Sanu suffered the injury on a punt return against the Philadelphia Eagles on Nov. 17, his third game with the Patriots, according to ESPN's Mike Reiss.
He was largely unproductive in eight regular-season outings with New England during 2019, hauling in 207 yards and one touchdown. The 30-year-old had one catch for 5 yards in the Patriots' playoff loss to the Tennessee Titans. He was acquired from the Atlanta Falcons for a second-round draft pick before the trade deadline.
With a non-guaranteed base salary of $6.5 million for 2020, Sanu could wind up as a salary cap casualty this offseason.