Lots of stories from lots of people about joint replacements; some go better than others. My wife is getting therapy and hears about different results from replacements by the same doctor. There are more variables than just the doctor. She also has a bad shoulder and using the walker bothers it. She would rather lean on me. That's what we're there for. A cane probably won't work for her either. So she is just getting better quicker out of necessity. That, and she's tuff.
My dad had a knee replaced in his eighties with quick recovery, little pain, little pain killers. He had had trouble with that knee since an injury as a young man on the farm. His father had a hip replacement, also in his eighties, it must have been in the '70s. Years later he said he didn't think he had more movement, but didn't have the pain. He wanted to do the other one when he was about 90 but they wouldn't do it bcause they said his circulation wasn't good enough.