Masters Thesis Defense - Computer Modeling of an L4 – L5 Spinal Unit
Date: August 9, 2005
Time: 2:00 PM
Location: LeBow Engineering Center, Room: 231
Advisor: Michele Marcolongo, Ph.D.
Lower back pain affects on average 50-90% of adults in this country, with 75% of back pain caused by degenerated lumbar discs. Degenerative disc disease is the major cause for disc degeneration which ultimately causes the discs to inadequately distribute stresses. Stress concentrations form in the disc leading to disc herniations and pain. A proper functioning disc distributes forces from within the nucleus pulposus to the outer cartilaginous ring; the annulus fibrosis.
In order to study the mechanism of lumbar spine mechanics, an L4-L5 computer model was constructed. Compared to testing actual cadaver specimens, computer models save valuable limited resources, time, as well as money. Computer tomography scans were obtained for a cadaver L4-L5 functional spinal unit. The CT scans were than used to create a geometrically accurate three-dimensional model using Materialize MIMICS software. The model consisted of three parts including the L4-L5 vertebra, annulus fibrosis, and nucleus pulposus. The geometry of the spinal unit was taken carefully into account in order to create the most accurate model possible.
The model was than input into Geomagics software where it was prepared for input into ABAQUS finite element software. Geomagics software was used specifically to smooth out the model’s surface contours in order to eliminate stress concentrations during analysis. ABAQUS finite element software was used to run the model and generated pressure and displacement distributions within the model. Ultimately, these results will be used to validate the model’s accuracy by comparing them to in vivo conditions.
The LeBow Engineering Center is located at the corner of 31st and Market Streets.