By Richard Clarke

Arsène Wenger insists that his medical team have done nothing wrong in their treatment of Jack Wilshere.

The Arsenal midfielder underwent ankle surgery on Monday evening and will be sidelined for "at least four months" according to the manager. The England international had been in a protective boot for a period in the hope that an operation was not necessary. Speaking ahead of the home game against Olympiacos, Wenger insisted he was happy with the treatment and rallied against any criticism of his backroom personnel.

"It's unfair because the club medical staff haven't made any mistakes on that front," he said. "It is unfortunate and we are all very sad at the club that it has happened to such a young boy.

"We were even more worried as it was a complicated procedure so it was a big relief yesterday for everybody at the club that the operation went well. I am convinced that the medical staff have not made any mistakes on this case.

"I think our red shirt attracts a lot of criticism [sometimes]," Wenger joked. "It shows we are a very popular club and it is something that we have to accept. It is part of the popularity of any club.

"The news from the operation is very positive but of course he will be out for  quite a long time. It is very difficult to predict how long he will be out, but at least four months certainly.

"During the period in the protective boot, the fracture he had didn't heal. Once that was clear, what I've 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.

"Jack had an early 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."

Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source 27 Sep 2011