Coach Mike Shanahan said Wednesday that Hankerson will have surgery on a damaged lateral collateral ligament and will likely require ''a few months'' of recovery.
Hankerson was hurt in the second quarter of Sunday's loss to the Philadelphia Eagles. He had emerged as the team's No. 2 wideout this season with 30 catches for 375 yards and three touchdowns.
It's the second time in three years that Hankerson's season has ended early. The 2011 third-round pick tore the labrum in his right hip when he was a rookie.
With Hankerson out, Shanahan said Joshua Morgan will start Monday night against the San Francisco 49ers. Morgan was inactive against the Eagles, a significant demotion for a player who signed a big free agent deal last year.
Rookie tight end Jordan Reed was unable to practice Wednesday as he recovers from a concussion. If Reed can't play Monday, Shanahan said Fred Davis will be active for the game. Davis has been on the inactive list for the last five games.
Defensive end Stephen Bowen was also sidelined from practice Wednesday with a left knee injury, and cornerback Josh Wilson sat out with an inflamed toe.
Cornerback E.J. Biggers, who hurt his left knee in Sunday's game, practiced as usual.