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CHAPTER 55 ■ OSSEOUS GENIOPLASTYHARVEY M. ROSEN

Osseous genioplasty is an autogenous method for changing thesize, or shape, or both of the mandibular symphysis. Althoughby strict definition it may involve merely recontouring the chinby burring away bone or by adding bone graft material, theterm generally refers to an osteotomy of the anterior mandiblein the horizontal (transverse) direction belowthe mental foram-ina (Fig. 55.1A). The osteotomy was first described in 1942 byHofer (1). The procedure remained rather obscure until 1964when it was popularized by Converse and Wood-Smith (2). It isnow the second most commonly performed osteotomy of thefacial skeleton for both reconstructive and aesthetic reasons(second only to rhinoplasty).

Osseous genioplasty is frequently performed for two rea-sons: (a) versatility; chin can be moved in any direction—sagittally, vertically, or transversely (Fig. 55.1B-D);and (b) a re-ceding chin or small mandible, or both, are common problemsamong white North Americans, occurring in approximately5% of the population (2). When these factors are coupled withthe emphasis that Western culture places on aesthetics and thebelief that a well-defined jaw line characterizes an aggressive,self-confident individual, it is little wonder that this operationhas grown in popularity. The ready availability of alloplasticmaterial such as silastic, however, has prevented osseous ge-nioplasty from becoming an operation that large numbers of plastic surgeons currently employ.

ALLOPLASTIC VERSUSAUTOGENOUS

The choice between alloplastic augmentation (chin implants)and osseous genioplasty for correction of the weak chin re-mains hotly debated among plastic surgeons. The proponentsof alloplastic augmentation cite the technical ease, the rela-tively low risk of complications, and the ability to perform theprocedure under a local anesthetic. Those who favor osseousgenioplasty point out the extreme versatility of an osteotomyin correcting three-dimensional deformity.

In an effort to select the correct procedure, one should sim-ply ask which procedure will provide the best correction for theparticular patient. Certain factors are indisputable: (1) Chinimplants can adequately correct mild to moderate volume de-ficiencies of the mandible at the level of the pogonion in thesagittal dimension (2). Chin implants cannot correct verticalexcess of the anterior mandible (3). Chin implants are unre-liable in correcting asymmetries of the anterior mandible inany plane of space (4). Although chin implants can modestlyincrease the vertical dimension of the anterior mandible bycovering its inferior border, this has significant potential forcomplications as the soft tissue in this area is relatively thin(5). Provided that chin implants are positioned directly overthe symphysis, as they should be, and not over the dental alve-olus, the labiomental fold will increase in depth following chinimplant placement.

Given thesefactors, the only appropriate candidates for chinimplantation are those with a mild to moderate sagittal defi-ciency of the chin accompanied by a shallow labiomental fold .All other patients who request surgical alteration of the chinshould be considered for osseous genioplasty.

One of the least mentioned, yet compelling, reasons tochoose osseous genioplasty instead of alloplastic chin augmen-tation occurs when surgical revision is indicated. Osseous ge-nioplasty is more amenable to revision because the soft-tissuechin has not been degloved and there is no scar capsule (as oc-curs in smooth implants) with which to contend. As a result,soft-tissue displacement closely follows skeletal displacement.Conversely, the soft-tissue response to removing a smooth im-plant, or to reducing its size, or to changing its position is un-predictable because the soft tissues have been degloved fromthe bone. In addition, the dead space created by the implantcapsule, which does not fully collapse, fills with blood, cre-ating more scar. Surgical excision of the capsule may causementalis muscle disfunction with subsequent lower lip ptosis.Accordingly, the aesthetic consequences of removing or chang-ing smooth chin implants are frequently undesirable.

Although a scar capsule maynot form with porousimplants,these implants can be very difficult to remove because of thesoft-tissue ingrowth.

TREATMENT-PLANNINGCONSIDERATIONS

Preoperative evaluation of the osseous genioplasty patient in-cludes a history and physical examination. The surgeon shouldascertain the patient’s specific aesthetic complaints and objec-tives as they relate to the lower face, including any concernsabout the height, the projection, and the symmetry in this area.Specific inquiries should be made into any history of orthodon-tic therapy, because such therapy may have been used to dis-guise an underlying class II malocclusion caused by a smallmandible.

