It was not determined how long he will be out.
Also during Thursday's game, Lions linebacker Brian Williams dislocated his left shoulder and left the game.
Stewart, who led the Lions with 1,021 yards rushing last season,
was hurt when he was hit at the line of scrimmage by Bills safety
Coy Wire and then tackled from behind by three other defenders.
Stewart lay on the field for several minutes as Lions trainers
tended to his right shoulder. He then gingerly held out his hurt
arm as he was led off the field and taken to the locker room for
The injury occurred during the Lions' second series of the game.
Stewart had 27 yards rushing on seven carries and one catch for 12
yards before getting hurt.
The series probably would have been Stewart's last of the game.
Information from The Associated Press was used in this report.