Comparison of dynamic performance of Jasti and Humanetics neckforms with an inter-lab validation

Abstract

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.