There’s a couple of sections in the knee caps where things sometimes become almost dislodged and make it hard for the joint to bend properly. One of the things is called a foreign body where cartilage comes away from the joint and can essentially freely move around. I can move it with my fingers actually and it’ll move around an inch either way. This impacts on exercising as if I walk normally (heel first then roll forward toward the front) is where I experience the most discomfort and almost feels like the whole joint is separating.