Shell, I hope your mom does well with this surgery. My dad recently went through this, and although it was very successful, I was not prepared to see my dad in that much pain. It is unlike anything else painwise according to others I know who have also been through this. I thought I'd tell you to just be prepared mentally, because I had to leave the room when the physical therapist came to work with him. I just could not stand it! He would almost pass out, the guy would stop, then as soon as he regained a little color...back at it!! It was just rough!
My dad is still doing his excercises over a year later, but he is walking much better and the pain is nothing compared to what it was prior to surgery. I will remember her and you and sister too as you care for her. I hope it all goes well.