I sat and watched an entire old school style knee replacement years back.
I could suddenly walk much better and the pain mostly went away about 30 minutes in.... somewhere about the time they took the big hammer out and started pounding the spike in place in the lower leg and the guy missed the end smashing just above the poor guy's knee [and his own thumb partially]
I wanted to laugh,,, but man that meaty smack sound put that thought away right quick.
Several years back I watched a shoulder replacement surgery video. Haven't had even a twinge in either shoulder since. Well not anything I would ever admit to anyway.