Physical examination should note the following five items:

1. Thesagittal position of thepogonionrelative to thelowerlip and the remainder of the mid and upper face. Thelower lip, not the mid or upper facial structures, deter-mines the extent to which the chin should be brought for-ward (6). Consequently, the chin should not be broughtforward any further than a vertical linedropped from thelower lip. When advancing the chin, the ratio of soft tis-sue to skeletal displacement is generally 1:1. If the lowerlip is recessive, as it may be in many individuals withsmall mandibles who are seeking chin enlargement, onemust be willing to accept a residual degree of sagittalweakness of the lower face relative to the mid and up-per face. This is aesthetically preferable to a chin thatis advanced beyond the lower lip, which invariably re-sults in a bizarre, artificial appearance. Undercorrection

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Grabb and Smith's Plastic Surgery , Sixth Edition by Charles H. Thorne.

Copyright © 2007 by Lippincott Williams & Wilkins, a Wolters Kluwer business.

558 Part V: Aesthetic Surgery

A

B

C

D

FIGURE 55.1. A: Standard location and orientation of the advancement osseous genioplasty. Note thatthe osteotomy is placed well below the mental foramina to avoid injury to the inferior alveolar nerve.The osteotomy extends well posterior to the vicinity of the molar teeth. The angulation of this osteotomyallows forward advancement of the chin without any vertical changes. B : Simultaneous advancementand vertical reduction of the chin. Note that two parallel osteotomies are performed with an interveningostectomy. C: Simultaneous advancement and vertical elongation of the chin. The interpositional materialtypically employed are blocks of porous hydroxyapatite. D: Lateral shifting of the symphyseal segment torestore lower-face symmetry.

in the sagittal dimension is always preferable to over-correction.

2. A qualitative assessment of the height of the lower faceas it relates to the midface. In a patient with verticalexcess of the lower face, one has the option to reduce thevertical height of the chin. This can be accomplished bytwo parallel osteotomies with an intervening ostectomyor a steeply oblique bone cut that allows the chin to beadvanced and superiorly repositioned.

3. The symmetry of the lower face. Osseous genioplastypresents the surgeon with the perfect opportunity to lat-erally shift the symphyseal segment either to the rightor the left to achieve a symmetric lower face. Similarly,the chin can be vertically elongated or shortened in anasymmetric fashion to correct vertical asymmetry.

4. The depth of the labiomental fold. Sagittal advancementor vertical shortening, or both, of the symphyseal seg-ment results in deepening of the labiomental fold (5).Conversely, vertical lengthening of the chin tends to ef-face or soften the fold. Accordingly, individuals with anormal or exceedingly deep fold who undergo advance-ment of the chin also should be evaluated for verticalelongation. This should be considered in a person with

a short lower face and in a patient with normal heightof the lower face, but never in a patient with excessiveheight in the lower face. The individual who has a com-bination of a long lower face and a deep labiomentalfold is never a candidate for chin surgery, and such apatient should be offered a more extensive orthognathiccorrection (5).

5. Examination of the occlusion. The majority of indi-viduals who request aesthetic enlargement of the chinhave class II skeletal deformities secondary to a smallmandible (5). This is a tip-off that coexisting problemssuch as abnormalities of lower face height and labiomen-tal fold depth may be present in addition to a “weak”chin. It is important to remember that prior orthodon-tic treatment can convert a class II malocclusion into aclass I occlusion but this does not correct the underlyingskeletal problems.

Although the extent of soft-tissue movement closely followsthat of skeletal displacement when advancing, shortening, orlengthening the chin, soft-tissue response to posteriorly reposi-tioning ofthechin is, atbest,0.5 to1. Surgical efforts to correct



Chapter 55: Osseous Genioplasty 559

an excessively prominent chin are not as predictable as thoseperformed to correct a small chin.

Radiographic evaluation of the chin should include aPanorex radiograph if periapical pathology of the anteriormandibular teeth is suspected. Any preexisting dental pathol-ogy in this area is an absolute contraindication to chin surgery.In addition, one may want to evaluate the vertical dimensionbetween the apices of the incisor roots and the inferior borderof the mandible when correcting a short chin. It is importantthat enough room exists both to perform the osteotomy and toapply fixation devices without risk to the roots of these teeth.

