49ers put CB Chris Davis on injured reserve, sign JaCorey Shepherd

SANTA CLARA, Calif. -- The San Francisco 49ers have lost cornerback and kick returner Chris Davis for the rest of the season. Davis suffered a knee injury while returning a kickoff in Thursday night's loss to the Arizona Cardinals and left the locker room on crutches.

Davis had served as one of the team's primary kick returners as well as playing some nickel cornerback. He had two tackles and a half sack in four games this season.

To replace Davis, the Niners announced they signed cornerback JaCorey Shepherd to a two-year contract. Shepherd was a sixth-round draft pick of the Philadelphia Eagles in 2015 when Niners coach Chip Kelly was still in charge in Philadelphia.

Shepherd missed all of his rookie season with a knee injury, the Eagles released him in September, and he then spent time on Philadelphia's practice squad before he was released again on Sept. 27. Like Davis, Shepherd also has some experience returning kicks in addition to his cornerback duties.

Davis' injury is the latest blow to a defense that continues to get hammered by health issues, particularly at cornerback. Starting cornerback Jimmie Ward remains out with a quadriceps injury and rookie Will Redmond is already on injured reserve, though he's a candidate to return at some point this season.

For now, the Niners have gone with Tramaine Brock and rookie Rashard Robinson as the starting outside corners with Keith Reaser serving as the primary nickel back.