The England international pulled out of the squad to face Stoke City on Sunday and was replaced by Serge Gnabry. However the slight damage to his posterior abdominal wall is not believed to be serious.
Wenger told the club’s official website: “Theo will be out for a few weeks. He has developed some damage to his posterior abdominal wall. It’s not a hernia, but it’s a little structural problem in his abdomen.
“He will have the procedure in Germany on Wednesday and, because it’s so minor, we can begin his rehab immediately. We are pleased it’s being dealt with quickly and he shouldn’t miss too many Arsenal matches. But he will miss the forthcoming international matches with England.”