The 19-year-old has not played a competitive match for the Gunners this season and on Monday underwent ankle surgery, which is expected to rule him out of contention until late February.
The Gunners boss told declared: "I don't think that the medical staff made any mistake on this case.
"It is unfortunate, we are all very sad at the club that it has happened to such a young boy.
"We were even more worried, but it was a big relief yesterday for everybody at the club that the operation went well."
Wenger continued: "The fracture he had didn't heal, what I have been told is that we had to go in quite quickly to repair it and that's why we decided to do it so quickly.
"He had an earlier fracture at the age of 16 that healed and around that he created another opening.
"Is it down to a kick, is it down to playing too much? I don't know, I am not a specialist, but that is unfortunately what happened. He told me he felt it the first time [when playing for England] against Switzerland."