In July 1974, Dodger pitcher Tommy John went on the 21-day disabled list with an elbow injury. But rest wasn’t enough, and the damage to the ulnar collateral ligament (UCL) in his pitching arm resulted in surgery, ending what had been a stellar start to his season.

Dr. Frank Jobe, the Dodger’s team physician, performed a pioneering surgical procedure he had devised to replace the damaged ligament. At the time, it was unclear whether John would be able to pitch again, with Jobe reportedly putting the odds of a full recovery at 1-in-100. But his return was eagerly anticipated and earned him and his arm a nickname.

On April 16, 1976, John was on the mound for the Dodgers as the first pitcher to ever come back from such and injury, going five innings but giving up a 3-run homerun that cost the Dodgers the game. Five days later, he was back on the mound, pitching seven scoreless innings in a pitchers duel with Houston’s J.R. Richard that ended in a 16 inning 1-0 Houston win.

Not only did Tommy John recover, he pitched for another 14 years. He won 20 games or more 3 times, starting in 1977. When he stepped on the mound on opening day in 1989 at age 45, it was his record-setting 26th season (later topped by Nolan Ryan). While it was his last season, he went on to coach and was even the commissioner of a newly formed baseball league in South Florida.

Jobe’s procedure would go from being a long-shot pioneering procedure to being so commonplace, some have estimated that one-third of all major leaguers have undergone it. The procedure is widely referred to as “Tommy John surgery” in honor of its namesake first patient.

While some say that 85% or more make a full recovery, others — including Tommy John’s own son — have a different assessment. But for Tommy John looking back, there’s no doubt about the positive outcome.