Sorry to hear about your father---hope he hangs in there---if I might suggest an option for his recovery---you'll want to discuss this with his Dr. of course---but many men over 75have osteoporosis (OP)---it sounds like he had a regular, standing height or less fall which is typically considered a "non-traumatic" breakage (because the bones shouldn't break that easily) which is often due to Osteoporosis. Did he have vertebral wedge, compression or crush fracture? Even if he doesn't have OP, it's difficult for a person of this age to heal quickly. There is only one drug therapy in the world that actuallyhelps the body to grow newbone---"Forteo"----it is indicated for men and women with OP---but it also very rapidlyheals bone in people without OP---it increasesthe activity of bone building cells (osteoblasts) by 218%. Just last year Forteo (synthetic Parathyroid hormone) pronounced For-tay-o was used by Michael Vick (falcons QB) to quickly heal his broken foot in order to get back on the field quickly. His recovery was around 1/2 normal time! Hope this helps---again, talk to his Dr. (I'm not a Dr.)
Good luck
BP