NASHVILLE, Tenn. -- Tennessee Titans linebacker Keith Bulluck has a torn left anterior cruciate ligament and will miss the rest of the season while outside linebacker David Thornton will have season-ending shoulder surgery later this week.
Coach Jeff Fisher announced Monday that test results show Bulluck tore his left ACL in the third quarter of their 27-24 overtime victory over Miami on Sunday in what might have been his final game with the franchise that drafted him 30th overall in 2000. The Titans were placing him on injured reserve Monday, and Bulluck will have surgery within two weeks.
Thornton had been deactivated against Miami as the Titans (7-7) hoped he might return.
Fisher called the losses devastating to the defense.
"David was playing very well this year when he was able to play and Keith, Keith is kind of the cornerstone of our defense, and he has been for so many years. I don't need to speak about the consecutive starts and production. He's gone from AFC defensive player of the week to gone for the remainder of the season," Fisher said.
Nine-year veteran linebacker Jamie Winborn signed a two-year deal with the Titans Monday morning, agent Jason Fletcher told ESPN.com's Paul Kuharsky.
"I feel as though he will be active for the remaining part of this season and play now," Fletcher said. "To what extent has not been explained to us. He has to learn the playbook. In the event they should make a playoff run, his experience was a factor in their interest in him."
Winborn has played with San Francisco, Jacksonville, Tampa Bay and Denver.
Bulluck was AFC defensive player of the week after intercepting two passes in a 47-7 rout of St. Louis on Dec. 13.
A 10-year veteran, Bulluck is the franchise's top tackler this season in the final year of his contract. He made his 127th consecutive start against Miami, second only to only London Fletcher of Washington (148) among linebackers. He led the team in tackles last season and had a team-high 113 tackles going into the game with Miami.
"It's a blow. But we'll plug people in, and we'll go on. That's all we can do," Fisher said.
Rookie Gerald McRath started three games this season for Thornton. Colin Allred, a second-year player out of Baylor, will replace Bulluck. Middle linebacker Stephen Tulloch will replace Bulluck calling the defensive play calls and wearing the helmet communication device as he did once Bulluck was injured against Miami.
Losing Bulluck hurts most with the San Diego Chargers (11-3) visiting Friday night in a must-win for the Titans to keep their dwindling playoff hopes alive for the final week of the regular season. Bulluck's cover skills will be missed trying to defend tight end Antonio Gates who already has 74 catches for 1,071 yards.
"If I know both of them the way I think, I think they'll continue to have a part in the defense and be vocal with the guys on the field," center Kevin Mawae said.
Fisher wouldn't discuss Bulluck's future. The linebacker turns 33 in April and will spend most of the offseason recovering from this injury.
"Those are things that will get worked out. I think the thing to add here at this moment is the loss and what that does for us to this point and also emphasize when you lose a player in the starting lineup, your players have to step up and play, and that's what we expect to have happen," Fisher said.
Bulluck wasn't available Monday but tweeted on his Twitter account that "I ain't go'n out like this. My spirits r gr8." He later added that his rehab hobby will be learning how to play his guitar.
Information from The Associated Press was used in this report.