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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5206_Библиотеки_им_академика_М_И_Перельмана
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S. Park
create a slim and attractive face, reducing the
width of the chin and modifying its shape are necessary in addition to resecting the mandible and
mandibular angle [3, 4]. Nowadays, many surgeons recognize the importance of considering the
mandible as a whole, and numerous efforts, for
example, the “V-line ostectomy” or “V-line surgery,” have been made to reduce the lower face,
more balanced and aesthetically pleasing [5–10].
The chin is a critical component of the lower
third of the human face and plays an important
role in the overall facial appearance and harmony.
It also determines one’s impression of an individual. For example, the impression for an individual with a small chin would be weak and
indecisive, while that for an individual with a
prominent, angular chin would be strong and
masculine. An aesthetically pleasing chin provides balance and symmetry to the rest of the
face, and most individuals have their own preference regarding the shape of their chin. These
preferences may differ from time to time, nation
to nation, and race to race. Therefore, the chin is
considered as a critical component of facial
esthetics and a symbol of ethnicity.
To begin with, it is necessary that the classication of the chin should be established in terms of
its frontal shape and width. The chin has been classied only in lateral shape or in vertical proportion
but this is the rst classication of chin in frontal
shape. The chin is dened superiorly by the labiomental sulcus, inferiorly by the gnathion, and laterally by a curvilinear line bounded by the right
and left marionette lines. The chin was analyzed
on the basis of several facial subcomponents and
their relationships with each other. According to
the distinct features of the subcomponents, including the lower central border, lower lateral border,
central–lateral border junction, geniomandibular
junction, lower facial line, and soft tissue component, we classied the frontal chin shape into eight
categories (Figs.10.1 and 10.2) [11].
central–lateral or geniomandibular junction,
and the overall contour of the lower facial line
is circular. Thus, the round chin appears to be
part of a round facial line.
2. Broad chin: A broad chin exhibits a curved to
at lower central border without a denite
central–lateral junction and with a convex
geniomandibular junction. This is the vertically shorted and at variation of the round
type, giving a U-shaped appearance to the
lower face.
3. Blunt chin: A blunt chin exhibits a curved
lower chin border and a smooth and clear central–lateral junction. Because this type has a
developed chin pad, it looks blunt in the frontal view.
10.2.1 Classication ofChin
1. Round chin: A round chin has a smooth,
curved lower chin border without a denite
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Fig. 10.1 Facial subcomponents used to derive our classication for the chin shape in the frontal view. Lower
central border (blue line), lateral borders (yellow dotted
line), central–lateral junction (arrow), geniomandibular
junction (dotted arrow), lower facial line (green dotted
line), and soft tissue overlying the chin (red dotted circle)
10 The V-Line Surgery: Narrowing Genioplasty withMandible Reduction
Fig. 10.2 Classication of the chin shape in the frontal view. From left to right: round chin, broad chin, blunt chin,
angular chin, trapezoid chin, triangular chin, pointed chin, and pear-shaped chin types
93
Fig. 10.3 Typical clinical photographs of representative cases with each chin type as per our classication. From top
left to right: round chin, broad chin, blunt chin, angular chin, from bottom left to right: trapezoid chin, triangular chin,
pointed chin, and pear-shaped chin types
4. Angular chin: An angular chin shows a charac-
teristic linear, wide lower central border with a
less developed chin pad. It also exhibits a sharp,
acute central–lateral junction, an angular geniomandibular junction, and a developed mandibular angle; consequently, the lower facial
line looks like part of an octagon.
ratio of the lower third of the face is smaller
than that with a triangular chin.
8. Pear-shaped chin: A pear-shaped chin is
dened by a concave geniomandibular junction, thus looking like a pear. For a better
understanding, typical clinical photographs of
each type are shown in Fig.10.3
5. Trapezoid chin: A trapezoid chin exhibits a
curved, narrow lower central border, smooth
central–lateral junction, and straight genio-
10.3 Patient Assessment
mandibular junction. This is narrower variation of angular chin. The difference from a
triangular chin is the presence of a horizontal
component in the lower central border.
6. Triangular chin: A triangular chin is dened
by a negligible lower central border with an
indenite central–lateral junction and a
straight geniomandibular junction, thus
appearing as an inverted triangle.
