Wenger also said Wilshire is a quick healer

Arsenal's medical staff have done it again! You have to hand it to them. By miles the most incompetent medical staff in the UK at least.
Wilshire was carrying an injury already in pre-season, then he limped out of the Emirates Cup. After that, they were waiting for God-knows-what (maybe a miracle?) before realizing he needed actual surgery. And now there's the result, his season is practically over. If he does come back in April, so what? He'll still need a couple weeks to gather pace and playing fitness again, and then... season over!
BTW, if Djourou, Vermaelen, Koscielny and Squilaci are all injured... who the hell will partner Mertesacker??