The four-time NFL MVP was in good spirits when he made his first public appearance on the field since having neck surgery Sept. 8.
"Save a copy for me for my scrapbook," Manning joked as he walked past the television cameras filming his arrival.
Those around Manning aren't elaborating about his medical recovery.
Fox Sports insider and NFL Network contributor Jay Glazer, citing an unnamed source, reported Sunday that Manning traveled to Europe for stem-cell treatment before his latest surgery. The procedure hasn't yet been approved for use in the United States.
Colts vice chairman Bill Polian and Tom Condon, Manning's agent, both declined to comment about the report following Sunday's 27-19 loss to the Cleveland Browns. On Monday, Manning's surgeons followed suit, and coach Jim Caldwell reiterated that the team wouldn't provide any additional details about Manning's progress.
Manning is expected to miss at least two months after having an anterior fusion to treat a nerve injury that was causing weakness in his triceps. Some doctors have said the recovery can take four months or longer, which could keep Manning out all season.
Manning had a prior surgery May 23, but that didn't fix the problem. The Colts hope this latest procedure will.
"He's convalescing from the surgery, and that will take a little while yet, and then at some point, the doctors will bring him back and assess his situation," Polian said on his weekly Monday night radio show. "We're not sure when that will take place. He's up and around, I can tell you that. But it is surgery, and there is a period of time where it takes its toll on you, and that's where he's at right now."
Without Manning, the Colts are off to their first 0-2 start since 1998, the quarterback's rookie season, and have scored just two touchdowns in eight quarters. Panicked fans are calling for changes, even replacing veteran Kerry Collins, who started the first two games.
"For the foreseeable future, it's not going to be the high-efficiency offense that we've been used to," Polian told radio listeners. "Kerry can't do that, nobody can. You could probably bring back Johnny U. (Unitas) and you wouldn't have that."
Copyright 2011 by The Associated Press