7. Pointed chin: A pointed chin exhibits a nar-
rower bigonial width and/or a vertically more
elongated chin height compared with the triangular type. Therefore, the width–height
In ID hospital, this classication is used when
assessing each patient’s chin shape and their
preference about the chin shape. Our investigation results indicated a discrepancy between the
actual prevalence and the patient preference;
patients prefer narrower chin shape (triangular,
trapezoid), while the actual shapes in Koreans
and Asians comprise broad, round, and angular
types. Therefore surgeon should customize the
correction surgery for the frontal chin shape
according to the actual shape and patient
preference.
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abc
S. Park
The width of chin is the most important factor
to determine the amount of narrowing. When surgeons consult with patient, careful assessment of
the present width of chin and desired width of
chin is critical. The amount of narrowing central
segment ranges from 4 to 14mm in most cases.
The height of chin is also important because
the width–height ratio eventually determines the
impression of chin. Ideal height of chin is considered as double the height of upper lip, in
other words, the distance from the subnasale to
the stomion. If the height is too long or too short
compared with the ideal one, vertical reduction
or lengthening should be performed simultaneously with narrowing genioplasty (Chaps. 11
and 12).
Then, asymmetry should be considered.
Signicant asymmetry of chin can be corrected
by midline shift and asymmetric central segment
resection (Fig.10.4).
Finally prole view of chin should be assessed
as introduced in Chap. 10. If the position of the
pogonion is backward or forward compared to
the ideal one, advancement or setback of the two
distal segments is required.
10.4 Surgical Techniques
1. The approach to the mid-symphyseal area
was accomplished with a conventional intraoral vestibular incision and subperiosteal dissection. Soft tissue attachment of the chin
was maintained to produce a maximum
narrowing effect and maintain the blood ow
to bony segments.
2. Horizontal osteotomy and two vertical osteotomies were designed as shown in Fig.10.2.
The amount of resection in the central segment was determined preoperatively, depending on the width of chin and the patient’s
desire. In proportion to the shape of the chin,
the shape of the central segment to be
resected can be altered from a rectangle to a
trapezoid.
3. After osteotomy was completed, the muscular attachment was stripped off, and the central segment was removed. Two segments
were approximated centrally and xed with
plates and screws.
4. Advancement or setback of the two segments
is also possible if correction of the prole is
de
Fig. 10.4 Illustrations of surgical procedures of the
V-line surgery. (a) Avoiding the inferior alveolar canal and
mental foramen, one horizontal and two vertical osteotomies were performed. (b) The central strip was removed.
(c) Two distal segments were approximate centrally. (d)
Fixation with plate and screws was performed. In order to
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prevent possible loosening and rotation, at least two
screws were used to x each distal segment. (e) Mandible
contouring starts from the anterior step to the posterior
ramus according to the planning. It is important to preserve inferior alveolar canal
10 The V-Line Surgery: Narrowing Genioplasty withMandible Reduction
95
required. In the case of asymmetric chin,
midline shift and asymmetric central segment resection are required.
5. After xation of distal segments, the bony
edge of the lateral and proximal mandible
remains. This is the different feature from
conventional angle resection. So, the surgeon
should check the exact amount of the bony
step between the lateral edge of distal segment and proximal mandible by direct vision
and manual palpation.
6. Then, mandible contouring starts from the
anterior part of the mandible. To avoid damage to the inferior alveolar nerve, guarded
saw is used at this point at least 2–3 mm
apart from the lower border of inferior alveolar canal.
7. Once the level of osteotomy is decided with
guarded saw, serial larger oscillating saws
are used to deepen osteotomy. If ostectomy
is done with full thickness, the bone segment
moves freely.
8. After ostectomy, the attachment of muscle to
the medial part of the mandible usually
remains. A large elevator or Bovie electrocautery is used to divide any remaining
medial pterygoid muscle bers from the
medial surface of the osteotomized segment,
allowing its removal.
9. If bony step is under-resected, it can be palpated over the skin and even can be seen. So,
the remained bony step should be trimmed
until achieving smooth transition from
geniosegment to contoured mandible by
rasping or additional osteotomy with oscillating saw.
10. A high-speed bur is used to reduce thickness
of mandible cortex and achieve overall
smooth contour. When using bur, it is impor-
tant to avoid soft tissue damage because
damage by bur is disastrous and cannot be
forgiven. If the operating space is too narrow,
surgeon should use retractors effectively to
obtain enough space to work with bur.
11. Before wound closure, massive irrigation
with normal saline is recommended to
remove any bone debris and to prevent
infection.
