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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5207_Библиотеки_им_академика_М_И_Перельмана.pdf
208
S. Park
later resorption. In cases of severe hypoplasia
with Class III deformity, orthognathic surgery
may be necessary to achieve the desired
correction.
This chapter will focus primarily on the use of
alloplastic implants for maxillary augmentation,
exploring the techniques, considerations, and
outcomes associated with this specic approach
to midface enhancement.
21.3 Patient Assessment
andConsultation
Physical examination is indeed a fundamental
component of preoperative assessment and planning in aesthetic augmentation procedures.
Reviewing photographs with the patient is a valuable practice as it aids in discussing aesthetic
concerns and goals. It provides a visual reference
that can help both the patient and the surgeon to
align their expectations and objectives for the
procedure.
In most cases, especially involving a surgically altered or traumatically deformed skeleton,
imaging techniques such as cephalometric
X-rays and computed tomographic (CT) scans
are essential. These imaging modalities provide
a detailed view of the skeleton in different planes
and in three dimensions, which is crucial for
accurate preoperative planning and successful
surgical outcomes. They are particularly valuable in complex cases where standard physical
examination and photographic assessments may
not sufce. The decision to omit radiologic
assessments is typically based on the procedure’s
nature and the specic anatomical area involved.
In such cases, the size and position of the implant
are determined based on the surgeon’s aesthetic
judgment, guided by their experience and the
patient’s physical examination.
In patients requiring midface augmentation, it
is common to nd that their intermaxillary skeletal relationships and occlusion are within the
normal range. However, some patients may
exhibit a Class III relationship with hypoplastic
maxilla. The use of alloplastic implants in the
paranasal area can simulate the effects of a LeFort
I osteotomy.
Patients seeking midface augmentation often
have simple and limited midface hypoplasia and
are looking to add volume and restore facial balance. A depressed paranasal area can accentuate
the nasolabial fold, giving an aged appearance.
This condition is associated with various degrees
of Binder syndrome. Flat suborbital area is frequently accompanied with prominent malar eminence and may give at and square impression.
Additionally, a at and sunken suborbital rim can
give the illusion of proptosis (bulging eyes).
Augmentation of the pyriform aperture can effectively increase the projection of the nasal base
and open the nasolabial angle. This technique
also helps to lessen the depth of the nasolabial
fold by smoothing it out from below. Previous
zygomatic reduction also may alter the orbitalmalar relationship and worsens the look of
depressed maxilla.
Paranasal pyriform aperture augmentation
increases the projection of the nasal base and
opens the nasolabial angle. It also tends to lessen
the depth of the nasolabial fold by effacing it from
below. This procedure makes people look younger
and richer and this is the reason of its Korean
nickname, “nobility surgery”.
21.4 Surgical Techniques
1. Alloplastic augmentation of the midface can
be performed under either local anesthesia
with sedation or general anesthesia. When
implants are placed through intraoral
approaches, general anesthesia with endotracheal intubation assures protection of the airway in case of bleeding.
2. Intraoral sulcus incisions are used likewise
other facial bone contouring surgery. These
incisions should be made with a sufcient
labial cuff to allow watertight mucosal repair.
Because the implant is a foreign body, watertight closure is important to prevent possible
21 Alloplastic Modication oftheMidface
209
contamination and inammation around the
implant (Fig. 21.1).
3. The medial extent of the incision is made just
lateral to the pyriform aperture not to place
incisions directly over the implant. Suborbital
augmentation is done through an intraoral
incision from the canine to the second premolar about 1cm above the upper gingivolabial sulcus.
4. Subperiosteal dissection exposes the area to
be augmented. In paranasal augmentation,
the infraorbital nerve usually does not need
to be exposed or identied. The extent of dissection should t to the size of implant.
Overly wide dissection can cause unnecessary large dead space which may cause
seroma collection and infection, while too
narrow dissection can cause distortion of
implant.
5. The choice of appropriate size and thickness
of implant is the most important factor for
successful augmentation. It is helpful to
place temporary implants over the skin surface to check the size and contour (Figs. 21.1
and 21.2).
6. Final adjustments to the implant are crucial.
Using a scalpel or scissors, the implants are
precisely carved to t the augmentation area.
