An X-ray revealed the fracture, and the Cowboys quickly ruled him out.
He is expected to undergo surgery but should return this season. According to Gehlken, Vander Esch will need four to six weeks to get back on the field.
So the Cowboys can place Vander Esch on injured reserve and activate him when his rehab is completed. The Cowboys already have placed linebacker Sean Lee on injured reserve, and he becomes eligible to return after missing two more games if his rehab is completed.
Joe Thomas replaced Vander Esch at middle linebacker.
Vander Esch missed seven games last season with a neck injury.
Starting tight end Blake Jarwin is believed to have torn his right anterior cruciate ligament. He will undergo an MRI on Monday to confirm his season is finished.
Reserve offensive tackle Cam Erving also left with a knee injury.
UPDATE 11:46 P.M. ET: The Cowboys confirmed Vander Esch’s injury.