The Gunners chief revealed Gibbs had suffered a setback in his recovery from a hernia operation.
The setback has not been specified and no time limit has been put on recovery but Wenger indicated that a loan move could be necessary.
“It depends now on Gibbs,” the Frenchman told Arsenal’s official website.
“He sees a specialist again today [Tuesday] and if something happens there that he has had a real setback then possibly, yes.”
Wenger warned that he would not go into any transfer dealings recklessly, however, and will only make a move if a worthwhile deal comes up.
"It is not a shop, you just take a good opportunity that is on the market when you can,” he added.
“Overall that's what we are doing at the moment. We are starting to look at players if Gibbs is not back.
“On the other hand we have good news on Bacary Sagna because he has started to run again yesterday and today.”
Sagna has been recovering from a broken leg and all the Gunners’ full-backs are also out long term.
Carl Jenkinson is out with a fractured vertebrate and Brazil international Andre Santos is set for a three-month absence after damaging ankle ligaments.
Wenger is expected to draft-in reserve team captain Ignasi Miquel at left-back in tonight’s game with Aston Villa.