I had hip replacement 8 years ago and a year later I was sliding down an icy hill in Antarctica.
The good news is I didn't have to go to rehab but did physical therapy at home and followed directions religiously and hip has been fine. I came home on a walker and two weeks later I was using snow thrower to clear driveway - just like walker but noisier!
The bettter news is when I average my age and age of hip I'm considerably younger!
Hope your dad gets better soon!