MANKATO, Minn. -- Minnesota Vikings' offensive linemen Jim Hough and Brent Boyd underwent arthroscopic surgery Wednesday night on their left knees and are expected to be out of action two to three weeks.
Boyd, 27, hurt his knee playing basketball before training camp started.
The guard missed most of the 1981 season with an injury to his other knee.
Hough, 27, who has been shifted from guard to center this year, has complained of knee stiffness since training camp opened July 21.
The Vikings announced the signing of ninth-round draft choice Keith Kidd, a wide receiver from Arkansas.
The Vikings acquired 6-foot-9, 310-pound offensive tackle Bobby Thompson on waivers from Green Bay Wednesday. He played five years with the Winnipeg Blue Bombers of the Canadian Football League and was named to the All-Western Conference All-Star team in 1982.
The Packers signed him as a free agent earlier this year.