The team said Friday the injury was discovered during an MRI earlier in the week.
Najera figured to play a reserve role this season. He played in 31 games last season for the Bobcats, averaging 2.2 points and 1.4 rebounds in 12 minutes.
The surgery was performed Friday by Bobcats team physician Dr. Glenn Perry.
The Bobcats open the regular season Dec. 26 at home against Washington.