The 27-year-old defender, a £10million signing from Ajax in 2009, is missing from Arsenal’s tour of the Far East while he recovers from his injury.
Wenger confirmed: “He has had a back problem and he has not been able to practice. How long he will be out for we don’t know but I think he will miss the start of the season.
“But that is the only reason he is not out here in Indonesia with us. There is no bad feeling because he wasn’t playing at the end of the season.
“It is just an unfortunate injury but certainly he will still be our club captain.”