INDIANAPOLIS -- Colts kicker Adam Vinatieri will be out four to eight weeks after having arthroscopic surgery on his right knee and the team waived starting defensive tackle Ed Johnson on Wednesday to make room for a new kicker.
Indianapolis signed veteran Matt Stover to replace the reliable Vinatieri, who had a piece of cartilage removed during the surgery.
The bigger surprise was Johnson. It's the second time he has been released by the Colts in 13 months. He was let go in September 2008 following an arrest on drug possession charges, and the Colts run defense struggled the rest of the season.
Colts coach Jim Caldwell said the release this time was for a different reason: Performance.
"Just overall, it was production. It was a lack thereof," Caldwell said. "I know some might be wondering if it was a character issue and it was not."
Johnson started four straight games after serving a one-game suspension because of his arrest, and had nine tackles. Indy had re-signed Johnson in May, part of an attempt to beef up the undersized middle of their defensive line.
On Monday, Johnson told reporters everything was "going great" and there were no internal problems. Indy's defense, which ranked in the bottom third of the league in run defense last season, is now ranked No. 15 and the Colts are 5-0.
Defensive tackles Daniel Muir and Fili Moala are now expected to get more playing time, and the Colts could use defensive ends -- Raheem Brock, Keyunta Dawson and Eric Foster -- at tackle, too. All three have made starts there in the past.
"It won't change as much for me, we just have to work hard and hope to get guys step up," said the other starting tackle, Antonio Johnson. "We've got to keep doing what we're doing."
Vinatieri was apparently playing hurt.
The best clutch kicker in NFL history did make a short field goal midway through the fourth quarter of Sunday night's rout at Tennessee, but Caldwell said he had complained his knee was sore the previous week. After doctors found loose cartilage in an MRI, the team thought it would be best for Vinatieri to have surgery during the bye week rather than try to play with the injury all season.
"He's tried to fight through it, he wanted to fight through it because he's a warrior," Caldwell said.
Vinatieri had surgery on his right hip and his right knee this summer, causing him to miss training camp. He is best known for making two winning kicks in the Super Bowl as well as the tying kick and winner in the "Snow Bowl," a playoff game that helped the New England Patriots win their first Super Bowl title.
The Colts expect him back this season because Vinatieri was not placed on injured reserve.
In the meantime, they'll rely on Stover, who started his career in 1991 with the Cleveland Browns, then went to Baltimore in 1996 when the team moved there.
Stover handled every important field goal attempt for the Ravens over the next 13 seasons. But after losing distance on his kickoffs and long field goal tries, Baltimore signed Steve Hauschka last season. Baltimore did not renew Stover's contract during the offseason.
Also Wednesday, quarterback Peyton Manning practiced without problems with his left knee, which he hurt just before halftime at Tennessee. Manning finished the game but said afterward he needed treatment for the soreness.