Wilshere will have surgery on Monday after the stress fracture he suffered in his right ankle in a pre-season friendly in July failed to heal naturally.
The English Premier League club defended their decision not to send the player for surgery sooner.
"Throughout Jack's injury, the club has been guided by the continuous advice of several world-renowned specialists," a statement on the club's website said late on Friday.
"The information attained this week has led to the conclusion that surgery is now required to gain an optimal response."
The 13-times English champions said a more detailed timescale for Wilshere's return would be decided after the surgery on his right ankle.
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