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Despite growing public health awareness of concussions and their cognitive sequelae, research has predominantly focused on generic bulk-head form impact metrics rather than the study of how brain tissue responds to head impacts. In this paper, the authors develop and validate a novel testing fixture that can configure standard head forms in an inverted orientation, with the future goal of testing inverted cadaveric specimens with gravity-driven perfusion of the head. The inverted testing fixture was integrated with an existing pneumatic linear impactor system and suspended a Hybrid III instrumented head and neck form on an x–ylinear sliding carriage. Validation studies compared impacts in upright and inverted orientations, with and without a football helmet, at 5.5 and 7.4 m/s. Angular velocity and linear acceleration measures were found to be similar. The results support the use of the novel fixture for studying inverted cadaveric specimens during simulated concussive impacts.

The Humanetics male 50th percentile Hybrid III neck is the most commonly used neckform for blunt impact testing. Other manufacturers, such as Jasti Co., have developed their own male 50th percentile necks that also meet United States government specifications. This study sought to evaluate the agreement in blunt impact performance measures on a subset of the National Football League helmet test protocol between an ATD that used the Jasti compared to the Humanetics Hybrid III neckform. Dependent measures included peak resultant linear acceleration (PLA), peak resultant angular acceleration (PAA), and peak resultant angular velocity (PAV). Results showed a lack of agreement according to the a-priori Type-I error rate of 0.05 between the Jasti and Humanetics for PLA and PAV (p< 0.001 and p= 0.003, respectively), but not PAA (p= 0.943). Statistically significant differences were observed for all Humanetics metrics and all but PAA for Jasti metrics in the lab-to-lab comparison. The lack of agreement was mainly due to the high-level of repeatability and low standard deviations between impacts for each system. Mean differences across neckform and lab-to-lab comparison for each impact measure were low in most impact cases but were observed to reach values that would be significant in the context of concussion and mTBI risk. These findings support the use of the Jasti neckform for blunt head impact testing in American football, but researchers should proceed with caution when comparing data between manufacturer devices.