Asked about Dupree's injury Thursday, coach Mike Tomlin said: "You can characterize it as official that Bud is out for the year with a significant knee injury."
Playing on the one-year franchise tag, Dupree will be a free agent after this season. He followed up his breakout 2019 campaign with another strong effort this season, recording eight sacks, two forced fumbles and 26 tackles. Along with T.J. Watt, Dupree was a foundational member of the Steelers' pass rush.
Steelers tight end Eric Ebron tweeted well-wishes to Dupree on Thursday, writing that he was "heavy hearted, but I know u will attack rehab/treatment and be back 100x better."
Replacing Dupree won't be easy. Rookie Alex Highsmith, the Steelers' third-round draft pick, is the top candidate to fill his role.
News of Dupree's test results was first reported by NFL Network.