ALLEN PARK -- Detroit Lions tackle Jason Fox's biggest obstacle has been staying healthy since he was drafted in 2010.

He is battling injuries once again.

Fox missed the Lions' first day of mandatory minicamp practice due to a knee injury. Lions coach Jim Schwartz does not expect Fox to practice at all this week.

"Anybody that didn't practice today was injury related," Schwartz said. "Everybody's in town and here. We got a lot of things we're trying to sort of make sure they don't sort of roll up on us. Jason's had a good offseason, but his knee was getting a little bit sore, and we decided to shut him down. You won't see him for the minicamp. Other guys you'll see back.

"Today was a light day. The next two days are going to be almost training camp length to practice, number of reps, things like that, and we didn't want to go three days in a row that way, but we wanted to build toward it."

Fox, a former fourth-round pick, was sidelined all of last season due to a broken foot suffered in training camp, and then a knee injury that required surgery. He currently is battling Lions rookie Riley Reiff for playing time, but general manager Martin Mayhew previously said it was a critical year for Fox because of his consistent health problems.

However, Fox was not the only player absent from Tuesday's activities.

Detroit Lions mandatory minicamp - June 12 9 Gallery: Detroit Lions mandatory minicamp - June 12

Lions cornerback Chris Greenwood, linebacker Stephen Tulloch (tedonitis in his knee), defensive tackle Sammie Hill and Louis Delmas (ankle) did not participate in Tuesday's practice. Detroit coach Jim Schwartz would not disclose the injuries to Fox or Hill.

In addition, Lions defensive end Cliff Avril missed practice because he refuses to sign the franchise tender place on him by Detroit earlier this offseason.

"There's a couple of guys we're holding out simply because of wear and tear," Schwartz said. "Other guys we shut down for this minicamp, and Jason was one of those guys."