In 1994, the National Football League (NFL) commissioned a series of studies analyzing concussions in professional football players. The first of these studies, published in the October Neurosurgery, provided the most specific details to date on the point and speed of impact in concussions that occurred during NFL games and on the biomechanical reaction of the head when a player suffers a concussion. “We hope that our findings will lead to improvement not only in football helmets but in head protection gear in general,” lead investigator Elliot J. Pellman, MD, told NEUROLOGY REVIEWS. Dr. Pellman is Chairman of the NFL Committee on Mild Traumatic Brain Injury.

LET’S GO TO THE VIDEOTAPE

Dr. Pellman and colleagues reviewed videos of plays that led to significant head injuries—mainly concussions—in NFL players between 1996 and 2001. From these videos, they were able to determine the location of impact on the injured player’s helmet and the speed of players just prior to collision.

The investigators identified 182 cases of concussion or severe impact to the helmet. The point of impact was unclear on video in eight collisions, leaving 174 for analysis. The investigators used three-dimensional video analysis to re-create 31 of the injuries using crash test dummies. During these reenactments, they collected further data on the speed of impact and the biomechanical response of the head to the impact.

UNIQUE DATA

Video analysis determined that 29% of the concussions were related to a strike to the face mask while the remainder involved a blow to the helmet shell. Helmet-to-helmet impact caused 61% of the cases; hard contact with another player’s shoulder pads or arm and hitting the head on the ground were each responsible for 16% of the concussions studied.

The typical scenario that resulted in a concussion involved a player running toward another player who was unaware of the impending collision. The player delivering the blow typically lined up his head, neck, and torso before impact and collided with the concussion victim at an average speed of nearly 21 miles per hour (mph). The unprepared player’s head was severely jarred, as shown by a mean change in head velocity of about 16 mph upon impact, the researchers reported.

That change was significantly greater in players who suffered a concussion than in those who were hit but uninjured and in those who initiated collisions that caused a concussion. The peak acceleration of the head after impact was also significantly greater for concussed players.

Concussions were strongly associated with impact-related translational acceleration of the head—that is, movement of the head in a straight line—and not rotation of the head. Also, concussion appeared most likely to occur when a player was struck on the face mask or side of the helmet, or fell so that the back of the helmet hit the ground. “These are all unique data, things we have never documented before,” Dr. Pellman noted.

INSTANT REPLAY

The next two studies in Dr. Pellman’s series, scheduled for the December 2003 and January 2004 issues of Neurosurgery, will offer a more in-depth look at the specific types of helmet impacts associated with concussions in NFL players. They will also describe the body positions that make the players most vulnerable to concussion and identify the most frequent signs and symptoms of game-related concussions.

The current study provided some preliminary data on the last topic. Based mainly on the reports of examining physicians, Dr. Pellman’s team determined that 21 of their reenactments were modeled after plays that actually did result in concussion; two more of the reenacted plays led to probable concussions. Memory problems and cranial nerve symptoms were the most common presenting symptoms in these players.

“Our ultimate goal is not to make improvements in football helmets, because we lack the expertise to do that,” related Dr. Pellman. “Rather, we hope to develop science that leaves helmet manufacturers and testers with no choice but to make improvements.”

NR

—Timothy Begany

Suggested Reading
Naunheim R, McGurren M, Standeven J, et al. Does the use of artificial turf contribute to head injuries? J Trauma. 2002;53:691-694.
Pellman EJ. Background on the National Football League’s research on concussion in professional football. Neurosurgery. 2003;53:797-798.
Pellman EJ, Viano DC, Tucker AM, et al. Concussion in professional football: reconstruction of game impacts and injuries. Neurosurgery. 2003;53:799-814.

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