Ulnar collateral ligament (UCLR) reconstruction, commonly called "Tommy John Surgery" after the New York Yankees pitcher who made it famous, is a procedure performed on Major League Baseball pitchers after they get a damaged or torn ulnar collateral ligament, a common elbow injury.  In 1974, Dr. Frank Jobe made medical history when he replaced the pitcher's torn medial collateral ligament with a tendon from John's forearm.

John then pitched for 14 more years and added 164 more victories - after an injury that had been career-ending in the past.

And that wasn't an anomaly. In a new study, researchers looked at the rate of return to professional pitching following ulnar collateral ligament reconstruction, the level of performance in pitchers returning to major league baseball, and the difference in overall performance between pitchers who underwent Tommy John Surgery and demographic-matched controls who did not. 

Researchers evaluated  the effects of ulnar collateral ligament reconstruction of pitchers between 1986 and 2012 using a number of performance-based statistics and compared them with matched controls: age, body mass index (BMI), position, handedness and Major League Baseball experience. 

Tommy John. Credit and link: MLBReports.com

In the year prior to Tommy John surgery, pitchers who would soon undergo
ulnar collateral ligament reconstruction
were outperformed by controls in terms of the number of innings pitched, games played and winning percentage. However, after undergoing  ulnar collateral ligament reconstruction, pitchers allowed significantly fewer walks and hits per inning pitched (WHIP), won a higher percentage of games, and recorded lower earned run averages (ERA) than prior to their surgeries.

After Tommy John surgery, pitchers also recorded higher winning percentages and lower WHIP and ERA in their post-surgical career than the control group.

Overall, 83 percent of UCLR patients were able to return to MLB, and their careers on average lasted an additional 3.9 years. 

Torn ulnar collateral ligament. Credit and link: Methodist Orthopedics

The authors of the study concluded that there is a high rate of pitchers returning to MLB following UCLR, with a significant improvement in pitching performance.