So... I have pretty bad ankles and knees. My doc claims I have the arthritis of a 60 year old (I'm 28 now) do to joint 'trauma' from playing sports my whole life. Anywho... I got fitted for some high end sports orthotics. They are soft and look just like a normal shoe insert. I also got fitted for some good running shoes. My question is this: what % of the cushioning is typically provided from the insole versus the actual shoe. The orthotics are starting to get pretty thin in places (and they aren't cheap)... so I'm wondering if I can keep using them as long as I replace my running shoes regularly.