DeCastro's injury hurts Steelers' stability

The Steelers have had to use three different starting lineups on the offensive line in the first three preseason games. It looks like they will have to use a different combination next week -- and might have to adjust their plans for the season.

Right guard David DeCastro was carted off the field in the first quarter of Saturday night's preseason game at Buffalo. The Steelers announced that DeCastro is out for the game with a right knee injury, but it's not known whether he could be out a couple of weeks or for the entire season.

Pittsburgh selected offensive linemen with its first two picks in the 2012 draft to provide long-term continuity. The Steelers went through 25 different offensive-line combinations last season, which ranked first the the NFL.

Through the first three games, only DeCastro and center Maurkice Pouncey are the only Pittsburgh offensive linemen who have started at the same position. Ramon Foster replaced DeCastro in the starting lineup, which means the Steelers go from the top guard taken in the 2012 draft to an undrafted player.