Annual Report - KL

DEPARTMENT ANATOMIE UND BIOMECHANIK

FACHBEREICH BIOMECHANIK

Dr.-Karl-Dorrek-Straße 30

A-3500 Krems an der Donau

T: +43 2732 72090–320

[email protected]

ANNUAL REPORT 2018

DIVISION

BIOMECHANICS

CONTENT

Content

Editorial ................................................................................................................................................................................... 1

Personal and Infrastructure ................................................................................................................................................. 2

Team ................................................................................................................................................................................... 2

BM Computer System ....................................................................................................................................................... 3

BMLab (Biomechanics Laboratory) ................................................................................................................................. 3

Teaching ................................................................................................................................................................................. 4

LINE Biomedical Engineering ........................................................................................................................................... 4

NEW: BME Line Examination ............................................................................................................................................ 4

Research ................................................................................................................................................................................. 5

Journal Publications .......................................................................................................................................................... 5

Presentations ..................................................................................................................................................................... 5

Research Partners ............................................................................................................................................................. 7

Funding Organisations ..................................................................................................................................................... 7

Company Partners ............................................................................................................................................................ 7

Activities & Events .............................................................................................................................................................. 13

Acknowledgements ............................................................................................................................................................ 22

EDITORIAL

Seite 1 Annual Report 2018 DIVISION BIOMECHANICS

Editorial

Willkommen zum Jahresbericht 2018 des Fachbereichs

für BIOMECHANIK. Auch dieses Jahr ist die Gruppe

weitergewachsen. Engagierte Mitarbeiter_innen

verstärkten unser Team, beginnen das Labor mit

Leben zu füllen, stärken unser Back-Office und den IT

Bereich. Die erfolgreiche Drittmitteleinwerbung führte

zum Start zahlreicher neuer Forschungsprojekte und

vergrößerte unser Forschungsnetzwerk. In diesem

Jahr wurde das erste von der KL geführte FFG

Forschungsprojekt mit den Partnern TU-Wien, Donau

Universität Krems sowie Braincon nach drei Jahren

erfolgreich abgeschlossen.

Im Hintergrund haben wir dieses Jahr mit meiner

zweiten Forschungsgruppe an der TU-Wien am

Entwicklungsplan und der Forschungsstrategie in

enger Abstimmung gearbeitet. Die Früchte dieser

Arbeit erwarten wir in den nächsten Jahren.

Zahlreiche PR Meldungen in unterschiedlichen Medien

zeigten ein allgemeines Interesse an unserer

Forschung vor allem im Bereich 3D Druck. Daneben

gibt es einen neuen Webauftritt unter biomech.kl.ac.at

sowie bmlab.kl.ac.at.

Unser Dank gilt den Förderinstitutionen speziell dem

Land NÖ sowie unseren bestehenden und neuen

Forschungspartnern. Last but not least danke ich allen

meinen Mitarbeiter für ihren Einsatz!

Welcome to the Annual Report 2018 of the division

BIOMECHANICS. Again, this year the group has

continued to grow. Dedicated employees joined our

team, started to fill the lab with life, strengthen our

back-office and IT area. The successful acquisition of

third-party funds led to the start of numerous new

research projects and increased our research

network. In this year the first FFG research project led

by KL with the partners TU Vienna, Danube University

Krems and Braincon was successfully completed after

three years.

In the background, we worked on our development

plan and research strategy this year in close

cooperation with my second research group at the

Vienna University of Technology. We expect see the

results of this work in the coming years.

Numerous PR reports in various media showed a

general interest in our research, especially in the field

of 3D printing. There is also a new website at

biomech.kl.ac.at and bmlab.kl.ac.at.

Our thanks go to the funding institutions especially the

state of Lower Austria as well as our existing and new

research partners. Finally yet importantly, thanks to all

my staff for their dedication and contribution!

Dieter H. Pahr

Head of Division Biomechanics

PERSONAL AND INFRASTRUCTURE


Personal and Infrastructure

Team1

DIETER PAHR UNIV.-PROF. DI DR.

CHRISTINA ARON BA

MARIA HÖPFNER ANDREAS REISINGER DI DR.

HEAD ASSISTANCE ASSISTANCE SCIENTIFIC STAFF (POSTDOC),

HEAD OF LABORATORY

LUKAS WARNUNG BSC

PETER KLINKA STEFANIE STELZER MAG. DR.

MORTEZA AMINI DI, MSC

LABORATORY TECHNICIAN IT TECHNICIAN SCIENTIFIC STAFF (POSTDOC) SCIENTIFIC STAFF (PHD)

SARAH-JANE

ESTERMANN DI, MSC

GEORG GAMAUF DI, MSC

NEDAA AMRAISH DI, MSC

TOBIAS HAFTNER MSC

SCIENTIFIC STAFF (PHD) SCIENTIFIC STAFF (PHD) SCIENTIFIC STAFF (PHD) SCIENTIFIC STAFF (PHD)

1 MA-Fotos © KL/A.Reischer & K.Ranger

[email protected]

PERSONAL AND INFRASTRUCTURE


BM Computer System

Starting with June 2018, Peter Klinka took over the system administration of our Linux network from DI Dr. Andreas

Reisinger. New workstations were bought, the fileserver was extended, and an LTO-7 backup tape was added to the

IT system. A Wiki was installed to share information of interest within the division biomechanics. The electronic

logbook of the laboratory (ELOG) was transferred to be reachable from the web.

