Vatanen, acquired in a trade with the New Jersey Devils on Feb. 24, joined the Hurricanes at the Philadelphia Flyers for the start of a five-game road trip but left the morning skate early.
"This is a tough injury. He came off (the ice early); that's not good," Carolina coach Rod Brind'Amour said. "We were hoping to get him closer to playing. Now it looks like he's further away."
Vatanen hasn't played since sustaining a lower-body injury blocking a shot against the Dallas Stars on Feb. 1. Though no return date had been set, it was possible he could have played on the Hurricanes' trip, which began with a 4-1 loss at the Flyers on Thursday and ends March 12 at New Jersey.
The Hurricanes, who are without defensemen Dougie Hamilton (leg) and Brett Pesce (shoulder), are three points behind the New York Islanders for the second wild card into the Stanley Cup Playoffs from the Eastern Conference.
Hamilton is out indefinitely. The Hurricanes said Thursday that Pesce had surgery on his right shoulder that will sideline him for the remainder of the season. Carolina is also without its top two goalies, Petr Mrazek (concussion) and James Reimer (lower body); each was injured against the Toronto Maple Leafs on Feb. 22. General manager Don Waddell said Monday each goalie will miss at least another week.
Vatanen had 23 points (five goals, 18 assists) in 47 games with the Devils. He can become an unrestricted free agent after this season.
"[Vatanen's] a piece, talking about injuries, to slide into one these holes we definitely have," Brind'Amour said, "but doesn't look like that's coming back any time soon."
NHL.com deputy managing editor Adam Kimelman contributed to this report