CHICAGO -- White Sox reliever Zach Putnam underwent Tommy John surgery at the end of last week, as announced by general manager Rick Hahn on Monday, and will be sidelined for the next 12 to 18 months.
Putnam posted a 1.04 ERA over seven games this season, but had not pitched since April 22. His '16 season ended June 20, eventually leading to elbow surgery to remove bone spurs.
"We knew when they went in to repair the elbow last winter, when they removed the chips, the ligament was not in great shape, but Zach and his doctors thought it was worthwhile for him to try to fight back and pitch through it," Hahn said. "Obviously, he was able to do it for a short period of time.
"Ultimately the ligament gave out. Zach deserves a world of credit for doing everything he could the last two years to fight his way back to contribute in the bullpen. Unfortunately, it didn't work out for him."
The surgery was performed by Dr. James Andrews, with Hahn adding that everything went smoothly.
Rodon's return becomes official
Carlos Rodon makes his first big league start of 2017 on Wednesday against the Yankees after missing most of the first three months due to left biceps bursitis. Rodon mentioned Sunday how he now has a set day-to-day work routine helping him stay strong.

"Let's put it this way: we've talked a lot about, development continues at the big league level," Hahn said. "Carlos obviously came very quickly through our Minor League system. He's always had tremendous stuff and the ability to get by based upon his stuff alone.
"As the innings start to add up and guys get a little bit older, then there's a need for a little bit of more regularity with a routine that perhaps they didn't have the need for in the past. Carlos has learned a lot from this experience and it's going to serve him well going forward."
Hahn would not name the pitcher Rodon is replacing in the rotation or on the roster.
More signings
The White Sox are expected to agree to terms with right-handers Lincoln Henzman (fourth round) and Kade McClure (sixth round) and catcher Evan Skoug (seventh round) on Tuesday. Skoug is expected to sign for over slot money.
No pressure to trade
Hahn was asked Monday if it's incumbent on him to make trades before the July 31 non-waiver Trade Deadline as part of the rebuild.
"No. God no," Hahn said. "We feel we have certain desirable players that would help other clubs and may fit better on their competitive windows then they do on ours right now. And we intend to be active each day in trying to further accomplish what we set out to do a year ago at this time.
"We simply can't force this time frame. If we are going to move talented players, we have to get what we feel is the appropriate value back or it's not going to happen."
There were no major trades made by the White Sox at this time last year. But as Hahn pointed out, the team got the return it wanted by moving Chris Sale in December.