I think you probably need to hide this for the 3 months surgery and treatment ( if you want to hide of course )
You can actually go to the city which u going to do the surgery before , knows everyone and etc.
And you have to take a holiday 1 month, the first day take a lot of pictures if different clothes, and well, in the second month you can say you have to do a surgery about an alignment or correction from both legs , and you find a good doctor ( you need actually to claim a lot about this discomfort before , before I mean 1 years and month by month so they know it’s painful to you bla bla bla )
And second month you had done your surgery already I will take just one more month to recovery so make sense you stay that one month.
This is if you will reach you goal in 3 months if is more make the calculation of this and bla bla bla .