The play didn't look particularly violent, as far as football goes. Philadelphia Eagles tight end Zach Ertz ran a short route over the middle of the field. The pass was on target, but it arrived at the same instant as a Seattle Seahawks defender. The players collided; both of them, and the ball, all fell to the ground.

Ertz got up slowly, then gingerly walked off the field. In a private tent on the team's sideline, medical staff put the player through series of tests. The diagnosis: a concussion.

On the other side of the country, in Northern California, when Zach's mother, Lisa, received the news she sat down on the floor of her kitchen and cried. 

As the mother of four boys, Lisa has had her fair share of triumphant moments: Now in his fifth NFL season, Zach, her oldest, is one of the league's best tight ends and was the Eagles' leading receiver this year. In addition to football, her sons have received awards and won championships for their play on the basketball court and the baseball field.

Like a lot of athletes' mothers, though, she's also had her share of scares. In 2011, when her son Shane was a senior on the Monte Vista High School football team, he took a blow to the head so severe that it knocked him unconscious for several minutes. Paramedics had to stabilize his body and move him onto a stretcher, and he was taken off the field in an ambulance. Lisa watched the entire thing from a few feet away. "It was hideous," she says. "Everybody silent, people praying. A friend had to drag me away down the field."

Shane, who was being recruited by Division I football programs, missed a week of school. The headaches lingered for weeks after. Eventually, he and his family came to the painful conclusion that he needed to quit the game forever.

At the time, Lisa made a promise to herself: When she found a way to do so, she would fight to make football safer.

Fast forward six years, and Ertz has become an advocate and occasional spokesperson for Seattle-based helmet startup Vicis. Co-founded in 2013 by a neurosurgeon, a mechanical engineer, and a former healthcare exec, the company has created a football helmet that's radically different than its predecessors. The helmet, called the Zero1, has a pliable outer shell that deforms if you press it firmly.

Vicis's design finished first among 33 helmets in a safety test conducted by the NFL in early 2017. In the NFL, where players are free to choose their own helmets, about 60 players have worn the Zero1 in games this year, including the Seahawks'​ Russell Wilson, the Chiefs' Alex Smith, and the Texans' Jadeveon Clowney.

Not among those wearing the new helmet: Zach Ertz. 

Much to the chagrin of his mother. "When your kids become adults," Lisa says, "you can suggest and you can guide and steer, and you can beg for certain things that are really important. But honestly, this is how he makes his living. There's only so much I can do."

Facing the Problem Head-On.

The Ertz family's dilemma highlights a challenge Vicis faces: Athletes are creatures of habit, especially at the highest levels. Football players know the risks of playing; creating a safer helmet doesn't mean they'll want to wear it, no matter how comfortable it is.

"He's been wearing the same helmet since high school," Lisa says. "He's so used to it." 

To address that, Vicis has designed its helmet to be easily customizable. It's offered in three sizes, and the pads inside can be fitted differently for different players. Still, in the NFL, where inches and milliseconds can mean the difference between winning and losing, familiarity often wins. 

Part of the solution, from both a public health perspective and a company growth perspective, is to get the helmet onto the heads of athletes at the lower levels. At this point, that's a tall order: The Zero1 sells for $1,500, four or five times more expensive than many of the helmets offered by the industry's incumbents, Riddell and Schutt. Currently, Vicis is working on a helmet geared toward youth athletes, which will have a more affordable price point.

In 2016, the startup launched the Vicis Foundation, a non-profit organization that raises money for communities and schools to get the sports equipment they need, from shoulder pads and jerseys to, of course, the Vicis helmet. It operates independently from the startup and Lisa serves as its president, tasked with fundraising for teams that can't afford to outfit their players. She first landed on the Vicis co-founders' radar in 2015; Zach had played in college with Seahawks receiver and Vicis investor Doug Baldwin.

"To me, it's about saving the sport," Lisa says. "It's such a unifier, and it means so many things to so many people. But it needs to be safer."

On Saturday Jan. 13, Zach's Eagles, the No. 1 seed in the NFC, will face the Atlanta Falcons in a playoff game in Philadelphia. Lisa will be there. Despite her fears and despite his team playing its home games 3,000 miles away, she travels to as many of his games as possible. This year, she's made it to eight.

"I watch through finger goggles," she says. Her usual strategy, she admits, is a Bloody Mary (or two) before game time. Then she gets to her seat an hour before kickoff, just to make sure she doesn't miss anything. When she can't make it to a game, she asks a friend or family member who lives nearby to go in her place. "My goal is that someone who loves my son is in the stands for every single game," she says. "I don't want him to ever look up and not see someone."

It's impossible to know whether Zach would have gotten his Dec. 3 concussion if he were wearing the Vicis helmet. The company is sure to note in interviews and in its promotional materials that no helmet can prevent concussions. But Lisa believes in the helmet, and predicts that he'll switch to it next year. "He's promised me he'll give it another try," she says.

Meanwhile, Zach has at least one game left to play this year--and maybe more. "The Super Bowl is February 5, and trust me, for Zach's sake I absolutely hope the Eagles are playing," she says. "That's your dilemma as a mom. You want your kids to see their dreams come true. But part of you wants your son to be home."