The sliding genioplasty procedure is an effective method of horizontal and/or vertical chin augmentation changes. In doing so the natural shape of the chin bone is changed from a smooth convex side profile to a much different sharply angled step configuration. While this shape change does to affect its ability to heal, even though there is decreased bone contact, it does have some potential aesthetic implications.
The resultant classic step deformity of the sliding genioplasty will cause the labiomental fold to deepen. As the fold represents a fixed location due to the attachment of the mentalis muscle. The superior soft tissue chin pad will fall in behind the advanced chin bone segment if it is advanced far enough. This is unavoidable and its management should be considered as part of the sliding genioplasty procedure.
Filling in the step of the sliding genioplasty has been successfully done by a variety of implant and grafting materials. The patient’s own bone would always be the ideal method to restore the convexity of the chin bone shape but few patients want to undergo a bone graft harvest to treat a purely aesthetic issue.
Short of a bone graft harvest, a method to create bone ingrowth into the step deformity is with the use of allogeneic or corticocancellous bone chips. This ‘out of the jar’ material can be used alone or mixed with the patient’s blood or platelet-rich plasma (PRP) to create a semi-putty composite. Either way it can be applied throughout the entire step deformity.
With its use I first like to apply a layer a gelfoam or surgical alone the exposed muscle surface behind the bony step to act as a base for the graft material. The bone chips are applied all the way back to the distal end of the osteotomy bone cuts. The bony step is completely filled in, obliterating the applied bone plate and screws. 5ccs of the graft material is typically what is needed for maximal fill.
A double muscle layer closure is done over the corticocancellous chip material with a final mucosal layer closure. While this graft material may expedite bony healing, its primary purpose is to act as a scaffold for bone ingrowth to lessen the magnitude of the step transition between the stable superior chin and the mobilized interior chin segments.
Dr. Barry Eppley
Indianapolis, Indiana