I really don't think a cartoon is the best place to be placing physical diagnosis. But about Toph calling Aang 'twinkle toes' it's becuase when he first faced her in The Blind Bandit he used airbending to make his landing undetectable to her vibration sensing. She called him twinkle toes becuase he was so light on his feet, and continues to call him that.

Also, in the future please put simple questions like this in the Ask A Question, Get An Answer thread at the top of the page.

Arthiritis occurs when there is a breakdown of cartilidge in between your bones, this usually happens with runners and stuff like that, they are constantly rubbing the bone agaisnt the cartilidge which then causes arthiritis as the bones to begin rubbing on each other. A gymnist may get it i suppose, but im not 100%.

Toph calls Aang twinkle toes because of episode 26, when he versed her in the earth rumble match and didn't want her to hear him so he used airbending to make his feet get less contact with the ground, so she called him twinkle toes. Hope that helps.

And next time you have a question, there is a thread stuck on the first page of the forum near the top, you should direct your questions there, thanks.

What ever happened to AAQ,GAA thread, did you even think about posting this in the right spot. Come on!! This thread is more than a waste of space.