It sounds like the reason Ben Roethlisberger isn't playing Sunday goes beyond his sprained right shoulder. According to ESPN NFL Insider Adam Schefter, Roethlisberger also injured his ribs Monday night against the Chiefs. This had been reported by the Pittsburgh Post-Gazette as well.
A source told Schefter that doctors are concerned that the quarterback's rib injury could lead to more internal damage if he were to play anytime soon. The rib injury, which occurred on the same hit that hurt Roethlisberger's shoulder, was described as rare and dangerous. This has become a bigger concern than the shoulder injury.
Since Roethlisberger took over as the starting quarterback in 2004, Pittsburgh is 86-37 (.699) with him and 7-5 (.583) without him.