ALLEN PARK, MICH. (AP)
Backus played for the Lions his whole career after being drafted in the first round out of Michigan in 2001. He started his first 186 games before a hamstring injury forced him to miss last year's Thanksgiving matchup against Houston.
Backus says in a statement he's content knowing he gave everything he had and played as hard as he could.
With Backus gone, Riley Reiff could step in at left tackle. Reiff was Detroit's first-round pick in 2012.
Also Thursday, the Lions re-signed long snapper Don Muhlbach to a one-year contract.