PITTSBURGH – Ryan Clark's life was upended on a football field, and not because of a big hit, a bad knee or a damaged hamstring.

The Pittsburgh Steelers safety never saw the problem that felled him nearly a year ago, ended his season and caused him to lose so much weight his teammates wondered if he could recover.

Clark's career nearly vanished in thin air.

Precisely, the high altitude in Denver, which aggravated a medical condition so serious that it resulted in Clark being rushed to a hospital following a game there last season, his spleen and gall bladder beginning to break down.

And he never felt it coming.

That Clark is playing again for the Steelers, at the safety spot opposite of Pro Bowl defender Troy Polamalu, is one of the NFL's comeback stories of the season.

“To me, I started the season with a victory even before we played a game,” Clark said. “It's a victory I'm here this season.”

To Polamalu, Clark's comeback is more than that.

“It's pretty much a miracle he's out there,” Polamalu said.

Clark initially didn't feel right following a 2005 game in Denver while playing for the Washington Redskins. He was diagnosed with a bruised spleen, but that wasn't nearly the extent of his problems.

Clark felt OK during the Steelers' last-minute 31-28 loss at Denver on Oct. 21, 2007, and he made his usual postgame phone call to wife Yonka back in Pittsburgh. But he became ill before the team charter left, and he had to be helped off the plane.

He spent a few days hospitalized with what was described as an inflamed spleen, but the condition didn't improve even after he returned to Pittsburgh. He had severe pain in his left side that made him unable to pick up his three young children and his weight began dropping from 205 pounds into the mid 170s.

Finally, after three miserable weeks in which he couldn't play and didn't respond to treatment, he consulted another doctor, who told him he had a sickle cell trait condition that caused blood vessels to burst and his spleen to become infected.

Within hours of seeking that second opinion, Clark's spleen was removed. His gall bladder, also affected by the condition, was taken out a few weeks later.

Making matters worse, one of his best friends, former Redskins teammate Sean Taylor, was shot to death five weeks after Clark became ill.

Finally, between the holidays, Clark began feeling better. He resumed working out in January, and he was back with the starters during voluntary team workouts last spring, although still a few pounds lighter.

“If you know Ryan Clark, you know he has great spirit and a great work ethic,” said coach Mike Tomlin, whose team is off this weekend. “Truth be known, I would have been surprised if he wouldn't have come back.”

The 28-year-old Clark jokes the recovery has changed the way he is perceived by the fans and media. He has had a successful six-season career despite not being drafted out of LSU.

Until his medical problem developed, Clark said, he got as many questions and comments from Steelers supporters about promising backup Anthony Smith as he did about himself. After Clark was healthy enough to play again, he began hearing nothing but positives from fans at training camp.

“I don't think you guys thought I was any good before,” he said, with a laugh.

Clark wasn't joking when he told reporters that Steelers medical personnel pressed him about why he didn't return last season, before his condition was properly diagnosed.

“I was made to feel like I was milking it,” Clark said. “(I got) fed up with it (and) felt mistreated. ... I felt like I was being talked to like I was uneducated and misguided.”

Clark hasn't repeated those remarks since last spring. The Steelers said Clark was properly treated, even though he was in severe pain until he sought outside medical help.

There are some lingering aftereffects: Clark needs six injections a year, must be careful when he flies and must treat any infection, even a minor fever, more carefully than most.

Still, Clark, normally one of the Steelers' most upbeat and talkative players, has been even more so now that he is playing again, mostly because he considers this season to be a gift.

His wife, normally not much of a football fan, made an infrequent appearance at training camp to celebrate his return. His 7-year-old son, Jordan, delighted in being old enough to attend his first game in person and to see dad wearing his No. 25.

“I'm always excited about playing football, but especially this year,” Clark said. “I couldn't be happier.”