Are smart mouthguards the answer to better concussion protocols?

The Washington Post

April 2, 2024

On Feb. 10, in the 17th minute of an international rugby match, Scotland’s George Turner made history. He was the first player in the annual Six Nations Championship, one of rugby’s premier competitions, to be flagged by a high-impact alert from an instrumented mouthguard, requiring him to be assessed by a sideline doctor.

World Rugby is the first sports governing body to implement instrumented mouthguards, also known as smart mouthguards, into its Head Injury Assessment protocol. The technology has been used for years as a research tool by doctors and professional sports leagues, including the NFL, and while the dangers of a concussion are well known, the ability to spot them during competition can be murky.

“One of the biggest reasons concussions are so hard to study is because they are actually a rare event,” said Éanna Falvey, World Rugby’s chief medical officer, adding that they happen about once every 700 to 800 tackles or roughly 1 every 2 games. “The problem with that is, that’s like trying to find the needle in the haystack: What’s that tackle that causes that incident?”

How World Rugby selected a smart mouthguard

World Rugby, which has 8 million players in 132 national member federations, rolled out its protocol in January after years of conducting studies. From four prototypes, officials at World Rugby chose the smart mouthguard produced by Prevent Biometrics, a Minnesota-based company.

Under the new system, a sideline doctor uses an iPad with Prevent’s app to monitor head impacts. When a player suffers a collision that reaches a designated threshold, the screen turns red, and the player’s number and team are identified in an alert. That player is pulled off the field, and a doctor conducts an assessment.

“This is not replacing the clinical process; this is in addition to it,” Falvey said, comparing the smart mouthguards to tools like video replay that are also used to assess potential head injuries. “It’s not making a diagnosis; it’s not telling you that the guy is concussed. It’s telling you that … this is a player who’s had an event and you want to have a look at this guy in a quiet room and you want to go through the tests.”

Adam Bartsch, Prevent Biometrics’ chief science officer, has been involved with the idea of a smart mouthguard for two decades. In 2003, while he was a graduate student from Ohio State University conducting research on crash-test dummies, he attended a seminar on the first data collected from football helmets during a biomechanics workshop in San Diego. During the question and answer session, John Melvin, a leading doctor on head impact research and a NASCAR safety consultant, suggested using mouthguards instead of helmets to get more accurate data. Bartsch instantly thought, “That’s where I need to put the sensors.”

The idea stuck with him. In 2009, while he was getting his PhD in mechanical and aerospace engineering, Bartsch was introduced to his new neurosurgery fellow trainee, Vincent Miele, who was an amateur boxer and ringside physician. Miele said there needs to be an “electronic TKO,” Bartsch said, to avoid boxers sustaining unnecessary punishment in the ring. From that meeting in the Cleveland Clinic cafeteria, the smart mouthguard was conceived. After almost a decade of research conducted by neurosurgeons and a NASA-trained mathematician, Prevent Biometrics secured the product’s intellectual property licenses with Cleveland Clinic, and Bartsch joined the company.

In 2021, World Rugby and Prevent Biometrics teamed up with the University of Otago to conduct a study in New Zealand, one of the few places where people were still playing community rugby during the coronavirus pandemic. More than 17,000 head acceleration events by hundreds of players from the under-13 age group to adults were analyzed. The peer-reviewed, independent study was published in 2023.

Initially, the mouthguards were used only as a medical research tool, but World Rugby said advances last year in fit and technology meant that it was ready to use the devices as part of its Head Injury Assessment protocol.

Determining the threshold for an alert

To transform the mouthguards from a research tool to an integral part of its in-game concussion assessment, World Rugby needed to identify when to trigger an alert.

“I think one of the challenges with instrumented mouthguards is the idea that there is a numerical threshold of acceleration … that is indicative of a concussion,” said Kristy Arbogast, research director of the Minds Matter Concussion Program at Children’s Hospital of Philadelphia. “The science doesn’t really support that. We all have our individual threshold for injury … so it’s hard to draw a black-and-white line.”

Gender, age, genetics and medical history can factor into someone’s susceptibility to concussions, so this product can’t be used as a diagnostic, she said, but for World Rugby, it’s “a second set of eyes” for potential head injuries that were missed by coaches, trainers and doctors.

The goal for World Rugby was to find a point at which a head acceleration event has a higher likelihood of being a concussion. To define that threshold, it needed data — and a lot of it. But it also didn’t want every head movement registered, so a baseline was set; the mouthguard collects only data on events above 8 g’s — short for G-force, the measurement of an impact on the body relative to planetary gravity.

“My kids jumping on the trampoline is about 8 g’s,” Bartsch said. “You get into a pillow fight, you’re talking about 10 to 15 g’s. A sledgehammer to a helmeted head — 60 g’s.”

In about three years, the mouthguards gathered information on more than 200,000 head acceleration events, Falvey said.

