My dad, 78 years old, lives on his own, has always been very active, tennis and walking, had prostate surgery about 4 weeks ago; the other morning he tried to stand up and fell down, he was taken to emergency room and then admitted to hospital - they still haven't determined medical problem and he still cannot walk - they want him to start physio, however, he says he cant walk - it's his right leg - he has a pain in his lower back down the back of his leg to his knee. He's had numerous tests and still nothing definite???