Introduction: Analysis of impacts in football has been limited to the use of helmet-based accelerometers that measure linear/rotational accelerations of a player’s head during impact. Recent work suggests this method is insufficient to completely describe the impact conditions that contribute to traumatic brain injury. Accelerometers and rate transducers cannot reliably measure impact velocities or maximum rotational accelerations, and do not take into account torso position. Modern video analysis methods can provide more complete information about impact conditions.

Methods: High-definition coaching film from all 14 games of the 2012 University of Alabama college football season was analyzed. Video analysis software was created to photogrammetrically reconstruct all helmet-to-helmet impacts using orthogonal views. Players’ helmets, back positions and angles were evaluated before and after impact. To accurately describe impact kinematics, tabulated results of each player’s helmet included x-, y- and z- position, impact location, and type of impact, allowing calculation of closing velocity, change in velocity, and rotational velocity using vector analysis in MATLAB.

Results: A representative sampling of 4771 observed impacts were analyzed by computer reconstructions of 248 plays. Data was classified into 11 scenarios based on player position categories of similar impact conditions. Closing velocities of impacts ranged from 1.0 to 24.1 mph. The majority of impacts were experienced by linemen, followed by offensive/defensive backs and quarterbacks. Of note, pre/post impact energy was largely conserved in all reconstructions, suggesting poor energy management by polycarbonate shells used in modern day helmets.

Conclusions: High-definition video analysis using semi-automated techniques is useful for the analysis of football impact conditions and provides additional information that is complementary to data from helmet-based accelerometers. Ongoing work includes reliability analyses and recreation of derived impact conditions using a Hybrid III sledtesting paradigm. Helmet accelerometer data and video analysis results will be correlated in a prospective study.

Patient Care: This novel method of analyzing helmet-to-helmet impacts describes the on-field impact energies that occur. Having this resource available is complimentary to predicate devices, allowing further evaluation of helmet-to-helmet hits and potentially improved helmet design.

Learning Objectives: 1. Describe the information needed and the variety of information that is calculated from this novel system. 2. Discuss why multiple video angles are needed for this type of analysis and why coaching film appears to be the superior manner to do so. 3. Discuss the range of closing velocities that were seen by various player weights and by player positions.

References: 1. Newman et. al, Verification of biomechanical methods employed in a comprehensive study of mild traumatic brain injury and the effectiveness of American football helmets, Journal of Biomechanics 38:1469–1481, 2005 2. Pellman et. al, Concussion in Professional Football: Reconstruction of Game Impacts and Injuries, Neurosurgery 53:799-814, 2003 3. Rowson et. al, Linear and Angular Head Acceleration Measurements in Collegiate Football, Journal of Biomechanical Engineering, 131:061016-1-7, 2009