Although the role of spinal posture and muscular activity on low back pain has been investigated, there is minimal understanding of the fundamental mechanisms of intervertebral disc injuries that occur during lifting after prolonged sitting or standing. This project will employ micromechanical testing techniques to compare the behaviour of disc tissue from injured discs between sitting and standing postures to identify the weakest disc regions during experimental micro-mechanical testing following failure during lifting. The findings of this research will lead to the development of failure criteria of the disc via multiscale computational models, as well as provide important data for the development of new treatment strategies.
My program of research aims to understand the fundamental multiscale properties of normal, degenerated and injured spinal discs, and their mechanisms of failure, and to develop medical devices to treat these problems. Low back pain is ranked globally as the greatest contributor to the number of years lived with disability and is the number one contributor to the non-fatal health burden in Australia. Injury to the disc can occur through awkward lifting postures or propagate over many years of repetitive lifting. In both cases, the disc can herniate (aka 'slipped disc') causing radiating nerve pain and disability. We use a range of equipment including a unique, world-leading six axis hexapod robot, a single axis materials fatigue testing system and a biaxial system for testing microscale portions of biological tissues. We also use scanning electron microscopy to visualise the micro-/nano-scale structure of disc tissue to understand mechanisms of failure. Collaborations can be developed with researchers across Flinders, or across Australia and internationally.
My programs of research bring together both experimental, computational and theoretical approaches to understanding the complex behaviour of composite biological materials across the nano-, micro- and macro-scopic scales. Current computational models of spinal discs, for example, are unable to account for the complex, non-linear, time-dependent, multi-phasic (solid, fluid, ionic, chemical-electric) properties of the disc tissue. These models employ a mix of both micro- and macro-scopic disc tissue properties, although data at the micro scale is lacking. It is believed that the disc tissue behaviour needs to be understood across each scale in order to understand the whole.
The novelty of my program of research lies in developing an understanding of how these tissues function across the hierarchical scales, specifically from nano-micro, micro-macro and nano-macro. This important understanding is not presently available and poses many challenges for researchers. This leads to many important, unanswered research questions such as:
1. At what scale does an understanding of biological tissue need to be quantified in order to describe the macro-scopic behaviour?
2. How does a multi-scale understanding correlate to macro-scopic behaviour.
3. What specific hierarchical information is required in order to create more-realistic computational models that are able to better predict macro-scopic behaviour?
4. What effect does tissue degeneration have on their multi-scale structural and functional properties and how can these be computationally modelled to provide a greater understanding of the disease process?
5. What tissue engineering approaches could be employed to repair diseased/damaged tissues based on this knowledge?
