The sliding genioplasty is an autologous form of chin augmentation that has its own distinct advantages. Its effect is based on the position of the natural bone, is stable long term and and has little risk of perioperative infection and no long term infection risks. But it is an imperfect chin augmentation procedure in that it disrupts the smooth line of the inferior border of the jawline at the back ends of the osteotomy line, can not make the chin wider and is more difficult to revise secondarily should additional augmentation be desired.
An alternative approach to any or all of these secondary sliding genioplasty issues is a chin implant overlay. Adding an implant to the front edge of the advanced chin bone provides some additional horizontal augmentation, widens the chin and may be able to cover over the inferior border bony stepoffs.
The placement of a chin implant overlay can be done either intraorally as was the original sliding genioplasty or from a submental skin approach. The submental approach is the better choice since getting the chin implant low enough is paramount and that is difficult in a scarred and often tight soft tissue chin pad. It is equally difficult to get the scarred tissue out of the bony step off region which is often fairly far back along the inferior border in a low angled horizontal osteotomy cut.
While the chin implant overlay is a reasonable secondary augmentation method it has its limitations. The posterior limbs of a standard chin implant are very thin and flexible and often can barely go past the bony step off. The inferior bone defect is alway larger than the wing of the chin implant trying to cover it. These limitations may not give the desired cover over the bony step off.
Because of these limitations the ideal approach to a sliding geniopalsty chin implant overlay is to have it custom made for the defects it is trying to cover. Thus the only reason to use a standard chin implant is cost and convenience…valid reasons to do so as long as it is recognized as to its potential limitations.
Dr. Barry Eppley
World-Renowned Plastic Surgeon