CHICAGO -- Pirates right-handed pitcher Jeff Karstens underwent surgery on his injured shoulder Friday and is not expected to begin pitching again until late August at the earliest.
Dr. Neil ElAttrache performed the surgery in Los Angeles after Karstens visited him earlier this week for a second opinion on his shoulder. Dr. ElAttrache "debrided" Karstens' rotator cuff and labrum, meaning he removed loose fragments of the tendons, according to the Pirates.
The Pirates also announced Saturday they had placed right-handed reliever Jared Hughes on the 15-day disabled list with right shoulder inflammation. The Pirates recalled outfielder Alex Presley to take his place on the 25-man roster.
Karstens, 30, has not pitched this season after experiencing shoulder discomfort early in spring training. He had a recent rehabilitation outing shut down after continued shoulder pain.
The Pirates signed Karstens to a one-year, $2.5 million contract after the Pirates non-tendered him ahead of the arbitration deadline last offseason.
When healthy in 2011 and 2012, Karstens was an effective pitcher with the Pirates. But he has struggled to maintain his health, especially the past two seasons. He missed more than two months in 2012 with right shoulder inflammation and did not pitch for three weeks later in the season with a right hip flexor injury.
In five seasons with the Pirates, Karstens went 23-25 with a 4.31 ERA and a 1.312 WHIP. The Pirates acquired Karstens, Jose Tabata and Ross Ohlendorf from the New York Yankees in 2008 in a trade that sent Xavier Nady and Damaso Marte to the Bronx.
Hughes, 27, is 1-2 with a 4.96 ERA this season. He walked off the field Saturday with athletic trainer Todd Tomczyk during pregame warm-ups and flew to Pittsburgh following the game for further evaluation.
Presley, 27, is hitting .286 with the Pirates, though he has bounced back and forth between the major and minor leagues. He was hitting .282 in 44 games with Class AAA Indianapolis.