Tommy John was a 31-year-old pitcher for the Los Angeles Dodgers when he damaged a ligament in his arm and underwent a brand-new surgery that would eventually be known by his name.
These days, though, the operation is more likely to be performed on athletes who are years away from the major leagues. Nearly 60 percent of Tommy John surgeries are for patients age 15 to 19, according to a 2015 study in the American Journal of Sports Medicine.

"In my practice there has been a ten-fold increase in high school and younger youth baseball players that required a Tommy John procedure since 2000 — a ten-fold increase," said Dr. Jim Andrews, a prominent orthopedic surgeon who practices in Gulf Breeze, Florida.
Andrews says that when young pitchers specialize in one sport and play it year-round, it puts them at risk for stressing or tearing the ulnar collateral ligament in the elbow. Surgeons use a tendon taken from somewhere else in the body to reconstruct the UCL.

Bryce Hill, 17, a pitcher for Seminole Ridge Community High School in Loxahatchee, Florida, decided to have the surgery after he tore the ligament in January.
"I could either get the surgery and then play baseball again or just hang up my gloves and not play ever again," he said.
For more on the Tommy John trend, watch TODAY's report.
Correction: An earlier version of this article said Dr. Jim Andrews practices in Birmingham, Alabama. He practices in Gulf Breeze, Florida.