The defenseman was injured blocking a shot by Pittsburgh Penguins defenseman Marcus Pettersson in the second period of a 3-1 win in Game 4 that completed a sweep in the best-of-7 Eastern Conference First Round.
The Islanders will play either the Washington Capitals or Carolina Hurricanes in the second round; that first-round series is tied with Game 5 at Washington on Saturday (8 p.m. ET; NBC, SN360, SN1, TVAS).
"Anytime you lose a regular, it's a loss," Islanders general manager Lou Lamoriello said Friday. "But fortunately for us we have the depth on defense and players are ready. It gives an opportunity to another player."
Thomas Hickey is expected to be the replacement for Boychuk, who was playing on New York's top defense pair with Nick Leddy. Luca Sbisa, who helped the Vegas Golden Knights reach the Stanley Cup Final last season, is an option.
"He's one of my best friends here," Hickey said of Boychuk. "That's tough news, but we got big goals, big aspirations. If someone's not getting bumped and bruised and a little banged up, we're probably not getting to that point. We just move forward. A new opportunity, and obviously ample rest time in between here. I think that's fortunate; give him some extra days to heal up without missing time. We'll see where it goes."
Hickey had four assists in 40 regular-season games. He was a mainstay in the Islanders lineup before sustaining an upper-body injury during a 4-1 win at the Colorado Avalanche on Dec. 17 that kept him out more than two months.
When he did recover, Hickey often found himself as a healthy scratch with the development of Devon Toews, who has been a key component of New York's success since being recalled from Bridgeport of the American Hockey League on Dec. 19. Toews had 18 points (five goals, 13 assists) in 48 games with the Islanders this season.
"It could have been a lot tougher watching, [but] we played so good," Hickey said. "It's easy to watch when the team's rolling and playing good like that.
"I think it was three times where I had two, three weeks in between games. Difficult, but I think each time I came back from the first game, I did really well. This is a different beast, but I had the intensity coming into those games after a long break.
"To amp it up for playoffs, from my perspective, it's easier and we're playing such a simple game. For me jumping back in, I'd rather do this than jump into a regular-season game. It's nice motivation, a nice opportunity. I've been wanting to get back in since Game 1, so I'm ready."
Boychuk wasn't the only player missing from Islanders practice Friday; forward Cal Clutterbuck, who was injured in Game 4 at Pittsburgh, took a maintenance day and is expected to be fine when the second round begins. Defenseman Scott Mayfield also had a maintenance day.
"It's not unexpected; these things happen," Lamoriello said. "If you watch the other series and you watched last night, you see it. You can't let it get in the way. That's why you have players working as hard as they do who are not in the lineup to be ready. They know that these type of situations inevitably will come about. Obviously it did for us. We have a player and players to fill those roles."
Boychuk had one assist and was plus-2 in 16:16 average ice time against the Penguins and 19 points (three goals, 16 assists) in 74 regular-season games. He won the Stanley Cup with the Boston Bruins in 2011 and has 30 points (13 goals, 17 assists) in 101 NHL playoff games.
"Johnny brings a lot of those intangibles in the locker room," Islanders coach Barry Trotz said. "Obviously, he's a high-compete, high-character guy. He'll be missed, but he's around the team all the time. He always brings his leadership."
Trotz did not seem concerned the Islanders could be rusty when they finally play again. He's optimistic the layoff provides extra time to heal.
"We're looking at it as an advantage," Trotz said. "We're getting people fully healthy, we're going to practice the right way, we're going to do some scrimmage, all those things. We'll be prepared, don't worry."