World Rugby then plotted out its mounds of data to find a balance to set its threshold. A number that’s too low could overwhelm the medical staff and disrupt the game with unnecessary evaluations. A number that’s too high could lead to no alerts and the questioning of the purpose of using instrumented mouthguards at all.

Falvey identified the sweet spot as having about one extra alert per game. At the 2024 Six Nations Championship, on-field doctors were flagged when a player’s mouthguard registered an acceleration above 70 g’s and 4,500 radians per second squared (rad/s2). The alert was sent only if both thresholds were reached.

As more data becomes available, these thresholds are subject to change. Falvey even suggested that within six months, they could find that G-force and angular acceleration might not even be the best measurement to use to determine when a player should enter concussion protocols.

World Rugby has already shown a willingness to move the numbers. As it was testing the protocols at last year’s WXV, a women’s international rugby competition, there were a high number of alerts — including one game that had four — so World Rugby adjusted the women’s threshold from 50 g and 3,500 rad/s2 to 60 g and 4,000 rad/s2 for the Women’s Six Nations Championship that began March 26.

While Falvey praised the mouthguard technology’s ability to flag potentially harmful incidents that may have previously been overlooked, he said the biggest prize in this implementation is the amount of data that’s being collected that can be used to lead to major changes in player safety.

“It’s a bit like people’s approach to the covid vaccine,” he said. “Me getting the vaccine was for my benefit, but in reality, it was all of society who benefited from everyone being vaccinated. What we’re trying to do here is get the data set big enough to make meaningful decisions.”

When it comes to trying to reduce head injuries, sports leaders are all on the same team, and the NFL said it is closely watching World Rugby.

“We’ll track carefully the success they have with [the mouthguards] and what challenges exist,” said Jeff Miller, NFL executive vice president overseeing health and safety.

Officials at World Rugby and the NFL said they share their data with each other and other sports organizations, information that can lead to rule changes and improvements in equipment.

A rugby player grips the ball while gritting her teeth. She is launched forward, almost horizontal, bent over two players of the opposing team as they try to tackle her. Three of her teammates run toward the scene. Two have head pads on.

“I think the different sports leagues have come together around sharing information a lot more in recent years,” Miller said. “… Those relationships grew stronger as we tried to navigate our way through covid by keeping our players safe.”

The mouthguards are also having an impact outside the sports world. The Department of Defense has been a client of Prevent Biometrics since 2017, using the devices to monitor blunt forces that can happen in parachute landing falls, combat training and other military activities.

“Football, hockey, lacrosse, rugby — they want to eliminate concussions and reduce the risk of their players because it’s a big deal,” Prevent Biometrics CEO Mike Shogren said. “And unlike a knee injury where it’s pretty easy with diagnostics to figure out what happened, this is an unknown. The DOD, World Rugby and all of our clients are sharing data. The bigger the data, the better.”

What to expect next in the effort to protect athletes

The NFL isn’t ready to include instrumented mouthguards in its concussion protocols, but it also hasn’t ruled it out.

“I would never say never,” Miller said. “Anything that helps advance player safety is something that we would take very seriously and consider. The system we have now with numerous experts, independent as well as club doctors and trainers, looking to identify players who need care is also one that has proven huge advances over where concussion identification was a few short years ago. … But if there is more that can be done with objective criteria, including data collection and sensor identification, that’s most certainly something we would take seriously.”

The NFL began using instrumented mouthguards for research in 2019 after realizing helmet sensors didn’t provide accurate data on head impacts.

“From an engineering perspective, this is a game changer because it’s anchored to the skeletal structure of the head,” said Arbogast, who worked with the NFL to help design its own instrumented mouthguard.

The NFL has continued to expand its use of the technology and has partnered with eight colleges and universities for a research initiative to gather data on more than 300 players.

A hand holds an iPad with many squares, varying between blue and gray, in front of a larger desktop setup. On the iPad’s case is a cardboard rectangle with a list of players.

For Prevent Biometrics, Shogren said, the biggest challenge it faces in growing its product is trust, and World Rugby buying in has increased its visibility and credibility around the world.

Bartsch said: “It might be a little hyperbolic, but the fact that we had that one alert [on Feb. 10] is sort of the end of the beginning of the tech, and now we’re launching off into broad usage of the tech and even deeper learning. [Artificial intelligence] is a real thing in this space when you have these massive data sets. The sort of things people are going to start teaching me about this data, I’m really excited about.”

But as the mouthguards become more affordable — Prevent’s product costs between $250 and $500 — Arbogast has concerns about it being marketed to a broader audience.

“I worry about it being implemented outside of a research study or controlled environment where a parent or coach doesn’t appreciate all these nuances and look at it as a red and green light,” said Arbogast, who has used instrumented mouthguards to research head injuries in boys’ and girls’ soccer, lacrosse and basketball.

“If an impact occurs and it’s not above some number, they immediately assume that the child is fine. And I think that’s where we veer toward where the technology isn’t helpful, and it may give us a false sense of security.”

As for using instrumented mouthguards as a research tool, she said, “I think this is the future.”

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