I am considering a sliding genioplasty over a chin implant because I am afraid of the implant shifting later in life. However, I have read that a consequence to SG is a step off in the jawline. I am a petite girl and have a skinny face/well defined jaw line so I am afraid of a step off being extremely apparent. How likely is it for this step off to be apparent with a 4mm advancement forward and a very small vertical advancement? Is there any way to prevent or treat a step off? Thanks