The Penguins are also without centers Sidney Crosby and Nick Bjugstad, each recovering from core muscle surgery.
Defenseman Brian Dumoulin is expected to be out at least eight weeks after having ankle surgery Sunday. Jack Johnson joined Kris Letang on the top defense pair, where Dumoulin normally plays, in practice Tuesday.
Justin Schultz returned to practice in a no-contact jersey after missing the past six games with a lower-body injury. The defenseman said he would likely need to practice a few more times before playing.
Schultz skated on a fourth defense pair Tuesday. His recovery was initially considered longer term.
"Just trying to get ready to get back into a game here," Schultz said. "I think I'm really close. ... I think I'm ahead of schedule now, so it's been feeling really good."
Stefan Noesen, signed to a one-year, $700,000 contract at the NHL level Monday, took line rushes at second-line right wing with McCann at center and left wing Alex Galchenyuk. He has 22 points (14 goals, eight assists) in 22 games with Wilkes-Barre/Scranton of the American Hockey League this season after playing 41 games with the New Jersey Devils last season.
"I don't think anybody would ever tell you they want to take things slowly," Noesen said. "For me, it's just going out there and playing hockey. Whatever happens, happens."
Hornqvist played right wing on the second line in the Penguins' most recent game, a 5-2 loss at the Blues on Saturday. Dumoulin was injured in his first shift of that game.
Through 27 games this season, Pittsburgh's injured players have included Crosby, Malkin, Letang, Rust, Hornqvist, Galchenyuk, Dumoulin, Schultz, McCann and Bjugstad.
"You can't think of that stuff," Johnson said. "Just take care of yourself. Be a pro. Control things you can control. There are some injuries you can't do anything about. There's bad ice in morning skate and [Rust] goes down in the corner. You can't control things like that.
"Other than that, take care of yourself. You train for the season, you train during the season, to stay healthy. Eat well. Get good sleep. Control things you can control."