Background: The sliding genioplasty is a well known autologous form of chin augmentation. It is not as commonly performed as chin implants as it is a more invasive and has less controlled dimensional changes. But for the patient who wishes to avoid an implant it is the only other option an d has not long term maintenance.
The sliding genioplasty is misnamed in contemporary context as there is no sliding of the bone that occurs. This was a valid concept when wire fixation was used as the upper and lower chin segments had to stay together and really did slide forward. But with plate fixation there is no longer any sliding of the bone. Rather it is more like a bone suspension with the plate holding out into ‘space’ so to speak with limited bone contact.
Because of plate suspension more than just a horizontal chin augmentation can be obtained in a modern bony genioplasty. Bending of the plates permits a wide variety of combined horizontal and vertical elongation effects. Since the chin plates have a 90 degree horizontal bar of titanium metal to the limbs of the screwhole legs, it requires bending of the plate at its legs to get a vertical elongation or shortening effect.
Case Study: This young male desired a sliding genioplasty for his chin augmentation. He had determined that the forward chin movements needed to be 6mm forward and 6mm down. The need for vertical lengthening in chin augmentation is evidenced by a deep labiomental fold, a pseudo submental chin pad and a short lower 1/3 of the face.
Under general anesthesia and through an intraoral approach a low horizontal bone cut was made to down fracture the chin. The mobilized bone was set into a combined horizontal and vertical chin advancement by bending a 6mm plate at 45 degrees from the superior screwhole legs.
With the advancement of the chin bone a significant bone gap was created. This was packaged with a bone paste created by the combination of cadaveric bone chips, vancomycin antibiotic powder and betadine solution. A three chin pad closure was then done over it with resorbable sutures.
His immediate intraoperative chin augmentation effect was evident with this multidimensional change.
1) A sliding genioplasty is a multi-dimensional chin augmentation that can incorporate a vertical change with a horizontal projection increase.
2) Genioplasty fixation plates come with measured horizontal increases, any vertical dimensional change requires bending of the plate.
3) Combined horizontal and vertical increases creates a bone gap which is best treated by allogeneic bone grafting.
Dr. Barry Eppley
World-Renowned Plastic Surgeon