Haggan was in the pile of players attempting to tackle Jets quarterback Tim Tebow on a 1-yard run, but a New York player landed on the linebacker's arm. The 6'3", 274-pound Haggan left the game with the team's medical staff and did not return.
He has played in seven games so far this season, recording 10 tackles and a sack.
In addition, St. Louis receiver Danny Amendola left the game just before halftime with a right foot injury after he changed direction and attempted to make a catch on an inaccurate pass. While the receiver returned in the second half, the injury did nothing to quell concerns about his durability. Amendola has left three of the past eight games with various injuries.
The third-year wide receiver has 50 catches for 538 yards and two touchdowns this year.