I recently took part in the Herts 10K run. It is a fantastic event; well organised and hugely popular with over 1000 runners of all ages. It is heartening to witness so many people, across the lifespan from childhood to old age, participating in a sport that they enjoy. Just before the race, I was chatting to a fellow runner about my job. He expressed surprise that, as a knee surgeon, I would be risking damage to my own knees by running.