Study by DHMC doctors evaluates efficacy of snowsports helmets

by Lauren Adler | 1/24/20 2:00am

A new study authored by trauma surgeons at Dartmouth-Hitchcock Medical Center suggests that wearing snow sports helmets may not protect against serious head injuries.

The study, published in the Journal of Trauma and Acute Care Surgery, found that while helmet use could mitigate the damage of some injuries — injured patients who wore helmets were half as likely as unhelmeted patients to suffer cervical spine injuries and only a third as likely to suffer skull fractures or scalp laceration — there were more injuries among skiers and snowboarders who wore helmets than those who did not. Helmeted patients were much more likely to sustain serious injury, intracranial hemorrhage, chest injury or lumbosacral spine injury. The researchers, led by Andrew Crockett and Eleah Porter from DHMC, also observed that even though helmet use nearly doubled over the course of the study, the rate of head injuries decreased by only six percent.

“[We noticed] an alarming trend — that more patients were coming in helmeted, but they were coming in severely injured,” Porter wrote in an email. “At times, more severely injured than their counterparts who were not helmeted. This was counterintuitive to us and most of the literature on helmets in ski trauma show the opposite.”

Porter and Crockett said they suspect that helmet wearers are lulled into a false sense of security that leads to more reckless behavior: while helmets do make people safer overall, they do not keep us as safe as we think they do.

Most helmet manufacturers voluntarily test their equipment to the standard set by the American Society of Testing and Materials’ Standard Specification for Helmets Used for Recreational Snow Sports, better known as ASTM F2040. This metric requires that helmets are tested in four different conditions (ambient, hot, cold and wet) by one- to two-meter drops onto three differently shaped anvils (flat, hemisphere and edge). 

The helmets hit these anvils with impacts of 98.1 joules, 58.8 joules and 49 joules, respectively. However, a relatively skilled recreational skier weighing about 200 pounds and traveling at about 40 miles per hour would hit a stationary object like a tree at about 14,500 joules. 

Additionally, ASTM F2040 does not require a shell penetration test — in which a 6.6-pound weight is dropped onto the helmet to determine the durability of the helmet’s hard shells — or a chin bar test, in which an 11-pound weight is dropped onto the helmet’s chin bar to determine its sturdiness. However, this test is more popular for motorsports helmets, as many snowsports helmets do not have chin bars.

Crockett referenced a joke from Seinfeld about skydivers: ‘You jump out of a plane, the chute doesn’t open, the helmet is now wearing you for protection.’

“This makes intuitive sense when you consider the forces involved in free-falling from the sky and smashing into the ground at high speed,” he wrote in an email. “It also makes sense when we discuss ski injuries. There, simply, are speeds at which the helmet may not be as protective as we would like, and it is at those speeds that it is ‘wearing you for protection’ and not the other way around.”

While snowsports helmets may not always fully protect users, skiers and snowboarders can still employ safe practices to keep themselves safe on the slopes.

PE Ski program director John Brady recommends that students not measure their progress by the steepness of the slopes on which they ski, as many injuries result from skiers and snowboarders attempting to tackle slopes outside of their ability.

“Stay in your comfort zone and learn to ski before you progress to more difficult terrain,” Brady said. “And, of course, skiing in control is the best way to prevent injury.”

Sean Norton, snowsports school director at the Dartmouth Skiway, also recommends that participants in snowsports follow the seven points of the National Ski Areas Association’s Responsibility Code: always stay in control and be able to stop; people farther down the mountain always have the right of way; do not stop in a location that obstructs a trail or is not visible from above; look uphill and yield to others when starting downhill or merging into a trail; always use devices to prevent runaway equipment; observe posted signs and warnings and keep out of closed areas; and before using any lift, know and be able to get on, ride and dismount safely.

But despite the equipment’s shortcomings, Porter, Crockett, Brady and Norton all strongly advocate for helmet use.

“We certainly encourage everybody to wear a helmet,” Norton said. “We require our students to, and everyone in our staff; we try to set a good example by wearing them.”