It means missing up to two months of the new campaign but Lewsey, who is recovering fast and is already back in the gym, is refusing to be downbeat.
He is making the most of his time off, watching the cricket, catching up with friends and making sure he returns in prime physical shape.
"I was only operated on a week ago and I have made spectacular progress since then," he said.
"When you get an injury you can see it one of two ways - you can either see it as a frustration or a blessing in disguise.
"Coming off the Lions tour, this gives me the opportunity to complete a proper pre-season programme, which I have found in the past to be massively beneficial.
"I needed the operation done because if I hadn't it would have gone seriously wrong during the season and then you are looking at a much longer lay-off."
Lewsey is making the most of his time off to make sure he returns refreshed and in prime shape.
And he should be back playing in time to feature for England in the November internationals against Australia, Samoa and New Zealand.
"It all depends how quickly I recover, how quickly I can get the mobility back," he added.
"It is only a week since the operation and we are pushing it as quickly as we can in the gym while making sure it is right.
"You are looking at somewhere between six to 10 weeks. I'm hoping to be back playing in time for the start of Wasps' European campaign and be available for selection for the autumn internationals.
"We will have to see how it progresses but I have always healed relatively quickly in the past. Hopefully this will be exactly the same."
Lewsey only returned to the club for the first time on Monday after deliberately staying away to recover from the Lions tour. He has watched no rugby at all since returning home.
Wasps' new director of rugby Ian McGeechan, one of the Lions coaches, said: "We had a chat about it in New Zealand. Josh had the toughest time on tour in terms of game time and level of opposition.
"We talked about him taking a longer break. He is back at the club now but he will make a protracted return. We won't hurry him back.
"It is important the Lions players get a mental break."