They are then thoroughly cleaned with
Betadine solution before being placed
through the intraoral incision. This process
ensures the implant is tailored to the specic
contours of the surgical site, enhancing both
the t and the aesthetic result.
7. The positioning of the implant is critical,
particularly in paranasal augmentation. If the
medial border of the implant is too distant
from the pyriform aperture, the augmentation effect may be insufcient, potentially
leading to unnatural demarcation.
Conversely, placing the implant over the pyriform aperture can negatively impact the
nasal airway and alter nostril shape.
Therefore, achieving a balance in implant
placement is key to both functional and aesthetic success.
8. In suborbital augmentation, the implant
placement requires careful consideration to
avoid the infraorbital nerve and to ensure
adequate augmentation. The placement must
be high enough to achieve the desired aesthetic effect but should avoid impinging on
the infraorbital nerve to maintain midface
sensation (Figs. 21.3 and 21.4).
9. Before securing the implant with screws, it’s
advisable to manually check the effect of
augmentation and symmetry by both visual
inspection and palpation. Generally, a minimum of two-point xation with screws is
recommended. This prevents implant rotation and ensures predictable outcomes. Care
should be taken to avoid the root of the
canine during screw placement.
10. Meticulous attention to hemostasis is necessary, as even a small amount of hematoma
can lead to infection around the implants.
Extensive irrigation with Betadine and saline
solution is recommended to minimize this
risk. Finally, the wound should be closed in a
watertight manner using 4-0 Vicryl sutures to
prevent potential complications and promote
optimal healing.
210
a b
ab
S. Park
Fig. 21.1 Paranasal augmentation. Note that intraoral
incision is made about 1cm above the upper gingivolabial
sulcus. Subperiosteal dissection exposes the area to be
augmented. The infraorbital nerve should be preserved.
Fig. 21.2 Implants for paranasal augmentation. The
implants used in ID hospital are shown. It is made of silicon, triangular shape with concave medial side to t to
Two points xation with screws are recommended to prevent rotation of implant. The root of the canine should be
avoided when the implant is immobilized with screws
pyriform aperture. The thickness of implants ranges from
2 to 6mm
ab
a b
21 Alloplastic Modication oftheMidface
211
Fig. 21.3 Suborbital augmentation. (a) Note that the
infraorbital nerve should be identied and preserved during the subperiosteal dissection. To avoid irritation or
compression to the infraorbital nerve, the superior border
of the implant should be trimmed. The posterior surface of
implant should be carved to obliterate the dead space
above the anterior surface of the zygoma. Implants are
xed with titanium screws in two points for immobilization. (b) Implants may be positioned on zygomatic body
to augment the maximum malar projection
Fig. 21.4 Implants for suborbital augmentation. The
implants used in ID hospital are shown. It is also made of
silicon like paranasal implants. Unlike the paranasal
implants, the shape is ovoid to rectangular with round border. The thickness of implants ranges from 2 to 6mm
212
S. Park
21.5 Key Technical Points
1. The success of facial augmentation largely
hinges on the appropriate selection and placement of implants. The right choice of implant
in terms of size, shape, and material, as well
as its accurate positioning, is essential to
achieving the desired aesthetic outcome and
ensuring the long-term stability of the implant.
2. The dissection should be sufcient to accommodate the implant without undue force or
distortion, yet not so extensive that it creates
unnecessary trauma or potential spaces that
might contribute to complications such as
seroma formation.
3. The use of two-point screw xation for immobilizing implants is a widely accepted prac-
tice. This technique provides stable
positioning of the implants, reducing the risk
of postoperative displacement or rotation,
which are critical for both the short-term
recovery and the long-term success of the
augmentation procedure.
4. Maintaining a clean operative eld and ensuring effective bleeding control are crucial in
preventing postoperative infections. Infection
remains one of the most signicant complications in implant surgery and can jeopardize
the outcome. Strict adherence to aseptic techniques, careful hemostasis, and perhaps the
use of prophylactic antibiotics are standard
practices to mitigate this risk.
abc
21 Alloplastic Modication oftheMidface
21.6 Case Study
Case 1
A 25-year-old man was planned for the malar reduction and V-line surgery. But, he had depressed
paranasal area because of recessed pyriform aperture. Thus, paranasal augmentation is performed using silicon implants of 5 mm simultaneously with the malar reduction and V-line
surgery. At 2-month follow-up after surgery, the result was satisfactory for paranasal area to
give more convex appearance to midface (Fig.21.5).
