INDIANAPOLIS – Peyton Manning’s passion for football runs through his veins.

His dad played, his older brother played, his younger brother still plays and now Peyton is working feverishly to return to the family business.

There’s no doubt Manning wants to come back in 2012, the question is whether it’s too risky for a 35-year-old quarterback with three neck surgeries in less than two years to keep playing such a violent sport.

“If he is healthy and he is pain free, I’d let him play, knowing there’s a slightly elevated risk (of a different disk injury),” said Dr. Anders Cohen, chief of neurosurgery and spine surgery at The Brooklyn Hospital Center. “Even a person off the street with this type of surgery has an elevated risk of an adjacent disk injury. He (Manning) might have a slightly higher risk than the person off the street, but you have to offset that against the fact that he’s a superior athlete.”

Cohen has not treated Manning but knows the procedure and recovery process well.

The surgeon makes an incision in the front of the neck, removes the soft disk tissue between two vertebrae and fuses the bones together with a graft.

Normally, it takes three to four months for the bones to firmly heal.

Manning needed the surgery to fix a damaged nerve that was causing weakness in his throwing arm. Why would Manning give up his football career?

He doesn’t need money. Since entering the league as the No. 1 overall pick in the 1998 draft, Manning has signed three contracts with the Colts worth a total of $236 million and earned millions more in endorsements.

He doesn’t crave fame. Manning doesn’t even use the popular social networking sites and has increasingly done his charity work behind the scenes.

He doesn’t have to build a Hall of Fame résumé. Manning already owns one Super Bowl ring more than inductees such as Dan Fouts, Dan Marino and Fran Tarkenton, and Manning ranks third all time in touchdown passes and yards passing.

He’s not even sure he’ll be in Indianapolis. If the Colts don’t pay a $28 million bonus in early March, Manning could become a free agent. If he goes elsewhere, he’d be starting from scratch after spending the past 14 years with the Colts.

Plus, he has two more reasons to worry – being healthy enough to play with his new twins.

“Last week’s decision on my CT scan and the X-rays, the doctors’ interpretation, was a good sign for my overall health and that was important to me,” Manning said recently on CBS’ pregame show. “Ashley and I have new twins, have 8-month-old twins, and it’s important for me to be in good health to play with them, to roll around on the floor and have some fun, so that was encouraging to me. The football thing will answer itself in the next few months.”

There are risks.

Over his lifetime, Manning runs a 15 percent to 20 percent chance of injuring a disk directly above or below the two that were fused in September, Cohen said.

Dr. Andrew Hecht, director of spine surgery at Mount Sinai School of Medicine in New York, concurs with Cohen’s assessment, though he said Manning runs no greater risk of injury than any other player on the field. Hecht has not treated Manning either, but has worked with Jets players.

“I have no concerns at all,” Hecht said. “There are numerous players playing in the NFL, Major League Baseball, the NHL and professional basketball that have had successful one-level fusions in the neck. If it’s solidly fused, there’s no risk. Any (player) can have an injury at another level, but so can anybody else.”

But finding comparisons to Manning’s case is tough. Few athletes rely exclusively on throwing a ball and even fewer have performed at such a high level for more than a decade.

Until this injury, it didn’t seem anything could slow Manning.

Two years ago, he led the Colts to a 14-0 start, the second Super Bowl appearance of the Indianapolis era and collected his record fourth MVP Award. Last season, with injured players going down all around him, Manning essentially willed the Colts to a seventh AFC South title in eight years and within one defensive stop of advancing in the playoffs. This year, with Manning, the Colts were supposed to be a Super Bowl contender.

Without him, it took 14 games just to get a win, but there has been promising news in recent weeks.

On Dec. 1, Manning was told the bones had healed and he could begin increasing his workout activity.

Cohen and Hecht said that diagnosis meant Manning could begin throwing a football as soon as he felt strong enough. On Dec. 14, 12 days after the most recent diagnosis, Manning pulled on his pads, strapped on a helmet and walked onto the practice field for a workout. He took snaps from center Jeff Saturday and threw passes to running back Joseph Addai, receiver Anthony Gonzalez and another receiver from the practice squad as team vice chairman Bill Polian and coach Jim Caldwell watched.

Polian and Addai both gave good reviews.

Those who know Manning best have few doubts he’ll be back in a No. 18 jersey next season.

“Yeah, I think he’ll play if he’s healthy,” said Saturday, one of Manning’s closest friends. “The guy loves the game.”

Offensive coordinator Clyde Christensen added: “I’ve probably been around some competitors that are equal to him, but no one that competes more than him. He loves the competition, the preparation, everything about it. ... He just loves to play football.”

Still, Manning must understand there’s a possibility something could go wrong.

Cohen and Hecht both say it’s a doctor’s responsibility to explain the potential consequences to Manning, and Christensen has promised to have that discussion too.

The other complication could be Stanford quarterback Andrew Luck, who is expected to be the No. 1 pick in April’s draft. Indianapolis is one of the front-runners to get the pick and could select Manning’s eventual successor, possibly creating tension in the ranks.

“It’s something you talk about,” Colts owner Jim Irsay said last month. “You discuss endless scenarios, who could be behind Peyton, how long you want him in that situation and how much money you have committed to the quarterbacks. Every scenario is possible, but I think theoretically you could have Peyton play two or three more good years and have someone behind him ready to go.”

But football without Peyton just doesn’t seem possible, even for his dad.

“He loves to play, and I think if he gets his health back, he’s still capable of playing,” Archie Manning said. “That’s his DNA.”