The New Orleans Saints placed right tackle Charles Brown and free safety Malcolm Jenkins on season-ending injured reserve.
Guard Ricky Henry and safety Jerico Nelson were signed off the Saints' practice squad.
Jenkins started all 13 games for the Saints this season, but left last Sunday's loss to the New York Giants with a knee injury that ultimately ended his season. He is likely to be replaced by Isa Abdul-Quddus.
Brown started eight games this season - seven at right tackle and one as a blocking tight end. But he has missed the past three games with his own knee injury. Brown also had his 2012 season cut short by a knee injury.
Henry has been on the Saints' practice squad all season after failing to make the Chicago Bears' opening-day roster. He was originally signed by the Bears as an undrafted rookie out of Nebraska in 2011.
Nelson was signed by the Saints as an undrafted free agent out of Arkansas after last April's draft.