12. After meticulous hemostasis with bipolar
electrocautery, wound closure begins with
periosteum approximation. It is important to
approximate mentalis muscle to proper position to avoid chin ptosis or irregular muscle
contraction, resulting in multiple folding of
skin over the anterior chin.
10.5 Key Technical Points
1. In genioplasty, horizontal osteotomy line
should be lower than the level of inferior alveolar canal. Surgeon must conrm the course
of inferior alveolar canal in panoramic cephalogram and computed tomography because
there are variations by individual.
2. The osteotomy line of mandible contouring
should be convex rather than straight or concave. If the osteotomy line from anterior end
to posterior end is too straight or concave, the
soft tissue appearance will be unnatural after
few months later.
3. It is very important to avoid over-resection
of the bony step at anterior end of osteotomy. Because if the bony step is overresected, it may cause further bony
resorption and soft tissue depression that
can cause unnatural pear-shaped appearance around the chin.
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10.6 Case Study
Case 1
A 22-year-old woman complained about her broad lower face. Her lower facial contour was at
which, in combination with her wide mandibular body, made her face appear broad and
U-shaped. Narrowing of the chin with reduction of the mandibular body made her chin appear
slender, and her overall lower facial morphology converted from U-shaped to V-shaped
(Figs.10.5 and 10.6).
Fig. 10.5 (Case 1)
Preoperative (above) and
6-month postoperative
views (below) of a
22-year-old patient who
had a U-shaped face and
at chin border
S. Park
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10 The V-Line Surgery: Narrowing Genioplasty withMandible Reduction
Fig. 10.6 (Case 1) Preoperative radiograph (above). Follow-up radiograph 6months after surgery (below)
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Case 2
A 29-year-old woman had a heavy lower face, soft-tissue fullness of the chin, and masculine
features. She desired slimming of the lower face and a more feminine appearance, with a pointed
chin. Narrowing genioplasty was performed followed by an additional resection of the lower
mandibular border to the angle. To create this new shape, soft tissue of the chin was released in
this case and properly redraped to reduce bunching (Fig.10.7). The patient was very satised
with the result.
Fig. 10.7 (Case 2)
Preoperative (above) and
6-month postoperative
views (below) of a
29-year-old woman who
had a heavy lower face,
soft-tissue fullness of
the chin, and masculine
features
S. Park
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10 The V-Line Surgery: Narrowing Genioplasty withMandible Reduction
99
10.7 Complications
andManagement
10.7.1 Neurosensory Decits
Neurosensory loss in the lower lip is a common,
yet typically transient, complication following
genioplasty. Studies on neurosensory changes
post-genioplasty indicate that temporary paresthesia occurs in about 12% to 70% of cases [12,
13]. Despite the wide range, these studies consis-
tently report that such temporary conditions
rarely result in permanent numbness, rendering
the risks for long-term decits negligible. Often,
these transient neurosensory decits are attributed to neurapraxia of the mental nerve during
surgical retraction. This kind of complication can
be reduced by minimizing dissection and exposure near the mental foramen. Moreover, osteotomies positioned too close to the mental foramen
elevate the risk of nerve injury. Surgeons must
therefore be particularly mindful of the mandibular canal’s course, especially near the mental
foramen. In more complex genioplasty procedures, where bone resection occurs near the mental foramen, the incidence of neurosensory issues
may be higher. This is due to the heightened risk
of direct injury to both the cutaneous and intramandibular courses of the mental nerve.
10.7.2 Hemorrhage
Hemorrhages or hematomas in the oor of the
mouth are mostly minor and tend to resolve on
their own. The bleeding typically originates from
the exposed cancellous bone or surrounding soft
tissue, with an increased risk in patients prone to
bleeding or those with hypertension. To mitigate
the risk of hemorrhage, it is crucial to ensure
meticulous hemostasis of both the soft tissues
and bone during surgery.
However, in the context of genioplasty and
mandibular reduction surgery, hemorrhage can
become a serious, life-threatening complication.
This is primarily due to the risk of airway obstruction caused by a hematoma expanding into the
oor of the mouth, which can elevate the tongue.
In these instances, the source of bleeding is usually direct injury to small vessels, particularly
arterioles. If a patient exhibits signs of dyspnea,
carefully opening sutures to decompress the airway may be necessary. However, this must be
done with caution to avoid exacerbating the situation with a sudden rush of blood, which could
potentially lead to asphyxia. In cases of rapidly
expanding hematomas, immediate airway management is imperative. This may involve the use
of a nasopharyngeal airway or, in some cases,
more advanced interventions.
