"He played two or three weeks with it, but the injury became worse against West Ham. It's a genuine physical injury. It is bone bruising. He cannot kick the ball at the moment," Wenger told BBC Sport on Friday.
Campbell had left Highbury during half-time following his substitution in Arsenal’s 3-2 loss to West Ham, an aspect which sparked rumours hinting off-the-field problems.
"I met Sol and we had a frank explanation. He is highly-motivated to do well and he spoke as well to the players. You do not walk out like he did when you are Sol Campbell if you have a problem, and he did that.
"We are all behind him and we support him. I believe he will support us as much as he can until the end of the season," Wenger added.
The England defender, who will sit out Arsenal’s games against Bolton and Liverpool, will also miss the team’s UEFA Champions League first-leg against Spanish giants Real Madrid.
"Yes, he will miss it [the Real tie]. The first leg certainly, the second I don't know, but the first certainly," Wenger was quoted as saying by Sky Sports.