Sam Bradford returned to practice on a limited basis Monday after he was cleared by an independent neurologist to return following a concussion he suffered on Nov. 15. He also had a separated left shoulder.

There was no word on whether Bradford would play Thursday against the Detroit Lions, or whether Mark Sanchez would make his second consecutive start. Coach Chip Kelly refused to discuss Bradford's injury.

When offensive lineman Lane Johnson was asked who he thinks will start, he said Sanchez without hesitation.

Bradford has not spoken to reporters since the injury. He is scheduled to speak to reporters on Tuesday, as is Sanchez.

Concussion woes

Tight end Zach Ertz was not at practice Monday after suffering a concussion on Sunday. Ertz is in the league-mandated concussion protocol. If he cannot play Thursday, the Eagles might need to add a third tight end to join Brent Celek and Trey Burton. Chis Pantale is on practice squad.

"He has been cleared to go to meetings, and we'll see where that clears as the week goes along here," Kelly said about Ertz. "We do know we're on a short week, though."

Running back Ryan Mathews remains absent because of a concussion he suffered the same day as Bradford. He has not attended practice since the injury.

Defensive lineman Cedric Thornton (ankle) did not practice. Left tackle Jason Peters (back) was limited.

Alonso's knee

Linebacker Kiko Alonso had only one tackle in 54 snaps on Sunday. Kelly said the Eagles have not considered shutting down Alonso to allow his left knee to get healthy. Alonso said he's healthy and his knee is not bothering him.

Alonso missed five games this season after arthroscopic knee surgery and missed all of last season with a torn anterior cruciate ligament. Alonso said he's the same player he was in 2013 with the Bills and his speed and explosiveness have not been affected.

"I feel 100 percent," Alonso said. "I feel great."

Alonso took responsibility for the third-quarter penalty on Sunday when the Eagles had too many players on the field. The penalty caused a first down. Alonso was supposed to come off the field in dime formation.

Secondary moves

The Eagles changed their nickel formation on Sunday, inserting E.J. Biggers into the lineup as the slot cornerback and moving Malcolm Jenkins back to safety in place of Chris Maragos.

"Every time we play nickel, we determine what the matchup is like and who the best matchup is," Kelly said. "[Biggers] has done a nice job when he has been matched up there on some of the things we did, and going into this game, that was the game plan going in."