ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

model, strain patterns varied across the transverse cross-section as well as in depth.
Another explant specific surface curvature model was created using the same protocol
and analysed. It was found that the stress and strain patterns predicted are indeed highly
dependent and sensitive to the surface curvature of the explants (Figure 6). Furthermore,
small surface adulations were found to cause significant shear stress patterns inside the
tissue (Figure 6).
Figure 6 Contour plot of deformation predicted for another explant specific surface curvature model.
Strain pattern differs from previous model. Maximum deformation was 1.953mm indicated in red. (left)
Contour plot of significant shear stresses observed in another explant specific surface curvature model,
compared to the homogenous shear stress on the magnitude of 1e -4 MPa in the flat surface mode.
Maximum shear stress was 0.147MPa indicated in red and the minimum was -0.238MPa indicated in
blue. (right)
6. CONCLUSIONS
The results from this study show that modelling of the exact surface geometry of the
explants is essential for accurate prediction of the magnitude and distribution of stress
and strains experienced inside the tissue during mechanical loading. A protocol has
been set up for creating finite element models with explant specific surface curvature.
The method uses dental putty to record the surface geometry of the condyles, thereby
eradicating the need for direct contact measurement techniques and reducing damage,
contamination and time delay for the gene expression studies to be carried out.
7. REFERENCES
1. Chan P.S., Schlueter A.E., Coussens P.M., Rosa G.J.M., Haut R.C. and Orth M.W.,
Gene expression profile of mechanically impacted bovine articular cartilage
explants, Journal of Orthopaedic Research, 2005, Vol. 23., 1146-1151
2. Thomas R.S., Clarke A.R., Duance V.C. and Blain E.J., Effects of Wnt3A and
mechanical load on cartilage chondrocyte homeostasis, Arthritis Research and
Therapy, 2011, Vol 3., R203
3. Fitzgerald J.B., Jin M., Dean D., Wood D.J., Zheng M.H. and Grodzinsky A.J.,
Mechanical compression of cartilage explants induces multiple time-dependent gene
expression patterns and involves intracellular calcium and cyclic AMP, The Journal
of Biological Chemistry, 2004, Vol. 279, Issue 19(7), 19502-19511
4. Donzelli P.S., Spilker R.L., Ateshian G.A. and Mow V.C., Contact analysis of
biphasic transversly isotropic cartilage layers and correlations with tissue failure,
Journal of Biomechanics, 1999, Vol. 32, 1037-1047
5. DiSilvestro M.R., Zhu Q., Wong M., Jurvelin J.S., Suh J.F., Biphasic