Wilshere has been ruled out of England's World Cup qualifiers against San Marino and Montenegro.
Wenger said: "Maybe I overplayed him, but only in the last two games. It's difficult to rest him because he's a winner and when I ask how he feels, he says "perfect". We do a regular scan and it showed bone bruising on the heel of his right foot.
"He had some inflammation where he had the surgery and he has been compensating to protect his left ankle. Every month he has scans on both ankles, but he feels no pain.
"The last time we let him carry on and it turned into a stress fracture, which is why the specialist said we cannot take this gamble."