Head coach Steve Wilks announced the veteran linebacker was a no-show after hyperextending his left knee during Thursday's session, according to the team's official website.
The MRI Bucannon underwent Friday revealed his ACL, MCL and meniscus are all intact, a source informed of the situation told NFL Network Insider Ian Rapoport. In addition to the hyperextension, Bucannon also is dealing with some bruising around his kneecap.
"He's fine. He's a tough player and I'm not worried about him," Cardinals defensive coordinator Al Holcomb said Friday. "He's fine."
Chalk it up as an injury to monitor. With more than a month until Week 1, Bucannon's fate is nothing to fret over yet.