Bills tight end Derek Fine's season is over after being placed on injured reserve because of a knee injury.
Fine will be replaced by Joe Klopfenstein, who was signed in free agency.
The moves came Wednesday, a day after defensive coordinator Perry Fewell was promoted to interim head coach following Dick Jauron's dismissal. Buffalo (3-6) plays at Jacksonville on Sunday.
Klopfenstein, a 2006 second-round draft pick, spent three seasons with St. Louis before being released in September. At 6-foot-5 and 252 pounds, he had 33 catches for 386 yards and two scores in 48 career games.