BMLab (Biomechanics Laboratory)

The lab is part of the core facility “Campus Krems” program from Lower Austria and was further equipped with a micro

computertomography system and a CNC milling machine.

CNC Milling

Machine PFX-

700

The PFX 700 is a gantry type 3 axis

vertical CNC milling machine. The

machine has a processing area of 500 x

700 x 400 mm in X x Y x Z. The

processing speed is approximately

8100 mm/min in X and Y direction and

4800 mm/min. in Z direction. The

machine is used for manufacturing

parts in plastics and metal as well as

for cutting samples from compact

bone.

CT Bruker

Skyscan 1173

The micro-computed tomography

system Bruker Skyscan 1173 (uCT), is

used for obtaining high precision

geometry data of small to mid-sized

samples in a nondestructive way.

Inside a scanning chamber, hundreds

of x-ray projections are taken from the

sample. From these, a reconstruction

algorithm is able to produce a 3D-

volume representation of the sample.

This so called 'voxel image' contains all

features from the inside of the sample

that were originally not visible from the

outside. Depending on the sample size,

resolutions down to 5 microns are

possible.

The complete lab equipment can be found under bmlab.kl.ac.at.

TEACHING


Teaching

LINE Biomedical Engineering

The division biomechanics is responsible for the teaching of the LINE Biomedical

Engineering in the health sciences bachelor program.

The BME curriculum consists of the following courses:

• Fundamentals of Mathematics (Mathematics)

Knittl David, Hanns Amri, PhDs (Sarah-Jane Estermann, Nedaa Amraish, Morteza Amini)

• Basic Concepts & Thermodynamics (Physics I)

Melanie Todt, Christian Bilik

• Medical Radiation Physics (Physics I)

Julia Lechner

• Mechanics (Physics II)

Dieter Pahr, Andreas Reisinger, Hanns Amri, PhDs (Georg Gamauf, Sarah-Jane Estermann, Nedaa Amraish)

• Waves and Optics (Physics III)

Melanie Todt, Christian Bilik

• Electricity and Magnetism (Physics IV)

Matthias Krenn

• Introduction to Biomaterials (Biomaterials)

Bernadette Duscher

• Virtual Human in the context of Musculoskeletal Diseases (Biomedical Engineering II)

Dieter Pahr, Sarah-Jane Estermann, Georg Gamauf

• Elective Biomedical Engineering with LEGO Mindstorms

Nedaa Amraish, Dieter Pahr, Georg Gamauf

NEW: BME Line Examination

At the beginning of the winter semester 2018/19, so called “Line Exams” were introduced, to grade the Biomedical

Engineering line of the “KL Health Sciences” study. A database of questions was created from which a line exam

sheet can be extracted in an automatized way using the in-house software medtool.

© KL/A Reischer

RESEARCH


Research

Journal Publications

L. Warnung, S. Estermann, A. Reisinger:

Mechanical Properties of Fused Deposition Modeling (FDM) 3D Printing Materials;

https://www.rtejournal.de/ausgabe-15-2018/4781

M. Frank, D. Marx, V. Nedelkovski, J.T. Fischer, D. H. Pahr, P.J. Thurner:

"Dehydration of individual bovine trabeculae causes transition from ductile to quasi-brittle failure mode";

Journal of the Mechanical Behavior of Biomedical Materials, 87 (2018), 296 - 305.

E. Klintström, B. Klintström, D. H. Pahr, T.B. Brismar, ö. Smedby, R. Moreno:

"Direct Estimation of Human Trabecular Bone Stiffness Using Cone Beam Computed Tomography";

Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 126 (2018), 1; 72 - 82.

S.C. Lu, E.E. Vereecke, A. Synek, D. H. Pahr, T.L. Kivell:

"A novel experimental design for the measurement of metacarpal bone loading and deformation and fingertip

force";

PeerJ, 6 (2018), e5480; 19 pages.

E. Soodmand, D. Kluess, P. Varady, R. Cichon, M. Schwarze, D. Gehweiler, F. Niemeyer, D. Pahr, M. Woiczinski:

"Interlaboratory comparison of femur surface reconstruction from CT data compared to reference optical 3D scan";

Biomedical engineering online, 17 (2018), 1; 29 pages.

A. Synek, D. H. Pahr:

"Plausibility and Parameter Sensitivity of Micro-Finite Element-Based Joint Load Prediction at the Proximal Femur";

Biomechanics and Modeling in Mechanobiology, 17 (2018), 3; 843 - 852.

Z.J. Tsegai, M.M. Skinner, D. Pahr, J. Hublin, T.L. Kivell:

"Systemic patterns of trabecular bone across the human and chimpanzee skeleton";

Journal of Anatomy, 232 (2018), 4; 641 - 656.

Presentations

M. Amini, D. Pahr:

"Influence of size-scaling on the mechanical behavior of printed bone microstructure";

Talk: The First International Conference on Materials, Mimicking, Manufacturing from and for Bio Application, Milan,

Italy; 2018-06-27 - 2018-06-29.

