The Germany goalkeeper broke down during Barca's 5-1 win at Villarreal on Sunday.
Barca announced this morning: "The tests carried out have confirmed that the first team player Marc ter Stegen has a complete break in the patellar tendon of the right knee. This afternoon he will undergo surgical treatment. At the end of the intervention, a new medical report will be provided.
"It should be remembered that the goalkeeper of Barça, starter in the match against Villarreal at the La Ceramica, he had to leave the field of play just before the break. The injury occurred in a play in which he tried to catch a high ball and stumbled on the fall.. Quickly, he asked for the change and left the game in great pain."
It's suggested Ter Stegen's season is now over due to the recovery period required.