Citing a history of concussions, most recently one last December that ended his 2009 season, free agent tight end Casey FitzSimmons has announced his retirement from the National Football League, reports John Niyo of the Detroit News.

"If it wasn’t for the concussions, I would not be retiring. It’s frustrating because the rest of my body is still capable of playing at a high level in the NFL. However, given the seriousness of the risk associated with continuing to play, I have to listen to the advice the team has given me", FitzSimmons said in a statement Niyo posted on Twitter.

FitzSimmons (6-4, 260) spent his entire seven-year career with the Lions, who signed him as an undrafted free agent out of Carroll College (Montana) in 2003. In 99 career games, including 25 starts, FitzSimmons caught 88 passes for 677 yards and 5 touchdowns, and also made 49 tackles, forced and recovered one fumble, and blocked a pair of kicks on special teams.