M. Amini, A.G. Reisinger, D. Pahr:

"An enhanced biomechanical femoral test setup to study multiple loading configurations in stance and sideways fall

orientations on the same specimen";

Talk: 8th World Congress of Biomechanics, WCB 2018, Dublin; 2018-07-08 - 2018-07-12.

D. Pahr:

"A Simple Multi-Material Domain Iso-surface Mesher for Medical Images";

Poster: 8th World Congress of Biomechanics, WCB 2018, Dublin; 2018-07-08 - 2018-07-12.

https://www.rtejournal.de/ausgabe-15-2018/4781

http://dx.doi.org/10.1016/j.jmbbm.2018.07.039

http://dx.doi.org/10.1016/j.oooo.2018.03.014

http://dx.doi.org/10.7717/peerj.5480

http://dx.doi.org/10.7717/peerj.5480

http://dx.doi.org/10.1186/s12938-018-0461-0

http://dx.doi.org/10.1007/s10237-017-0996-1

http://dx.doi.org/10.1111/joa.12776

RESEARCH


D.H. Pahr:

"Comparison of morphological analysis software systems";

Talk: ECTS 2018, Valencia (invited); 2018-05-26 - 2018-05-29.

D. H. Pahr:

"Bone density frequency models - new insights into age, sex and treatment related changes";

Talk: Austrian Bone Conference 2018, Wien; 2018-11-23 - 2018-11-24.

D. H. Pahr:

"Image processing, modeling, and simulation";

Talk: Additive Manufacturing in Medicine - 1st Symposium, Wien; 2018-11-28.

D. H. Pahr, M. Amini, A.G. Reisinger:

"Biomechanical measurement of the fracture risk of a human femur in multiple load directions based on DIC";

Talk: The First International Conference on Materials, Mimicking, Manufacturing from and for Bio Application, Milan,

Italy (invited); 2018-06-27 - 2018-06-29.

A.G. Reisinger, D. Pahr:

"Visco-Plastic Mechanical Properties of Implanted Bone Screws Identified by Rheological Modeling";

Poster: 8th World Congress of Biomechanics, WCB 2018, Dublin; 2018-07-08 - 2018-07-12.

I.C. Skrna-Jakl, D. H. Pahr:

"Numerical Investigations of the Out-of-plane Stiffness Behavior of Hybrid Core Sandwich Panels";

Talk: 13th World Congress on Computational Mechanics (WCCM2018), New York; 2018-07-22 - 2018-07-27.

M. Stipsitz, P.K. Zysset, D. H. Pahr:

"An efficient solver for large-scale simulations of voxel-based structures using a nonlinear damage material model";

Talk: 6th European Conference on Computational Mechanics (Solids, Structures and Coupled Problems) (ECCM 6),

Glasgow, UK; 2018-06-11 - 2018-06-15.

A. Synek, J. Dunmore, T.L. Kivell, M.M. Skinner, D. Pahr:

"Using an inverse bone remodelling approach to predict joint loads: Sensitive enough to detect different habitual

activities?";

Talk: 8th World Congress of Biomechanics, WCB 2018, Dublin; 2018-07-08 - 2018-07-12.

Z.J. Tsegai, M.M. Skinner, D. H. Pahr, J. Hublin, T.L. Kivell:

"Trabecular bone ontogeny in the forelimb and hindlimb of chimpanzees";

Poster: 8th Annual Meeting of the European Society for the study of Human Evolution (ESHE), Faro, Portugal; 2018-

09-13 - 2018-09-15.

Remark: D. H. Pahr has a double affiliation at TU-Wien and KL Krems.

RESEARCH


Research Partners

Funding Organisations

Company Partners

RESEARCH


ACCURACY AND PRECISION OF FULL FIELD SURFACE STRAIN MEASUREMENTS

Nedaa Amraish (1,2), Andreas Reisinger (2), Dieter H. Pahr (1,2)

1 Division Biomechanics, Karl Landsteiner Private University, Krems, Austria

2 Institute for Lightweight Design and Structural Biomechanics, TU-Wien, Vienna, Austria

Introduction

Mechanical strains of biological tissues have been extensively

investigated using strain gauges or extensometers. Both

techniques are accurate, but do not reveal full-field strain

distribution on a sample’s surface, which is important for

biological tissue such as bone. Digital Image Correlation (DIC)

is an optical method that tracks the displacement of

recognized features (speckles) on the surface of the sample

and derives a full-field surface strain field [1]. Although, DIC

is a promising technique, it is not a turnkey system. The

average noise level at zero-load can reach up to 500 µstrain

which is half the physiological strain in bone tissue [2]. This

noise, if not eliminated, prevents accurately detecting the real

strain distribution. The goal of this study is to investigate the

accuracy and precision of the DIC method based on steel

samples and to develop a protocol, which can be used for

bone later on.

Methods

The commercial DIC system Aramis (GOM GmbH, Germany,

see Figure 1) is used in this study. Nine standardized metallic

samples are prepared according to ASTM guidelines for

tensile tests. The accuracy and precision of the DIC outcomes

are evaluated at zero and several non-zero load steps within

the elastic limit.

Figure 1: (a) Samples sprayed with white color (b) brushed with

black speckles (c) Sample mounted on the Z030 machine.

