Ideas and Innovations

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Craniofacial/PediatricCoronal-splitting Reduction Genioplasty Combinedwith Bilateral Osteotomies of the Mandibular
Inferior Border for Macrogenia
Toshitsugu Hirohi, MD

Summary: There are various types of chin deformities, and the least establishedsurgical method for deformity correction may be reduction for anteroposteriormacrogenia. Anteroposterior macrogenia is commonly corrected by either setback genioplasty or burring reduction, but these approaches are less likely to produce aesthetically pleasing results. Both procedures have poor reduction effects
because of the low response rate of soft tissues to skeletal alterations. There is ahigh likelihood of chin ptosis and flattening. Setback genioplasty can also yieldstep deformities at the inferior mandibular border. To overcome these drawbacksof conventional methods, I developed a novel technique of coronal-splitting reduction genioplasty. I have performed more than 83 procedures with a high successrate over the past 10 years. Alloplastic chin implant-shaped bone fragments wereresected from the prominent bony chin, in which the average thickness of resectedbone was 8.2 mm. Sufficient sagittal reduction effects were then achieved in mostcases, although the soft tissue response rate remains 25%–50%, as reported inthe literature. The no-degloving technique with cephalic suspension of the mentalis muscle prevents chin ptosis. Combined bilateral oblique osteotomies of
the inferior mandibular border contribute to minimizing obvious postoperativechin flattening. Moreover, macrogenia can be large in multiple planes, including
anteroposterior, vertical, transverse, or their combinations. This new technique
can handle all three planes by combining both bilateral oblique osteotomies of
the inferior mandibular border and burr ostectomy. Overall, these findings suggest that the coronal-splitting genioplasty method may replace conventional methods for correcting macrogenia. (Plast Reconstr Surg Glob Open 2024; 12:e5725; doi:
10.1097/GOX.0000000000005725; Published online 8 April 2024.)INTRODUCTION

The chin has a strong influence on facial aesthetics
and harmony on both frontal and profile views. Somequantitative analyses are used to assess the position of thechin relative to the overall face, nose, and lips.1 Briefly, if
the soft tissue pogonion lies anterior to the most projecting portion of the lower lip, anteroposterior macrogenia
may exist.2 Anteroposterior macrogenia is commonly corrected by either setback genioplasty with a plate or burring of the pogonion.3,4 However, these approaches areless likely to produce aesthetically pleasing results. First,
From Ritz Cosmetic Surgery Clinic, Tokyo, Japan.
Received for publication January 9, 2024; accepted February 15,2024.
Copyright © 2024 The Author. Published by Wolters Kluwer Health,Inc. on behalf of The American Society of Plastic Surgeons. Thisis an open-access article distributed under the terms of the CreativeCommons Attribution-Non Commercial-No Derivatives License 4.0(CCBY-NC-ND), where it is permissible to download and share thework provided it is properly cited. The work cannot be changed inany way or used commercially without permission from the journal.
DOI: 10.1097/GOX.0000000000005725

both procedures may provide insufficient surgical effects
because of the low response rate of soft tissues to skeletal
alterations.4 Second, there is a high likelihood of chin ptosis, which can be quite unaesthetic.5,6 Third, an unnatural,
flattened appearance of the chin may result.7 Fourth, setback genioplasty can yield step deformities at the inferiorborder of the mandible.3
In 2011, I developed a new technique of coronal-splitting
reduction genioplasty to overcome these drawbacks of conventional methods. This innovative technique was inspiredby alloplastic chin augmentation for microgenia. I thought
that, in contrast, an alloplastic implant-shaped bone fragment could be removed with better results for anteroposterior macrogenia. The osteotomy was performed in a similarmanner as in sagittal splitting ramus osteotomy.
Disclosure statements are at the end of this article,
following the correspondence information.

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