Amitabh Bachchan, who normally begins Kaun Banega Crorepati standing at the centre of the stage, appeared seated during his opening monologue. The reason was simple. The 83-year-old actor had slipped and fallen during the previous day’s shoot and injured his left knee. He said the injury was not serious, but standing was uncomfortable, so he chose to remain seated for the opening.It is the kind of everyday accident most people would brush off as “just a fall”. But as we get older, the body does not always respond to a fall in the same way. A stumble that might once have ended with a scraped knee can, in later years, result in a fracture, head injury or a longer loss of mobility.And the reason is not simply that older bones are “weak”.