Vegas did not say when the injury occurred for the forward, who had one assist in 18:43 of ice time in a 4-2 loss to the Buffalo Sabres on Tuesday.
Karlsson was fourth on the Golden Knights with 34 points (10 goals, 24 assists) in 49 games this season; he has two assists in his past 10 games.
Forward Nicolas Roy, who has five points (two goals, three assists) in 11 NHL games, was recalled from Chicago of the American Hockey League on Wednesday and played 11:19 in a 4-2 win against the Ottawa Senators on Thursday, when the Golden Knights were coached in their first game by Peter DeBoer after Gerard Gallant was fired Wednesday.
