Following up on this week's Team Notes. ... As the Chargers start to get ready for Sunday's game against the Broncos, one of their key offensive players remains sidelined.

Receiver Keenan Allen (heel) did not participate in Wednesday's practice, according to the team's injury report.

The Chargers hope Allen will be sound enough to play against the Broncos, but he has not played since the Dec. 10 loss to Denver. In just 13 games, Allen has 108 receptions for 1,243 yards with seven touchdowns this season.

Fellow receiver Josha Palmer (concussion) did not practice.

It wasn’t immediately clear when Palmer was hurt. Chargers interim coach Giff Smith said Palmer reported to the team’s headquarters Sunday complaining of concussion symptoms and was promptly placed in the NFL’s protocol. It wasn’t certain whether he could play Sunday.

“It’s just day by day,” Smith said.

Tight end Nick Vannett (back) was limited.