Is there ever a need to replace them? The plastic arch support (I wear the green ones) don't deform much if at all with use and unless the foam insert wear all the way down, do you really need to replace the insoles?? The podiatrist that I saw recommmended I give OTC orthotics a try before deciding if I want to go with custom orthotics. He made a point that OTC orthotics are usually only a temporary solution since they will have to be replaced a couple of times a year whereas custom orthotics can last several years. Of course, I realize custom orthotics is usually how podiatrists make a good source of their money.