Lumbar disc prolapse occurs more frequently in those who are engaged in repetitive lifting and is the cause of sciatica, radiating pain down the back and legs due to an impingement on the spinal cord. The injury is thought to occur over time, as high repetitive (sub-failure) stresses are created within the disc leading to a gradual disc prolapse. These stresses are further increased by improper lifting technique which includes straight knees, holding the object far away from the body, and twisting. However, the mechanism for herniation under repetitive loading is still unclear. This could be due to the fact that reproducing gradual herniation in a laboratory setting has proven difficult as there are limitations regarding the application of realistic loading using materials testing systems. Internal measurements of disc tissue deformations can provide detailed information on the initiation and propagation of disc injury. This presentation of my PhD work will discuss the relationship between combined repetitive bending and twisting movements of normal cadaver lumbar segments, and the progression of three-dimensional internal disc deformation during loading, which may lead to disc prolapse and macroscopic tissue damage.
Dhara Amin is currently a Ph.D. candidate at Flinders University, conducting research in spine biomechanics. She graduated with a Bachelor’s degree in Mechanical Engineering from the University of Delaware in 2013. That year, she was awarded the Whitaker International Fellowship to complete 12 months of research under the supervision of John Costi at Flinders University in Australia. Her research during the fellowship focused on the six degree of freedom mechanical properties and internal strains of the intervertebral disc under physiological and complex loading. Australia was so wonderful that she continued her work from the fellowship as a PhD candidate. In addition to her PhD, Dhara is clinical researcher looking at metal ion concentrations in patients before and after removal of spinal instrumentation as well as a research engineer for the Medical Device Partnering Program, which is a program that supports the development of medical devices via collaboration between research, industry and the government.
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