To better understand concussions, scientists often rely on two less-than-ideal options: crash-test dummy-like models and human cadaver heads. Oren Petel thinks there’s another way.
The Carleton University mechanical and aerospace engineering professor is developing a synthetic head-form that would mimic how an athlete’s brain and skull respond to a hit or a fall. At his lab, he’s using what he learns from the way human cadaver brains jostle and bounce upon impact to try to recreate some of those characteristics with a rubbery brain encased in a polymer skull.
By creating a biofidelic head-form (one that can simulate the real thing), Petel hopes to improve the testing of helmet performance and gain insights about how concussions occur to better protect athletes’ brains.
“A lot of focus has been on new materials and new helmet designs, but we’re trying to come from a different kind of fundamental approach of how are we evaluating injury? And can we come up with a new way?” Petel says.
Amid concerns about concussions and chronic traumatic encephalopathy (CTE), a degenerative disease tied to repetitive hits to the head, sports equipment manufacturers are seeking innovations to try to make their helmets safer, while many researchers have set their sights on improving diagnosis and treatment. Petel says less attention has been paid to the development of better tools and methodologies for evaluating helmets and measuring concussive injuries.
Currently, helmet-testing typically involves putting a helmet on a plastic or aluminum head-form, similar to those of crash-test dummies, and performing drop tests or impacting it in a certain way, he says. Various acceleration and motion measurements are taken to determine the risk of injury, based on computer modelling, clinical evidence and data recorded from devices embedded inside helmets worn by athletes while playing.
But Petel seeks a more direct method. He says his goal is to create a head-form that, using a high-speed X-ray camera, would allow researchers to actually see what goes on inside, including how a brain deforms, or stretches and distorts. (Cadaver heads, which are scarce and rely on donors, are not used in helmet-testing, due, in part, to their variability and the large number of tests required to bring a helmet to market.)
Petel’s collaborator Blaine Hoshizaki, director of the University of Ottawa’s Neurotrauma Impact Science Laboratory, said helmets were originally designed to prevent catastrophic head injuries, such as skull fractures. But neither helmets nor the standards for testing them were intended to protect against conditions such as concussion or CTE.
While Hoshizaki said helmets cannot actually prevent concussions, they can mitigate some of the risks. And having a head-form that can more accurately measure injury will help produce better data “to guide the development of ... safer standards and safer helmets,” he said.
But beyond the potential applications for helmet design, obtaining better data may shed light on other opportunities to reduce the risks, such as changing the rules of contact sports, he suggested.
“Sports can be managed; you don’t have to run people in the head to play a game,” Hoshizaki said.
The team is taking a head-form – initially developed by Defence Research and Development Canada’s Valcartier Research Centre for assessing blast injuries – and modifying it for sports use. It is also adding anatomical features, such as a brain stem.
It’s a process that requires repeatedly comparing how incremental changes to the head-form behave against the response of human cadaver heads.
When cadavers become available, they undergo magnetic resonance imaging (MRI) scans at the Royal Mental Health Centre in Ottawa. They are then taken to Carleton University, where various impact experiments are conducted on them using a high-speed X-ray camera. MRI scans are performed a second time and neurosurgeons dissect them. The data collected is then used to refine the research team’s computer model, as well as the head-form.
While Petel said it may take years before the head-form is ready for use in standard helmet-testing, he and his team are already working with some sports equipment companies to try to apply some of their research.
At the Alzheimer’s Disease and CTE Center at Boston University, Lee Goldstein, an associate professor of psychiatry, said he applauds the Ottawa team’s efforts to develop a biofidelic head-form, since it would help scientists better understand how energy forces are translated into brain injuries. But he was wary about its potential use for improving helmet design.
There is no evidence to suggest a better helmet would prevent the long-term consequences of repetitive trauma, he said. Moreover, advances in helmet design may give people false-assurance that they are protected.
Goldstein’s own research has shown CTE is not tied to concussions, but rather to hits to the head. So even if a company can say it has created a better helmet that reduces the incidence of concussion, he said, “it doesn’t mean you’re going to reduce CTE.”
The best way to protect against such damage is to avoid head impact in the first place, he said. “The bottom line still stands: the fewer hits to the head, the better.”
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