Avril missed most of the 2017 season after sustaining a neck injury in Week 4.
The Seahawks have released defensive end Cliff Avril with a failed physical designation, the team announced Friday.
Avril sustained a neck injury last season in the first quarter of Seattle's Week 4 win over the Colts. He was placed on injury reserve, meaning he was not eligible to return until Week 14. However, Avril did not play for the rest of the year.
Because of Avril's career-threatening injury, some speculated that he might retire. But Avril told SI's Greg Bishop that he planned to return.
Selected by the Lions in the third round of the 2008 NFL draft, Avril spent his first five years with Detroit before joining Seattle prior to the 2013 season.
He was a key member of the Legion of Boom defense that carried Seattle to Super Bowl XLVIII victory. He recorded 11.5 sacks in 2016 en route to being selected to his first Pro Bowl and has 74 sacks for his career.