Howard's operation was Tuesday in New York, and the Wizards said he is expected to make a full recovery in six to eight months.
Howard was injured in a game against the Chicago Bulls on Feb. 22, when he collided with an opponent. That was only his fourth game with Washington after coming over in a seven-player trade with the Dallas Mavericks on Feb. 13.
He had operations on his left ankle and left wrist last offseason. Howard was an All-Star in 2007, when he averaged 18.9 points in 70 games. He had his best season a year later, when he averaged 19.9 points.