NUI Galway – UL Alliance First Annual ENGINEERING AND - ARAN ...

Computational Modeling of Ceramic-based Bone Tissue Engineering Scaffolds
Doyle, H. 1 , McHugh, P.E. 1
1 Department of Mechanical and Biomedical Engineering, NUI Galway, Ireland
Email: h.doyle1@nuigalway.ie
Abstract
Biomaterial bone scaffolds are required to have a
unique combination of stiff mechanical properties and
high porosity to ensure cell differentiation. In this work,
a finite element analysis is conducted to determine the
effects of varying scaffold material properties and
geometry on scaffold performance.
1. Introduction
Tissue engineering biomaterial scaffolds have the
potential to facilitate the regeneration of damaged or
diseased bone tissue. For effective scaffold
performance, high porosity and pore interconnectivity
are required to ensure cell penetration; in addition,
adequate mechanical properties to support physiological
loads during tissue regeneration are required.
The aim of this research is to address the need for
detailed micro-structural design of these scaffolds to
optimize their performance, by using high-resolution
computational modeling in combination with
experimental analysis of manufactured bone scaffolds
for validation.
2. Methods
High resolution finite element models of repeatable
scaffold geometries [1] , see Fig. 1, were modeled under
1% compression using Abaqus finite element (FE)
software. Two different scaffold geometries (labeled the
0/90 and Luxner geometries [1] ) were modeled, and each
was run with three different material properties (PCL,
PCL-Ha and Ha). The maximum and minimum
principal stress and strain distributions were analyzed to
compare the performance of the different geometries
and materials.
Figure 1: Scaffold geometries (a) 0/90 and (b)
Luxner.
3. Results
The results of this analysis show a very similar strain
distribution with mode values at -0.3% and +0.2% for
maximum and minimum principal strain distributions
65
respectively for both geometries. The compressive
stress results for both 0/90 and Luxner scaffolds are
shown in Fig. 2. Both tensile and compressive stresses
in the Luxner PCL-Ha scaffold were further away from
the material strength than for other materials, and
stresses were more evenly distributed in the 0/90 PCL-
Ha scaffold compared to the other materials.
Figure 2: Minimum principal stress results for 0/90
and Luxner scaffolds.
4. Conclusions
These results indicate that the strains experienced by
the scaffolds may not be very different. As the strain
experienced by cells seeded on scaffolds has been
shown to influence cell differentiation [2] , this may mean
that cell differentiation in this case would be
independent of material or geometry.
Increasing the ceramic content of the scaffolds
should, by rule of mixtures, increase scaffold stiffness.
The results show this to be true for the 0/90 scaffold but
not for the Luxner scaffold. The reasons for this result
need to be studied further.
Luxner PCL-Ha scaffold stresses were shown to be
further away from the material strength than for the
other materials indicating that it is less likely to fail and
therefore more suitable for scaffold fabrication. Stops [2]
has shown that stress concentrations in a scaffold can
lead to failure. This suggests that failure is less likely to
occur in the 0/90 PCL-Ha scaffold than for the other
materials.
7. Acknowledgements
EMBARK scholarship from the Irish Research
Council for Science, Engineering and Technology.
8. References
[1] Cahill, S., M.Eng.Sc., NUI Galway, 2009.
[2] Stops, A. PhD, NUI Galway, 2009.