Hips are evidently more successful than Knees.
2 Knee replacements absolutely destroyed my
Dads life. Never the same and eventually bed ridden.
Lots of mates have had hips and all ok.
Of the 6 I know who have had Knee replacements
only 1 is as good as a normal person. The others
wish they never did it!---Cant reverse it!
So looking at stem cell etc and prolonging while Im good
best option in my view 5-10 yrs is a lot in this field.
The knees aren't as good as the originals, but at least you can walk. Before the replacements I could only walk about 300-500mtrs, then had to sit down due to the pain, now I can walk all day no problems. The only down side I have found is you can't kneel on them, so it is either lay down or sit down, to do jobs at that height, like some car jobs and jobs in kitchen cupboards etc. I had my first knee done 11 years ago, second 8 years ago, hip was done 5 years ago.
They stuffed up the hip, one leg slightly shorter than the other, so perpetual limp, no pain just a poxy limp.
With regard the operation, the knees are an 8 out of 10 for pain, the hip 3-4 out of 10.
It has been well worth doing, for quality of life, but if you are to get it done research your specialist. A good place to start is the therapy pool at the hospital, talk to people who have had it done, the surgeon is the key to a good result. IMO
With regard your Dad, it may be more about when he had it done, knee replacement prosthesis's improved hugely about 12-14years ago. They found a way to super harden the polyethylene rubbing block, between the metal joints, so they now last 25-35 years without problems, apparently well I certainly hope so.
A bit of topic, but it is an important decision, well worth discussing.