In the second period of Game 2 of the Stanley Cup Final, Jack Eichel was skating across the middle of the ice when he got rocked by Matthew Tkachuk.

It was one of the most vicious -- yet clean -- hits you will see. Eichel's helmet popped off as the Vegas center got on all fours. He bobbled up, winced and skated directly to the Golden Knights dressing room.

A scrum broke out on the ice as panic set in elsewhere. Eichel was less than two years removed from artificial disk replacement (ADR) surgery on his neck, a procedure that had never been performed on an NHL player before. "He hit me on the shoulder," Eichel said. "But I was more worried about the whiplash."

Dr. Mark Lindsay, Eichel's chiropractor and confidant, received a flurry of texts -- including from San Francisco 49ers running back Christian McCaffrey, Eichel's rehab partner for the first three months post-operation. Everyone wanted to know if Eichel would be OK.

"Every time I watch him, I get nervous," said Dr. Chad Prusmack, the neurosurgeon who performed Eichel's procedure. "I've been less and less nervous lately."

But on this night, Prusmack waited in angst. "I almost threw up," he said.

Eichel returned for the third period. On his first shift back, he recorded an assist. Turns out, he just got the wind knocked out of him.

"In a sort of selfish way, I was happy when Jack got hit," Lindsay said. "Because it showed the resilience of what we did."

Eichel's medical saga -- his quest for this specific surgery and subsequent blockbuster trade to Vegas -- rattled the NHL. Eichel unequivocally fought for himself, showing agency and gumption that's rare for NHL players who operate in an environment where they're conditioned to conform.

"The hardest part is some people want you to fail in some ways," Lindsay said. "But someone had to be the pioneer. Years from now, we'll be talking about this as the Jack Eichel surgery, in the same way as Tommy John."

EVEN BEFORE EICHEL became just the second freshman to win the Hobey Baker Award while at Boston University, he was touted as the next great American hockey star. Eichel's explosive first two strides are as impressive as anyone's; his blend of size, power, creativity and vision forecast greatness. The Buffalo Sabres drafted Eichel at No. 2 in 2015, right behind Connor McDavid. But Eichel's early career was defined by individual success -- scoring 137 goals in his first five seasons, being named captain at age 21 -- amid team frustration, as the Sabres extended the NHL's longest playoff drought.

And then he injured his neck.

Eichel can't pinpoint exactly when the issues began. "A few years ago, I started dealing with some symptoms," he said. "It wasn't necessarily something that was going to keep me out of the lineup, but I was dealing with it and playing through it."

In a March 2021 game against the Islanders, Eichel hit his head against the boards, which resulted in a herniated disk in his neck. He missed the rest of the season.

Sabres doctors first recommended Eichel take a conservative approach, avoiding surgery and instead rehabbing. When the condition worsened, the Sabres recommended anterior cervical diskectomy with fusion (ACDF), the traditional gold standard for NHL players. The ACDF surgery has been around for about 50 years, whereas the ADR surgery was much more recent (around 10 years).

Eichel's personal medical team didn't just want to fix Eichel's disk. It wanted to account for how that disk affected the rest of Eichel's body while protecting the traits that made him elite.

"The spine has three curves, and the reason it's shaped like that is because it's for movement," Lindsay said. "The best athletes in the world move with these transition areas in the spine. Guys like Connor, Cale Makar, Patrick Kane, Jack, the outliers, they move really well there."

Lindsay rehabbed several NFL players who had the fusion surgery, and he didn't like the resulting rigidity in a segment of the spine.

"In hockey, you're moving and the puck is moving," Lindsay said. "When you see it with Jack on the ice, he's very fluid in his movement. He would have lost that, just to make it super simple, he would have lost the accuracy to make those nice passes that he makes."

Lindsay encouraged Eichel and his father, Bob, to fly to Colorado to visit Prusmack for a second opinion.

"The fusion has been proven and safe in contact sports, such as football, rugby and hockey," Prusmack said. "But it's not ideal."

Prusmack presented Eichel with a life argument: If he got the fusion, every 10 years, he would run a 10-15% chance of needing another surgery.

"Let's say life expectancy is 80 and Jack is 20," Prusmack said. "Well, 60 times 10[%] is more likely than not he'll need another fusion in his lifetime, and he may need several. That could be a problem when he's older. ... I don't know if Jack knows what it means to be a grandfather. I don't know if I do, but I'm there to help him with the goal in hand: He wants to play hockey. So I have to contextualize that issue. But I also need to protect Jack for whatever may happen down the road."

EICHEL BECAME BULLISH about ADR. However the NHL's collective bargaining agreement with the NHLPA says teams get final say over a player's medical care. The issue had rarely been raised by players before. Many didn't even know the rule existed. Suddenly, it was the hottest topic in the NHL.

Sabres doctors felt there was no data that gave them comfort that it would be successful for a hockey player and what the game entails. Eichel wasn't working a desk job. He was contracted for millions of dollars for a sport predicated on his health, and they wanted to be confident he would be cleared to play.

Eichel contested Buffalo's stance with the league and the players' union. Of a panel of spine surgeons, most, if not all, sided with the Sabres. Nobody was willing to be the first. Doctors had to account for the worst possible outcome: paralysis if an artificial disk gets shot into the spinal cord upon impact from a hit. Prusmack pushed back on this, saying: "To my best knowledge, no, there has never been a documented case of that. Even in high speed car accidents, it remains intact."

