Green Bay Packers safety Sean Richardson's playing days could be over after a neck injury that will not only cost him the rest of the 2015 season, but also could end his career.

Richardson's injury is similar to a herniated disc he suffered in 2012, a league source confirmed to Press-Gazette Media on Friday evening. His injury in 2012 required fusion surgery of the C-5 and C-6 vertebrae.

The Packers listed Richardson as "out" for Sunday's game against the St. Louis Rams. He was a full participant at Wednesday's practice, but was listed as limited during Thursday's padded practice and a non-participant Friday.

It took Richardson one day short of a full year to return to the field after his first neck injury. The re-injury is expected to force early retirement, according to the source.

The Packers have traditionally been extremely cautious with any player after suffering a neck injury. They never cleared safety Nick Collins and tight end Jermichael Finley after herniated discs at the C-3 and C-4 levels of their vertebrae, ending their careers.

Richardson, undrafted out of Vanderbilt in 2012, had blossomed into a key special teams player and backup safety in the Packers' defense. The Packers matched a $2.55 million offer sheet Richardson signed with the Oakland Raiders this offseason, a sign of his value to the team. He played 48 defensive snaps with two tackles through the season's first four games, and he also had a special teams tackle. and follow him on Twitter @ByRyanWood