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. 2018 Apr 16;7(4):510-519.
doi: 10.11138/mltj/2017.7.4.510. eCollection 2017 Oct-Dec.

Finite element comparison between the human and the ovine lumbar intervertebral disc

Gloria Casaroli  1 , Tomaso Villa  2   1 , Fabio Galbusera  1
Affiliations

Finite element comparison between the human and the ovine lumbar intervertebral disc

Gloria Casaroli et al. Muscles Ligaments Tendons J. .

Abstract

Introduction: Nowadays it is still not clear which loading conditions are responsible for lumbar intervertebral disc failure. Many studies have been conducted to investigate the effect of different loading conditions on the herniation processes, and many of them were based on the ovine model. However, the biomechanical similarities between the human and the ovine lumbar disc have been demonstrated in the main planes only, whereas it is not known if they are comparable under complex loading conditions too. The aim of this study was to compare the mechanical response of the ovine and the human lumbar intervetebral disc under complex loading conditions, in order to investigate differences and similarities between the species.The loading scenarios described in a finite element study on a human lumbar segment were applied to a model of the ovine disc, and the results were then compared.It has been shown that combined loads generated highest strains in both the models, and the maximum strains had the same location in the posterior or in the postero-lateral region of the annulus, according to the loading scenario.

Conclusion: The ovine disc can be used in spinal research to investigate herniation process under any loading conditions.

Level of evidence: V.

Keywords: animal model; anisotropic hyperelastic; finite element analysis.

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Conflict of interest statement

Conflict of interest None.

Figures

Figure 1
Figure 1
Schematic representation of the reference systems used for the different loading scenarios. For the combination of (a) flexion - extension (FL-EX) and lateral bending (LB), the x and the y axes were incrementally rotated by an α angle of 15 degrees around the z axis; for the combination of (b) FL-EX and axial rotation (AR), the x and the z axes were incrementally rotated by 15 degrees around the y axis; for the combination of (c) AR and LB, the y and the z axes were incrementally rotated by 15 degrees around the x axis.
Figure 2
Figure 2
Resulting rotations generated by the combination of (a) flexion-extension (FL-EX) and lateral bending (LB), (b) FLEX and axial rotation (AR), (c) AR and LB.
Figure 3
Figure 3
Comparison between the ovine and the human maximum Intradiscal Pressure values under all the applied loading scenarios (adapted from Schmidt et al.9). FL means flexion, EX means extension, LB means lateral bending and AR means axial rotation.
Figure 4
Figure 4
Comparison between the ovine maximum circumferential strain of the annulus fibrous and the human maximum fiber strains under all the applied loading scenarios (adapted from Schmidt et al.9). FL means flexion, EX means extension, LB means lateral bending and AR means axial rotation.
Figure 5
Figure 5
Location of the maximum circumferential strain in the ovine finite element model. The red line includes the area indicated by Schmidt as characterized by the most strained fibers in the human healthy disc. FL means flexion, EX means extension, LB means lateral bending and AR means axial rotation.
Figure 6
Figure 6
Comparison between the ovine and the human maximum shear strain at the interface between the annulus and the endplate under all the applied loading scenarios (adapted from Schmidt et al.9). FL means flexion, EX means extension, LB means lateral bending and AR means axial rotation.
Figure 7
Figure 7
Location of the maximum shear strain in the ovine finite element model. The red line includes the area indicated by Schmidt9 as characterized by highest shear strain in the human healthy disc. FL means flexion, EX means extension, LB means lateral bending and AR means axial rotation.
See this image and copyright information in PMC

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