Thomas exited the game in the second quarter, and the Broncos said his return was questionable. He caught two passes for 3 yards before the injury.
A fourth-year veteran, Thomas is third on the Broncos with 38 receptions for 423 yards, and he leads the NFL with 12 touchdown receptions. Jacob Tamme is the Broncos' only other healthy tight end, as Virgil Green sat out with an ankle injury.
The Broncos also lost running back Montee Ball when he reaggravated the groin injury that kept him out of Denver's last five games. Ball came back in after a brief exit, but left the game again after dropping a pass. The team announced he was questionable to return.
Denver entered the game 7-2 and with a one-game lead in the AFC West. St. Louis is 3-6, last in the NFC West.
- Mike Fiammetta