Players using current football helmets aren't adequately protected against hits to the side of the head, which can lead to sometimes-lethal concussions and brain swelling, researchers said.
Ten helmets tested by researchers reduced the likelihood of traumatic brain injury by an average of 20 percent compared with no helmet in a simulation using crash test dummies. The most effective helmet reduced the risk by only 30 percent, according to data released Monday.
Concussion risks in sports are under increasing scrutiny as some deaths among young football players may have been prevented if those with head injuries had been kept off the field, according to a 2011 study in the journal Pediatrics. Research published in January 2013 found abnormalities in the brains of former National Football League players compared with those who didn't play the game. Current tests of helmets focus on impacts that lead to broken skulls, and don't adequately assess the chances of traumatic brain injury, researchers said.
"None of them are fantastic, sadly, and maybe that's the take-home message," John Lloyd, the study author and the research director at San Antonio, Florida-based Brains Inc., said in a telephone interview. "Maybe if football players realized that their helmet only reduced their concussion risk by 20 to 30 percent, they'd lead with the head less often."
Professional sports leagues, including the NFL and Major League Baseball, have changed their medical protocols for treating players with head injuries in response to concussion data. Football is the deadliest sport among youths, and 12 percent of football deaths are caused by head or neck injuries involving students who returned to the game after a concussion. Helmets may provide another target to make sports safer, Lloyd said.
The researchers used a crash-test dummy head and neck to see how well they'd respond with and without helmets to 12 mile- per-hour impacts. They conducted 300 tests, and also tried to measure how much the brain twists in the head. The tests allowed the neck to flex on impact, to better simulate rotational forces.
"When the head comes to a sudden stop, if it's rotating, the brain material is twisting inside the head," Lloyd said. "That can cause concussion and brain injury, including life- threatening subdural hematomas."
The best helmet reduced the likelihood of concussion by 30 percent, Lloyd said. That may be because it was lighter than the other helmets, causing the head and neck to rotate less. It wasn't as good at providing protection against direct impacts that might shatter the skull, and didn't perform as well on standard tests, he said.
The study also found that football helmets fared better against linear impacts, which lead to bruising and skull fracture. Compared with dummies with no helmets, the football helmets reduced the risk of skull fracture by 60 to 70 percent and reduced the risk of brain bruising by 70 to 80 percent.
The research was released in advance of a presentation at the American Academy of Neurology's annual meeting starting April 26 in Philadelphia.
Lloyd suggested that taking the facemask off the helmet and switching to a soft helmet may help diffuse the impact, leading to fewer brain injuries. This is how the scalp works to protect the brain, moving to allow force to be spread and absorbed, he said. Helmets made of softer materials and without facemasks were used in football more than 50 years ago.
"If we got away from hard helmets, we could use advanced materials to provide protection for the head and brain," he said. "The only downside is you wouldn't have anything to attach a faceguard to."
Brains Inc., a company focused on the biomechanics of traumatic brain injury, supported the study.