My mother had both of hers replaced, after reaching the age of 70. Took her 6-8 weeks to be independent. She's 92, they still work pretty well. The artificial joints, the surgery, and the rehab have surely come a long ways since then.
Yikes. I dunno, but pay extra for the one that makes the "Duu du du du du du du du du.." sound.
My last surgery they gave me a bunch of stuff to drink the morning of, oddly enough. Then the cut both sides of my neck and removed about 50 lymph nodes.