GREEN BAY, Wis. -- Josh Sitton's career with the Green Bay Packers is over.

The Packers released the three-time Pro Bowl offensive lineman Saturday, after being unable to trade him.

"We want to thank Josh for his contributions during his time in Green Bay. He has been an important part of the success we have enjoyed on the field," Packers general manager Ted Thompson said.

"While these decisions are never easy, this was done with a focus on what is best for the team and the growth of the offensive line. We wish Josh and his wife, Kristen, all the best in the future."

The Packers spent part of Saturday trying to trade Sitton before the NFL's deadline to cut rosters to 53.

Sitton, 30, was entering the final year of a five-year, $33.75 million contract. He was scheduled to make $6.450 million in base salary and roster bonuses this season.

Reached via text message after the Packers made the news of his release official and he did not answer his phone, Sitton stuck to clichés when asked about his shocking departure.

"I really don't want to talk, man," Sitton wrote. "I'm thankful to the organization. It's a tough business."

It's a surprising move given Sitton's longevity -- he has started 110 of 112 possible regular-season games since 2009 -- but he has experienced back issues the past couple of seasons. In fact, he said he lost weight this offseason in an effort to take some of the stress off his back.

"I'm very optimistic of his prospects for playing for a number of additional years," Sitton's agent, Jack Reale, told ESPN's Josina Anderson. "He's coming off of maybe his best camp in the last four years. He's lighter, and he is in better shape. He is coming off of a Pro Bowl season and he just turned 30.

"I think he's got lots left. I think all the teams that he has been playing against for the last several years are certainly aware of that, and certainly teams within their division. So we will see what happens."

Sitton was one of four offensive line starters entering the final seasons of their contracts. The Packers will need salary-cap space if they want to retain left tackle David Bakhtiari, right guard T.J. Lang and center JC Tretter -- all of whom will be free agents after this season.

By releasing Sitton, the Packers wipe off his $6.150 million base salary plus $400,000 in per-game roster bonuses from their salary cap. There's no dead money because Sitton did not have any remaining signing-bonus proration counting on this year's cap.

It's not immediately clear how they plan to replace Sitton in the lineup, but they have several candidates, including Lane Taylor and Don Barclay. It's also possible they could move right tackle Bryan Bulaga to guard and play rookie second-round pick Jason Spriggs at Bulaga's old spot. Or they could move Tretter to guard from center once Corey Linsley is recovered from the hamstring injury that had him on the physically unable to perform list all of training camp.

Information from ESPN's Jason Wilde was used in this report.