Source: Mike Iupati has MCL sprain

An MRI taken Monday confirmed an MCL sprain for San Francisco 49ers guard Mike Iupati, a source told ESPN NFL Insider Adam Schefter.

Iupati was carted off to the locker room during the 49ers' 23-20 loss at New Orleans on Sunday. He was seen leaving the locker room on crutches and with his knee in a brace.

During the game, Iupati was replaced by Adam Snyder.

The 49ers' offense is struggling. It has not been able to cross the 200-total yard plateau in two straight games, and it had five three-and-outs Sunday.

Information from ESPN NFL Insider Adam Schefter and ESPN.com San Francisco 49ers reporter Bill Williamson contributed to this report.