The 24-year-old has been sidelined for almost two years by a succession of injuries, one of which left him needing to have part of his kneecap removed.
O'Brien has not played for the club since the 0-0 draw with Blackburn on October 18, 2008, but is now fit and hoping for a loan move to get some action under his belt.
He told the Bolton News: "I have spoken to the manager and it's an option - but it's whether a club wants me or not. We will have to wait and see.
"I have not been involved in the first team at the moment and have been playing reserve-team football, so it's a step up to be playing competitive football in the Championship.
"The last two years have been pretty grim, but if someone had told me a year ago I would have to go out on loan to play football, I would have snapped their hand off because it didn't look like I would ever play again.
"There have been some dark days. The first surgery wasn't a success and, after the second one, they weren't very optimistic about the outcome because I'd had a piece of my kneecap taken out.
"I have still got a long way to go, but the only way I'm going to get there is by playing games."
Source: Team Talk
Source: Team Talk