thank you for the question
there is no such thing as a scarless surgery but the vast majority the time in the hands of an experienced surgeon any incisions would be very difficult to see after they healed. Additionally, if you're taking a posterior approach than you should be in good shape. It's relatively infrequent that incisions behind the year have unsightly scarring. One last thing I would recommend is to do this under local anesthesia there's really no need for sedation.
I hope that helped
Chase Lay, MD
Web reference: http://chaselaymd.com/Otoplasty__Ear_Pinning_.php