San Francisco signed Elflein to a contract Friday, David Lombardi of The Athletic reports. The offensive lineman then suffered a calf injury in practice, per Kyle Madson of NinersWire.
The 49ers have dealt with multiple injuries to their offensive line in training camp, so Elflein was brought in as veteran depth. However, he wasn't able to make it through individual drills, and head coach Kyle Shanahan said after practice that Elflein pulled his calf. It's not clear how much time the 30-year-old will miss, but San Francisco may now need to bring in another player to reinforce their lineman corps.