The samples were tested under tensile load in the Zwick

(Z030) machine (ZwickRoell GmbH, Germany) and the full-

field strain field was tracked. The first accuracy check was

applied at zero-load, where 10 images were captured by

Aramis while the sample was mounted on the testing

machine without any load applied. The second accuracy

check was conducted on the results of the tensile testing. To

reduce the noise generated by the Aramis system, the results

were filtered by applying a 2D Discrete Fourier Transform

(DFT) with which a low-pass filter is applied in the frequency

domain [3].

The accuracy and precision were determined between the

full-field strains 휀DIC and strains obtained from an

extensometer 휀REF by calculating the root mean squared

error (RMSE) from a pixelated strain image 𝐼(𝑖, 𝑗).

𝑅𝑀𝑆𝐸 = √1

𝑛

1

𝑚∑ ∑ [휀DIC(𝑖, 𝑗) − 휀REF(𝑖, 𝑗)]

2𝑚𝑗=1

𝑛𝑖=1 (1)

Results

The average noise level for steel samples at zero-load is less

than 200 µstrain (Figure 2). It was higher during loading (up

to 300 µstrain). Filtering in the frequency domain with a low-

pass filter (kernel size of 4 pixels) reduced the RMSE to less

than 200 µstrain for loaded samples (Figure 3).

Figure 2: Mean RMSE of Aramis strain field compared to

reference

Figure 3: Mean RMSE of Aramis strain field compared to

references

Discussion

DIC is a versatile method to track full-field strain on the

surface of the sample. In the next step, the pre-tested test

protocol should be applied to biological tissue such as bone.

References

1. Sutton et al, Springer, 2009.

2. Fung, Springer, 1981.

3. Baldoni et al, J Strain Analysis, 51(6):416-430, 2016.

RESEARCH


NEW METHOD FOR DEGRADATION TESTING OF MAGNESIUM-ALLOY IMPLANTS UNDER DYNAMIC

LOADING CONDITIONS

Georg Gamauf (1), Dieter H. Pahr (1,2), Andreas Reisinger (1)

1. Division Biomechanics, Karl Landsteiner Private University, Krems, Austria

2. Institute of Lightweight Design and Structural Biomechanics, TU-Wien, Vienna, Austria

Introduction

Biodegradable materials are becoming increasingly

important in osteosynthesis to stabilize fractured bones, thus

eliminating the need of a second surgery for the removal of

the implant. Magnesium (Mg) is one of the main materials for

such biodegradable implants [1]. Recently, an alloy of Mg, Zn

and Ca (ZX00) was developed, which shows improved

properties regarding mechanical stability, biocompatibility

and degradation behaviour [2]. However, the degradation

behaviour under cyclic mechanical stress such as in the

human body has not been sufficiently studied.

The aim of the overall project is to evaluate the in-vitro rate

of degradation of this material under dynamic loading

conditions and the influence of different testing parameters.

To simulate in-vivo conditions, the sample is immersed in

simulated body fluid (SBF) [3]. In this work, such a new test

setup including a study protocol is presented.

Methods

The newly designed test setup (see Figure 1) allows static and

dynamic loading of Mg ZX00 specimens, immersed in SBF, on

a Zwick (LTM5) machine (ZwickRoell, Ulm, Germany). The SBF

is kept at pH 7.45±0.06 and a temperature of 37°C

throughout the testing time of up to several days [4]. Easy

assembly and disassembly of the setup must be ensured to

enable the removal of the sample in regular time intervals.

Monitoring of degradation is done via hydrogen evolution

method and microCT scanning. The hydrogen evolution

method allows live monitoring of the amount of produced

hydrogen which is stoichiometrically linked to the amount of

degraded Mg [5]. Micro-CT scans, performed on a Skyscan

1173 (Bruker microCT, Kontich, Belgium), visualize the

volume loss of the sample.

Figure 1: Schematic drawing of the newly designed test setup

To prove the applicability of microCT imaging, a Mg ZX00

sample was immersed in SBF for four weeks at zero load.

Micro-CT scanning was conducted with a resolution of 6 µm

using 90 kV and 200 µA before and after the sample was

exposed to SBF. Oxide layer thickness was measured on 6

points equally distributed across the degraded sample’s

circumference.

Results

In the first phase of the project, the test setup was designed

and manufactured (see Figure 2). Evaluation of the first static

degradation tests showed that the oxide layer formed during

the degradation process can be distinguished from non-

degraded areas. Layer thickness was found to be 0.17 ± 0.07

mm after 4 weeks of degradation (see Figure 2).

Currently, dynamic degradation tests are being carried out.

Upcoming results are expected to provide understanding of

the relationship between testing parameters and

degradation behaviour.

Figure 2: left: non-degraded sample, right: 4 weeks degraded

sample.

Discussion

The developed method allows the application of static and

dynamic loads on specimens, submerged in SBF. It was

proved that micro-CT scans enable precise measurement of

oxide layer thickness and non-degraded magnesium volume.

The design of the setup allows quick mounting and

unmounting of the specimen in order to perform micro-CT

scans in certain time intervals. Additionally, live

measurement of degradation by the means of hydrogen

collection is possible. Future tests will provide information on

how the degradation behaviour changes under the influence

of different loading conditions.

