The Nanomechanical Behaviour of The Human Annulus Fibrosus

Author: Radhwa Ginting

Ginting, Radhwa, 2024 The Nanomechanical Behaviour of The Human Annulus Fibrosus, Flinders University, College of Science and Engineering

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The degeneration of the intervertebral disc (IVD) is a prevalent musculoskeletal condition that commonly presents as low back pain. The development of more effective treatments may be facilitated by a greater understanding of the mechanisms underlying disc degeneration. The Annulus Fibrosus (AF) is a structural component primarily composed of type I collagen which plays a significant role in the disc's reaction to mechanical loading. To achieve a more thorough examination of the disc and accurately identify the impact of disc degeneration on different anatomical regions within the disc, it is critical to investigate the mechanical properties of the disc at the nanoscale. This can be accomplished by studying collagen type I fibrils extracted from the AF fibre bundles obtained from circumferential sections of both healthy and degenerated discs under ambient conditions and become the main focus of this study. The study involved the isolation and examination of the nanomechanical characteristics of the circumferential regions of both healthy and degenerated discs. A comparison was made between two specific circumferential regions within the disc namely the anterior lateral and posterior regions. The idea of this comparison was to evaluate the structure and Young's modulus of the individual fibril by subjecting them to the same load. Following a 30-minute thawing time at room temperature, the fibrils would undergo testing after being removed from the Phosphate Buffered Saline (PBS) solution. To determine the topographical and mechanical properties of the sample, the Bruker Multimode 8 instrument engages in physical interaction with the cantilever tip positioned between the probe and the specimen during the scanning process of the collagen fibrils' surface. The calculation of Young's modulus is performed by the utilisation of the Hertz model. The results of the study indicate that the Young's modulus is greater in the anterior lateral sections in comparison to the posterior parts. Additionally, it was observed that degenerated discs had an apparent influence on the increased Young's modulus value when compared to the healthy discs. The comprehensive evaluation of the study's findings is important due to the limited sample sizes and limits imposed by the testing apparatus. Future research should consider evaluating collagen fibrils in a thoroughly hydrated environment to imitate the physiological condition more effectively and to provide additional clarity, particularly in the posterior region.

Keywords: Intervertebral Disc (IVD), Annulus Fibrosus (AF), nanomechanical properties, collagen fibrils, collagen type 1, AFM, Young's modulus

Subject: Engineering thesis

Thesis type: Masters
Completed: 2024
School: College of Science and Engineering
Supervisor: John Costi