Laboratory Reconstructions of Concussive Helmet-to-Helmet Impacts in the National Football League
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Annals of Biomedical Engineering ( 2020) https://doi.org/10.1007/s10439-020-02632-8
Concussion Biomechanics in Football
Laboratory Reconstructions of Concussive Helmet-to-Helmet Impacts in the National Football League JAMES R. FUNK ,1 RON JADISCHKE,2 ANN BAILEY,1 JEFF CRANDALL,1 JOE MCCARTHY,2 KRISTY ARBOGAST,3 and BARRY MYERS4 1
Biocore LLC, 1627 Quail Run, Charlottesville, VA 22911, USA; 2McCarthy Engineering Inc, 2280 Ambassador Drive, Windsor, ON N9C 4E4, Canada; 3Center for Injury Research and Prevention, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA; and 4Department of Biomedical Engineering, Duke University, Durham, NC, USA (Received 18 August 2020; accepted 18 September 2020) Associate Editor Stefan M. Duma oversaw the review of this article.
Abstract—Seventeen concussive helmet-to-helmet impacts occurring in National Football League (NFL) games were analyzed using video footage and reconstructed by launching helmeted crash test dummies into each other in a laboratory. Helmet motion on-field and in the laboratory was tracked in 3D before, during, and after impact in multiple high frame rate video views. Multiple (3–10) tests were conducted for each of the 17 concussive cases (100 tests total) with slight variations in input conditions. Repeatability was assessed by duplicating one or two tests per case. The accuracy of the input conditions in each reconstruction was assessed based on how well the closing velocity, impact locations, and the path eccentricity of the dummy heads matched the video analysis. The accuracy of the reconstruction output was assessed based on how well the changes in helmet velocity (translational and rotational) from the impact matched the video analysis. The average absolute error in helmet velocity changes was 24% in the first test, 20% in the tests with the most accurate input configuration, and 14% in the tests with minimal error. Coefficients of variation in 22 repeated test conditions (1–2 per case) averaged 3% for closing velocity, 7% for helmet velocity changes, and 8% for peak head accelerations. Iterative testing was helpful in reducing error. A combination of sophisticated video analysis, articulated physical surrogates, and iterative testing was required to reduce the error to within half of the effect size of concussion. Keywords—Biomechanics, Brain injury, Crash test dummy, Hybrid III.
Address correspondence to James R. Funk, Biocore LLC, 1627 Quail Run, Charlottesville, VA 22911, USA. Electronic mail: [email protected]
INTRODUCTION The reenactment of sport-related concussions using crash test dummies is becoming an increasingly common method for studying the biomechanics of head injury.5,6,12,13,20,22,25,26,32 Sport provides an environment in which concussions occur regularly and are frequently captured on high-quality video. In helmeted sports such as American football and ice hockey, video analysis can provide detailed kinematics for the players’ helmets, but not necessarily their heads. However, video analysis can be supplemented by a laborato
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