Vikings linebacker Michael Mauti was placed on injured reserve because of an arthroscopic knee surgery unrelated to the three torn anterior cruciate ligaments he suffered in five seasons at Penn State, Vikings coach Mike Zimmer said earlier today.

Zimmer indicated that the injury wasn't serious.

"It's kind of like my kidney stones; it's minor to somebody else," Zimmer said. "It was more of a clean-up kind of thing."

To replace Mauti on the roster, the Vikings signed offensive tackle Carter Bykowski off San Francisco's practice squad. Bykowski was a seventh-round pick in 2013 and has been on the 49ers practice squad for two seasons. He is from Eden Prairie, and played college football at Iowa State.

Bykowski is 6-7 and 310 pounds. After playing tight end as a freshman at Iowa State, he redshirted a season while being converted to tackle. He was with the Cyclones for five years (2008-12).

Bykowski won two state football titles at Eden Prairie, and was also a standout on the basketball team before graduating in 2008.