New insights into the viscoelastic and failure mechanical properties of the elastic fiber network of the inter-lamellar matrix in the annulus fibrosus of the disc

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Date
2018-07-10
Authors
Tavakoli, Javad
Costi, John Jack
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Rights
© 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. This manuscript version is made available under the CC-BY-NCND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/
Rights Holder
© 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Abstract
The mechanical role of elastic fibers in the inter-lamellar matrix (ILM) is unknown; however, it has been suggested that they play a role in providing structural integrity to the annulus fibrosus (AF). Therefore, the aim of this study was to measure the viscoelastic and failure properties of the elastic fiber network in the ILM of ovine discs under both tension and shear directions of loading. Utilizing a technique, isolated elastic fibers within the ILM from ovine discs were stretched to 40% of their initial length at three strain rates of 0.1% s−1 (slow), 1% s−1 (medium) and 10% s−1 (fast), followed by a ramp test to failure at 10% s−1. A significant strain-rate dependent response was found, particularly at the fastest rate for phase angle and normalized stiffness (p < 0.001). The elastic fibers in the ILM demonstrated a significantly higher capability for energy absorption at slow compared to medium and fast strain rates (p < 0.001). These finding suggests that the elastic fiber network of the ILM exhibits nonlinear elastic behavior. When tested to failure, a significantly higher normalized failure force was found in tension compared to shear loading (p = 0.011), which is consistent with the orthotropic structure of elastic fibers in the ILM. The results of this study confirmed the mechanical contribution of the elastic fiber network to the ILM and the structural integrity of the AF. This research serves as a foundation for future studies to investigate the relationship between degeneration and ILM mechanical properties.
Description
Published by Elsevier Ltd. All rights reserved. This manuscript version is made available under the CC-BY-NCND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (Sept 2020) in accordance with the publisher’s archiving policy
Keywords
Inter-lamellar matrix, elastic fibers, annulus fibrosus, mechanical property, material property, ovine model
Citation
Tavakoli, J., & Costi, J. J. (2018). New insights into the viscoelastic and failure mechanical properties of the elastic fiber network of the inter-lamellar matrix in the annulus fibrosus of the disc. Acta Biomaterialia, 77, 292– 300.