Karney, the starter at his position coming into the season, has not played since Week 11. The Rams had phased him out of the offense in part because Karney did not factor on special teams and it was tough to justify setting aside one of 45 game-day roster spots for a part-time blocker.
Karney is active again for two reasons:
Karney's replacement, Brit Miller, landed on injured reserve after suffering a knee injury against Kansas City in Week 15.
Rookie tight end Mike Hoomanawanui is unavailable while recovering from an ankle injury. Hoomanawanui had been lining up at fullback in addition to tight end, providing a measure of flexibility that Karney could not offer.
Rams running back Steven Jackson has expressed support for Karney over the years. He likes running behind Karney in the team's base personnel package featuring two backs and one tight end.