The University of Pittsburgh Medical Center said Sunday that the surgery went well. It didn't mention the student by name, but says he's still listed in critical condition.
Spokesman Rick Pietzak says it's the student's fourth and last scheduled surgery.
Seventeen-year-old Jared Boger is among four students still hospitalized following Wednesday's attack at Franklin Regional High School. He's at UPMC Presbyterian, while three others are in critical condition at Forbes Hospital.
Sixteen-year-old Alex Hribal faces four counts of attempted homicide and 21 counts of aggravated assault in the attack.
The school will resume classes Wednesday and teachers will return to work Monday.