10.7.3 Unsatisfactory Chin Shape
The occurrence of an overly sharp chin shape
after surgery highlights the importance of thorough preoperative consultations. During these
discussions, surgeons should clearly explain the
various shapes and degrees of chin narrowness
and sharpness, as well as how these factors interplay with the overall mandibular structure. It’s
crucial to reach a consensus that aligns the
patient’s preferences with the surgeon’s plan.
While rare, excessively sharp chins may necessitate corrective surgery. However, additional bone
grafting to the central portion of the chin is challenging. Vertical reduction of the chin can mitigate sharpness by decreasing its height. Releasing
soft tissue around the distal bone segments can
also help soften the chin’s sharpness by subtly
increasing its width. Another viable option is free
fat injection, which can adjust the chin’s contour
and soften its appearance.
10.7.4 Double Contour
inGeniomandibular Junction
Double contouring or depression at the geniomandibular junction, which some patients experience after genioplasty or mandible contouring, is
often caused by a bony step between the lateral
edge of the distal geniosegment and the medial
edge of mandible contouring. This can result
from surgical technical errors or excessive narrowing of the chin, leaving insufcient space for
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100
S. Park
contouring the mandible’s medial edge without
risking injury to the inferior alveolar nerve.
In addition to excessive narrowing of chin,
excessive ostectomy on the distal portion of the
proximal segment in mandible contouring can
create a double contour due to a bony gap. Since
it is very difcult to correct this deformity, it is
recommended not to over-resect the distal portion of the proximal segment, and if needed,
additional rasping can be performed to reduce the
remaining edge.
Soft tissue damage around the lateral aspect of
the geniosegment during the procedure can also
lead to thinning of soft tissue and subsequent
adhesion, contributing to the appearance of double contouring. In cases where double contouring
is due to a bony step, it can be corrected by augmentation with fat graft or alloplastic materials
such as silicone, Gore-Tex, and MEDPOR.If the
cause is soft tissue adhesion, releasing the adhesion can improve the appearance. The author
often uses layers of Gore-Tex to camouage bony
gaps or depressed soft tissue. However, if the
double contouring results from soft tissue sagging, especially from the cheek along the mandibular border during post-surgical recovery,
laser-assisted liposuction and lifting procedures
are recommended. These procedures, detailed in
another chapter (Chap. 15), can effectively
address the sagging and improve the contour.
10.8 Discussion
The decision whether to just reducing mandible
or to performing V-line surgery is difcult for
both patients and surgeons. First of all, surgeons
should differentiate the patients whose chin must
be corrected. If chin is too wide, short or long, or
retrogenia or progenia, concomitant genioplasty
is recommended in mandible reduction surgery.
If geniomandibular junction is at to concave,
mandible angle reduction alone can improve
overall lower facial line. So this is a relative indication of V-line surgery. If patients request more
slender chin shape according to their preference,
it is also a relative indication. Overall facial har-
mony regarding the width–height ratio is an
important consideration.
Performing a central strip chin osteotomy,
which involves a horizontal cut and two vertical
cuts, is a straightforward and safe procedure for
surgeons with basic craniofacial surgical skills.
However, precision is key. Inaccurate execution
can lead to misalignment of the bone edges,
resulting in suboptimal bone union. Therefore,
for surgeons who are not fully experienced in this
technique, it’s advisable to avoid creating multiple pieces, overly small segments, or asymmetric
shapes during the osteotomy. Ensuring accurate
alignment and stability of the bone segments is
crucial for optimal healing and achieving the
desired aesthetic outcome.
The amount of central resection should be
individualized depending on the width of the chin
and the patient’s need. In our practice, it ranged
from 4 to 14mm. Resection is usually symmetric
in width and shape. However, in case of asymmetry, the center of the strip was lateralized to the
more prominent side. The design of central strip
resection can also be altered from rectangular to
trapezoidal and made to modify the shape of the
chin narrower. Advancement or setback of the
chin is also possible if a change of prole is
required.
Creating a smooth transition from the genioplasty segment to the lateral contouring part,
without leaving any bony step-off or protuberance, is a challenging aspect of the combined
genioplasty and mandibular contouring procedure. In some cases, patients with fatty faces and
chins have reported immediate postoperative
issues with soft-tissue bunching. However, this
complication tends to resolve over time. Partial
dissection and redraping of the soft tissue attachments around the chin area have proven effective
in mitigating these issues and enhancing the
overall outcome of the procedure.
References
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