Islanders head coach Ted Nolan said he believed there was a fracture and that he expected Martinek to miss four to six weeks.
"It's tough, you never like seeing guys going off on a stretcher," Islanders winger Trent Hunter said. "Marty's a huge part of our team, so we'll just hope he's able to recover quick."
At 12:16 of the first period Martinek was heading back into his own zone to retrieve the puck when he took a hit from Canadiens rookie Guillaume Latendresse into the end boards.
As he was falling to the ice, Martinek's left ankle appeared to turn underneath him. Martinek remained on the ice for several minutes before being taken off on a stretcher.
"I was just finishing my check," Latendresse said. "When I turned around I saw him go down, but I don't know what happened."