Compressive strength of elderly vertebrae is reduced by disc degeneration and additional flexion

Maquer, Ghislain Bernard; Schwiedrzik, Johann Jakob; Huber, Gerd; Morlock, Michael M.; Zysset, Philippe (2015). Compressive strength of elderly vertebrae is reduced by disc degeneration and additional flexion. Journal of the mechanical behavior of biomedical materials, 42, pp. 54-66. Elsevier 10.1016/j.jmbbm.2014.10.016

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Computer tomography (CT)-based finite element (FE) models assess vertebral strength better than dual energy X-ray absorptiometry. Osteoporotic vertebrae are usually loaded via degenerated intervertebral discs (IVD) and potentially at higher risk under forward bending, but the influences of the IVD and loading conditions are generally overlooked. Accordingly, magnetic resonance imaging was performed on 14 lumbar discs to generate FE models for the healthiest and most degenerated specimens. Compression, torsion, bending, flexion and extension conducted experimentally were used to calibrate both models. They were combined with CT-based FE models of 12 lumbar vertebral bodies to evaluate the effect of disc degeneration compared to a loading via endplates embedded in a stiff resin, the usual experimental paradigm. Compression and lifting were simulated, load and damage pattern were evaluated at failure. Adding flexion to the compression (lifting) and higher disc degeneration reduces the failure load (8–14%, 5–7%) and increases damage in the vertebrae. Under both loading scenarios, decreasing the disc height slightly increases the failure load; embedding and degenerated IVD provides respectively the highest and lowest failure load. Embedded vertebrae are more brittle, but failure loads induced via IVDs correlate highly with vertebral strength. In conclusion, osteoporotic vertebrae with degenerated IVDs are consistently weaker—especially under lifting, but clinical assessment of their strength is possible via FE analysis without extensive disc modelling, by extrapolating measures from the embedded situation.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute for Surgical Technology & Biomechanics ISTB

UniBE Contributor:

Maquer, Ghislain Bernard; Schwiedrzik, Johann Jakob and Zysset, Philippe

Subjects:

500 Science > 570 Life sciences; biology
600 Technology > 610 Medicine & health
600 Technology > 620 Engineering

ISSN:

1751-6161

Publisher:

Elsevier

Language:

English

Submitter:

Ghislain Bernard Maquer

Date Deposited:

13 Jan 2015 15:07

Last Modified:

28 Feb 2017 02:30

Publisher DOI:

10.1016/j.jmbbm.2014.10.016

BORIS DOI:

10.7892/boris.61659

URI:

https://boris.unibe.ch/id/eprint/61659

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