Eichel told the Sabres he wanted to be traded. He failed his Sabres physical ahead of the 2021-22 season, and GM Kevyn Adams stripped Eichel of his captaincy, saying that role belonged to a player who wanted to be in Buffalo.

At this inflection point, Eichel switched agencies to CAA Hockey. Time was of the essence as he felt increased numbness in his arm from the constant pressure to his disk. Eichel's new agent, Pat Brisson, worked with the Sabres to find a solution.

"Most general managers we spoke with were interested in a trade," Brisson said. "However, the majority did not have clearance from their medical staff to get involved in this unprecedented situation."

Brisson and Eichel collected additional opinions. They sent Eichel's MRI and visited top specialists across North America. Some agreed with the ADR, but, frustratingly for Eichel, many top doctors still wouldn't side with them. Dr. Robert Bray, a neurological spine surgeon in Los Angeles, ordered a full neurological evaluation, then wrote a letter stating it was urgent for a decision to be made one way or another. That created traction. But, Brisson admitted, only a small handful of NHL teams were willing to take on the risk -- either their medical teams wouldn't allow it, or owners didn't want to take on the remaining five years of a contract paying $10 million per season for a player with so many medical questions. Further complicating matters: Buffalo ownership insisted they wouldn't retain any money on Eichel's contract, which limited the market.

In November 2021, the Golden Knights made the gamble in a blockbuster trade involving two players (Alex Tuch and Peyton Krebs) and two draft picks (a first- and a second-rounder). Eichel was on Prusmack's operating table a week later.

And then the real work began.

"Honestly," Eichel said. "I had no idea what to expect. I was just so happy that chapter was over and I could focus on doing what I love again."

GOLDEN KNIGHTS MEDICAL DIRECTOR Jay Mellette worked on a rehab plan and was comfortable allowing Lindsay to lead the way. In fact, Vegas covered most of the costs -- with an NHL franchise supporting outside help and opinions a rare move.

Lindsay was stationed in Charlotte, North Carolina, having already committed to helping McCaffrey -- then with the Carolina Panthers -- through rehab for an ankle injury.

Lindsay asked McCaffrey if it was OK for Eichel to join too.

McCaffrey, just four months older than Eichel, welcomed a new friend and gladly shared resources, like his personal chef. After all, the rehab process can be isolating and monotonous.

"My approach, you're not just coming to a clinic on a Tuesday or Thursday," Lindsay said. "It's a full-time job."

Five days after surgery, Lindsay had Eichel back on the ice skating -- with no neck brace.

"I wanted him to get back into the natural flow of skating and movement as soon as possible," Lindsay said. "He was pretty rigid at first. Pretty stiff. I had him on the ice three days a week, just stickhandling. It was an emotional change for him. The frustration of dealing with everything he had to go through, being sidelined for so long. Getting back onto the ice was significant for him, emotionally."

But Lindsay knew Eichel's body was a mess after having overcompensated for his neck for so long.

"His pelvis needed a lot of work," Lindsay said. "He was inefficient in overall movements, and that's what I had to unwind."

Lindsay focused on rediscovering normal spinal movements and fluidity. Eichel and McCaffrey went rock climbing. They spent a lot of time in the pool, on trampolines and mimicking animal movements.

"It's amazing how normal I felt so quickly," Eichel said.

Eichel debuted for the Golden Knights in February 2022, three months after surgery and 11 months since his last NHL game. Eichel admitted he wasn't quite himself as he adjusted back. He was apprehensive of what it would be like to get hit. He also entered later in the season, at a time when the intensity ramps up, and the Golden Knights were already battling for a playoff spot. And, of course, the pressure and spotlight was on him.

For the first time in its history, Vegas missed the postseason, something Eichel had become used to.

AFTER A SUMMER of health and full training camp, Eichel bounced back. Lindsay lived in Las Vegas this season and works with Eichel every day he's home that's not a game day.

In Eichel's first playoffs, he's thriving, with 23 points in 21 games, second on the team to linemate Jonathan Marchessault. And Eichel is getting the most praise for his defensive play.

He is now one win from hoisting a Cup. "It's just crazy to think of how I got in this position," Eichel said. "I'm really fortunate to be here, to be part of this organization."

Eichel hopes his story can be an example for other players to advocate for what they believe in for medical treatment. Within a year of Eichel's surgery, two other NHL players also got ADR: Tyler Johnson of the Chicago Blackhawks and Joel Farabee of the Philadelphia Flyers. Eichel said a half dozen other players have reached out for his advice.

Prusmack is proud of what they accomplished but is incredulous over why they even had to fight. The NHL's CBA runs through the 2025-26 season. Prusmack has known Buffalo's doctor for years, calling him an "exceptional surgeon and good person." But Prusmack believes there are inherent biases when you report to a team (Prusmack previously served as a neurosurgical consultant for the Denver Broncos).

"The fact that an institution or team has trump value when you have to invasively cut somebody open, I think that needs to be changed," Prusmack said. "It's why Jack's story is so important. You now have elements of coercion based off economic agreements, which should not be part of our health system. Jack did what he did for the right reasons. I'm proud of him; that's hard to do in our culture."

Eichel said he doesn't feel any effects from the surgery at all; the only sign is a pink scar on the front of his neck.

"I'm so grateful for everyone who helped me get here," he said. "I've never been happier."