Kaeding suffered the injury on the opening kickoff of Sunday's season opener against Minnesota, which Percy Harvin returned 103 yards for a touchdown.
Kaeding got twisted around attempting to make a tackle on the play and eventually left the field on a cart. San Diego won the game, 24-17.
Kaeding, in his eighth season out of Iowa, is 173-for-200 on field goal attempts in his career with the Chargers.
To replace Kaeding, the Chargers signed kicker Nick Novak to a two-year contract Tuesday.
Novak has played for the Arizona Cardinals (2005), the Washington Redskins (2005 and 2006) and the Kansas City Chiefs (2008), connecting on 19-of-30 career field goal attempts and on all 32 extra-point tries.
San Diego also released safety C.J. Wallace and signed defensive end Ogemdi Nwagbuo to a one-year deal Tuesday.