Bradford was returning to Minnesota on Tuesday night and will await the team's decision on whether the club will place him on injured reserve when it activates Teddy Bridgewater to the 53-man roster on Wednesday.
Andrews removed several loose particles from Bradford's knee, cleaned up some ragged cartilage and smoothed out a bone spur, sources said. Andrews has communicated to the club that he is hopeful the procedure will ease the pain that Bradford has been experiencing but offered no assurances on the ultimate outcome, per one source.
Bradford's knee joint and structure has been previously deemed stable by team orthopedic doctors, as well as Andrews, who repaired the quarterback's two prior ACL tears in 2013 and 2014.
The Vikings got Bradford in a trade with the Philadelphia Eagles, in which Minnesota gave up a first- and fourth-round pick.
Bradford, acquired after Bridgewater dislocated his knee, played a relatively injury-free season in 2016 despite the team's pass protection problems.
Bradford then opened the 2017 season in spectacular fashion on Monday Night Football, throwing for 346 yards and three touchdowns to lead the Vikings to a 29-19 victory over the New Orleans Saints. However, he woke up the following day experiencing significant pain and swelling in his left knee. He has played in only one game since, against the Bears on Oct. 9, from which he had to be removed because of the pain.