Kade Durnin knew right away that something was badly wrong.

“It’s unlike any other feeling that you’ve probably ever had, in terms of arm pain,” the 19-year-old college pitcher says in an interview with CNN Sports. “It feels like you got hit in the funny bone – it’s just not very funny.”

Durnin was training his arm when he felt a pop. Before long, a doctor was delivering the news that no pitcher wants to hear: He had torn his ulnar collateral ligament (UCL).

It is an injury which has plagued Major League Baseball for the best part of the last century. The ligament in your elbow which connects the bone in your upper arm to the one in your forearm – and is only about as strong as “a piece of celery” – tears, leaving you unable to throw and facing a very length spell on the sidelines.

This season, the likes of Gerrit Cole, Corbin Burnes and Shane Bieber have all had Tommy John surgery – the most popular procedure to repair a torn UCL – while Japanese superstar Shohei Ohtani made his long-awaited return to the mound after almost 22 months away following the second elbow surgery of his career.

Dr. Christopher Ahmad, Tommy John expert and head team physician for the New York Yankees, has performed the surgery on some of the biggest names in baseball. But he has also been privy to the other side of the story.

“The alarms are going off on how devastating this problem is to the youngest players,” he says in an interview with CNN Sports.

“When I first started doing Tommy John surgery about 25 years ago, the population who I was operating on who needed the surgery were essentially very high-level players – they were college prospects destined to be professional, or professional players.

“Now, the population who needs the surgery most are kids.”

Of the 10-15 Tommy John surgeries that he performs every week, Ahmad estimates that between eight and 10 are on high school children, with some even still in middle school.

Such a high number of young players going under the knife is a relatively new phenomenon.