The three-year veteran tried to play through the injury during training camp, but coach Mike Munchak said Sunday that McRath had decided to have the surgery.
McRath says he aggravated his knee Aug. 6, when the Titans practiced against Atlanta in Georgia. The linebacker had tried to rest his knee, but he says he couldn't run well and didn't want to hold back his teammates.
The Titans drafted the 6-foot-3, 228-pound McRath in the fourth round out of Southern Mississippi in 2009. He played on special teams and in passing situations on defense in 2011.