hey man, I did external LATN Tibias in Feb this year - used to do powerlifting for years before the surgery. You'll lose a lot of muscle- i mean a LOT! Your glutes, hamstrings, quads and calves all will atrophy beyond belief - crutches and wheelchair are no good to retain muscle. I'm just getting back into gym since a month but it's probably atleast another 3-4 months before I can squat my body weight.
My upperbody strength has almost returned back to normal tho. I was out of gym for almost 6 months (also due to lockdown)