ENGLEWOOD, Colo. -- The fact that it took 401 days for J.D. Walton to return to the 53-man roster is evidence of the severity of the fractured ankle he suffered last season, and the difficulty in healing that resulted in further surgery in June. That procedure came nine months after he succumbed against the Raiders on Sept. 30, 2012, and was the final detour that led the Broncos to Manny Ramirez as their starting center.

Four months before Walton's second surgery, Head Coach John Fox had said at the NFL Scouting Combine that Walton would be the first-team center when training camp began. But as a result of all the time missed, he returns as a backup to Ramirez.

Ramirez has improved over the course of the season and is under contract for next year, which makes him likely to remain the center for the foreseeable future. But Walton, whose contract expires after this year, gives the Broncos another experienced contributor in reserve, which comes in handy for a line that has been besieged with injuries this season.

Denver now has three centers on its 53-man roster: Ramirez, Walton and Steve Vallos. Both Vallos and Ramirez have played guard in the NFL, so they offer positional flexibility. Should another rash of injuries hit the offensive line, the Broncos could shuffle the group, use Ramirez and/or Vallos at guard and use Walton at center, the only position he's played on this level.

Being a reserve upon his return isn't what Walton or the Broncos once envisioned, but it's the reality that comes with a severe leg injury and Ramirez's proficiency in filling the void. Now Walton is an insurance policy, and given the Broncos' run of injuries this year, it would surprise no one if they need to use him at some point in the next three months.