This spring, there were a lot of questions surrounded Cardinals starting pitcher Chris Carpenter.

Carpenter, the 2005 Cy Young Award winner, had helped the Cardinals win the 2006 World Series. But he made just four starts in 2007 and ’08 combined. After undergoing Tommy John surgery in 2007, he missed most of 2008 before returning to the mound. But that comeback was cut short by a nerve problem in the back of his right shoulder.

“I’m confident in the way that I feel,” Carpenter told reporters in March. “I’m confident that I’m going to be fine and I’m going to go out and pitch and be successful just like I always have. But after so many ups and downs in the last two years, there’s at times some doubt.”

Not any more. Carpenter is a Cy Young contender again after compiling a 17-4 record with a 2.24 ERA. He’s a big reason why the Cardinals were back in the playoffs, and he’s among a number of players who made the postseason after undergoing Tommy John surgery.

The list includes the Yankees’ A.J. Burnett, the Twins’ Carl Pavano and the Red Sox’s Billy Wagner.

About 75 major-league players had undergone the surgery, including the Royals’ Joakim Soria and Bruce Chen. Many, like Soria, come back better than ever. But in the early 1970s, an injured arm was a career killer.

When John’s left elbow gave out 35 years ago, he asked orthopedic surgeon Frank Jobe to help salvage his career. Jobe took on the challenge, but it was no easy task.

“I was nervous because we didn’t know what we were doing,” Jobe recalled in a phone interview.

Of course, Jobe was basically inventing the surgery, so he couldn’t guarantee that it would be successful.

“John talked it over with his wife and his father,” Jobe said, “and came back and said, ‘Let’s do it.’.” He said, ‘This is what I want to do because I don’t want to quit pitching. I can’t earn this much money in Terre Haute, Ind.’ ”

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Tommy John surgery sounds more akin to Dr. Frankenstein than baseball.

The ulnar collateral ligament (UCL) connects the humerus bone (upper arm) to the ulna (a forearm bone). If the UCL is damaged, a surgeon will use a patient’s healthy tendon — Chen’s was taken from his left wrist — to replace the ligament.

Drilling holes near the joint in the humerus and ulna, the surgeon attaches the tendon by looping it through the holes in a figure-eight pattern. It sounds simple and it usually is; surgery often takes about an hour.

The thing is a ligament connects bones, but a tendon attaches muscle to a bone.

“The elbow is basically dead tissue,” said James Andrews, the famed orthopedic surgeon in Birmingham, Ala., who has done nearly 500 operations in the last three years alone. “It’s not living tissue, so Mother Nature has to come in and remodel it. It has to develop a blood supply.

“It becomes a remodeled living substance, so it has to go through a whole regeneration process. That’s why you can’t really start throwing until four months. You have to go through minimal steps of progression to gradually apply the stress, so it learns to be a ligament.”

For a week or so, the elbow is in a hard brace and by the third week, the patient can start performing such exciting activities as combing his hair.

By the fourth month, a pitcher builds slowly, going from flat-ground throwing to tossing 60 feet without a mound to throwing from the mound at low velocity.

“If you skip steps with this procedure, you get ahead of the strength development of what we call the tensile properties of the new ligament,” Andrews said. “Then you get sore and you have to back up and start over.”

Chen underwent the surgery on Oct. 30, 2007 and missed the entire 2008 season before signing a minor-league deal with the Royals in March. He said the recovery process was tough.

“You have to start very slow,” said Chen, who has a jagged scar on his left elbow. “Sometimes, you actually have to hold back, because you can’t throw it hard at the beginning. You have to learn to be patient. It’s a long process. You’re over there working out and you know you’re not going to pitch for a whole year, so it’s frustrating.”

Rehabilitation can take about a year and it’s often another year before a pitcher is back to presurgery arm strength. However, some pitchers have said they throw harder after the surgery than before.

Jobe believes that’s true.

“The reason they get stronger is the intensive rehab program they get after it’s done,” he said. “They get bigger and stronger because they get older and they become a mature adult and they get a rehab program that not only rehabs their arm, but their back and their core muscles and legs, the whole body.”

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Before his surgery in 1974, Tommy John reached double-digits in victories nine times as he racked up 124 wins with the Indians, White Sox and Dodgers.

John won 10 games with the Dodgers in 1976, his first season back, and went on to win 20 games three times. He pitched in the World Series three times and compiled 164 victories.

“What I’m most proud of, and I don’t know if anybody from the surgery can say this, but I pitched 13 years after the procedure and I never missed a start,” John said on his Web site. “I had not one iota of trouble.”

The surgery has benefited non-pitchers as well. Royals shortstop Mike Aviles underwent the procedure on July 8. It’s also helped athletes from javelin throwers to NFL quarterbacks like the Panthers’ Jake Delhomme.

Most surgeries, however, are on pitchers. But what’s surprising is the age of many of the patients. Andrews estimates that just 30 percent of the surgeries he performs are on professional baseball players.

“I did one a couple weeks ago, believe it or not, that was coming out of the seventh grade going into the eighth grade and tore his ligament completely in two,” Andrews said. “He had to have Tommy John’s to continue playing baseball.

“The big story on this anniversary is why are these kids getting hurt so often?”

Andrews, president of the American Orthopaedic Society for Sports Medicine, said the organization is starting a national initiative to determine what can be done to limit the injuries for kids.

“The injury pattern has just gone crazy,” Andrews said. “We’re seeing more high school kids with elbow and ligament injuries than we are in the other levels.

“In the early 90s, we may have done surgery on two or three high school kids a year and it escalated in 2000 to where I was doing 45 or 50 a year. One year, I think I had 70 high school age or younger that I did here.”

Andrews believes younger athletes are being pushed too hard and it’s taking a toll on their bodies. Even if they get to the majors, their arms can give out.

That means making the difficult decision to have Tommy John surgery. Unlike John, Chen could take comfort in knowing he wouldn’t be the first to face the procedure.

“A lot of people have the experience, and I was able to talk to other people and know what kind of setbacks and things to expect,” Chen said. “It’s definitely something I wouldn’t wish on anybody, but if you have to have it, it’s not the end of the world, you can actually come back and resume your career.

“I did a lot of research. I wanted to know what they were going to do. But I’m good at playing baseball, they’re good at doing the surgery and they know what they’re doing. I just wanted to go to one of the best ones. I couldn’t do anything. My arm was in their hands.”

More arms and careers are being put in the care of doctors. Perhaps the two most established are Lewis Yocum, Jobe’s colleague in California who performed Chen’s surgery, and Andrews.

Through the years, Andrews has trained 290 doctors to do the procedure. It’s one reason why an experimental surgery 35 years ago has become commonplace.

“I thought we probably would never do it again,” Jobe said. “Then other people starting doing it and now most every baseball doctor either has a place to get it done or does it himself.”

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