The Rams said Monday that they wouldn't place Bulger on season-ending injured reserve.
Kyle Boller will start at quarterback for the Rams in this Sunday's game against the Seattle Seahawks. He has played in three games this season -- his first with the Rams after five with the Baltimore Ravens -- and thrown for 481 yards and two touchdowns with three interceptions.
Boller finished a 36-17 loss to the Green Bay Packers after Bulger injured his rotator cuff on a sack. Boller then started the next two games, a 35-0 loss to the San Francisco 49ers and a 38-10 loss to the Minnesota Vikings, before being shaken up in that second contest and replaced by Bulger.
Bulger underwent an MRI exam on his groin and hamstring Monday and was due for a second MRI on what the Rams believed was a swollen knee. He also was to be tested for concussion-related symptoms Tuesday.
"Marc Bulger's pretty banged up," Spagnuolo said before the leg injury was revealed. "Marc's got a few things going on."
Spagnuolo was hopeful that guard Richie Incognito can return after missing three games plus the bye week with a foot injury.
The Associated Press contributed to this report.