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Emily Brown Advisor: Dr. Gary Bledsoe BE@SLU REU, Summer 2009 Saint Louis University. Biomechanical Testing of the Lumbar Intervertebral Discs. Background. Lumbar spine Contains 5 vertebrae Highest loads Most prone to degenerative disc disease.
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Emily Brown Advisor: Dr. Gary Bledsoe BE@SLU REU, Summer 2009 Saint Louis University Biomechanical Testing of the Lumbar Intervertebral Discs
Background • Lumbar spine • Contains 5 vertebrae • Highest loads • Most prone to degenerative disc disease From: http://www.backpain-guide.com/Chapter_Fig_folders/Ch05_Anatomy_Folder/Ch5_Images/05-4_Overall_Spine.jpg
Intervertebral Disc Anatomy • Annulus Fibrosus • Nucleus Pulposus • Vertebral End Plate From: http://indyspinemd.com/Images/normalAnat/IntervertebralDisc.jpg
Intervertebral Disc Biomechanics • Compression • Failure of end plate • Torsion • Most damaging to disc • Degenerated Discs • Lower load to failure From: http://www.biomechanika.cz/index.php?lang=en&pg=laborator-mechanickych-zkousek
Lab Goals • Study biomechanical properties of orthopedics • Orthopedic devices • Plate fixators • Interbody spinal fusion cages • Spine • Intact lumbar segment • Individual intervertebral discs
Rationale • Methodology for use on fresh lumbar spines • More accurate model for in vivo studies • Finite element model • Degenerative disc disease • Comparing normal tested discs to patients' discs
Intervertebral Disc Project • Mechanical Testing • Compressional • Torsional • Compressional/Torsional Combination • Analysis
Methods and Materials • MTS • Testing • Collection of data • Discs from 3 human cadavers • L1-L2 through L4-L5
Specific Goals • Grip system for discs in testing • Measure biomechanical properties • Stress v strain • Elastic modulus • Determine effects of formalin fixation on disc properties
References • Farafan HF, Cossette JW, Robertson GH, Wells RV, Kraus H: The Effects of Torsion on the Lumbar Intervertebral Joints: The Role of Torsion in the Production of Disc Degeneration. J. Bone and Joint Surg., 52: 468-497, 1970 • Nixon J: Intervertebral disc mechanics: a review. Journal of the Royal Society of Medicine, v79(2): 100-104, February 1986 • Panjabi M, White A: Basic Biomechanics of the Spine. J of Neurosurgery, 7(1): 76-93, 1980 • Urban J, Roberts S: Degeneration of the intervertebral disc. Arthritis Research and Therapy, v5(3): 120-130, March 2003 • Wilke H, Krischak S, Claes L: Formalin Fixation Strongly Influences Biomechanical Properties of the Spine