Osmo-inelastic response of the intervertebral disc annulus fibrosus tissue. (September 2020)

• Record Type: Journal Article
• Authors: Derrouiche, Amil; Zaouali, Ameni; Zaïri, Fahmi; Ismail, Jewan; Qu, Zhengwei; Chaabane, Makram; Zaïri, Fahed
• Is Part Of: Proceedings of the Institution of Mechanical Engineers. Volume 234:Number 9(2020)
• Page Start: 1000
• Page End: 1010
• Publication Date: 2020-09
• Subjects: Annulus fibrosus -- chemo-mechanical coupling -- stress–stretch response -- transversal strains -- regional variation -- strain-rate -- osmolarity; Biomedical engineering -- Periodicals; Medical instruments and apparatus -- Periodicals; 610.28
• DOI: 10.1177/0954411920936047
• Languages: English
• ISSNs: 0954-4119

Abstract

The aim of this article is to provide some insights on the osmo-inelastic response under stretching of annulus fibrosus of the intervertebral disc. Circumferentially oriented specimens of square cross section, extracted from different regions of bovine cervical discs (ventral-lateral and dorsal-lateral), are tested under different strain-rates and saline concentrations within normal range of strains. An accurate optical strain measuring technique, based upon digital image correlation, is used in order to determine the full-field displacements in the lamellae and fibers planes of the layered soft tissue. Annulus stress–stretch relationships are measured along with full-field transversal strains in the two planes. The mechanical response is found hysteretic, rate-dependent and osmolarity-dependent with a Poisson's ratio higher than 0.5 in the fibers plane and negative (auxeticity) in the lamellae plane. While the stiffness presents a regional-dependency due to variations in collagen fibers content/orientation, the strain-rate sensitivity of the response is found independent on the region. A significant osmotic effect is found on both the auxetic response in the lamellae plane and the stiffness rate-sensitivity. These local experimental observations will result in more accurate chemo-mechanical modeling of the disc annulus and a clearer multi-scale understanding of the disc intervertebral function.