Hello mate and welcome to the forum.
I'm not medically trained but cannot recall anyone else suffering with swollen ankles and feet following surgery. In fact, most of us complain of 'things' that should swell but no longer do, after the op. đ
Joking apart, you're obviously suffering, and I'd seek medical advice. I'm glad that everything else is going okay.
Oh, I've just remembered. I'm pretty sure that I was supposed to wear surgical stockings for a while after surgery. Presumably these aid blood flow to the legs? So maybe there maybe a link with your feet swelling and the op?