BALTIMORE -- Pitcher Charlie Morton underwent season-ending Tommy John surgery Thursday and will miss between 12 and 18 months.
General manager Neal Huntington said Morton's injury was caused by deterioration of his right elbow ligament over time.
"Picture a rope that, over time, a little piece of the string breaks, a little piece of the string breaks, a little piece of the string breaks," Huntington said. "We just got to a point in time where it was no longer functional."
Already on the disabled list with right elbow inflammation, Morton felt discomfort after throwing long toss and a bullpen session Sunday and was shut down for evaluation.
Morton had pitched through discomfort probably longer than he should have, Huntington said. Morton said he first started experiencing elbow issues after a May 12 start against the Houston Astros and made three more starts after that.
"He competed through it as long as he possibly could," Huntington said. "It got to a point in time where he felt like he couldn't compete with it anymore, it wasn't functional anymore."
Named after the pitcher Tommy John, the surgery repairs the ulnar collateral ligament by replacing it with a tendon from another part of the body, often the wrist or hamstring. Orthopedic surgeon Dr. James Andrews performed the surgery in Pensacola, Fla.
Some pitchers have the ligament snap in one pitch while other have it whittle away and can still maintain their effectiveness, Huntington said.
Once a career-threatening injury, more than 85 percent of major league pitchers who have it return without any complications. Teammates A.J. Burnett, Erik Bedard, Brad Lincoln and Jason Grilli have all had the surgery.
Morton had brought up his elbow issues with Grilli before Thursday.
"You kind of know in your mind that something's not feeling right," Grilli said. "It's hard because when you're out there, we all pitch with aches and pains and either one you know something might be detrimentally wrong. You still want to be out there. I give him credit for going as long as he did. Who knows when he just couldn't take it as much anymore."
Grilli said it seems like there are more pitchers in the majors "with the zipper on their elbow" than not, pointing to a scar on his arm that he got after his 2002 Tommy John surgery.
"It's never a fun bit of news, but when you look at the success rate and the recovery, he's just missing time now," said Grilli.
The two exchanged texts Thursday, and Grilli told his teammate that he can always count on his support.
"It's a long, slow process and it's hard to see baseball go on without you," Grilli said. "That's the most painful part of any surgery."
Morton was placed on the 15-day disabled list on June 1, retroactive to May 30, with the elbow injury. He also had offseason surgery to repair a torn hip labrum and missed the first week and a half of the season.
He went 2-6 with a 4.65 ERA in nine starts.
Huntington said the Pirates will first look at the pitchers who have already started major league games this season to fill the void -- a list that, without Morton, includes six pitchers. Though a handful of starting pitchers are throwing well for Class AAA Indianapolis, Huntington said he does not anticipate adding one of them to the active roster.
"We hope not because that means we've got another pitcher injured," Huntington said.