Manning will need 4-6 weeks to recover from knee surgery

Indianapolis Colts quarterback Peyton Manning is sacked only 3.4 percent of the time he attempts a pass, but recent surgery to remove the infected bursa sac in his left knee has temporarily left him down for the count.

Though the prognosis for his return for the regular-season opener against the Bears is good, Manning, who talked to reporters via conference call from his home, painted a scary picture of his recovery. The Colts reported to training camp in Terre Haute, Ind., Thursday while Manning was completely immobilized at home.

By Friday morning, he will have missed the first meeting, practice and organized activity of his football career. An NFL iron man in the mold of Brett Favre, Manning is pained not being with his Colts teammates.

"I have my leg constantly compressed and elevated," Manning said. "I'm still on IV antibiotics and still trying to keep the risk of infection from returning as low as possible. We feel at this point that the infection has resolved itself, but to be up there around 150 guys is probably not the smartest thing at this point. Once we feel like this infection is totally out of the woods, and maybe not as susceptible to it returning, then they feel like it will be safe for me to return."

Colts president Bill Polian labeled the knee problem as more of a disease than injury. He's confident Manning is on the road to recovery. Still, it has to be scary to know the franchise quarterback has a drain coming out of his left knee and an IV in his left arm.

Tom Santi, a tight end taken in the sixth round, suffered a similar problem when his knee became infected while he was at the rookie symposium in the San Diego area in late June.

Manning has had trouble with the knee since the beginning of the offseason, but the situation turned into a crisis on July 14.

"I experienced some swelling during the offseason, but it didn't cause me to miss any sort of workouts," Manning said. "I had a great offseason as far as weight lifting. My throwing, my running and my conditioning were as normal as in past years. I was controlling the swelling with treatment and occasional draining. We felt like we had control of it."

Then, on July 14, Manning experienced knee pain which he compared to a person having appendicitis.

"I woke up on that Monday [July 14] in severe pain," Manning said. "I really had trouble walking. I knew something wasn't right so I jumped on a plane and flew to Indianapolis right away and determined there was an infection. And that's what kinda caused the pain."

That led to successful surgery to remove the bursa sac, which has a recovery period of four to six weeks. Manning said the good news is the pain is gone and recovery has been good. The bad news is he has to wait until doctors clear him and proclaim his left knee infection-free to join his teammates at camp.

"I haven't been able to do a whole lot," Manning said. "I can do some of my upper body stuff with my right arm. I can work with my rotator cuff and I can toss the ball around. I can watch film. I can read. I can watch TV. I can catch up on calls with friends. The main thing I've been doing is trying to follow doctors' orders and keep the leg elevated.''

What doctors told Manning is this is a rare infection for an athlete. It's something that affects carpenters, plumbers and people who are constantly banging their knees.

Jim Sorgi will handle the starting quarterback duties while Manning recovers. Colts players are confident Manning will return. Some say it will take only a day or two before Manning has the timing of the offense back.

"It might be like he's on speed," center Jeff Saturday said of the day Manning returns to the practice field. "We'll have to slow him down a bit. He'll be so excited to get back. We'll all be in Week 2 or 3 and we'll all have beat-up legs and be exhausted and he'll be ready to roll. We'll have to tone him down just a bit. We might make him run a treadmill before we let him come out to practices with us."

Until then, Manning just wants to do the right thing for his knee. Once the knee is right, he'll have to work on getting back to his game and his rhythm.

"This is pretty uncharted territory for me," Manning said. "I really don't have an idea of how much time I need because I've never had to experience it. I've always taken all the repetitions and had a hundred percent of the participation in training camp and minicamps and whatnot. So it's a little uncharted territory for me. Obviously you hope through 11 years with me … with the minicamps and the summer school that I have enough deposits in the bank in order to be ready for this season."

The Colts believe, though, Manning will be fine.

Senior writer John Clayton covers the NFL for ESPN.com.