SURGICAL TECHNIQUE

Although reports exist describing osseous genioplasty underlocal anesthesia with intravenous sedation (7), it is best under-

taken under general anesthesia with orotracheal or nasotra-cheal intubation and full protection of the airway. Hemostasisis facilitated by infiltration with a dilute epinephrine solution.The soft-tissue incision is placed at least 1 cm away from thedepth of the mandibular buccal sulcus onto the lower lip andis 2 to 3 cm in length. The mucosa and submucosa are in-cised, bringing the mentalis muscle and its median raphe intoview. Once these muscles are very superficially incised, the an-gle of the soft-tissue incision changes so that it is parallel tothe mucosa of the lip. This direction is maintained until theanterior mandibular surface is reached, leaving a large amountof mentalis muscle attached to the mandible for later mus-cle reapproximation. A subperiosteal dissection of the symph-ysis is performed. The dissection is continued inferiorly onlyfar enough to allow exposure for performing the osteotomyand for applying fixation devises. Complete degloving of thesymphysis is not recommended because of the unpredictable

A B

C D

FIGURE 55.2. A 35-year-old woman with a small mandible and increased lower face height. A,B: Thereis lip strain, with superior dislocation of the soft-tissue chin pad and a shallow labiomental fold. Surgicalcorrection will effect an 8-mm advancement of the chin and a 5-mm reduction in its height. Simultaneousrhinoplasty will be performed.C,D: Postoperatively, the lip strainhas been eliminated and thelabiomentalfold has been deepened. Note that the chin has been advanced no further that the most anterior positionof the lower lip. (From Rosen HM. Aesthetic refinements in genioplasty: the role of the labiomental fold.Plast Reconstr Surg. 1991;88:760, with permission.)



560 Part V: Aesthetic Surgery

reattachment of the soft tissues to the bone and the potentialrisk for development of soft-tissue ptosis, that is, a witch’s chin(8). Exposure is continued laterally so that both mental nervesare identified. Posterior dissection is carried to the inferior bor-der of the mandible directly below the molar roots.

Once the soft-tissue dissection is completed, a fissure burrscores a vertical mark in the midline chin, allowing it to beappropriately positioned in the transverse dimension. The re-ciprocating saw is used to perform the horizontal osteotomyat least 4 mm below the mental foramina to protect the infe-rior alveolar nerves. As previously mentioned, the osteotomyis carried as far posteriorly as possible to allow for a gener-ous volume of skeletal displacement. This provides for natural-looking results and avoids waist lining and excessive visibilityof the inevitable step in the inferior border of the mandible.

Cortical cuts should be completed with the reciprocating saw,avoiding unnecessary prying downward of the symphyseal seg-ment, which may cause fracturing. Following mobilization of the symphysis, it might be necessary to detach the anteriorbelly of the digastric muscles from the lingual surface if exten-sive anterior dislocation is anticipated. After full mobilizationis achieved, fixation devices are applied to hold the chin seg-ment in the desired location. Although plate and screws arepopular, it is perfectly acceptable to use wire fixation.

If vertical shortening of the chin is desired, it is usually ac-complished by performing two parallel horizontal osteotomiesand removing the intervening segment of bone. If vertical elon-gation is desired, it is most often done by interposing blocksof hydroxyapatite into the osteotomy gaps created by inferiorrepositioning of the symphysis.

A B

C D

FIGURE 55.3. A 28-year-old mancomplaining of a small chin. Physical examination demonstrateda classII malocclusion with deficient sagittal projection of the chin as well as decreased height of the lower face.A,B: In addition, there is a deepened labiomental fold. Surgical planning included a 6-mm advancementand 6-mm elongation of the chin. C,D: The postoperative views demonstrate an increase in the height of the lower face andan apparent decrease in the depth of thelabiomentalfold. Again, thechin wasadvancedno further than the most anterior position of the lower lip. (From Rosen HM. Aesthetic refinements ingenioplasty: the role of the labiomental fold. Plast Reconstr Surg. 1991;88:760, with permission.)



Chapter 55: Osseous Genioplasty 561

Following fixation, the wound is copiously irrigated withdiluted povidone-iodine (Betadine) solution and closed in lay-ers. The mentalis muscle is repaired using interrupted suturesto help avoid soft-tissue ptosis and subsequent development of a witch’s chin (8). The mucosa is repaired using interrupted 3-0chromic sutures. By placing the incision well out onto thelowerlip, there is sufficient soft tissue to close without tearing the tis-sues. This helps to minimize subsequent wound contaminationand possible infection. No dressings are applied.

