The 6-foot-5 Robinson started all 34 games last season, averaging 6.6 points and 5.6 rebounds as Pitt reached the second round of the NCAA tournament. His best game was a 26-point, 11-rebound effort against Louisville on Jan. 16.
During his two-season career, Robinson had not missed a game to injury. The surgery was performed Wednesday.
Pittsburgh, the Big East Conference preseason favorite, opens its season Nov. 8 against Rhode Island. Robinson could miss as many as 10 games if he is out for six weeks.