The Vikings added safety John Lowdermilk to their practice squad on Tuesday and released linebacker Terrance Plummer from the same unit.

Lowdermilk, a son of former Vikings center Kirk Lowdermilk, was a standout at Iowa and signed with San Diego in May after going undrafted. John Lowdermilk , 6-2 and 210 pounds, was released in the Chargers' final cuts in September.

Kirk Lowdermilk played for the Vikings from 1985-92, and John was born in Edina before his father's final season in Minnesota. Kirk Lowdermilk, a third round pick out of Ohio State in 1985, finished his career with the Colts (1993-96).

The Vikings' starting safeties, Harrison Smith and Andrew Sendejo, both have left knee injuries. The Vikings finished Sunday's victory in Atlanta with backups Antone Exum Jr. and Robert Blanton as their only two safeties. Anthony Harris, another safety, is also on the practice squad.