The Falcons announced Tuesday that Weatherspoon will miss the entire 2014 season after suffering an Achilles tendon injury at practice.
"During Sean's run today with our medical staff, he suffered an injury," Falcons coach Mike Smith said. "We sent Sean to the doctor for some additional testing and evaluation and unfortunately the results showed that he ruptured his Achilles tendon.
"Sean had been working extremely hard to get back on the field, but regrettably he will miss the entire 2014 season. He will have a procedure done in the near future and we expect him to make a full recovery."
Weatherspoon, 26, had been working his way back from a knee injury that ended his 2013 season after Week 15. Injuries have become a recurring theme for Weatherspoon; he started last season on short-term injured reserve with a foot issue.
This is an extremely tough blow for a shaky Falcons defense that was counting on Weatherspoon to bring some stability to the middle of the unit. The timing is particularly devastating for Weatherspoon, who is entering the final year of his contract.