A Headform for Testing Helmet and Mouthguard Sensors that Measure Head Impact Severity in Football Players GUNTER P. SIEGMUND, 1,2 KEVIN M. GUSKIEWICZ, 3 STEPHEN W. MARSHALL, 4 ALYSSA L. DEMARCO, 1 and STEPHANIE J. BONIN 5 1 MEA Forensic Engineers & Scientists, 11-11151 Horseshoe Way, Richmond, BC V7A 4S5, Canada; 2 School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; 3 Matthew A. Gfeller Sport-Related Traumatic Brain Injury Research Center, Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; 4 Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; and 5 MEA Forensic Engineers & Scientists, Laguna Hills, CA, USA (Received 17 March 2014; accepted 31 May 2014) Associate Editor Stefan M Duma oversaw the review of this article. Abstract—A headform is needed to validate and compare helmet- and mouthguard-based sensors that measure the severity and direction of football head impacts. Our goal was to quantify the dynamic response of a mandibular load- sensing headform (MLSH) and to compare its performance and repeatability to an unmodified Hybrid III headform. Linear impactors in two independent laboratories were used to strike each headform at six locations at 5.5 m/s and at two locations at 3.6 and 7.4 m/s. Impact severity was quantified using peak linear acceleration (PLA) and peak angular acceleration (PAA), and direction was quantified using the azimuth and elevation of the PLA. Repeatability was quan- tified using coefficients of variation (COV) and standard deviations (SD). Across all impacts, PLA was 1.6 ± 1.8 g higher in the MLSH than in the Hybrid III (p = 0.002), but there were no differences in PAA (p = 0.25), azimuth (p = 0.43) and elevation (p = 0.11). Both headforms exhibited excellent or acceptable repeatability for PLA (HIII:- COV = 2.1 ± 0.8%, MLSH:COV = 2.0 ± 1.2%, p = 0.98), but site-specific repeatability ranging from excellent to poor for PAA (HIII:COV = 7.2 ± 4.0%, MLSH:COV = 8.3 ± 5.8%, p = 0.58). Direction SD were generally <1° and did not vary between headforms. Overall, both headforms are similarly suitable for validating PLA in sensors that measure head impact severity in football players, however their utility for validating sensor PAA values varies with impact location. Keywords—Concussion, Brain injury, Validation, Repeat- ability. INTRODUCTION Sport-related head impacts can cause concus- sions, 7,8,15,20,22 and valid methods of measuring the direction and severity of these head impacts are needed to better understand and ultimately prevent these injuries. Various devices already exist for measuring athlete head kinematics, including helmet-based sen- sors, 6,21 mouthguard-based sensors, 4,9 and earpiece- based sensors. 13,17 There is, however, no common platform on which to validate and compare these dif- ferent devices. Various surrogate headforms have been used to de- velop and/or validate the different devices. An automo- tive crash test dummy head (Hybrid III) and a sport- standard headform (National Operating Committee on Standards for Athletic Equipment—NOCSAE) have been used to evaluate helmet-based sensors. 1,2,11,14,21 Although both headforms are widely used and included in industry or government head injury prevention stan- dards, neither headform has a mandible or dentition to accommodate a mouthguard. A modified NOCSAE headform with the jaw portion removed has been used for proof-of-concept tests of a mouthguard-based sensor, 9 but has not been further developed. A custom headform with an articulating mandible was built by one mouth- guard developer, 4 but it is not widely used and its biofi- delity and repeatability have not been demonstrated. A new headform with an articulating and load-sensing mandible was recently developed to measure the impact attenuation capabilities of mouthguards. 5,24,26 Although mandibular load sensing capabilities are not needed for validating mouthguard-based sensors, this headform’s Address correspondence to Gunter P. Siegmund, MEA Forensic Engineers & Scientists, 11-11151 Horseshoe Way, Richmond, BC V7A 4S5, Canada. Electronic mail: gunter.siegmund@meaforensic.com Annals of Biomedical Engineering (Ó 2014) DOI: 10.1007/s10439-014-1052-2 Ó 2014 Biomedical Engineering Society