Keith, placed on injured reserve on Tuesday, also will undergo arthroscopic knee surgery.
Jeremy Bridges is the probable replacement, but the Cardinals added depth at the position by signing tackle D'Anthony Batiste, who played in five games for Denver before he was released on Oct. 16.
Left tackle Levi Brown, Arizona's starting right tackle in his first three seasons, will not move to the right. "What you don't want to do is make a two-position change," Whisenhunt said.
The Associated Press contributed to this report.