I'm after some advice on insoles. i have very flat feet and suffer from arthritis also in my feet and have been told i need mid foot surgery by my surgeon. i'm looking for some insoles that aren't expensive as iv'e recently been having a few knee issues on my right knee which i think me be down to the flat feet. iv'e been running slightly longer distance and since this iv'e had very bad pain in the right outside of the knee.
so looking for any advice on cheapish insoles that may help to balance the feet if possible