Parenting elderly parents

I am part of the "sandwich" generation - I take care of small kids as well as elderly parents. There comes a time, if you are lucky enough, that your relationship dynamics change: you start to parent your own parents. My parents moved to Houston in 2001 and my eldest sister and I have been taking care of them. Some times it scares me how much they trust my opinions when it comes to medical treatments. Just because my job requires me to answer questions all day long, they think I know "all the answers"!

My father fell and fractured his femur in three places yesterday. Unfortunately when this accident happened (in my sister's garage), no one was at home and we still don't know how much time elapsed between his fall and his rescue. When my sister and her husband came home around 5:30 pm and opened the garage, that's when they found him. He was still conscious and screamed for help. Ambulance rushed him to the hospital and his xray showed the fractured bone. 

The orthopedic surgeon did his best to repair the damage by installing a rod and two screws. My father who recently had his pacemaker replaced (needed new batteries) seems like the bionic man - heart running on batteries and now a metal rod is holding this leg together. I wonder what his recuperation would be like? Would he be able to walk independently again? It saddens me to see my so fragile parents become more frail every day. I shudder to think of the day when they may not be here. I have always felt so protected around them. Even though I have become their caretaker, they are still my parents who will love me the most no matter what.