General manager Darcy Regier announced Friday the center is expected to miss four to six months, and will have surgery to repair the injury in the next couple of days.
Roy was hurt a day earlier in the first period of a 4-3 loss to Florida. Carrying the puck into the Panthers' zone, Roy was driven into the boards by defenseman Dmitry Kulikov.
Roy leads the Sabres with 35 points (10 goals, 25 assists) and team forwards in ice time (20:03) over 35 games this season.
The injury is a big blow for the offensively inconsistent Sabres (14-17-4), who are tied with Florida for 11th in the Eastern Conference.