biodegradable Magnesium

(1)

BRIC - Bioresorbable Implants for Children BRIC - Bioresorbable Implants for Children

In vivo Micro CT Evaluation of

biodegradable Magnesium

Implants

BRIC - Bioresorbable Implants for Children

From Bioresorbable Material to Sensor Applications

in Medical Technology

(2)

Contact leses - Blood glucose

(3)

Chronical disease – acute disease/injury

• _{Online monitoring}

• _{Patient individulized medicine}

• _{Reducing resources}

• _{Faster reintegration in normal life}

(4)

Healing – dynamic process

• _{Implants are to rigid}

• _{Changes in healing are not defined}

• _{Biomechanical changes during healing}

unclear

• _{Total hip arthroplasty – no knowledge}

about patient individual biomechnical

For example:

(5)

Healing – dynamic process

• _{Online information in the area of}

injured brain

• _{Stimulation during healing}

• _{Observing the function of new cells}

For example:

brain damage

(6)

Miniaturism – perfect body with no

artificial parts

For example:

(7)

Conventional materials

• Stain

• Titanium and its alloys

(8)

Biodegradable materials

• Appropriate materials:

–Metals: Mg, Fe

–Ceramics

–Polymers:

–Polylactide acide (PLA), Poly(3hydroxybutyrate)

(PHB)

(9)

Drawbacks of conventional materials

• _{Through abrasion released toxic components can}

lead to

inflammatory reactions

(Allen, 1997)

• _{Rigidity of metal implants reduces}

micro-movements essential for fracture healing („

stress

shielding

“

)

• _{Long time application can lead to}

_{implant loosening}

(Jacobs, 1998)

• _{Current metallic implants need a}

_{second operation}

(10)

(11)

Bioresorbable materials - a new

approach

• No second operation for implant/sensor removal

is necessary

–

reduced morbidity

–

reduced patient stress

–

cost reduction for health care system by modulating

(12)

Leoben

Graz

Wien

ETH Zürich

Heraeus

AT&S Leoben

Technical University Vienna

University of Natural Resources

and Life Sciences Vienna

Collaboration partners

(13)

Development of biodegradable

Materials

• ETH Zurich

–

Development of biodegradable metals

• Magnesium

• Iron

• Technical University Graz

–

Development of biodegradable polymers

(14)

In vitro material testing

• Technical University Graz

–

in vitro degradation testing

• Medical University Graz

(15)

Material characterization

• Technical University Vienna

–

Testing of mechanical properties

• AT&S Leoben

–

Surface characterization

• Perthometer

(16)

In vivo studies

• Medical University Graz

–

Continuous µCT monitoring

(17)

• Medical University

Innsbruck

–

Histomorphological

(18)

In vivo studies

• University of Natural Resources and Life Sciences

Vienna

(19)

In vivo testing

• Technical University Vienna

(20)

PHB – Poly(3-hydroxybutyrat)

• same mechanical properties as PLAs

(21)

Material

6 groups (n=6) of cylindrical pins

(length: 8mm, diameter: 1,6mm)

– PHB

– PHB + 3% ZrO

₂

(added to improve visualization in µCT)

– PHB + 3% ZrO

₂

+ 30% Herafill® (alternative bone material)

Coatings of Mg-Alloys:

– PHB

– PHB with TBA connected

– P

LD

LA (Heraeus®)

(22)

Methods

• µCT Scans

(23)

(24)

(25)

PHB Zr sagittal

1m

3m

6m

9m

(26)

PHB Zr + 30% Herafill sagittal

1m

3m

6m

9m

(27)

Calculation Degradation

PHB + Zr

PHB + Zr +

10%H

PHB + Zr +

30%H

% Decrease

(28)

µCT Implant Visualisation &

3D bone formation (6m)

(29)

Results µCT

Significant decrease of

bone volume with ZrO2

in month 1 and 6

(30)

Histological Slices

Zoom



Percentage

of bone

adherence

on the

implant

length

(31)

Results Histological Slices

Tendency of

increasing bone

adherence in

samples with ZrO2 +

Herafill® in month 6

(p=0,012)

Significant decrease

of bone adherence

with ZrO2 in month 6

(p=0,024)

(32)

Coatings of Mg-Alloy

PHB

(1w)

PHB/TBA (1w)

PLDLA

(1w)

(33)

Summary

• Addendums enable µCT visualisation of PHB

implants

• ZrO

₂

decreases osteoconductive properties of

PHB significantly

• Bone tissue formation can be improved by adding

Herafill®

• Coating not appropiate enough



after 1w

degradation and gas formation of alloy visible

• No differences between coatings

(34)

On-going fields of work

• Material improvement (crosslinking of PHAs, new

metal alloy compositions)

• Implant surface modification (Micro-arc

oxidation, coatings)

• Combination with additives to improve bone

tissue reaction (Heraeus)

(35)

Techniker:

Leopold Berger, Masterstudent, TU Wien

Dipl.-Ing. Anna Celarek,PhD Studentin, TU Wien

Dipl.-Ing. Dr. techn. Martin Koller, TU Graz

Dipl.Ing. Martin Meischel, BoKu Wien

Univ.Prof. Dipl.-Ing. Dr.techn. Franz Stelzer, TU Graz

Ao.Univ.Prof. Dipl.-Ing. Dr.techn. Elmar Tschegg, TU Wien

Univ.-Prof. i.R. Dr.phil. Stefanie Tschegg; BoKu Wien

Ass.Prof. Dr.rer.nat. Frank Wiesbrock, TU Graz

Mediziner:

PD Dr Christoph Castellani, Ass.-Arzt, Meduni Graz

Dr Peter Ferlic, Ass.Arzt, Med Uni Graz

Dr Michael Fiedler, Ass. Arzt UKH Graz

Dr Stefan Fischerauer, PhD-Student, Med Uni Graz

Dr Tanja Kraus, OÄ, Meduni GrazDr.med.univ.

Dr Karin Pichler, PhD-Student, Med Uni Graz

Gustav Schmöller, Medizinstudent, Med Uni Graz

Dr Eva Widni, Ass Ärztin, Med Uni Graz

Dr Silvia Zötsch, Med Uni Graz

Prof. Dr. Annelie Weinberg

Industriepartner:

Dr. Andre Kobelt, Heraeus

Dr. Klaus-Dieter Kühn, Heraeus

Dr. Mario Krassnitzer, ATS

Dr. Hannes Voraberger, ATS

Chemikerin:

Forschung:

Dipl.Biol, Dr.rer.nat. Heidi Schmitt

Materialwissenschaftler:

Dr Anja Hänzi, ETH Zürich

Prof. Dr Peter Uggowitzer, ETH Zürich,

Prof. Dr. Jörg Löffler, ETH Zürich