My Husband Is 74 Years Old, And He Fell At

My husband is 74 years old, and he fell at home and fractured badly, his hip. He had surgery the next morning and a rod was put from the hip down to his knee. When he bends his knee, just a little, where the screw is, creaks, and it hurts him all the time. Why would a rod have to be put all the way from the hip to the knee?? And why would it creak, when moved?? thank you!