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

equired to replicate the deformation of the disc observed.
This study has presented a novel method for combining MRI and CT data to construct
specimen specific models of the intervertebral disc, with accurate geometries of both the
soft and hard tissues. The AF has been represented as a homogenous component with
linear-elastic behaviour and does not, in this study, include distinction between lamellae
or interlamellar interactions. A previous study 5 has shown that the representation of
interlamellar interactions can affect the gross biomechanical behaviour of a disc model,
with a 53% increase in radial bulge observed with frictionless interlamellar interactions
in comparison to a homogenous AF. Future work will focus on implementing a
lamellar structure into specimen specific models, and incorporating better material
models, with the aim of improving model performance and understanding more about
the behaviour of these tissues and interactions.
6. CONCLUSIONS
A method was developed for capturing MRI data of the disc’s soft tissue that
will facilitate the construction, calibration and validation of computational
models.
The combination of CT and MRI data facilitated specimen specific modelling
that captured the internal soft tissue geometries with increased accuracy.
Future work will include the representation of inter-lamellar mechanics in
specimen specific models and the validation of specimen specific models against
MRI data of the soft tissues.
7. REFERENCES
1. Li, H. and Wang, Z., Intervertebral disc biomechanical analysis using the finite
element modeling based on medical images, Comp Med Imaging Graph, 2006 30(6-
7): 363-70.
2. Schmidt, H., Heuer, F. et al. Application of a new calibration method for a threedimensional
finite element model of a human lumbar annulus fibrosus, Clinical
Biomechanics, 2006, 21(4): 337-344.
3. O'Connell, G.D., et al., Human internal disc strains in axial compression measured
noninvasively using magnetic resonance imaging. Spine, 2007. 32(25): p. 2860-
2868.
4. O'Connell, G.D., H.L. Guerin, and D.M. Elliott, An Anisotropic Hyperelastic Model
Applied To Nondegenerate And Degenerate Annulus Fibrosus. Proceedings of the
Asme Summer Bioengineering Conference 2008, Pts a and B, 2009: p. 1107-1108
5. Luxmoore, B.J. et al., Modelling Interlamellar Cohesion in the Annulus Fibrosus,
Proceedings of the British Orthopaedic Research Society Annual Meeting, 2011
6. Marchand, F. and A. M. Ahmed, Investigation of the Laminate Structure of Lumbar-
Disk Anulus Fibrosus, Spine, 1990, 15(5): 402-410.