Creation of circumferential tears in ovine lumbar intervertebral discs

Author: Kurt Van Ryswyk

Van Ryswyk, Kurt, 2019 Creation of circumferential tears in ovine lumbar intervertebral discs, Flinders University, College of Science and Engineering

Terms of Use: This electronic version is (or will be) made publicly available by Flinders University in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. You may use this material for uses permitted under the Copyright Act 1968. If you are the owner of any included third party copyright material and/or you believe that any material has been made available without permission of the copyright owner please contact with the details.


Low back pain is a cause of significant impairment, reduced quality of life, lost productivity, and direct medical costs in the global population. Low back pain is strongly correlated to herniation of lumbar intervertebral discs (IVDs) which is also related to disc degeneration and to circumferential tears in the Annulus Fibrosus (AF). The study of annular circumferential tears would be very useful for future spinal research but such studies but have been limited in scope due to the difficulties of inducing such tears in healthy IVDs and the confounding factors involved in studying degenerated IVDs.

The purpose of this project was to develop a low-cost method, capable of reliably creating inner annular delaminations in IVDs. High-pressure fluid injection was selected as the most promising method to induce delaminations. A simple injector device was developed using a syringe adaptor to a commonly available pneumatic fluid dispenser with time control. To test the effectiveness of the injection device, ninety-seven IVDs were harvested from forty-three stored sheep spines, hydrated under a physiological preload, and injected in the anterior annular region

Circumferential delaminations were successfully induced at pressures between 413 and 690 kPa (60 to 100 psi) with a mean success rate of 56%, and a maximum success rate of 86% for 80 psi injections. An analysis of variance (ANOVA) was carried out, but results were highly variable. It was shown that there was a marginally significant relationship between injection duration and delamination length (P < 0.1), but no significance was shown for injection pressure vs delamination despite supporting trends.

This study was exploratory and had several challenges and limitations. Spines recruited for the study were mostly specimens rejected from other projects. As such many were smaller discs or came from spines which included some damaged discs and variation in disc quality was inevitable. The injection method was been shown to be successful but highly varied in results. Future work would include performing a study with specimens of uniform age and quality to more accurately establish optimal injection parameters.

Keywords: In Vitro, Ovine Spine, Intervertebral disc, IVD, Injection, Circumferential tears, Delamination, Annulus fibrosus

Subject: Engineering thesis

Thesis type: Masters
Completed: 2019
School: College of Science and Engineering
Supervisor: John Costi