First of all I hope your dad pulls threw alright with it.. As others have stated some have recovered really well with it and some have done not so great... I have a friend that never followed his rehab to a "T" and ended up 2 years later going back in and having it replaced again.. So it is important for him to follow what the doc and rehab says he needs to do.. I also had an old friend " Like a grandfather " who was a neighbor to me until he died have both a knee replacement and a hip replace. He went out deer hunting with me and enjoyed it a lot.. Sure there was times it would swell up and ache but he got around ok.. He was slowed down quite a bit but still was able to get out there and enjoy what he liked to do.. His worse problem was getting in and out of the boat.. I am thinking because it had limited how high he could lift his leg up.. Not 100% sure though.. Again I wish your dad good luck as well..