates:

• Ti alloys

• Mg alloys

Co-Cr alloy 316L chromium-nickel steel

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50 mm struts

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Why 3D printed porous metals?

3D printing allows for:

– Patient-specific perfect fit

complexity for free

– Shorter surgery time

– Longer implant lifetime

– Fast recovery

– Reduced hospitalization

– Reduced costs

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Porous scaffolds facilitate:

• Bone-ingrowth, “union”

• Good fixation through

surface roughness

• Avoiding stress-shielding

(Young’s modulus)

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• May reduce or eliminate:

– Secondary removal surgery

– Long term complications, e.g.

• biofilms

• allergic reactions

• Offer higher strength and toughness over current absorbable

(polymeric/ceramic) implants

• Improve pediatric care

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Why absorbable metals?

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Bio-absorbable alloys

Daily Allowance

700 mg 10-20 mg 15 mg

Y.F. Zheng et al. Materials Science and Eng R77 (2014): 1-34. 15

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• pure Fe + 2 Fe-based alloys (Fe10Mn1Pd, Fe21Mn0.7C1Pd wt%)

• implanted transcortically into rat (growing) femurs

• inspected @ 4, 12, 24 and 52 wks post.

• questionable temporary implants (e.g., osteosynthesis)

Kraus + Weinberg et al. Acta Biomaterialia

10 (2014) 3346–3353 16

Ø 1.6 mm pins

rat femur, 52 w

Fe corrodes too slow ..

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• stents

• zinc degradation seems to combine the

desirable aspects of Fe alloys, i.e., in vivo

longevity, with harmless degradation of Mg

alloys.

• requires further development to achieve

desired mechanical properties

• results are promising

1st paper: Bowen et al. Adv. Mater. 2013, 25, 2577–2582.

Zn-modified surfaces: Wang et al. Applied Surface Science 403 (2017) 168–176 17

Zn corrodes faster, but ..

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Amerstorfer et al. Acta Biomaterialia 42 (2016) 440–450

Kraus + Weinberg et al. Acta Biomaterialia 8 (2012) 1230–1238 18

Ø 1.6 mm pins

rat femur, 24w

Mg corrodes rather fast ..

..but performed well in vivo over 24 mths

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Corrosion behavior

Seitz et al. Adv. Healthcare Mater. 2015, 4,

1915–1936 19

• Anodic reaction: Fe → Fe2+ + 2e−

• Cathodic reaction: ½ O2 + H2O + 2e− → 2OH −

• Ferrous hydroxide formation: Fe2+ + 2e− → Fe(OH)2

co-formation or -precipitation of goethite (α-FeO(OH)) and magnetite (Fe3O4) possible

• Anodic reaction: 2 Zn → 2 Zn2+ 4e-

• Cathodic reaction: O2 + 2H2O + 4e- → 4OH-

• Zn(OH)2 formation: 2 Zn2+ + 4OH- → 2 Zn(OH) 2

• ZnO formation: Zn(OH) 2 → ZnO + H2O

• Anodic reaction: Mg → Mg2+ + 2e-

• Cathodic reaction: 2 H2O + 2e- → H2 + 2OH

• Mg(OH)2 formation: 2Mg2+ + 2OH- → Mg(OH)2

..neutral – alkaline pH

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Material properties

Tensile/compressive strength

(MPa)

1,500

1,000

500

0 0 100 200 300 (GPa)

Polymers BONE

Mg

Ti a

lloys

Co

-Cr

allo

ys

Ste

el /

Fe

Al 2

O3

ZrO

2

Young’s modulus

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Degradation control

Necessary load-bearing strength

Bioabsorbable implant

Bone

healing

Functional phase

Absorption phase

time

sta

bil

ity

Permanent implant

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SynerMag® 410

• strength and mechanical benefits

• suitable for high-load-bearing areas

• good biocompatibility

Marukawa et al., J Biomed Mater Res Part B. 2016. 104B:1282–1289. 22

anodized Mg PLLA

@ 4 wks post

ISO 13485 certification

Biotronik

Magmaris®

stent

2016

world’s 1st clinically

proven Mg-based

resorbable

scaffold;

CE mark;

in GE, B, DK,

NL, CH, E, etc.

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http://www.syntellix.de/newspresse 23

• Symptomatic Hallux valgus

• 19.000 MAGNEZIX® implants

• >30 countries

July 2016

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Li et al. Acta Biomater. 2017 Dec 12. pii: S1742-7061(17)30764-X 24

AM biodegradable porous Mg

Design:

• Struts = 400 mm

• Pore size = 600 mm

• Density = 67%

diamond

lattice

10 mm

11.2 mm

WE43 4 wt% yttrium

3 wt% rare earths

Topological characterization (mCT):

• as-built struts = 420 mm

• Density = 64%

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Li et al. Acta Biomater. 2017 Dec 12. pii: S1742-7061(17)30764-X 25

WE43 degradation test

5% HCl/5% HNO3 (EtOH)

polishing

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AC Jones 2011, Elastic Properties of the Human Proximal Femur - ANU Repository; chap. 5 26

trab. bone

WE43 mechanical properties

Instron

10 kN load cell

ISO 13314:2011

5% HCl/5% HNO3 (EtOH)

polishing

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WE43 cytocompatibility

Ti64

WE43

ISO 10993 adjustments for degradable

biomaterials needed!

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Conclusions

• 1st proof-of-principle of 3D-printed porous Mg-scaffolds as bone

substituting material

• providing proper support (≤ 4 wks in vitro biodegradation)

• just 20% volume loss within 4 wks in vitro

• moderate cytotoxicity in vitro (ISO 10993)

Pure WE43 itself may not be ideal for cell adhesion, but appropriate

design and coatings may allow future orthopedic applications

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Acknowledgements

Johan van der Stok

Amir Zadpoor

Yageng Li

Harrie Weinans

Saber Amin Yavari

Lucas Jauer

Prathusha Pavanram

Jule Schenkel

Athanassios Fragoulis

Kai-Uwe Schröder

Stephan Ziegler

Maximilian Voshage

Tim Van Cleynenbreugel

Jan Schrooten