References

1. Staiger et al., Biomaterials, 27 (9):1728-1734, 2006

2. Krystian et al., European Cells and Materials, Vol.

30. Suppl. 3., S.20, 2015

3. Gonzalez et al., Bioactive Materials, 3(2):174-185,

2018

4. Hofstetter et al., Corrosion Science, 91:29-36, 2015

5. Song et al., Magnesium Technology, 255-262, 2001

Acknowledgements

This work was supported by the government of Lower

Austria, contract No. K3-F-639/004-2017

RESEARCH


DIGITAL RECONSTRUCTION of THE 30,000 YEAR OLD DOUBLE BURIAL OF NEWBORNS FROM

KREMS-WACHTBERG

Thomas Einwögerer1, Anja Grebe2, Marc Händel1, Dieter H. Pahr3.4, Regina Plail3, Ulrich Simon1,

Stefanie Stelzer3, Maria Teschler-Nicola5, Lukas Warnung3 1. Institute for Oriental and European Archaeology OREA, Austrian Academy of Sciences, Austria

2. Department for Arts and Cultural Studies, Faculty of Education, Arts and Architecture, Danube University Krems, Austria

3. Department of Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria

4. Institute for Lightweight Design and Structural Biomechanics, Vienna University of Technology, Austria

5. Department of Anthropology, Natural History Museum Vienna, Austria;

Double infant burial of Krems-Wachtberg

The palaeolithic double infant burial from Krems-Wachtberg

(Fig. 1) provides the exceptional opportunity to study

different biological and behavioral aspects of one of the the

earliest modern humans in Europe. In general, infants,

especially newborns, are underrepresented in the fossil

record. The excellently preserved neonates are therefore

unique and precious for palaeoanthropological research.

Initially, the burial was recovered as a block in 2005, and later

in 2015, the bones were carefully excavated in the laboratory.

During this excavation, surface scans were made

documenting every step of the bones' exposure.

Aims of the project

The aims of this pilot study are firstly, to digitize one of the

babies and to virtually reconstruct parts of the skeleton.

Secondly, these 3D models will be combined with the surface

models made during the excavation. Thirdly, we seek to

create a catalogue of criteria and parameters for how to

handle the bones and to archive and share the data that are

produced throughout this study.

Materials and Methods

To digitize the bones, a SkyScan µCT-scanner is used that is

part of the Core Facility at the Division of Biomechanics of the

KL University. Although overall well preserved, the infant

remains are fragile and delicate. Before operating with the

original bones, we therefore aim to set up a test scan series

in order to understand and document how to handle such

finds and to set up a methodological framework to transport

and scan the bones. The test materials included human

remains from medieval sites in Austria, as well as Fauna from

the original site of Krems-Wachtberg.

Prospective steps include scanning and reconstruction of the

original bones. The combination of the µCt scans and the

surface models will enable us to reconstruct the chaîne

operatoire of the burial, and to document post-sedimentary

processes through time.

Figure 1: The 30,000 year old burial was initially recovered as a

block and then excavated in the laboratory. The bodies were

covered in red ochre and were assembled with body ornaments.

The burial was protected by a mammoth scapula. Image:

Natural History Museum Vienna, Department of Anthropology

Summary

The digitization of the infant burial is an important and

necessary step to being able to handle and analyze the bones

in a non-invasive way, as well as to archive and share the data

with the scientific community. Moreover, the results of this

study will add to the understanding of ritual behaviors of the

first modern human inhabitants of Austria.

Funding

This research was funded by the the federal state of Lower

Austria and the NÖ Forschungs- und Bildungsges.m.b.H.

(NFB).

https://graphemica.com/µ

https://graphemica.com/µ

RESEARCH


t [s] h [mm]

MACROINDENTATION OF LIVER TISSUE AND 3D PRINTING MATERIALS FOR COMPARISON OF

TACTILE PROPERTIES

Sarah-Jane Estermann (1,2,3), Christian Müller-Guttenbrunn (1), Dieter H. Pahr (1,3),

Andreas Reisinger (1)


2. Austrian Center for Medical Innovation and Technology, Wiener Neustadt,

Austria

3. Institute for Lightweight Design and Structural Biomechanics, TU-Wien,

Vienna, Austria

Introduction

Anatomical models, made of materials, that accurately

replicate the mechanical properties of actual biological

tissues, are indispensable in research, teaching, and surgical

training. However, the very soft and viscoelastic nature of

many tissues demands innovative manufacturing

technologies such as additive manufacturing (AM) to replace

conventional, oftentimes cumbersome, silicone casting [1].

The aim of this work is to quantify the tactile properties of

porcine liver tissue and potential AM materials: a spherical

indenter is utilized to mimic a fingertip palpating the material

(Fig. 1) to identify parameters, representing how a material

feels to touch.

Fig. 1: Inspiration for test setup (A); silicone cube sample

(30x30x30 mm) during test (B).

Methods

Testing is conducted on an electro-dynamic testing machine

(LTM5, ZwickRoell GmbH & Co. KG) with the 15 mm diameter

indenter positioned in its upper clamps (Fig. 1B). Quasi-static

(QS) loading and un-loading up to 5 N and, in a second set of

experiments, force relaxation for 15 minutes at 5 mm

deformation are performed on 9 specimens of each material

(SA 13 silicone with varying silicone oil concentrations (0%,

20%, 30%), Shore 00 silicones (S00 30 and S00 20),

commercially available AM polymer TP (TangoPlus, Stratasys

Ltd.), and fresh porcine liver).

