Zach Aston-Reese underwent successful left shoulder surgery, Jim Rutherford announced on Monday.
The surgery was performed by team physician Dr. Dharmesh Vyas at UPMC Montefiore Hospital.
The Penguins did not specify what the exact injury to Aston-Reese's shoulder was. The injury is unrelated to what sidelined Aston-Reese for a month to finish the regular season, because that injury was a lower-body injury.
Aston-Reese is expected to be sidelined for six months as a result of the surgery, a timeline that would keep him out until February. The 2020-21 NHL season is expected to begin in December.