Hello Clare Prop,
I got both of my hips changed within 1 week about 4 years ago, I was 54 by this time. After 2 weeks in hospital and 2 weeks at a special rehabilitation hospital I went back home and 4 weeks later I was the first time on my motorcycle.
Of course it will be different case by case and I was physically very fit, otherwise the docs would never change both hips within this short period. During the reha I have seen people in the age 70+ with only one side changed and much more problems to recover then I did.
Regarding the medical it was a no brainer, 3 month after the the ops I was checked by the AME and could return to flying. Today I have not a single problem. Go for it!