According to Jeff Legwold, Broncos center J.D. Walton underwent another operation Monday on his ailing left ankle and may be lost for the season. A few minutes after his original tweet, Legwold adds that the team hopes to get Walton back by late October or early November.
Cecil Lammey of ESPN Denver suggests this could prompt the team to bring back Dan Koppen, who remains an unrestricted free agent.
The Broncos first signed Koppen last September, just a few weeks before Walton suffered a season-ending dislocation and fracture of his ankle against Oakland.
Walton had been held out of OTAs and was limited to individual drills during minicamp last week, and had told the official site earlier in the month that he was aiming for 100% health by the time training camp rolled around.
In his absence, Manny Ramirez worked as the first-team center, with expectations that 2011 draftee Philip Blake would also compete for the starting gig in camp.
Denver figures to, at the very least, place Walton on their PUP list, which would make him ineligible to play in their first six games. However, his participation last week could preclude his eligibility for that designation.
There's also revocable IR, but that is not available until September 3.
Updated 2:21pm ET