Updated:PITTSBURGH (AP) (AP)ong> - Ben Roethlisberger's sprained right shoulder is just the start of his problems.
The Pittsburgh Steelers quarterback said Wednesday he also dislocated a rib while getting sacked in the third quarter of Monday night's win against Kansas City. Roethlisberger sprained the SC joint in his shoulder on the play but says the rib issue is a bigger concern.
Roethlisberger said doctors are concerned the rib could cut into his aorta. He's already been ruled out of Sunday's game against the Baltimore Ravens. Backup Byron Leftwich will start in his place, though Roethlisberger doesn't believe the injuries will end his season.
"I don't think so, I don't know though but I'm not a medical expert," Roethlisberger said. "I just know I'm going to do what I can to get back."
Roethlisberger added he's in considerable pain and has slept just four hours over the last two nights. He wore a black sling in the locker room to prevent the rib from moving around. Doctors are worried if the rib gets jostled before it heals it can cause internal bleeding.
"I can move (the arm) around, that's not the issue," Roethlisberger said. "Sometimes when I do move it the rib will kind of pop out of place again, which is pretty painful. I just try to keep it as still as I can for the most part."
The quarterback added the pain level is "nine on a scale of 1-10."
The Steelers (6-3) have won four straight to pull within a game of first-place Baltimore (7-2), but Roethlisberger left the 16-13 overtime win over the Chiefs in the third quarter after getting slammed to the ground by Kansas City linebackers Tamba Hali and Justin Houston.
The two-time Super Bowl winner underwent extensive testing Tuesday to determine the extent of the injury to his throwing shoulder. He was waiting further word on Wednesday about how to move forward because of the unusual nature of the injury.
"From what (the doctor) said he's trying to talk to experts because there is no case study over the exact same thing," Roethlisberger said. "From what I heard, from what he told me it was a 1998 rugby player or something."
Leftwich completed 7 of 14 passes for 73 yards after replacing Roethlisberger. He will be making his first start since 2009 when he played for the Tampa Bay Buccaneers.
The former first-round pick has been plagued by injuries the last two seasons and said he felt a little rusty after seeing his first regular season action in nearly two years, though coach Mike Tomlin anticipates the rust to wear off this week.
"I'll trust his assessment if that's his assessment, but I'm not overly concerned about it," Tomlin said. "We got a lot of ball in front of us this week. If he is the guy, he'll get a great opportunity to prepare and we'll expect him to play winning football."
The Steelers have managed to survive without Roethlisberger before. They are 7-5 in games without their franchise quarterback since 2005, including a 4-1 mark over the last two seasons. Roethlisberger missed the first four games of the 2010 season after being suspended for violating the league's personal conduct policy, but Pittsburgh started 3-1 behind Dennis Dixon and Charlie Batch, who will serve at Leftwich's backup on Sunday.
Batch filled in nicely last December when Roethlisberger was sidelined with an ankle injury, throwing for 208 yards in a 27-0 win over the St. Louis Rams.
Leftwich is 0-6 in his last six games as a starter, his last victory coming on Oct. 8, 2006 while playing the Jacksonville Jaguars, who selected Leftwich with the seventh overall pick of the 2003 draft.