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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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8 The Basic Principles inOsseous Genioplasty
Fig. 8.2 Proportionate analysis of the chin. (a) The aesthetic facial proportion of 1:1:0.8. (b) In microgenia, the lower
face is vertically decient. (c) In retrogenia, the proportions may be the same as in a normal ideal face
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is small horizontally or vertically or even in combinations. If the chin is positioned posterior to its
ideal position whether it is small or not, the term
“retrogenia” is used. However, retrogenia secondary to mandibular retrognathia can be called
as “pseudoretrogenia.” In “macrogenia,” the chin
is large in horizontal or vertical planes or even in
both planes. Large chin caused by soft tissues
alone can be termed as “pseudomacrogenia.”
Long-face deformity producing clockwise rotation of a normal mandible may cause “pseudomicrogenia.” These classications of chin
dysmorphology can be useful to guide the appropriate surgical approach to the surgeon.
The height of the lower face is important when
evaluating the chin and selecting the appropriate
surgical approach. For instance, if a patient has a
short lower face, there may be a need to elongate
the chin. Conversely, a long lower face might
require shortening procedures to achieve a balanced appearance. This assessment is typically
conducted through a proportionate analysis,
dividing the face using specic anatomic landmarks. These landmarks include the trichion (the
hairline’s starting point), glabella (the point
between the eyebrows), subnasale (the area just
under the nose), and menton (the lowest point of
the chin). By utilizing these reference points, the
face can be divided into three distinct parts.
Traditionally, it has been considered ideal when
these three divisions of the face are of equal
length, constituting equal thirds [4]. However,
particularly in the context of Asian facial aesthetics, the ideal proportion has evolved, and a ratio
of 1:1:0.8 is increasingly viewed as more aesthetically pleasing. This shift reects a nuanced
understanding of facial harmony and beauty ideals, acknowledging the diversity in aesthetic preferences across different populations and cultures
(Fig.8.2).
Various analyzing methods were introduced to
assess the facial prole, which the surgeon can
use as a guide in evaluating the chin relative to
the overall face, nose, and lips. For example, in
the McNamara analysis, a line perpendicular to
the Frankfort horizontal plane is drawn through
the nasion, and the distance from the pogonion to
the line is assessed (Fig.8.3). The Arnett analysis
is for soft tissue cephalometric analysis. Distance
is measured between the soft tissue pogonion and
a line placed through the subnasale perpendicular
to the natural horizontal head position called the
“true vertical line (TVL)” (Fig.8.3) [5]. Another
method to analyze the chin position is by assessing the projection of pogonion from the N to B
line (cephalometric line from nasion to B point)
[6]. The authors nd the McNamara analysis and
the Arnett analysis quite useful.
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Fig. 8.3 Prole analysis of the chin. (a) In the McNamara
analysis, a line perpendicular to the Frankfort horizontal
plane (line 1) is dropped through the nasion (line 2, nasion
perpendicular line). (b) In the Arnett soft tissue cephalo-
8.4 Surgical Technique
Operations are performed under general anesthesia through orotracheal intubation. Local anesthesia solution containing 1% lidocaine and 1:100,000
epinephrine is inltrated along the proposed incision line and dissection area, submucosally and
also subperiosteally. A labial incision midway
between the labial sulcus and the lower lip vermilion is made from the canine to the opposite canine,
avoiding division of the frenulum. Subperiosteal
dissection is then performed to expose the midsymphyseal region. The dissection should not be
done to totally deglove the inferior border of the
mandible which may disturb blood supply to the
bone segment. Great care should be taken to identify the mental nerves and to protect them during
dissection. Dissection should be performed sufciently posterior for adequate visualization and
access for the osteotomy [1].
metric analysis, a line perpendicular to the natural horizontal head position is dropped through the subnasale
(true vertical line)
After dissection is completed, the symphyseal
midline should be marked above and below the
planned osteotomy. The osteotomy line should be
designed at least 5 mm below the mental foramen, and the horizontality of the line should be
double-checked. Then the osteotomy is completed with a reciprocating saw. As the distal
bone segment gains mobility to allow manipulation, the segment should be advanced or set
backed as planned according to preoperative prole analysis and rigidly xed with plates and
screws (Fig.8.4) [7].
Meanwhile, a reduction or lengthening genioplasty can be performed to correct the chin deformity either with vertical excess or shortness.
Usually when chin shortening is needed by a vertical reduction procedure, a horizontally parallel
bone segment is removed from the chin (Fig.8.5).
After a reduction genioplasty, an additional marginal osteotomy or shaving is required as a step
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8 The Basic Principles inOsseous Genioplasty
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Fig. 8.4 Operative procedures of genioplasty. (a) Labial
incision is made at least 5–6 mm inferior to the sulcus
avoiding division of the frenulum. (b) The mandible is
exposed below the mental foramen and lateral along the
inferior mandibular border. (c) Horizontal osteotomy is
made with a reciprocating saw. (d, e) Distal bone segment
is mobilized according to the preoperative plan. (f)
Fixation is done with plate and screws
c d
Fig. 8.5 Operative procedures of reduction genioplasty.
(a) Labial incision is done. (b) Mid-symphyseal exposure
and design of osteotomy line. Note that the shaded part is
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to be removed and the midline is marked. (c) Removal of
the middle bone segment. (d) Fixation is done with plate
and screws
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deformity can be noticed on each side of the chin.
The steps may be approached through the same
genioplasty incision with or without an exten-
The vertical height of the bony portion left in the
center is in accordance with the amount that the
chin is to be lengthened vertically (Fig.8.6).
sion, but an additional incision may be needed in
cases with large steps. When the patient has a
short lower face, a lengthening genioplasty may
be planned to achieve ideal facial proportions [8].
