Tkachuk replaces teammate Drake Batherson, who injured his ankle in a 5-0 home win against the Buffalo Sabres on Tuesday.
Batherson was pursuing the puck behind the net late in the first period when Sabres goalie Aaron Dell hit him. He fell into the end boards awkwardly and twisted his ankle.
"I was just trying to buy some time for my defenseman and step into [Batherson's] lane," Dell said after the game. "I hope he's all right. I wasn't trying to hurt anybody."
Batherson had to be helped off the ice. Dell was not given a penalty but was suspended three games by the NHL on Wednesday for interference.
"It's a bad play and it's an unfortunate thing that a young kid's not going to be able to go to an All-Star Game," Senators coach D.J. Smith said. "It's dangerous."
The 2022 NHL All-Star Skills presented by DraftKings Sportsbook is Feb. 4 (7:30 p.m. ET; ESPN, SN, SN NOW, TVAS), and the 2022 Honda NHL All-Star Game is Feb. 5 (3 p.m. ET; ABC, ESPN+, SN, SN Now, TVAS) at T-Mobile Arena.
It would have been the first NHL All-Star Game for Batherson. The forward leads the Senators with 34 points (13 goals, 21 assists) in 31 games.
Tkachuk is second to Batherson with 27 points (12 goals, 15 assists) in 33 games. The forward also played in the 2020 All-Star Game.
