Questions about total knee replacement surgery

Both my grandma and 2 of my aunts have had the surgery. None of them did the rehab. They all walk very very stiff legged and can't walk that well at all on a non smooth surface. My mom always tells people that your surgeon will fix your structural defect. It's up to you if you walk unable to bend your knee or run, which my 65 year old mom with a fake knee can do.