213
de f
Fig. 21.5 Case 1. A 25-year-old man was performed
paranasal augmentation using silicon implants of
5 mm simultaneously with the malar reduction and
V-line surgery. At 2-month follow-up after surgery, the
result was satisfactory for paranasal area to give more
convex appearance to midface
214
Case 2
A 26-year-old woman was planned for the suborbital area augmentation simultaneously with
the malar reduction surgery. The prole was at to concave on midface, thus looked older than
her age. The thickness of silicon implant used was 4mm. At 2-month follow-up after surgery,
the prole view was improved at to convex, and she was satised with the result (Fig.21.6).
abc
S. Park
def
Fig. 21.6 Case 2. A 26-year-old woman was planned
for the suborbital area augmentation simultaneously
with the malar reduction surgery. The thickness of sili-
con implant used was 4 mm. At 2 month follow-up
after surgery, the prole view was improved at to
convex and she was satised with the result
21 Alloplastic Modication oftheMidface
215
21.7 Complications
andManagement
21.7.1 Infection
Infection risks are heightened in the presence of
a foreign body, such as an implant used in midface augmentation. This is attributed to the
reduced minimal infecting dose of bacteria like
Staphylococcus aureus, as demonstrated in animal models. The impaired bacterial clearance
around the implant exacerbates this risk. When
microorganisms linger on an implant’s surface,
they adhere through nonspecic physical forces
and eventually form biolms. These biolms,
consisting of bacteria clustered within an extracellular matrix, adhere to the implant and effectively shield the bacteria from the host’s
immune defenses and antibiotics. Due to the
resilience of these biolms, treating implantrelated infections with antibiotics alone often
proves ineffective. Consequently, the standard
management of such infections typically
involves the removal of the implant, coupled
with antibiotic therapy and diligent wound care.
This approach underscores the importance of
preventive measures and early intervention in
the case of suspected infection.
21.7.3 Migration ofImplant
This complication is relatively rare when a twopoint xation approach is applied to the implant.
However, migration can occur if the screws used
for xation become loosened, rendering the xation ineffective. Another contributing factor to
implant migration is excessively wide dissection
without adequate xation. If xation is not utilized, the dissection should be precisely tailored
to the implant’s dimensions to minimize the risk
of migration.
21.7.4 Asymmetry
Asymmetric contouring in facial implant surgeries is not classied as a complication but is often
considered a dissatisfactory outcome. It is, in
fact, the most frequent reason for subsequent
implant removal or repositioning procedures.
Therefore, surgeons must exercise considerable
care and precision in placing the implants symmetrically. To achieve this, it is recommended to
use direct visual assessment and palpation from
the surface of the skin to ensure symmetry before
proceeding with the nal immobilization of the
implants using screws.
21.7.2 Sensory Disturbance
Sensory disturbance following alloplastic midface augmentation often results from the compression of the infraorbital nerve by the inserted
implant. Persistent symptoms of paresthesia
beyond 1day warrant serious consideration for
immediate removal of the implant to avert permanent nerve damage. This issue is most likely due
to the mobilization of the implant after soft tissue
closure. Therefore, careful visualization of the
infraorbital nerve both before and after implant
placement, coupled with secure xation using
screws, is crucial in preventing such sensory
disturbances.
21.8 Discussion
The use of alloplastic implants for facial skeletal
contour restoration and improvement dates back
to the 1960s and 1970s. During this period, surgeons began employing materials like Silastic
sponges and solid polyethylene to reconstruct
post-traumatic, post-ablative, and congenital
defects. In the subsequent decades, particularly
the 1970s and 1980s, the new era began with the
potential of using alloplastic materials for aesthetic facial enhancement. Surgeons developed
techniques utilizing remote incisions to place
biocompatible materials under well-vascularized
216
S. Park
soft tissues, thus reliably altering the contours of
the facial skeleton.
The primary materials used for skeletal augmentation of the midface include silicone and
porous polyethylene. Silicone implants offer several advantages: they are easy to sterilize (by
steam or irradiation), can be shaped with scissors
or a scalpel, and can be secured with screws or
sutures. Clinically, silicone implants are welltolerated with no known allergic reactions. Their
smooth surface prevents soft tissue ingrowth,
facilitating easy removal if necessary. However,
disadvantages of silicone implants include the
potential for underlying bone resorption, the risk
of migration if not adequately xed, and the possibility of visibility of their brous capsule in
cases of thin soft tissue coverage.
