"It's frustrating," Heatley said in a report on the team's Web site. "It was kind of an unlucky play, but that's hockey. I'll just rehab as quick as I can and try to get back as quick as I can."
Heatley was injured in the Senators' 3-2 win over the Detroit Red Wings Saturday.
The injury ends his string of 207 straight games. Since joining the team 2 1/2 seasons ago, Heatley has played in every game.
"If there's a positive," Heatley said, "I'll get some rest here and be ready for the end of the season and the playoffs."
Heatley, who has 25 goals and 56 points, has likely lost his shot at a third straight 50-goal season.
Coach John Paddock said "it's certainly not a nice thought" to lose a player of Heatley's caliber for such a long stretch.
"You're talking about a real goal scorer ...," Paddock said.