My 11yo nephew was just diagnosed with this. He has the extra bones and flat feet. We are going with him to Hawaii in a few weeks (pre-surgery). Water shoes (Tevas, etc.) and most other shoes have always rubbed him wrong. I want to find him some good, supportive water shoes that don't rub wrong on the inside of his foot. He'll be at the beach most days in Hawaii...I don't want to make his problem worse. I just ordered him several Chaco sandals to try. If they don't work (ie - rub in the wrong spot), what should we try next?

In addition, he's likely going to need surgery to remove the problem. Any advice?

Thanks!

Paleochick,
I had an accessory navicular removed 10 years ago; although it took away the pain over the navicular, it eventually caused my entire arch to fall in. Now I have just had reconstruction surgery on that foot.
When your nephew has the surgery make sure that the posterior tibial tendon is reattached to the navicular by drilling a hole in the navicular and placing a plug in the hole to hold the tendon in place. I believe my problems resulted from not securing the posterior tibial tendon correctly. Do the research to learn exactly what the surgeon is planning to do. Your nephew is too young to develop more foot problems!
Footjoy

Paleochick,
I forgot to mention: rather than trying to find the perfect shoes, you might try applying some thick moleskin over the navicular. This would provide a cushion between his navicular bone and his shoes.
Footjoy