Rapoport noted Tuesday that an MRI confirmed the initial diagnosis after Gerry Dulac of the Pittsburgh Post-Gazette first reported the severity of the injury.
This is another blow for Dupree after he started the 2016 season on the injured reserve list with an abdominal injury in need of surgery and played just seven games. However, he had been durable beyond that, appearing in all 16 games as a rookie in 2015, as well as in 2018 and 2019. He also played in 15 games in 2017.
The No. 22 overall pick in the 2015 draft entered the 2020 season with 31.5 career sacks as a dangerous playmaker on the pass rush after he broke through with a career-best 11.5 sacks in 2019.
The 27-year-old has eight sacks this season.
Pittsburgh still has T.J. Watt at outside linebacker and will likely turn toward Olasunkanmi Adeniyi and Alex Highsmith to carry more of the load.
Even with those other options, Dupree is a force on the defensive side. The Steelers' Super Bowl chances will take a hit with Dupree on the sideline.