The sliding genioplasty is a long established method of chin reshaping. While often perceived as being for horizontal augmentation only, it offers much more diverse dimensional chin changes. Vertical lengthening/shortening as well as width narrowing can also be done by internal wedge bone removal as well. When horizontal augmentation is done for the downfractured bone segment an inevitable bony step occurs in the normally convex anterior surface of the chin bone. The magnitude of this step deformity depends on the amount of horizontal bone movement done or in the length of the bony step.
This common step deformity that occurs in a horizontal advancement sliding genioplasty comes with the aesthetic sequelae of deepening the labiomental fold. As the labiomental fold externally occurs at the level of the origin of the mentalis muscle which is well above the level of the bone cut, the overlying soft tissues collapse into it creating a deeper labiomental fold. Such a postoperative soft tissue development is well known and a wide variety of strategies has been promoted to present it. The obvious solution is to fill in the bony defect of which a wide variety of materials have been used.
In the November 2019 issue of the Journal of Craniofacial Surgery an article was published entitled ‘Bonegraft Wrap Technique -Avoiding Accentuated Labiomental Groove After Genioplasty.’ In this paper the authors present a wrap technique designed to avoid the occurrence of unaesthetic deep labiomental fold in genioplasty. Their technique uses a particulate bone graft that is wrapped in a collagen Surgicel mesh which is placed over the osteotomized segment of the chin at the location of the fixated titanium plate and screws.
It is clear that eliminating the step bony defect is helpful in ameliorating the deepening of the labiomental fold. While an autogenous bone graft as this paper advocates would be ideal, few patients want to have a bone graft harvested to do so. A variety of synthetic implants, including bone cements, have been placed into the bony step and I have never seen an infection from so doing…but that is always a potential concern.
As a result I prefer to use allogeneic or cadaveric corticocancellous bone chips. Placed into an exposed marrow space of the chin tissue ingrowth will occur along with some eventual bony replacement. The chips are good at filling all the defects of the step deformity and their porosity allows early fibrovascular ingrowth. The fill can be aggressive because the malleability of the chips do not exert excessive pressure on the wound closure.
Dr. Barry Eppley