Vikings place Sam Bradford on injured reserve after surgery, Teddy Bridgewater activated

As the Vikings welcomed Teddy Bridgewater back to their active roster, the quarterback they acquired in the wake of Bridgewater's 2016 knee injury is heading to injured reserve with his own knee issues.

The Vikings placed Sam Bradford on IR on Wednesday morning to make room for Bridgewater's return from the physically-unable-to-perform list.Bridgewater will dress for Sunday's game at Washington and will backup starter Case Keenum.

Bradford had played just six quarters this season, winning NFC Offensive Player of the Week honors for his 346-yard performance against the New Orleans Saints in Week 1 but missing the team's next three games after an awkward step in that game awakened problems in the left knee Bradford twice had surgically repaired.

He returned to start against the Chicago Bears on Oct. 8, but was pulled in the second quarter for Keenum after completing just five of his first 11 passes for 36 yards. The Vikings took the unusual step of making sports medicine director Eric Sugarman available to the media the day after the game, to say all parties (including Bradford) had agreed the quarterback should play in the game. Sugarman attributed Bradford's issues that day to "wear and tear" in his left knee, which had been repaired in both 2013 and 2014 after the quarterback tore his ACL.

Bradford had made several trips to see specialists for his left knee in recent weeks, receiving Regenokine treatment in an attempt to reduce inflammation in his knee. ESPN reported Tuesday night that Dr. James Andrews performed an arthroscopic operation on Bradford's knee, removing loose particles, cleaning up cartilage and smoothing out a bone spur in an attempt to reduce the pain in his knee.

Andrews, according to the report, found no structural damage in Bradford's knee; the Vikings have also repeatedly said there were no structural issues with the quarterback's knee.

Bradford must sit out a minimum of eight weeks, which would make him unavailable until the first week of the playoffs at the earliest.

Bradford, who turned 30 on Wednesday, is one of three Vikings QBs who will be a free agent after this season. The team could have kept him on the roster in hopes that he would be able to return before the end of the season, but that would have meant carrying four quarterbacks following Bridgewater's return or exposing Kyle Sloter to waivers while trying to move him to the practice squad.

A league source said Tuesday it was unlikely the team would risk losing Sloter, whom it paid nearly triple the NFL practice-squad minimum in September. Sloter was added to the Vikings' active roster before a Week 2 game in Pittsburgh, where Bradford's knee issues first caused him to miss a game.