New Orleans linebacker Chris Chamberlain will miss the season after injuring his left knee in Friday night’s game against Jacksonville, interim coach Joe Vitt said Saturday.

Chamberlain is not a starter, but he is a versatile backup capable of playing all three linebacker positions and has intimate knowledge of new defensive coordinator Steve Spagnuolo’s system after playing for him with the St. Louis Rams the past three seasons.

“He was a great communicator among his teammates,” Vitt said. “He was always looking to help his teammates get better here. He was a perfect fit for what we were trying to get done here. That’s a blow. It’s a setback for us.”

Chamberlain injured his knee in the first quarter and was taken from the sideline to the locker room in a cart. He started 13 games for the Rams last year, making 81 tackles with two sacks and an interception.

“You don’t fill the void right away,” Vitt said. “Our defense is a work in progress. We’ll have to sit down [Sunday], step back a little bit and restack the boards. We may have some position changes. Right now we don’t have someone in the building who has Chamberlain’s knowledge of the defense and can really play Sam, Mike or Will with efficiency and production.”

Vitt said he did not have any specifics on the type of knee injury Chamberlain had, adding that X-rays Friday night and an MRI taken Saturday morning revealed Chamberlain would be out for the year.

Will Herring and Jonathan Casillas are the Saints’ top two remaining reserves at linebacker. Herring backs up Scott Shanle on the strong side, and Casillas backed up David Hawthorne on the weak side.

Vitt said the news for two other injured players was better.

Tests revealed that the sprained ankle WR Andy Tanner suffered was not as bad as the Saints originally thought. Tanner could put almost no weight on his leg as he was helped off the field by trainers.

Safety Isa Abdul-Quddus, who exited with a head injury and was held out for precautionary reasons, passed his concussion tests and has been cleared to practice Monday.

The Saints also announced Saturday they had waived and reached an injury settlement with CB A.J. Davis, a rookie free agent who injured an ankle against New England in the second preseason game.

Follow Saints reporter Guerry Smith on twitter @CBSSportsNFLNO.