My knee started making popping and grinding sounds and seems like it is catching. This only happens when I go from a crouched position to standing up or I am lying on my back with my knee bent and go to extend it. I saw a nurse practioner today and she thought it might be a torn meniscus. It does not hurt running and I have done anything out of the ordinary in the past couple of days to cause this to start. Any ideas would be appreciated.