Note: This piece follows-up on my earlier overview of concussion research: http://secondlevelfootball.wordpress.com/2012/05/04/football-and-brain-injury/
The Virginia Tech-Wake Forest Center for Injury Biomechanics (CIB) is one of the most impressive injury research institutions around. While it’s best known for studies performed by the Virginia Tech branch on football helmets, the Center is a diverse operation. The bulk of the VT head injury office’s floor-space is actually devoted to classified military research, mainly related to vehicle crashes and IED impacts. The institute also studies the safety of civilian vehicles in crashes and the safety of children’s toys; the Wake Forest portion conducts a great deal of automotive work.
The CIB operates from within the VT-WF School of Biomedical Engineering and Sciences. Running the school is Dr. Stefan Duma, who also happens to be the man responsible for kick-starting modern helmet research and making it a topic of public interest. Duma has co-authored hundreds of papers on impact injuries; his work has lately included research on head impacts in baseball players, how organs are affected by crashes, and how vehicle-related impacts affect pregnant women. Duma has also been the key force behind the rapid growth and rising prominence of biomedical engineering at VT.
Almost all of his head-safety projects (as well as those of the faculty, staff, and students beneath him) are funded either by the National Institutes of Health, which is a federal organization that awards research grants to promising health projects, or the Department of Defense. The Center for Injury Biomechanics takes no money from the companies whose products are researched; even speaking fees are donated to youth football programs for the purpose of buying safer helmets.
Monitoring Player Impacts
Virginia Tech’s work in the field of helmet safety can be broken into two parts—lab experiments and fieldwork. The fieldwork ramped-up shortly after Duma’s arrival in 2000. Since there was little data on what happened on the college football field with regard to helmet impacts, that was where work needed to start. The first major step was outfitting 38 Hokies with HITS, or Head Impact Telemetry System, which is an electronics suite manufactured by Simbex.Helmet Impact Telemetry System; the piece at lower-left is the helmet sensor suite. Image courtesy Simbex.
HITS includes both computerized impact-reporting devices consisting of helmet sensors and the sideline computers that monitor the helmet sensors. The helmet sensors are simple accelerometers that measure linear and rotational impacts. They’re housed in a flexible plastic strip that also contains a battery and WiFi transmitter. The strip mounts inside a player’s helmet, where it fits between the side and crown cushions.
The collected data is wirelessly transmitted to a laptop computer on the sideline where it’s not only stored for later analysis, but also used for real-time monitoring of how hard (and where on their heads) players are getting hit. You’ll see images and TV footage of the computer being carted around inside a formidable looking crate packed with black egg crate cushioning (included in the image above), and you’ll also see all of it–computers and carrying crate–contained within a clear, rainproof plastic housing that looks like it could double as protection for the Pope. HITS also includes pagers that medical staff can wear to receive instant alerts on high-g impacts.
The entire VT team is being monitored by HITS, as are the teams for several other schools. This means nearly every single hit experienced by thousands of players across the country has been pooled and analyzed. The upshot is that undiagnosed concussions have been greatly reduced in teams using the equipment, perhaps to the point of being eliminated.
In my previous post I mentioned how a Tech player stayed on the field after receiving a concussion. The player was Brandon Manning in 2003; despite the concussion, he not only stayed on the field but led the Hokies with 16 tackles in the game. Since Manning stayed in the game, the concussion went unnoticed by trainers. Manning himself didn’t think enough of the hit to report it.
Thanks to HITS, Tech researchers/trainers are now notified immediately when any player’s head receives an impact acceleration at or near concussion-levels. When this happens, the player is immediately pulled from the practice or game for an evaluation—the system is even fast enough to routinely have players pulled from the field between plays. Its main limitation is signal problems encountered by players at the edges of the endzone.
Testing Helmets in the Lab
When enough impact data was collected, it was time to test helmets in the lab. This required that many varieties of adult football helmets be subjected to controlled impact testing. As the picture below shows, the process isn’t too different from using a crash test dummy in a car. The testing device is called a drop tower, and consists of a dummy head fixed to a vertical frame, which itself is fixed to an impact platform. Helmets (without facemasks) are fixed to the dummy head and dropped from various heights and with various parts of the helmet shell hitting the platform.Drop tower prior to helmet-mounting; standing at right is Stefan Duma. Image courtesy Virginia Tech.
The ability of the helmets to dampen various blows is measured and applied to probability data collected from the thousands of actual impacts recorded in on-the-field testing. This mix of helmet resilience and risk data is called STAR, or Summation of Tests for the Analysis of Risk. Fittingly, the helmets are judged on a “star” scale, with 5-star helmets providing the most protection against severe acceleration, and helmets with fewer stars performing less-well as the stars are reduced.
The results of these tests are made publicly available at http://www.sbes.vt.edu/nid. The first batch of results ran counter to the expectations of some, particularly in terms of helmet cost and intent. First, higher cost didn’t necessarily correlate to greater impact reduction—several 4-star helmets cost less than a similarly priced helmet that was demonstrated to be the worst tested. Second, as a few coaches at the Duma presentation I attended noted, several helmets marketed at skill positions showed better safety performance measures than some helmets marketed for use by players in the box.
There are some limitations to what the CIB is doing with researching helmet safety and concussions. Their goal is reducing high-risk head collisions either by improving helmet safety or reducing practices that lead to high-risk head collisions. It’s important to realize that their work is informed by well-documented research on acute brain injuries. While they’re certainly creating data that’ll be useful in measuring long-term health outcomes of concussions, we don’t have enough information to really understand the risk factors. The CIB researchers also aren’t in the position of commenting on the long-term effect of sub-concussive impacts. That’s the realm of epidemiologists and clinical neurologists, not biomechanics and engineering folks. I think the smart money is that the CIB’s work is going to improve long-term outcomes for football players across the country, but that’s still far from proven.
More specifically, we have to understand that the end result of their work will not be a concussion-proof helmet. Creating a helmet that would allow for the game to continue being played as-is while also being impervious to concussions is beyond our current technology. The CIB’s helmet safety guidelines are creating helmets that are better at distributing impact energy, which will reduce head acceleration in properly tensed and positioned players. Even the highest-rated helmet isn’t of much help in unexpected hits where there’s no muscular tension and skeletal alignment to resist impacts, or in angled hits that the human body has difficulty opposing.
Finally, the team is working on refining its testing methods. They plan to further investigate the ability of helmets to reduce rotational forces, to test helmet differences at varying temperatures that might alter the properties of the helmet shell and cushion, and possibly to include tests with facemasks. I doubt any of these refinements would significantly change STAR results–the variables have a measure of theoretical and statistical predictability–though more data is never a bad thing.
Because I thought it deserved its own space, I’ll talk about VT’s youth football research (and youth safety issues in general) in a later post.