The force-displacement curves, resulting from the QS tests,

yield a contact stiffness of the unloading curve 𝑆 [2] and an

equivalent spring stiffness 𝑘. The relaxation curves are

interpreted with a discrete Prony series approach and - based

on a generalized Maxwell model - the loss factor tan 𝛿 is

calculated for 1 Hz [3].

Results

Tab. 1 lists the results for the measured QS parameters, while

Fig. 2A and 2B, respectively, depict typical force-displacement

curves and the force relaxation plots for the different

materials.

Material 𝑘[N/mm] 𝑆[N/mm] tan 𝛿[ ]*

TP 2.51 ± 0.05 5.49 ± 0.23 0.53 ± 0.04

0% oil 2.43 ± 0.25 3.84 ± 0.36 0.04

20% oil 1.74 ± 0.07 2.56 ± 0.10 0.03

30% oil 1.37 ± 0.02 1.97 ± 0.05 0.03 ± 0.001

Liver 1.13 ± 0.22 10.57 ± 1.83 0.10 ± 0.18

S00 30 0.85 ± 0.01 1.28 ± 0.04 0.04 ± 0.01

S00 20 0.53 ±0.01 0.80 ± 0.01 0.13 ± 0.02

Tab. 1: Spring stiffness 𝑘, and contact stiffness 𝑆 of QS

macroindentation and loss factor 𝑡𝑎𝑛 𝛿 for 1 Hz. *Preliminary

results.

Fig. 2: Typical force 𝐹 vs. displacement ℎ curves for QS tests (A);

force 𝐹 vs time 𝑡 plots for the first 200 seconds of force

relaxation tests, omitting TP due to much higher force response

than the other materials (B).

Discussion

The presented method, allows quantifying tactile properties

for comparative assessment. Regarding spring stiffness, SA

13 silicone with a 30% oil fraction is the material that

compares best to liver. TP, however, is more similar to liver in

respect to contact stiffness. To mimic the time-dependant

properties of liver, a more viscous material is required (i.e.

hysteresis in the QS curves and pronounced relaxation

behaviour). For 1 Hz the loss factor of S00 20 was closest to

that of liver.

References

1. Qiu et al., Adv Mater Technol, 1700235, 2017.

2. Oliver and Pharr, J Mat Res, 7:1564-1583, 1992.

3. Jolacha et al., Int J Solid Struct 67-68:169-181,2015.

Acknowledgements

The project was funded by the NFB Science Call Dissertations

2017, and the research center ACMIT (funded by COMET,

BMVIT, BMDW, the Federal State of Lower Austria, and

Standortagentur Tirol

F [N

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F [N

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B A

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A B

RESEARCH


EFFECT OF SELECTED SCAN PARAMETERS ON QCT BASED BMD ESTIMATIONS OF A FEMUR

Morteza Amini (1), Andreas Reisinger (1), Dieter H. Pahr (1,2)


2. Institute of Lightweight Design and Structural Biomechanics, TU-Wien, Vienna, Austria

Background

Finite element models (FEM) based estimates of bone

strength can be used to o predict fracture risk of patients

susceptible to osteoporosis in order to decide on

administering any therapies [1]. A key ingredient of a valid

FEM is material models. Elastic modulus of FEM elements can

be directly mapped from Quantitative Computed

Tomography (QCT) scans of bone. In this method, a

calibration phantom consisted of a few (usually 3 to 5) rods

with known hydroxyapatite (HA) densities is placed together

with the scanned sample/subject. The Hounsfield Units (HU)

of the scanned rods and their known density result in a linear

HU-Density relationship which is used to map the bone

mineral density (BMD) to the elastic moduli [2].

Unlike scanning patients, which has a well-defined protocol,

scanning cadaveric samples, which is the main approach in

FEM validation studies, has no standard procedure. As a

result, the scanning process until extraction of BMD values

based on HU can be affected by many parameters [3]. The

goal of this study was to determine the effect of such

parameters on the QCT-based BMD estimations of a

cadaveric femur.

Methods

Sample: Proximal portion of a cadaveric human femur was

cut and embedded in epoxy. The sample was clamped in

water-filled container (Figure 1).

Scanning: A 3-density HA phantom (HU0, HA100, HA200)

was used to capture QCT scans of the sample (Toshiba

Aquilion Prime, res: 0.625x0.625x0.25 mm3).

A set of 8 parameters were tested:

o Pre-filter (the physical lens that determines the

achievable field of view)

o Current

o Field of view (FOV)

o Bone Filter (image processing step done for patient hip

scans)

o Repetition (exact same parameters repeated)

o Off-center-vertical (positioning the bone vertically off-

centered in the scanner FOV)

o Off-center-horizontal (positioning the bone horizontally

off-centered in the scanner FOV)

o Phantom presence (effect of presence of the phantom in

the scan on BMD calculations)

o Bone presence (effect of presence of bone in the scan on

BMD calculations)

Total of 15 scans were taken (scans with combined

parameter alterations are excluded from this report).

BMD calculation: Using medtool 4.2 (Dr. Pahr Ingenieurs e.U.,

Austria) image processing functions, the HA rods were

segmented to get the HU-BMD calibration relationship. The

same portion of the bone was cropped in every scan to

calculate the total BMD of the proximal femur.

