Student: Casey Silva
Project Mentors: Dr. Brian Kelly – Barrow Neurological Institute
Dr. Vincent Pizziconi – SBHSE
Dr. James Abbas – SBHSE
YouTube Link: View the video link below before joining the zoom meeting
Zoom Link: https://asu.zoom.us/j/97255248135
Zoom meeting time: 10am – noon
Abstract
There are currently limitations to our understanding of spinal posterior fixation constructs in terms of full-field strain distributions. Better characterization of spinal screw/rod constructs will lead to more informed clinical decisions and lower rates of construct failure. The purpose of this project was to validate Digital Image Correlation (DIC), an optical measurement method, for spinal biomechanical testing through spinal rod analysis. This was done by comparing the effectiveness of DIC measurements to gold standard mechanical strain gauges at recording data from controlled mechanical testing. Testing was performed by applying a controlled load via MTS frame to straight CoCr spinal rods in accordance with ASTM-f1717, regarding unilevel posterior spinal fixation constructs. Strain was recorded via the tandem application of DIC and mechanical gauge techniques, to validate DIC. After a baseline efficacy of DIC measurement was established, a first look was taken at the behavior of differently bent spinal rods in terms of strain distribution. A bent spinal rod using a traditional bending technique (i.e. handheld French Bender), was compared to a spinal rod bent using a relatively new method based on digitized analysis and more tightly controlled bend radii (Bendini, Nuvasive Spine, CA). This validation and preliminary analysis of bent rods have established a protocol for spinal biomechanical testing and analysis via DIC, determined the efficacy of DIC in measuring spinal rod strain, and laid the foundation for future studies to elucidate strain profiles on mechanically bent spinal rods to determine how rod strain distributions vary as a function of the bending method used or the severity of the bending angle.