Bayern's Van Buyten to have foot surgery
"The Belgian international will be operated on later on Saturday," the club said in a statement.
"We will have a serious prognosis of how long he will be out after the surgery," said Bayern doctor Hans-Wilhelm Muller-Wohlfahrt.
Van Buyten clashed with Gladbach forward Marco Reus and was taken off in the 76th minute.
Bayern saw their Bundesliga lead shaved to one point after the defeat against Gladbach in the first league match after a one-month winter break.
They are still in the running in the Champions League and the German Cup.