Figure 1: Left: Proximal femur sample embedded and clamped

in a water container. Center: Phantom and water-filled sample

container ready for scan. Right: mid-section of the CT scanned

sample.

Results

Two scans differing only in one parameter were paired to

calculate the corresponding effect on the BMD. Most clinically

relevant values were chosen. The effect is reported in %

absolute difference between the BMD values of the paired

scans (Table 1).

Parameter Comp. values %Abs. diff.

Pre-filter M – L 1.97

Current

FOV

Bone filter

Repetition

Off-center-vert.

Off-center-hor.

Phantom pres.

Bone pres.

150 – 300 mA

320 – 400 mm

NA

NA

58 mm

48 mm

NA

NA

0.42

0.15

3.32

0.34

6.28

0.8

0.41

17.64

Table 1: Percentage of absolute difference between the proximal

femoral BMD calculated for the paired scans differing only in

one parameter.

Discussion and Conclusion

Based on the results, due to high density of bone compared

to phantom rods, presence of bone largely affects the BMD

values, while phantom presence is negligible. Also, vertical

miss-placement is much more important than horizontal

offset. This means two side-by-side bone samples should be

scanned simultaneously to stay clinically accurate. And

finally, non-filtered images using the large pre-filter should be

used. In the next step, using elastic volume registration

methods and a template volumetric mesh, location-specific

effect of these parameters will be studied on multiple

samples.

References

1. Zysset P, et al, J Clin Densitom 18:359–392, 2015.

2. Keyak JH, et al, J Biomech 31:125–133, 1997.

3. Knowles N.K, et al, J Exp. Ort, 3:36- 52, 2016.

ACTIVITIES & EVENTS


Activities & Events

BIOMEX-Workshop on Biomechanical Imaging, Sweden

Dieter Pahr was the Keynote speaker with “Activities in biomechanics –today and tomorrow” In

Sweden in Huddinge at the BIOMEX-Workshop on Biomechanical Imaging, February 2018.

Articles Projekt “Best Mg Alloy”

(WN-Nachrichten; Chemiereport), January & March 2018.

Open House Day

The Division Biomechanics took part at the Open House Day of the KL. Andreas

Reisinger and Lukas Warnung were showing biomechanical experiments, March

2018.

© KL/S.Tragschitz

ACTIVITIES & EVENTS


ÖGOuT-edvanced education seminar “Osteoporose”

Dieter Pahr was given a speech on “Biomechanik des Knochens” at the ÖGOuT (Österreichische Gesellschaft für

Orthopädie und Traumatologie) education seminar on „Osteoporose“, March 2018.

Tecnet - Resarch to value workshop

„Wie könnten maßgeschneiderte Knieprothesen zum Vorteil von PatientInnen auf den Markt gebracht werden? An dieser Frage haben wir mit Prof. Pahr und Team von der Karl Landsteiner Privatuniversität in einem r2v Workshop gearbeitet.“, March 2018.

© KL/D.Pahr

Articles in newspaper and internet

“Wird Hornhaut aus dem 3D-Drucker kommen?“ “Knochenjob” für die Wissenschaft“

(NÖN),l February 2018. (Kronen Zeitung), March 2018.

ACTIVITIES & EVENTS


“Knochenjob: Biomechaniker” (Standard), May 2018. “Was das Herz begehrt”: (Südtiroler Wirtschaftszeitung)

October 2018.

“BREAK EVEN”: New laboratory creates excellent conditions for studying bones at KL Krems”, Pressbox (Press Release),

March 2018

“Auf Biegen & Brechen: Top-Labor schafft optimale Bedingungen für Knochenarbeit an KL Krems” (http://neue-

pressemitteilungen.de), May 2018.

Chemiereport

„So zugfest wie das biologische Vorbild“, Jungforscherin Sarah-Jane Estermann im Porträt (Chemiereport 2018.05), July

2018.

https://www.chemiereport.at/sites/default/files/uploads/printausgaben/chemiereport-2018-05_web.pdf

http://neue-pressemitteilungen.de/

http://neue-pressemitteilungen.de/

ACTIVITIES & EVENTS


CityRUN Krems 2018

This year, the division Biomechanics participated with 2 teams called

“BioMechTrio” and the “Bonebreakers” at CityRUN 2018 in Krems, April2018.

©KL/S.Tragschitz

left: Andreas Reisinger, Lukas Warnung and Christina Aron, the

“BioMechTrio” ©KL/S.Tragschitz

right: Jalil Nourisa, Georg Gamauf and NedaaAmraish,

the “Bonebreakers” at the finish ©KL/S.Tragschitz

Hiking Day 2018

For the first time the Division Biomechanics made a hiking day: Dürnstein, Vogelbergsteig, June 2018.

©KL/C.Aron

8th World Congress of Biomechanics (WCB) in Dublin 2018

in Ireland, Dublin, (http://wcb2018.com/), July 2018.

