Quote ="saint at wire"So apparently anywhere on the body apart from the knee is OK?
Bizarre RFL.'"
Not really bizarre. It's an issue with the knee joint, which doesn't have muscle to protect it (like the thigh does) and which doesn't have any give in it when hit from the side. I think also it has to be a hit side on to the knee when the leg is straight for a penalty to be given as that is when the knee is most vulnerable as it is at its least flexible. The thigh, however, has loads of muscle around it to protect the bone from impact.