The nature and seriousness of the injury is not known.
Koppen, 33, started 12 games for the Broncos in 2012 in place of J.D. Walton, who suffered a broken ankle vs. Oakland on Sept. 30. Walton had offseason surgery on the injured ankle and is on the active / physically unable to perform list.
UPDATE 2:51 p.m. ET: Guard Manny Ramirez is the Broncos’ center for the time being, according to Klis. Per the Post, reserve center C.J. Davis suffered a leg injury Saturday, further stressing the depth at center at least in the short term.