Interaction of external head impact parameters on region and volume of strain for collisions in sport

Abstract

Collisions with the head are the primary cause of concussion in contact sports. Head impacts can be further characterized by velocity, striking mass, compliance, and location (direction). The purpose of this study was to describe the interaction effects of these parameters on peak strain in four brain regions and the volume of strain for collision impacts. A pendulum test setup was used to deliver impacts to an adult Hybrid III headform according to four levels of mass (3, 9, 15, and 21 kg), four velocities (1.5, 3.0, 4.5, and 6.0 m/s), two impact locations (through the centre of gravity and a noncentre of gravity), and three levels of compliance simulating unprotected, helmeted, and well-padded conditions in sport. Headform accelerations were input into a brain finite element model to obtain peak strain in the frontal, temporal, parietal, and occipital lobes and the volume of the brain experiencing 0.10, 0.15, 0.20, and 0.25 strains. Centre-of-gravity impacts created the highest strains (peak and volume) under low compliance and non-centre-of-gravity impacts produced greater strain responses under medium and high compliance conditions. The temporal lobe was the region that consistently displayed the highest peak strains, which may be due to the proximity of the impact locations to this region. Interactions between mass and velocity displayed effects where the 9-kg mass had higher peak and volumes of strain than the 15-kg mass at velocities of 3.0 and 4.5 m/s. This study demonstrates the important role of interacting impact parameters on increasing strain responses that are relevant to the spectrum of diffuse brain injuries, including concussion.

Accident reconstructions of falls, collisions, and punches in sports

“…Previous investigations evaluating the relative effect of impact parameters on head and brain dynamics demonstrated compliance to contribute to the greatest increases in peak linear and rotational acceleration, meanwhile impact velocity created the greatest increases in peak strain. 1,5,23,[41][42][43] Therefore, it is no surprise that impactor compliance differences between the four impact events in this study contributed to significant differences reported in mean peak linear and rotational accelerations and pulse durations ( Figure 5). Linear and rotational acceleration pulses were averaged and plotted, along with AEstandard deviations for each of the four types of head impact events, to illustrate the unique acceleration curve shapes for each event (Figure 8).…”