ENGLEWOOD, Colo. (AP) — The Denver Broncos signed free-agent center Dan Koppen, bringing the 11-year veteran back after J.D. Walton had offseason surgery on his left ankle.

Koppen signed with the Broncos last October and started 12 regular season games after Walton first hurt his ankle. Walton was expected back this season but needed more surgery this offseason.

Koppen played his first nine seasons with the Patriots.

The Broncos have injury issues on their offensive line, with guard Chris Kuper (ankle) and tackle Ryan Clady (shoulder) still recovering from surgery. Backup Manny Ramirez took most of the snaps at center during Denver’s offseason practices, but the Broncos decided to bring back Koppen, whose teams have gone 108-28 in games he has started.