Anybody who knows me relatively well will know that I am a huge pro-football fan (33 days till Hall of Fame Game Cowboys vs. Cardinals, but who’s counting?) But many fanatics, myself included, often severely overlook the risks that athletes take when they play sports: traumatic brain injury one of many not yet fully understood. Brain injury extends far from sports, however, including military implications and even normal day life—surprisingly, motor vehicles are only the third leading cause of traumatic brain injury (TBI), landing behind ‘falls’ and ‘individual being struck by another object’ (Meaney 2).
Dr. Bass’ Injury and Orthopaedic Biomechanics Laboratory seeks to dig deeper into different aspects of brain injury; my mentor Chris and I hope to investigate the key mechanism of TBI. Currently, two branches of ideology exist in regards to how mild traumatic brain injury arises; the first believes that mainly direct impacts to the head, linear velocities and accelerations, are the key mechanisms of head injury and the second school conjectures that rotational velocities and accelerations cause head injury. A plethora of experiments (Gennarelli, Eucker) have concluded that head rotation is the greater cause of mild traumatic brain injury, but the exact mechanism of TBI, whether angular velocity or acceleration and whether parameters to measure concussion include shear strain, relative displacement, shear stress, pressure waves, etc. remains to be confirmed. Currently, some of the main parameters used to determine and assess level of brain injury are cumulative strain damage measurements (CSDM), maximum principal strain (MPS), and maximum pressure.
This summer, a twofold process will be used to analyze the true mechanism that is causing shear and strain in the brain. First, a program called LS-DYNA/LS-PrePost will be used to analyze the finite element analysis SIMon model. The SIMon (Simulated Injury Monitor) was made to evaluate injury potential by directly imposing measured responses on a finite element model, which allows deformation and predicts how a product reacts to real world forces.
Second, a gel will be used for hands-on experimentation. A built device will allow different accelerations and constant velocities to be manually created and the resulting strain will be reflected in the gel—different colors (similar to figure 4) will appear and can be compared to the strains found from the SIMon model. Although the materials are different (SIMon model set brain material versus brain-like gel), the strains should reflect relatively the same values.
Finally, an experiment will be conducted to attempt to understand the effect of shear shock waves on the brain. Currently, the exact effect of instantaneous pressure waves and energy mounts from shear shock waves (hemorrhages, microcavitations, etc.) is unknown. In order to visualize injury that MRI scans usually cannot pick up on, the same device as the gel experiment will be used to give impact to a pig’s brain. Different boundary conditions will be placed; the pig’s skull will be replaced with a clear, transparent, skull cap in order to visualize the interior of the brain during the impact. Analyzing the effects of shear shock will allow better understanding of how these waves truly contribute to traumatic brain injury. Although the ideas are still preliminary, by the time NFL season rolls around, I hope to have delved deeper into my research project and reaped some interesting results!