According to the team, Walton's latest surgery will keep him out until mid-October. Denver's final game of October comes in Week 8 (Oct. 27) when the team hosts the Washington Redskins. The following week is Denver's bye, so Week 9 appears to be a realistic date to expect Walton's return.
Walton had previously been recovering from a 2012 early-season surgery that had kept him out of the Broncos' OTAs this offseason. In his absence, 30-year-old Manny Ramirez—Denver's 6'3", 313-pound all-around backup offensive lineman who saw time at guard last season when Chris Kuper went down—has been playing center with the first-team offense.
Behind Ramirez is Philip Blake (27, 6'2", 311 lbs.), who is entering his second season with the team after being selected in the fourth round (108th overall) out of Baylor by the Broncos last April. Prior to his senior season, Blake was drafted by the Montreal Alouettes in the 2011 CFL draft, but opted instead to finish his college career.
A third option for the team could be free-agent center Dan Koppen (6'2", 296 lbs.).
After spending nine years with the New England Patriots and winning two Super Bowls as Tom Brady's center, Koppen was released by the Patriots last September. Looking for depth at the position, the Broncos quickly picked up the veteran center.
Three weeks later, Walton went down with an ankle injury and Koppen was thrust into the starting lineup. Koppen went on to start the final 12 games of the season, allowing just one sack and being penalized once.
After his one-year deal expired this offseason, Koppen went un-signed through the early stages of the free agency signing period. A 33-year-old veteran, Koppen remains on the open market.
Koppen helped the Broncos finish the season with a 13-3 record after a rough 2-3 start. Having familiarity with quarterback Peyton Manning, signing Koppen would make sense for the team, to provide depth, at the very least.
As of now, Ramirez, a player who allowed 6.5 sacks last season, is the team's write-in starter. Signing the experienced Koppen to a one-year deal could help provide relief to Denver's ailing offensive line.