© KL / D.Pahr

E. Benca (MUW), M. Amini (KL), A. Reisinger (KL), A. Synek (TUW), D.H. Pahr (TUW, KL) at the conference venue.

http://wcb2018.com/

ACTIVITIES & EVENTS


Dieter Pahr elected to ESB Council

During the WCB in Dublin Dieter Pahr was elected to Council of the ESB

(European Society of Biomechanics) as chair of the publication committee, July

2018

https://esbiomech.org/welcome-to-the-european-society-of-biomechanics-

esbiomech/council/, July 2018

Junge Uni 2018

At the „Junge Uni der FH Krems“ our PhD Sarah-Jane Estermann conducted a workshop “Ein Blick ins Innere”, July

2018.

http://www.jungeuni.at/fileadmin/downloads/junge_uni_2018_low.pdf

©KL/S.Tragschitz

https://esbiomech.org/welcome-to-the-european-society-of-biomechanics-esbiomech/council/

https://esbiomech.org/welcome-to-the-european-society-of-biomechanics-esbiomech/council/

ACTIVITIES & EVENTS


Symposium “Individualisierte Implantat-technologien

The Division Biomechanics hosted a symposium together with Zwick Roell at the KL in Krems, August 2018.

Modellierung und Simulation: Vom realen Objekt zum Finite Elemente Modell Nutzen und Anforderungen -

Prof. Dieter Pahr, Karl Landsteiner Privatuniversität für Gesundheitswissenschaften, Krems

Mikro-Computertomographie Analytik - zerstörungsfreie, produktionsbegleitende Prüftechnologien für F&E

und QM – Dr. Andreas Reisinger, Karl Landsteiner Privatuniversität für Gesundheitswissenschaften, Krems

©KL/D. Pahr

PM Wissen Episode 3 (Servus TV)

“Knochen/Knorpel züchten". October, 2018.

P.M. Wissen asks exciting questions and gives surprising answers. Every week we embark on a new journey into the

world of tomorrow. Episode 3 poses the question: “Can we soon grow back bones artificially?” The answer to this

question and information on the topic "Bone & cartilage breeding" will be explained by Univ.-Prof. DI Dr. Dieter

Pahr, Professor in Biomechanics at KL University. To see, October 18th 2018, at 8.15 p.m. in P.M. Wissen at

ServusTV.

MiniMed Presentation

At the beginning of the winter semester 2018/19 Univ.-Prof. Dr. Dieter

Pahr gave a speech together with Univ.-Prof. Dr. Stefan Nehrer on the

widespread disease Osteoporosis at the Danube University Krems.

(https://www.minimed.at/veranstaltungen/termin/ knochenfestigkeit-2018-10-

03/) ,October, 2018.

“Knochen/Knorpel züchten" MiniMed-Presentation October, 2018.

https://www.minimed.at/veranstaltungen/termin/%20knochenfestigkeit-2018-10-03/

https://www.minimed.at/veranstaltungen/termin/%20knochenfestigkeit-2018-10-03/

ACTIVITIES & EVENTS


“Osteoporose - wenn die Knochen schwächeln - aus dem Blickpunkt eines

Biomechanikers“.

Artikel aus den Bezirksblätter Krems, October 2018.

Core Facility Opening

The core facility Krems – a modern research infrastructure – was opended in October 2018.

©KL/M.Meitz

5 Jahre KL

Karl Landsteiner Private University in Krems celebrates its 5th birthday. October 2018.

©KL/S.Tragschitz

ACTIVITIES & EVENTS


Technopol breakfast

November 2018.

science.talk spezial

Gelenke, Knorpel, Knochen - Biomedizin des Alterns vom 14.11.2018 um 23.40 Uhr, November 2018.

©KL/M.Meitz

Medicine is faced with new challenges by the growing society. Barbara Stöckl discusses with the KL researchers

Dieter Pahr and Stefan Nehrer the latest achievements of the biomedicine of ageing.

Young Researchers Calender 2019

"We must succeed in continuing to inspire as many young people as

possible to careers in science and research. Lower Austria will need the

brightest minds in the future as well. The young scientists in the Young

Researchers' Calendar 2019 are the best role models here. With their

impressive research topics, they are perfect flagships for Lower Austria as

a research location," explained Petra Bohuslav, State Councillor for

Economics and Technology.

November Model is DI Sarah-Jane Estermann, young scientist at KL

University.

Photocredit: Stefan Krupica-Klein

ACTIVITIES & EVENTS


How we conduct/make mechanics lesson

In the course of their Mechanics lecture, the first-semester students of the BA Health Sciences are studying the topic:

"Elasticity of Materials". The students conducted a hands-on experiment under the guidance of Dr. Andreas Reisinger

and Dr. Hanns Amri: The weight of individual students was measured using the elongation of a steel rope that was

attached to the roof of the KL building.

©KL/M.Meitz

Division Biomechanics meets ILSB

In December 2018 we had our first “whole group meeting” of the KL and TUW research group of Dieter Pahr at the

TU-Wien.

©KL/D.Pahr

A. Starikova, L. Warnung, M. Stipsitz, G. Gamauf, N. Amraish, A. Reisinger, S. Estermann, M. Amini, A. Lorenz, S. Stelzer, A. Synek, D.

Pahr, M. Frank, L. Steinr (from left to right)

ACKNOWLEDGEMENTS


Acknowledgements

The division biomechanics depends significantly on financial support from public funding agencies including

governmental and non-governmental institutions, as well as industry. Finally, we would like to thank all co-workers,

colleagues, collaborators and rectorates for their time and support during 2018.

Documents

Annual Report - KL