The holding midfielder faces a lengthy spell on the sidelines after picking up a groin problem in the shock 3-0 defeat against Hamburg on Saturday afternoon
The holding midfielder picked up a knock in the opening 45 minutes and was consequently taken off at half-time.
Bender underwent a series of test on Sunday to determine the extent of the injury and BVB have now announced that he will be out of action for an estimated two-and-a-half months.
"Sven Bender has suffered an inflammation of the pubic bone. Team doctor Markus Braun reached his diagnosis after the midfielder underwent further examination on Sunday," a statement on the official Dortmund website reads.
"Bender needs to avoid any sporting exertion for six weeks and Braun predicts a subsequent four-week recuperation period."
The 24-year-old has made 27 appearances in all competitions for Dortmund so far this season.