Hi
Sinus tarsi syndrome is often due to stiffness as a result of overpronation i find. I stand by taping not working. Especially in a 12 year old, PF taping can close down the sinus tarsi and restrict calcaneal rotation. I used to use taping for this, I just wasnt getting good results. Chuck in some orthotics and let it move I say - but hey, everyone is different and that is the beauty of it..