MINNEAPOLIS -- After waiting most of the season for defensive tackle Sharrif Floyd to return from a knee injury, the Minnesota Vikings decided to move on Monday.

The Vikings placed Floyd on injured reserve, ending the former first-round pick's season after he played in only one game this year. Floyd, who has struggled with knee injuries throughout his time in Minnesota, had a Sept. 22 operation on his right knee, but the Vikings didn't think at the time that Floyd would be out all season.

They'd kept the 25-year-old on their active roster until Monday, when they brought Toby Johnson up from their practice squad.

"We kept hanging around and hanging around, and it was just, we may need the roster spot at some point," said coach Mike Zimmer, who added that Floyd had not had another surgery after the Sept. 22 operation.

Now the Vikings will have to decide what kind of a future Floyd has in Minnesota.

The 23rd overall pick in the 2013 draft has been a productive player when he's been on the field, but injuries have often been part of Floyd's story in Minnesota. After the 2014 season, when Floyd missed two games and was limited in two others because of knee issues, Zimmer said Floyd had to "understand it's a big man's game." Floyd missed three games a year ago, when he had an operation to remove cartilage from his left knee during the season, and didn't play after the Vikings' Sept. 11 season opener in 2016.

The Vikings picked up Floyd's fifth-year option in May, but assuming his issues aren't significant enough to trigger the option's guarantee against injury for the 2017 season, the Vikings could cut him without penalty by the start of the league year in March. Floyd's option would pay him $6.757 million if the Vikings kept him on the roster next year.

Asked whether he'd been able to fully assess Floyd's work, Zimmer said, "Yeah, I think I can assess him. I don't really want to assess him to the media. I'll assess him to [general manager] Rick [Spielman] when we sit down and talk."