The surgery began Wednesday morning, and experts say the star rookie may face a lengthy rehabilitation that could jeopardize the start of his 2013 season, The Washington Post reported Wednesday.
Doctors will determine if another ligament in his right knee, the anterior cruciate, was damaged as well, a person familiar with Griffin's condition said.
The newspaper reported Monday an initial MRI exam showed possible tears in two ligaments.
Griffin was examined Tuesday by orthopedic surgeon James Andrews near Pensacola, Fla.
Team officials had no comment about the results of Andrews' exam, but the decision to conduct surgery suggests Griffin had suffered a complete lateral collateral ligament tear. Griffin tore the anterior cruciate ligament in the same knee in 2009, while a sophomore at Baylor University.