Kevin Dineen told reporters of Versteeg's injury early Thursday as the team prepared to take on Boston later in the evening.
Versteeg scored on Tuesday in Florida's 3-2 loss to Tampa Bay but was hurt when hit by Lightning player Radko Guda.
After bouncing around the NHL for a few seasons, Versteeg landed nicely in Florida in 2011-12, scoring 23 goals and 31 assists. He helped the Panthers make the playoffs for the first time since 2000.
But this season has been a disaster for team and player. Versteeg was earlier sidelined by a chest injury and had just two goals and two assists in 10 games.
Florida, in last place in the Eastern Conference, had already lost veteran centre Stephen Weiss to a season-ending wrist injury.