Fellow defender Johan Djourou is also out for six weeks with a shoulder injury, meaning Arsenal will rely heavily on Sebastien Squillaci (right) in his debut season at the club.
The Frenchman's form has been patchy but Wenger has faith in him.
He said: "I think he had a good start to the season and then had a little dip in December. The recent games he played, like Stoke, he did well so I am not worried about him."
Wenger also revealed that Arsenal are considering playing a charity match in Japan for the victims of the earthquake and tsunami.
