A person who has spoken with Gronkowski told NFL Media Insider Ian Rapoport that the injury-prone star will have surgery Thursday to repair both ligaments.
The procedure will be performed by Dr. James Andrews.
The knee reconstruction will be the eighth known surgery of Gronkowski's playing career.
In the past two years, Adrian Peterson and Robert Griffin III have returned by Week 1 after undergoing similar surgeries in January. Gronkowski will have to be diligent in his rehabilitation schedule to maintain that pace.
For the second season in a row, Gronkowski is unlikely to be a major factor in the offense until October or later.
The latest "Around The League Podcast" recapped all the Wild Card Weekend action.