General manager Jason Botterill based Hunwick's prognosis on offseason medical evaluations in making the announcement Wednesday, about two weeks before the Sabres report to training camp.
Hunwick was initially hurt last summer and the injury forced him to miss the first two months of the season. He was limited to playing 14 games.
Buffalo acquired the 34-year-old with forward Conor Sheary in June 2018 as part of a trade with the Pittsburgh Penguins. Hunwick has 25 goals and 119 points in 535 career games. He is entering the final year of his contract and set to make $1.75 million.
The Sabres are expected to place Hunwick on the long-term injured list, which will allow the team to free up space under the salary cap. Buffalo was projected to be about $1 million over the $81.5 million salary cap after re-signing defenseman Jake McCabe and goalie Linus Ullmark earlier this month.