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Disclaimer:  The information provided in this blog post is intended for educational purposes and not legal advice. For specific legal inquiries, please consult an attorney. The information provided in this blog post is intended for the sole purpose of reconstructing accidents and injuries and not for serving as a risk management resource.

LISKE Injury Biomechanics Expert, Dr. Marshall Kendall has extensive experience in traumatic brain injury and sport-related concussions. He holds multiple patents in helmet technology and brings unique expertise to cases involving helmets such as motorcycle and bicycle accidents, as well as impact sports including American Football, Hockey, and Mixed Martial Arts (MMA).

In one of his peer-reviewed published papers ^[1] “Accident reconstructions of falls, collisions, and punches in sports” he compared four types of head impact events through reconstruction. The following provides an abstract of his study.

Impacts to the head are the primary cause of concussive injuries in sport and can occur in a multitude of different environments. Concussions in impact sports involve head contact that can occur in numerous different ways. In 2015, the leading causes of concussion were identified as falls (42%), transport collisions (40%), and being struck by or against an object (18%) ^[2]. The study further revealed that of the “struck by or against an object”, 71% of these concussions occurred in sport or recreation. Each event is composed of combinations of impact characteristics (striking velocity, impact mass, and surface compliance) that present unique loading conditions on the head and brain. The purpose of this study was to compare falls, collisions, and punches from accident reconstructions of sports-related head impacts using linear, rotational accelerations and maximal principal strain of brain tissue from finite element simulation.

This study compared four types of head impact events through reconstruction. Seventy-two head impacts were taken from medical reports of accidental falls and game videos of ice hockey, American football, and mixed-martial arts. These were reconstructed using physical impact systems to represent helmeted and unhelmeted falls, player-to-player collisions, and punches to the head. Head accelerations were collected and were input into a finite element brain model used to approximate strain in the cerebrum associated with the external loading conditions.

Significant differences were found for peak linear and rotational acceleration magnitudes (30–300 g and 3.2–7.8 krad/s²) and pulse durations between all impact event types characterized by unique impact parameters. The only exception was found where punch impacts and helmeted falls had similar rotational durations. Regression analysis demonstrated that increases to strain from unhelmeted falls were significantly influenced by both linear and rotational accelerations, meanwhile helmeted falls, punches, and collisions were influenced by rotational accelerations alone.

This study illustrates that the four distinct impact events created unique peak head kinematics and brain tissue strain values. These distinct patterns of head acceleration characteristics suggest that it is important to keep in mind that head injury can occur from a range of low to high acceleration magnitudes and that impact parameters (surface compliance, striking velocity, and impact mass) play an important role on the duration-dependent tolerance to impact loading.

References

[1] Kendall, Marshall, et al. "Accident reconstructions of falls, collisions, and punches in sports." Journal of concussion 4 (2020): 2059700220936957.

[2] Newman, James A. "Head injury criteria in automotive crash testing." SAE Transactions (1980): 4098-4115.

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