PATIENT EXAMPLES

The following patient examples illustrate the versatility of theosseous genioplasty.

Patient 1

The patient (Fig. 55.2) is a 35-year-old women with a smallmandible, increased lower face height, and a modest com-ponent of lip strain. As a result, the soft-tissue chin pad issuperiorly dislocated, causing effacement and shallowness of the labiomental fold. Surgical correction involves advance-ment and vertical shortening of the chin. The segment wasadvanced 8 mm and shortened 5 mm. A rhinoplasty was alsoperformed. Note that as the chin is advanced the labiomentalfold deepens with improved definition. The lip strain has beeneliminated. The chin has been advanced no further than thelower lip.

Patient 2

This 28-year-old man (Fig. 55.3) complained of having a smallchin. Physical examination demonstrated that he had a smallmandible and a class II, deep bite malocclusion. In additionto a lack of projection of the chin, there was decreased heightof the lower face relative to the midface and an exaggerated,deepened labiomental fold. Surgical planning involved a 6-mmadvancement and 6-mm lengthening of the chin. In the post-operative views, note the softening of the labiomental fold andapparent decrease in its depth. Note again that the chin is ad-vanced no further than the most anterior position of the lowerlip.

COMPLICATIONS

In a recent report of a large series of patients undergoing os-seous genioplasty by three experienced craniomaxillofacial sur-geons, the complication rate was low (3). Lower-lip paresthesia

occurred in 5.5% of the patients. Soft-tissue infection was re-ported in 3% of patients.

Although not reported as a complication, the most frequentproblem associated with osseous genioplasty is the undesirableaesthetic result. Such an outcome is caused by errors in bothtreatment planning and technique. The most commonly com-mitted error in treatment planning is overadvancement of thesymphyseal segment, resulting in an unnatural, bizarre appear-ance, with the chin well in advance of the lower lip. It bearsrepeating that the osseous genioplasty is a powerful tool andthat modest advancement of the chin goes a long way. When indoubt about the extent of advancement, one should err on theside of conservatism and undercorrect in the sagittal dimension.

The most commonly encountered aesthetic problem relativeto surgical technique is failure to extend the osteotomy cut farenough posteriorly. This can result in an hourglass deformitywith excessive tapering of the mandible in the area immediatelyposterior to the osteotomy. This can be largely avoided if theosteotomycut is extended back to themolar teeth, as it is placedin an area where abundant soft tissue is present to mask anynotching of the inferior mandibular border.

CONCLUSION

The osseous genioplasty represents the most versatile proce-dure that the plastic surgeon has available to enhance the bal-ance and proportion of the lower face. It is a powerful toolthat can yield dramatic results if the surgeon performing theprocedure knows that it cannot change the sagittal position of the lower lip. It behooves plastic surgeons to become familiarand comfortable with the procedure so that the alternative—alloplastic chin augmentation—will notbe used in patients whowould benefit more from a skeletal correction.

References

1. Greenberg ST, Pan FS, Bartlett SP, et al. Complications of osseous genio-plasty. Proc Northeastern Soc Plastic Surg 1985;92.

2. Converse JM, Wood-Smith D. Horizontal osteotomy of the mandible. Plast Reconstr Surg . 1964;34:464.

3. HoferD. Die osteoplastiche verlaegerund des unterkiefers nachvon Eiselbergbie mikrogenie. Dtsch Zahn Mund Kieferheilkd . 1957;27:81.

4. Bell WH, Proffit WR, White P, eds. Surgical Correction of Dentofacial De-formities. Philadelphia: WB Saunders; 1980:685.

5. Rosen HM. Aesthetic refinements in genioplasty: the role of the labiomentalfold. Plast Reconstr Surg . 1991;88:760.

6. Rosen HM. Aesthetic guidelines in genioplasty: the role of facial dispropor-tion. Plast Reconstr Surg . 1995;95:463.

7. Spear SL, Mausner ME, Kawamoto HK. Sliding genioplasty as a local aes-thetic outpatient procedure: a prospective two center trial. Plast ReconstrSurg . 1987;80:55.

8. Zide BM, McCarthy JG. The mentalis muscle: an associated component of chin and lower lip position. Plast Reconstr Surg . 1989;83:413.



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