The 24-year-old Germany international was substituted at half-time on Saturday as Dortmund suffered a shock 3-0 defeat against Hamburg.
Although he could return before the Bundesliga campaign ends on May 10, Bender will have little time to prove his fitness prior to Joachim Low announcing his squad for the 2014 World Cup in Brazil.
A statement on Dortmund's official website read: "Sven Bender has suffered an inflammation of the pubic joint.
"The full extent of the injury was revealed after a scan by BVB team doctor Markus Braun at the Knappschaft Hospital in Dortmund on Sunday.
"Bender has been told to rest completely for six weeks, after which he will need approximately four more weeks to build up strength again, according to Dr Braun."
Bender, the twin brother of Bayer Leverkusen midfielder Lars, has earned seven caps for Germany.
