My knee has no cartilage, absolutely none. I had a slight knee pain and felt if I walked more it would go away. WRONG answer. I went to the gym every morning and walked the track for an hour. It finally got so bad I could not walk without excruciating pain. By the time I was able to see the ortho surgeon there was nothing between the bones in my knee. So now I am looking at a replacement knee as they do not put zerk fittings in knees....