Polyethylene, a simple carbon chain polymer
of ethylene monomer, is used in facial implants
with a porosity ranging between 125 and 250μm.
This porosity allows for brous tissue integration
into the implant’s surface. The advantages of this
integration include reduced implant migration
and less likelihood of eroding the underlying
bone. The porous nature also provides some exibility and adaptability to the implant. However,
these features come with drawbacks: the soft tissue ingrowth makes removal of the implant more
challenging and infection more vulnerable.
21.8.1 Hard Implant Versus Soft
Tissue Augmentation
Midfacial augmentation is often necessitated by
either soft tissue or skeletal deciencies, each
requiring a tailored approach. For issues stemming from soft tissue, techniques such as autogenous fat grafting or the use of various soft tissue
llers are effective. These methods address volume loss typically associated with aging, like
senile atrophy or sagging. Fat injection can easily
restore cheek volume. However, these techniques
have limitations, particularly when addressing
skeletal issues, due to restricted volume capacity
and resorption over time.
On the other hand, skeletal augmentation
using alloplastic implants offers a more predict-
able and lasting solution for enhancing the contours of a hypoplastic midfacial skeleton. While
bony resorption underneath the implant can
occur, its impact is generally minor in the midface compared to areas like the chin. While soft
tissue augmentation is useful for addressing volume decits due to soft tissue problems, alloplastic implants are more suited for providing
structural enhancement and addressing skeletal
insufciencies in the midface.
21.8.2 Host-Implant Interaction
Autogenous bone grafts, despite their long history of use, are characterized by varying degrees
of remodeling post-revascularization, leading to
changes in volume and shape. This unpredictability in the nal shape and volume makes them
less suitable for aesthetic midface augmentation
purposes, where precise outcomes are often
desired.
For skeletal augmentation of the midface, the
biocompatibility of the implant material is paramount. There should be an acceptable interaction
between the implant material and the host tissue.
Alloplastic implants, which are typically not broken down enzymatically by the host, maintain
their volume and shape over time. The body’s
response to these implants involves forming a
brous capsule around them, effectively isolating
the implant from the surrounding tissues.
The surface characteristics of the implant are
crucial in determining the nature of this encapsulation. Smooth-surfaced implants tend to result in
a smooth-walled capsule. In contrast, porous
implants allow for varying degrees of soft tissue
integration, leading to a capsule that is less dense
and less well-dened. This difference in capsule
formation can inuence the long-term stability
and integration of the implant, as well as its interaction with the surrounding tissue.
21.8.3 Immobilization
For facial implants, ensuring proper immobilization is crucial. Many surgeons opt to stabilize
21 Alloplastic Modication oftheMidface
217
the implant’s position by suturing it to the surrounding soft tissues or using temporary transcutaneous pullout sutures. However, for midface
augmentation, screw xation of the implant to
the underlying skeleton is highly recommended.
This method of xation effectively prevents any
movement of the implant and ensures its close
adaptation to the bone surface.
The benets of screw xation are twofold.
Firstly, it eliminates the possibility of implant
movement, which is essential for maintaining the
desired aesthetic outcome and ensuring the stability of the implant. Secondly, screw xation
helps to eliminate any gaps between the implant
and the native skeleton. These gaps can lead to an
unintended increase in augmentation and serve as
potential spaces for the formation of hematoma
or seroma, both of which can complicate the
postoperative course.
Implant failure due to breakage or tearing of
the implant should be meticulously avoided while
using screw. This can be achieved through direct
visualization during the surgical procedure,
ensuring the implant is handled and positioned
correctly without undue stress or distortion. The
careful handling and secure xation of implants
are key steps in achieving successful outcomes in
facial augmentation surgeries.
References
1. Yaremchuk MJ. Skeletal augmentation. In: Neligan
PC, editor. Plastic surgery, vol. 2. 3rd ed. Seattle:
Elsevier Saunders; 2012. p.339.
2. Yaremchuk MJ, Israeli D. Paranasal implants –
correct midface concavity. Plast Reconstr Surg.
1998;102:1676–84.