The osteotomy for the lengthening genioplasty
procedure contains a horizontal osteotomy with
two vertical osteotomies in an upside-down trapezoidal shape [8]. While designing the line for
the horizontal osteotomy, it is important to leave
a small amount of the bone in the middle portion.
Fig. 8.6 Operative
procedures of
lengthening genioplasty.
(Left) (a) A horizontal
osteotomy line and two
vertical osteotomy lines
are designed with a
small segment left in the
center. (b) Osteotomies
are carried out with a
reciprocating saw. (c)
After removing the
distal bone segment in
the midportion, the two
lateral bony segments
are approximated in the
center. (d) Bone
segments are xed with
a microplate and screws.
(Right) Illustration of
operative design. (e)
Bony design. (f) Central
bony segment is
removed. (g) Lateral
segment is
approximated. (h)
Fixation is done with
microplates
and to make a slim lower face, a narrowing genioplasty is indicated [9, 10]. Horizontal osteotomy
and two vertical osteotomies are designed as the
amount of resection in the middle bony segment
should be determined preoperatively. In cases
with asymmetry, the center of the middle segment should be lateralized to the more prominent
side. After the osteotomy is completed, the middle segment is removed, and the two lateral seg-
For correcting deformity of transverse excess
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8 The Basic Principles inOsseous Genioplasty
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Fig. 8.7 Operative procedures of narrowing genioplasty.
(a) A horizontal osteotomy line and two vertical osteotomy lines are designed. (b) Osteotomies are carried out
with a reciprocating saw. (c) After removing the middle
ments are xed in the center (Fig.8.7). To obtain
a more natural-looking and smooth curvature in
the lower border of the mandible, further osteotomy or shaving on the lateral steps is usually
required [10]. Resection of bony steps can be
extended to the mandible angle when performed
as a combination with the mandible contouring
procedure [11].
bone segment, the two lateral bony segments are xed
with a microplate and screws in the center. (d) Bone segments are removed during surgery
segment as postoperative stability is essential
for aesthetic renements.
2. During reduction genioplasty, the lower oste-
otomy should be done prior to upper osteotomy
in order not to lose control of the distal segment. Also, as surgeons tempt to reduce more
during the surgery, the chance of nerve injury
might increase. It is important not to jeopardize
the nerve in order to reduce more height [1].
3. The amount of lengthening during a lengthen-
8.5 Key Technical Points
ing genioplasty procedure is 2–3mm in most
cases [8]. Far exceeding this average may
1. When adjusting the genial segment in an
anteroposterior dimension, a pre-bent plate is
preferred to precisely control the amount of
advancement or setback (Fig.8.8) [7]. At least
two screws should be placed in each mobile
cause problems such as bone instability, extra
tension across the wound, lip tightness, lip
eversion, or mouth closure disturbance.
4. When planning the narrowing genioplasty
procedure, the amount to be narrowed depends
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on several factors such as the width of the
chin, patient’s desire, and the course of the
mandibular canal, usually ranging between 4
and 14mm [10].
5. Though easy to overlook, soft tissue control is
one of the most important factors when performing genioplasty. By using an absorbable
suture, the muscles and periosteum can be
pulled in an upward direction and xed to the
plate. Such procedures would avoid soft tissue
sagging and ptosis secondary to the bone
reduction [1].
6. After a genioplasty is completed for chin
advancement, vertical chin reduction, or chin
narrowing, the bony steps on each sides of the
chin-mandible junction may be troublesome.
In such cases, either shaving the steps with a
bone rasp through the genial incision or ostectomy with an oscillating saw through an additional lateral incision intraorally may be
required [7, 10].
Fig. 8.8 Pre-bent titanium plates used in genioplasty.
Plates are used for controlling the degree of anteroposterior adjustment during chin advancement or setback in
accordance with preoperative measures
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8 The Basic Principles inOsseous Genioplasty
8.6 Case Study
Case 1
A 20-year-old man has undergone advancement genioplasty to correct his weak- looking chin.
5mm were advanced and the retrogenia was signicantly improved. The patient was satised
with the result. Surgical results after 6 months were compared with preoperative views
(Fig.8.9).
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Fig. 8.9 Advancement genioplasty in a 20-year-old man. Chin was 5mm advanced. (Above) Preoperative
images. (Below) Postoperative images
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Case 2
A 28-year-old woman had setback genioplasty to correct the proles of her protruding chin.
The chin was retruded 2mm posteriorly and optimal proles were achieved. She was satised
with the surgical results. Postoperative views of 6 months after the surgery were shown
(Fig.8.10).
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Fig. 8.10 Setback genioplasty in a 28-year-old woman. Chin was setback 2mm with a concomitant narrowing
procedure. (Above) Preoperative images. (Below) Postoperative images
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8 The Basic Principles inOsseous Genioplasty
Case 3
A 42-year-old woman has undergone reduction genioplasty to reduce the vertical length of her
chin. Four millimeters were reduced vertically to achieve an optimal facial proportion. The
patient was pleased with the result, and the surgical results after 6 months were compared
(Fig.8.11).
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Fig. 8.11 Reduction genioplasty in a 42-year-old woman. Chin was vertically reduced 4 mm. (Above)
Preoperative images. (Below) Postoperative images
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Case 4
A 23-year-old woman underwent a lengthening genioplasty procedure to correct her short chin.
The lengthening genioplasty was combined with a narrowing procedure and a mandible angle
reduction surgery. Twelve millimeters of chin narrowing and 2mm of vertical lengthening were
performed (Fig.8.12).
Fig. 8.12 Lengthening
genioplasty in a
23-year-old woman.
Chin was lengthened
2mm with a
concomitant narrowing
procedure. (Left)
Preoperative images.
(Right) Postoperative
images
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