The procedure, which will be performed by team physician Neal ElAttrache, will be done arthroscopically and will help determine the cause of the inflammation Ryu has been dealing with since spring training. The Dodgers are prepared for the likelihood that Ryu will not pitch for them this season.
The Dodgers have given no timetable for Ryu's return, largely because the cause of the injury remains a mystery until ElAttrache takes a look inside the shoulder. Manager Don Mattingly was asked Wednesday whether there is a chance Ryu could pitch for the Dodgers this season if the surgery doesn't uncover any major structural damage.
"I didn't get that feeling," Mattingly said.
The latest MRI on Ryu's injury was inconclusive, and Mattingly said the topic of surgery surfaced only in the past few days. He called the loss of Ryu "a test for our club."
"Hyun-Jin's just a quality starter. Every time he takes the ball, you just knew you were going to get a quality outing pretty much every game, against, really, any team. He had weapons for a lot of hitters," Mattingly said. "Knowing you're going to have to replace those innings, obviously it's not the ideal situation. It's an opportunity knocking for Carlos Frias, Mike Bolsinger, guys like that."
Ryu's first attempt to return without surgery in March was aborted when he felt tightness in the shoulder during a bullpen session.
Dodgers president of baseball operations Andrew Friedman acknowledged Tuesday that he wasn't optimistic Ryu would be able to return to the mound this season.
"It hasn't progressed as quickly as we all hoped, and he's worked extremely hard to get back. It just isn't happening as quickly as he would like," Friedman said. "It's not a totally clear-cut, black-and-white issue. It's more involved than that. We have an excellent doctor in ElAttrache and a very good medical department, and everyone is putting their heads together to see what makes the most sense."
Ryu is the second Dodgers starter to be lost to surgery. Brandon McCarthy has undergone Tommy John elbow reconstruction and is expected to be out until around the 2016 All-Star break.
Ryu's surgery could send the Dodgers into a full-scale search for a starting pitcher, although they have had surprisingly good results internally. Frias and Bolsinger have given the Dodgers solid spot starts.
The Dodgers also have Brandon Beachy under contract for $2.75 million as he tries to work his way back from a second Tommy John surgery. Beachy, who threw a bullpen session Monday, is expected to go on a minor league rehab assignment soon, and his return, presuming he has no setbacks, is expected in June.
"He's making progress," Mattingly said. "Mentally he's moving forward. He's getting closer and closer to games."
Ryu is 28-15 with a 3.17 ERA in two seasons for the Dodgers.