Nothing strikes fear in the heart of a baseball fan more than hearing the name of their team's star pitcher and the words "Tommy John surgery" in the same sentence. The surgery involves replacing the worn-out or deteriorated ulnar collateral ligament in a hurler's elbow with a tendon from another part of the body, and it was first performed back in 1974. Since then, over 500 major leaguers have had the procedure, and it puts the athlete out of the game for at least one full calendar year. Over time, more players have been able to return with most, if not all, of their talent intact. But bad luck, a poor work ethic, or a misguided rehab period can derail the player's career even further—sometimes out of baseball entirely.

When 20-year-old left-handed pitcher Thomas Edward John Jr. made it to the major leagues in 1963 as a Cleveland Indian, there weren't many options for pitchers who sustained serious injuries to their throwing arms. At that time, very few ballplayers were willing to undergo surgery on their arms, as it almost always meant the end of their careers. Players started to undergo arthroscopic knee surgeries then, but if a pitcher had a throbbing arm, they used palliative measures to treat it. Hall of Famer Sandy Koufax retired in 1966 at age 30 because he suffered from chronic arthritis in his pitching arm and was worried that if he didn't stop playing baseball, he wouldn't be able to use his left hand for the rest of his life. (He said the cortisone injections, codeine, Butazolidan, and Capsolin he took at times to numb the pain left him "half high" on the mound.)

For the first 10 years of his career, Tommy John was known as a decent pitcher who couldn't throw very fast. The speed of his fastball was never anything to write home about, but he had a curveball that had helped him rack up a 28-2 record in high school. After two years on the Indians, John spent 1965-1971 as a member of the Chicago White Sox. The morning after a start in which he threw a complete game shutout, his arm hurt so much he couldn't even brush his teeth. (He wound up resting his arm on the sink and moved his face back and forth against the bristles of the toothbrush.) Despite the incident, John would later describe the pains he felt in the first half of his career merely as "soreness."

A trade to the Los Angeles Dodgers in 1972 gave John's career new life (his career record at that point was 84-91). Dodgers pitching coach Red Adams gave him confidence in the fastball everybody told him was too slow, pointing out it was the movement of his fastball that was the key. In his first year as a Dodger, John went 11-5, but on September 23, 1972 he jammed his pitching elbow while sliding into home base. Some bone chips in the elbow were jarred loose, ending his season. The team physician, Dr. Frank Jobe, cleaned up his elbow during the offseason, but Jobe and John's elbow would become reacquainted soon enough.

By July 17, 1974, John had transformed into a top-notch pitcher. He was 13-3 on the season when he delivered a pitch to Montreal Expo Hal Breeden that would change everything. "Right at the point where I put force on the pitch, the point where my arm is back and bent, something happened," Tommy John told Sports Illustrated. "It felt as if I had left my arm someplace else. It was as if my body continued to go forward and my left arm had just flown out to right field, independent of the rest of me. I heard this thudding sound in my elbow, then I felt a sharp pain." The pitch completely missed the strike zone. Amazingly, after rupturing the medial collateral ligament of his left elbow, he tried throwing another pitch (it sunk and hit home plate).

When John's arm didn't heal after a month's worth of rest, Dr. Jobe suggested a novel idea. Jobe had earlier grafted a tendon on a polio patient's ankle for stabilization, and he thought that maybe a tendon could be grafted to a pitcher's elbow, too. Without the surgery, Jobe told John that he would never pitch in the majors again. With the surgery, Jobe bumped those odds up to one in 100. After taking a brief moment to think about it, John said, "Let's do it."

On September 25, 1974, Jobe removed a tendon from John's right wrist and attached it to his left elbow. A second surgery was needed a few months later because the ulnar nerve was damaged, John's arm atrophied, and his pitching hand wrenched into a claw. After that, the rigorous rehabbing began. Still without feeling in two of his fingers, John taped the damaged digits to the fully-functioning ones so he could grip a baseball. He threw it against a wall until he got tired, later saying that he looked as polished "as a little boy throwing a ball against the steps of his back porch." He was also told to squeeze blobs of Silly Putty in his hand. In June 1975, he was finally able to uncurl his two paralyzed fingers. By late September, he was able to throw three innings in an exhibition.

John returned to the Dodgers' starting line-up in 1976 and posted a 10-10 record for the season. But it was the next year when John really excelled. In 1977, he finished second in voting for the Cy Young award and threw a complete game victory in the NLCS to send his team to the World Series. It was that pennant-clinching performance when Tommy John knew for sure he was back, maybe better than ever.

Incredibly, John didn't retire until 1989, at the age of 46. He played in 26 major league seasons over his career—only Nolan Ryan and Cap Anson, with their 27 seasons of service, have played more in the history of Major League Baseball. John won 124 games before the surgery, and 164 after the ulnar collateral ligament reconstruction.

Because of the miraculous recovery of its pioneering patient, the term "Tommy John surgery" stuck. And why isn't it named for the doctor who invented it? Dr. Jobe has a simple explanation: "He has two first names—Tommy and John. It kind of just rolls off the tongue."